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3 Mission Readiness and Cost Assessment INTRODUCTION AND OVERVIEW The ârealism of preliminary technology and management plans, and cost estimatesâ is a primary assessment criterion called for in the statement of task for this study (see Appendix B). The assessment of the five Beyond Einstein mission areas against this criterion is necessarily comparative. Two specific criteria are used for the assess- ment: mission readiness and cost. The Committee on NASAâs Beyond Einstein Program assessed mission readiness in terms of the technical and management readiness challenges faced by the five Beyond Einstein mission areas. Technical readiness elements include the instrument, spacecraft, operations, and technical margins. Management readiness elements include team organization, schedule, and other special challenges. The committee has attempted to assess the relative readiness of each candidate mission to proceed into mission development in fiscal year (FY) 2009. While a number of mission requirements and system design parameters were provided to the committee, the assessment was focused on those most germane to mission technical readiness. The cost assessment was done through an independent estimation of the probable cost. For purposes of this study, âmission developmentâ is defined as that point when the mission sponsor(s) commits to commence funding of the mission with the intent to proceed to flight. Technology readiness is a key consideration in the decision to proceed to mission development and, therefore, was a primary concern in the committee assessment of mission readiness. Ideally, mission development should not commence until all new technologies necessary for mission success have reached a Technology Readiness Level (TRL) of at least 6 (see the definitions of TRL levels given in the subsection below entitled âTechnology Readiness and Degree of Dif- ficultyâ). Experience has shown that NASA and other missions pay the price when a mission enters development prematurely. In 2007, the National Research Council (NRC) recommended that âto enable an accurate assessment of science success and overall life-cycle costs, NASA should, in presenting potential missions to future survey committees, also distinguish between projects that are ready for implementation and those that require significant concept design or technology investment.â The terms âmargins,â âallocations,â âreserves,â and âcontingenciesâ are used consistent with definitions in recent announcements of op- â portunity, such as: âNASA Announcement of Opportunity, Mars Scout 2006 and Missions of Opportunity, May 1, 2006, Appendix B, Section G, #13.â National Research Council, A Performance Assessment of NASAâs Astrophysics Program, The National Academies Press, Washington, â D.C., 2007, p. 42. 66
MISSION READINESS AND COST ASSESSMENT 67 Unless otherwise cited, the information presented herein and the assessments of the committee were based on information supplied by the candidate mission teams in response to the committeeâs Request for Information (RFI) (see Appendix E) and the subsequent written answers provided in response to additional questions from the committee. Disparity of Scale and Maturity The five Beyond Einstein mission areas include two, Constellation-X (Con-X) and Laser Interferometer Space Antenna (LISA), that are of the scale of a Great Observatory, have a single mission concept, and were funded at the multimillion-dollar level over a number of years prior to the initiation of the study. The three probe mission areas, Black Hole Finder Probe (BHFP), Joint Dark Energy Mission (JDEM), and Inflation Probe (IP), are about one-third to one-half the scale of the other two. Each has multiple mission concepts and was funded at a variety of levels and over various time frames. Most of them received NASA funding of only $200,000 over 2 years, although one of the JDEM missions, Supernova Acceleration Probe (SNAP), has had substantial time and funding invested in its definition by the Department of Energy (DOE). This disparity of scale and maturity among the five mission areas is a fact that cannot be ignored in the assessment and is the key reason that the assessment must be comparative. Indeed, to try to normalize the missions in order to judge them against an absolute scale would mask the very information needed for a realistic assessment. The spacecraft bus or particular spacecraft components are included in some of the instrument technology tables because the mission team included them it its technology listings. The committee decided to keep the same lists as those of the mission teams. In a few cases there was insufficient information to do a complete assessment of a particular mission concept within a mission area. Technology Readiness and Degree of Difficulty As part of the technical readiness assessment, the standard NASA definitions of TRLs were used in the assess- ments (see the list of definitions below). TRL definitions are open to some interpretation and are often interpreted differently by different people (e.g., by technology or project personnel versus independent assessors). Because TRL overestimation has led to schedule and cost issues for many space programs in the past, the definitions were applied rigorously and conservatively in this assessment. That is, if there was any uncertainty in the assignment, the committee selected the more conservative (lower) TRL level or assigned a range (e.g., TRL 3-4). The normal NASA standard is that a TRL of 6 or higher should be achieved prior to proceeding into development. The sim- plified definitions of TRLs that the committee used are as follows: TRL 1. Basic principles observed and reported. TRL 2. Technology concept and/or application formulated. TRL 3. Analytical and experimental critical function and/or characteristic proof-of-concept completed. TRL 4. Component and/or breadboard validated in laboratory environment. TRL 5. Component and/or breadboard validated in relevant environment. TRL 6. System/subsystem model or prototype demonstrated in a relevant environment (ground or space). TRL 7. System prototype demonstrated in a space environment. TRL 8. Actual system completed and âflight-qualifiedâ through test and demonstration (ground or flight). TRL 9. Actual system âflight-provenâ through successful mission operations. NASA, NASA System Engineering Processes and Requirements, NPR 7123.1A, March 26, 2007. Available at http:\\nodis3.gsfc.nasa. â gov. Ibid. â
68 NASAâS BEYOND EINSTEIN PROGRAM For the degree of difficulty (DoD) of achieving at least TRL 6 prior to development, the committee used the five-level scheme used in past NASA literature (see below)., DoD estimates (not required from the mission teams) are also somewhat subjective. Again, the ratings assigned in this document are the best estimates of experienced technology developers working with information supplied by the candidate mission teams. Initial estimates were discussed with the full committee at the third committee meeting (see Appendix D), and were revised on the basis of the committee membersâ inputs and the latest inputs from the mission teams. As with the TRL estimates, the DoD ratings are considered to be conservative. The DoD definitions used in this assessment are as follows: âââI. Very low degree of difficulty anticipated in achieving research and development (R&D) objectives for this technology; only a single, short-duration technological approach needed to be assured of a high prob- ability of success in achieving technical objectives in later systems applications. â II. oderate degree of difficulty anticipated in achieving R&D objectives for this technology; a single tech- M nological approach needed; conducted early to allow an alternate approach to be pursued to be assured of a high probability of success in achieving technical objectives in later systems applications. III. High degree of difficulty anticipated in achieving R&D objectives for this technology; two technological approaches needed; conducted early to allow an alternate subsystem approach to be pursued to be assured of a high probability of success in achieving technical objectives in later systems applications. IV. Very high degree of difficulty anticipated in achieving R&D objectives for this technology; multiple tech- nological approaches needed; conducted early to allow an alternate system concept to be pursued to be assured of a high probability of success in achieving technical objectives in later systems applications. â V. The degree of difficulty anticipated in achieving R&D objectives for this technology is so high that a fundamental breakthrough in physics, chemistry, and so on is needed; basic research in key areas needed before system concepts can be refined. Cost Assessment A schedule and cost assessment was performed to provide an understanding of each Beyond Einstein missionâs probable cost. The schedule assessment for each mission concept is contained in the individual discussions in the section below (âMission Readiness Assessmentsâ), while the cost assessments for each mission concept are given in the next major section (âMission Cost Assessmentsâ). Consistent methodologies were used to independently estimate cost and development time for the 11 Beyond Einstein mission concepts and to compare them with pre- vious missions of similar scope and complexity. In order to provide a realistic expectation of the cost range for various Beyond Einstein mission classes, the independent estimates and the mission teamâs own proposed plans were considered. The committee also assessed life-cycle costs and potential funding profiles against the available NASA Beyond Einstein funding wedge and non-NASA budget contributions as part of the considerations in making its recommendations. James Bilbro and Robert Sackheim, âManaging a Technology Development Program,â paper presented at the Workshop on Process for â Assessing Technology Maturity and Determining Requirements for Successful Infusion into Programs, September 2003. John C. Mankins, âResearch and Development Degree of Difficulty (R&D3)â White Paper, Advanced Projects Office, Office of Space Flight, â NASA Headquarters, Washington, D.C., March 10, 1998. NASAâs FY 2007 budget request projected NASAâs level of support for Beyond Einstein missions covering the years FY 2007 through â FY 2011. This projection begins to increase significantly in FY 2009 and continues to increase through FY 2010 and FY 2011. The projected increase is identified in the report as the âBeyond Einstein funding wedge.â
MISSION READINESS AND COST ASSESSMENT 69 MISSION READINESS ASSESSMENTS Black Hole Finder Probes CASTER Mission CASTER Technical Challenges: Instrumentâ There are multiple technology readiness issues with the Coded Ap- erture Survey Telescope for Energetic Radiation (CASTER), and it is clear that more technology development will have to occur on the detector, scintillators, coded aperture, and collimator shielding technique before the concept can be considered ready for mission development. Table 3.1 summarizes the CASTER technology readiness. The Burle Planacon tube has been selected as the readout sensor for CASTER and similar photo-multiplier tubes (PMTs) have been used many times in space applications. The CASTER design, however, is not flight-rated, and the CASTER Request for Information response states: âWe currently have no experience with this device.â An alternate (the Hamamatsu H8500) is available, and the mission team considered it, but the Burle Planacon was chosen because it has the potential to be more rugged. The CASTER RFI also states: âA program to fabricate and test . . . would raise the TRL of this device to 5 or perhaps 6,â but it does not appear that a concerted effort in this regard is in place. The CASTER design shows one of the Burle Planacon 8 Ã 8 detectors in each detector module, with 16 detector modules per âdetector tileâ and 9 or more detector tiles in the instrument. Based on these inputs, the detector TRL is rated as 2-3 and the DoD is rated as II-III. The mission team is pursuing more than one alternative. The description of the coded aperture mask states that âthe combined requirement of fine angular resolution, wide FoV, and broad energy range places severe requirements on the parameters of the coded mask. In the case of CASTER, the requirements are more challenging than those of any coded mask that has been used in space (e.g., SIGMA or Swift).â Shielding, opaqueness, and other issues will need to be resolved. Further, in order to achieve the required sensitivity, CASTER will require a very large number of detector modules and will present manufacturing problems similar to those encountered in Swift. In the absence of additional information on the coded mask, the committee estimates of TRL and DoD are 2-3 and II-III, respectively. The lanthium bromide (LaBr3) scintillators are similarly in an early state of development. The material has been fabricated and some environmental testing has been done. A significant effort will be required to bring LaBr 3-based scintillators to TRL 6 from the committeeâs current rating of TRL 2-3. The DoD for the scintillators is judged to be III, based on both the existence of a known issue to be resolved (e.g., internal background) and unknown issues that may surface as testing of this low-maturity technology is conducted. CASTER Technical Challenges: Spacecraftâ The CASTER observatory is extremely heavy and has a unique con- figuration, and the structure will present a serious technical challenge to design. In addition, little work has been done to date by any of the spacecraft contractors to accommodate the very large, very heavy CASTER instrument with the bus. The size, mass, long configuration, and associated high center of gravity location make it unclear that any currently available expendable launch vehicle (ELV) can accommodate the CASTER mission. Table 3.2 lists the requirements imposed on the spacecraft by the CASTER mission. CASTER Technical Challenges: Operationsâ In order to achieve the science goals discussed in Chapter 2, the spacecraft will primarily operate in a scanning mode. For CASTERâs nominal scanning mode, the spacecraft is zenith pointed and the large field of view (FOV) of the imager array will cover a significant fraction of the sky every orbit. To further maximize the sky coverage, the spacecraft pointing direction will be continuously scanned (at a low scan rate) in a direction perpendicular to the orbital plane. The offset will be on the order of Â±20Â°, with the spacecraft pointing direction moving either above or below the plane on successive orbits. The standard mode of instrument operation will be a mode in which individual processed events are transmitted to the ground. The telemetry stream in this case will also include housekeeping data and occasional raw event messages to monitor Mark McConnell, University of New Hampshire, âCASTER, A Candidate Concept for the Black Hole Finder Probe,â presentation to the â committee, January 30, 2007.
70 NASAâS BEYOND EINSTEIN PROGRAM TABLE 3.1â CASTER Technology Readiness Summary Heritage TRL DoD Changes from Previous Program Committee Committee Element Mission Similarity Mission/Comment Rating Rating Rating Detectors None known N/A Baseline approach identified: current 3 2-3 II-III and light laboratory prototype uses a Planacon sensors tube by Burle Industries. Alternative is a Hamamatsu flat panel PMT. Scintillator Some use in N/A Lanthanum bromide (LaBr3) scintillator 4 2-3 III medical industry, material has been developed and shows no known flight promise, but testing is in early stages. heritage Coded Swift, SIGMA Basic Smaller and thicker mask than Swift. Not 2-3 II-III aperture design Complex mask and program literature stated indicate that the mask pattern has not been specified. Collimator None known N/A Baseline design chosen and trade studies Not 2-3 II-III shield appear to be in early stages. stated NOTE: N/A, not applicable. Other acronyms are defined in Appendix G. instrument health. In addition, this mode will include spectral accumulations from the shield elements, at some commandable integration time. Upon the receipt of a burst trigger signal, the instrument will be placed into a special burst accumulation mode (which has not yet been defined). The onboard event processing will use raw events from a single module as input. The goal of the onboard processing will be to apply a camera imaging algorithm that reduces the 64 pulse-heights to an estimate of the location of the photon interaction site (x, y, and z). The mission team will be exploring various algorithms for high-rate processing of these data. One option is a neural-network-based algorithm. The mission teamâs experi- ence using neural network algorithms for the processing of event location data from the Compton Gamma Ray Observatoryâs Compton Telescope will be of benefit here. Events with multiple interaction sites require special attention. First, these events must be recognized as such. Then they must be processed to make a determination of where the first interaction site was likely to have been. In the case of multiple interactions, it is the first interaction site that is of interest and that would be used to specify the (x, y, z) location. Events with multiple interaction sites would be flagged in the event message. The CASTER operations are straightforward and not a significant challenge. The development of algorithms may be somewhat challenging, although the mission teamâs experience provides confidence that it will be done successfully. CASTER Technical Marginsâ The CASTER mission concept is still in an early conceptual stage, with only notional estimates for size, weight, power, and other performance parameters, making it difficult to thoroughly assess the margins of the proposed design. It is clear, however, that the CASTER mission will require a very heavy instru- ment and spacecraft. The CASTER teamâs current mass estimate totals 14,700 kg (13,740 kg [dry mass] + 960 kg [propellant]). Accommodating a spacecraft of this size to the desired orbit (500 km circular orbit at 0Â° inclination) will be challenging. As the orbit inclination increases, passage through the South Atlantic Anomaly (SAA) will both reduce the available observing time and introduce an increased level of background. Although SAA pas- sages are tolerable, the ideal orbit would be an equatorial orbit to eliminate the SAA passages and maximize the geomagnetic rigidity. An equatorial orbit also provides a low background for high-energy x-ray and gamma-ray missions. However, the proposed launch vehicle, a Delta IV-Heavy, cannot achieve this inclination. This launch
MISSION READINESS AND COST ASSESSMENT 71 TABLE 3.2â CASTER Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude Pointing About 1Â° control, about 5 arcmin knowledge No challenge determination and control Tracking 0.5 deg/min No known requirement Jitter/stability 1 deg/s No challenge Power Orbital 1,370 W, payload Drives array size average 550 W, spacecraft 480 W contingency Worst case 2,240 Wâtotal bus Array size Data storage â 6.4 GB (4 orbits) No challenge Structure Payload 8,950 kg Extremely large vehicle, very heavy launch Spacecraft 2,500 kg loads; only notional illustrations shown on arrangement of payload in spacecraft bus Contingency 2,290 kg Total 13,740 kg Margin 6,860 kg Thermal â Not specified Unknown Radio-frequency Downlink Average data rate: 2.2 Mbps Unknown if this rate is available communications 200 Mbps downlink via TRDSS Ka band Uplink Not specified Unknown Alignment â Not specified Unknown Propulsion Delta-V Required delta-v (velocity increment) is unknown; Unknown 800 kg propellant allocated in mass tables. NOTE: Acronyms are defined in Appendix G. vehicle would be able to reach an inclination of 15Â° with zero mass margin and could comfortably reach a 28Â° inclination with more than 50 percent margin. It is possible that a non-U.S. launch vehicle could have the capa- bility to launch CASTER into the desired orbit; however, the use of a non-U.S. launcher would require approval through an interagency policy coordination process. CASTER Management Challengesâ If selected, the CASTER team will be led by a principal investigator from the University of New Hampshire, with project management support from Southwest Research Institute (SwRI). Key team members are from Louisiana State University; the University of Alabama, Huntsville; the Los Alamos National Laboratory; and the University of California, Berkeley. This is a modest-sized team, and the management of the team itself presents no special problems. However, owing to the number and seriousness of issues associated with this mission, the technical management could be quite challenging. There is no known significant foreign contribution planned for CASTER, thus lessening International Traffic in Arms Regulations (ITAR) problems and eliminating the missionâs vulnerability to foreign government priority changes. The CASTER mission schedule shows launch 4.5 years after the preliminary design review (PDR), which is tight even if progress is made by the mission in raising the TRLs of the elements listed in Table 3.1. The critical path, predictably, is through the test program of the flight instrument. It was not possible to determine how much reserve is included in the proposed schedule. Completing the technology development and detector production activities will pose a significant schedule risk for the project.
72 NASAâS BEYOND EINSTEIN PROGRAM CASTER Unique Challengesâ Technology development related to the detector system and the huge mass and size of the assembled instrument are the main challenges to CASTER. EXIST Mission EXIST Technical Challenges: Instrumentâ The High Energy Telescope (HET) cadmium-zinc-telluride/applica- tion-specific integrated circuit (CZT/ASIC) and Low Energy Telescope (LET) silicon detector/readout electronics are not expected to be major engineering challenges for the Energetic X-ray Imaging Survey Telescope (EXIST) mission. Heritage from other programs exists, but the technology requirements are more complicated than what has been demonstrated in the past, and packaging the electronics will be challenging. Significant development work is being pursued, and a successful demonstration on the ProtoEXIST1 flight planned for 2008 should raise the TRL for the HET and demonstrate readout and postprocessing electronics for both the CZT and silicon (Si) detectors. There is still development work to be done to reach a full TRL of 4. The yield on 64 pixel ASICs has been about 40 percent, and it does not appear that a 256 pixel unit has been fabricated or tested. The HET array and processing are more complicated than what has been used in the past, but the heritage and the descriptions given of ongoing efforts suggest that the development effort will be reasonable, and the DoD is rated II. The LET Si hybrid pixel detector has heritage from other programs, but EXIST requires several departures from these ex- isting systems. The mission teamâs response to the committeeâs RFI notes that âsome development is underway through a separate NASA Phase 1 SBIR.â This indicates that the TRL is low, and the committee has assessed it at 3. The heritage suggests that the DoD should not be high (DoD = II). The LET electronics are similar to those of the HET, and a successful ProtoEXIST flight combined with ongoing development efforts should raise the TRL in 2008. The technology readiness for EXIST is illustrated in Table 3.3. TABLE 3.3â EXIST Technology Readiness Summary Heritage TRL DoD Changes from Previous Project Committee Committee Element Mission Similarities Mission/Comment Rating Rating Rating High-energy ProtoEXIST Basic design, Coded mask telescopes and shielding: 5-6 3-4 II detectors imagerâ materials components demonstrated in laboratory; (19 telescopes) balloon. the departure from the current state Swift/BAT of the art is minimal. Both Cd-Zn-Te (CZT) array and readout electronics are more complicated than proven systems. Planned ProtoEXIST flight in 2008 should raise TRL. Low-energy Commercial Unknown Uses Si detectors for the Low Energy 3 3 II detectors (32 product Telescope (LET). Larger pixels, telescopes) spectrographic readout of each pixel. Prototype developed under SBIR by Black Forrest Engineering. Coded- SIGMAâ Unknown 5 mm tungsten mask for the High <4 3 II-III aperture Russian Energy Telescope (HET). telescope INTEGRAL- New laminate required for pinhole ESA pattern. Shielding/anti- None Not Uses cesium iodide (CsI) scintillators <4 3 II coincidence applicable with PMTs and light pipes around CZT system detectors. NOTE: Acronyms are defined in Appendix G.
MISSION READINESS AND COST ASSESSMENT 73 The coded-aperture mask technology is based on prior work and requires a laminating technique. While this is relatively new, the technique has been demonstrated in the laboratory. The pinhole pattern and the actual laminate construction of the masks for the two types of telescopes will require significant development. Based on this, the committeeâs estimates of the coded-aperture mask technology are 3 and II-III, respectively. The shielding/anticoincidence system also presents a challenge. Both passive and active shielding will be used. The dimensions are large, and fabrication and packaging will present issues. While the current TRL is judged to be low (TRL = 3), no major obstacles are foreseen, and the DoD for the shielding is judged to be II. The manufacturing of the large number of subsystems will also be a challenge. In addition, the On-board Burst Alert system has to be developed and debugged. This system will be a driver to the spacecraft attitude determina- tion and control (AD&C) system. EXIST Technical Challenges: Spacecraftâ Spacecraft accommodation requirements for EXIST are listed in Table 3.4. EXIST Technical Challenges: Operationsâ EXIST is a full-sky imaging mission performing a survey in the 10-600 keV and the 3-30 keV energy range every 90 minutes. The HET and LET are composed of 19 and 32 TABLE 3.4â EXIST Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude determination and control Pointing 1 arcmin control No challenge 5 arcsec knowledge Tracking 15Â° nodding Unknown Jitter ~15Â° nodding scan No challenge Power Orbital average 1,912 W payload with 30% contingency Drives array size 957 W bus with 9% contingency 2,869 W with 22.1% contingency Worst case 1,912 W Array size Data Storage â 18 GB Cost Structure Payload 6,339 kg/20% contingency Size, cost Bus 2,451 kg dry mass Size, cost Total/margin 9,709 total wet mass/3,191, 32.7 on Atlas 551 Appears satisfactory; good margin but expensive expendable launch vehicle. Thermal â Not specified Unknown Radio-frequency communications Downlink 5 Mbps science data rate TDRSS access time 200 Mbps via TDRSS required. Uplink TDRSS No challenge Alignment â None No challenge Propulsion Delta-V 260 m/s for orbit maintenance and disposal. Mass, cost, safety Pressurized bipropellant design. NOTE: Acronyms are defined in Appendix G.
74 NASAâS BEYOND EINSTEIN PROGRAM subtelescopes, respectively, and each subtelescope of the HET and LET has 21Â° Ã 21Â° and 16Â° Ã 16Â° fully coded FOVs, respectively. The satellite is zenith-pointed with the fan beam perpendicular to the orbital direction, and the satellite executes a continuous sinusoidal ânoddingâ motion with amplitude +/â15Â° perpendicular to the orbital ram to dither the fan beam ends between the two orbital poles to cover the full sky during each orbit. The EXIST instruments handle and record each x-ray event one by one. The event data stream goes into two independent parallel processing channels: (1) the event collecting system and (2) the Fast On-board Burst Alert System (FOBAS). Both the HET and the LET perform these two processes independently. In the event collect- ing system, each valid event will be time-tagged and recorded. These data will be telemetered to ground by the Tracking and Data Relay Satellite System (TDRSS) Ku band (200 Mbps limit) with six contacts per day of about 6 minutes each. EXIST flight operations and data processing parallel the Swift mission experience. While this provides as- surance that EXIST flight operations and data processing are not particularly challenging, the higher data rates involved may make the onboard and ground processing more demanding. EXIST Technical Marginsâ The proposed EXIST spacecraft is in the conceptual stage, with some basic design trade studies completed. The EXIST mission concept appears to have good technical margins for size, weight, power, and other performance parameters, consistent with the maturity of the overall system concept. EXIST is a relatively heavy spacecraft (9,700 kg wet) and would ideally be flown in an equatorial orbit (0Â° inclination). However, because of the performance limits on available launch vehicles, the EXIST mission will be flown in a 20Â° inclination orbit. EXIST Management Challengesâ The EXIST team is led by a principal investigator at Harvard University and the Harvard-Smithsonian Center for Astrophysics and includes team members from Goddard Space Flight Cen- ter (GSFC); the University of California, San Diego; the University of California, Berkeley; Yale University; Cambridge University; Marshall Space Flight Center (MSFC); and many other institutions. It is expected that the management support will be from GSFC since it has been so deeply involved with EXIST for the past few years. There are no unusual project management challenges other then the schedule, as discussed below. The proposed schedule shows 4.25 years from PDR to launch. This is judged to be quite tight, given the extent of the detector-production effort and the roll-up of instrument assembly into an observatory. EXIST Unique Challengesâ The large weight of EXIST requires a large and expensive expendable launch vehicle. Mass reduction is a particular challenge that EXIST faces if it is to be affordable. Constellation X-Ray Observatory Con-X Technical Challenges: Instruments This subsection describes the technology readiness of the Con-X mission, with special consideration given to the readiness of the microcalorimeters and the x-ray optics. The Con-X team has had several years to develop these key technologies and as a result produced multiple breadboards and prototype units to use in quantifying performance and reducing risk. Table 3.5 is a summary of the Con-X technologies and their current state of de- velopment. There are multiple technologies with a TRL of 5 or lower that present challenges for the mission if it is to be ready to begin development in 2009. The length of the list is due in part to the thoroughness of the Con-X team, which has been careful to identify all new technologies necessary for the mission. The Con-X observatory employs two telescope systems: the Spectroscopic X-ray Telescope (SXT) and the Hard X-ray Telescope (HXT). The design of the Flight Mirror Assembly (FMA) optics used in the SXT is driven in large part by the need for large collecting area and high angular resolution. Key parameters of each of the four SXT optics are listed in Table 3.6.
MISSION READINESS AND COST ASSESSMENT 75 TABLE 3.5â Con-X Technology Readiness Summary Heritage TRL DoD Changes from Previous Project Committee Committee Element Mission Similarities Mission/Comment Rating Rating Rating SXT FMA Einstein, Wolter Type I optics, thin Combine angular resolution 4 3-4 II mirror ROSAT, mirror segments (ASCA, demonstrated by XMM- fabrication ASCA, Suzaku), mass production Newton with number of Chandra, (ASCA, Suzaku), mandrel mirror segments and a real XMM-Newton, fabrication (XMM- density demonstrated on HEFT, Newton), hundreds Suzaku and HEFT. Suzaku of co-aligned mirror segments (ASCA, Suzaku), moderate angular resolution (XMM- Newton), areal density (Suzaku, HEFT). SXT FMA Chandra Many more mirror Over 2,000 individual 3 3 III-IV mirror segments than Chandra segments to be aligned. assembly but alignment budget less Two methods being demanding. evaluated. XMS- XQC Microcalorimeter Increased pixel count, 4 4 II micro- suborbital technology, wafer multiplexed readout, calorimeter payload, processing, operating cryogen-free operation. Suzaku-XRS temperature, ADR technology, data processing. XMS-ADR XQC Same basic technologies Multistage ADR, passive 4-5 4-5 II suborbital as XRS-ADR. Con-X heat switches, somewhat payload, requires broader operating more complex control Suzaku-XRS range and increased algorithm. Multiple cooling capacity because component demonstrations of the larger arrays. completed. Continuous operation is anticipated. XMS-cryo Under Low vibration, minimum Possibly use 3He instead 5 4-5 II cooler development power. of 4He to achieve lower for JWST operating temperatures. Joint development effort with JWST and TPF: three alternatives being pursued. XGS- Sounding Basic fabrication Required technology 4 4 II grating rockets, techniques, alignment advances (line density, Einstein, tolerances, number of facet size) have been Exosat, grating elements, data demonstrated separately; Chandra, analysis. Both line a flight prototype is to be XMM-Newton density and facet size are developed and tested in increased compared to 2008. prior applications. continued
76 NASAâS BEYOND EINSTEIN PROGRAM TABLE 3.5â Continued Heritage TRL DoD Changes from Previous Project Committee Committee Element Mission Similarities Mission/Comment Rating Rating Rating XGS-CCDs ASCA, Number and size of basic Low-energy QE requires 4 3-4 II Chandra, fabrication processes, backside processing XMM-Newton, backside thinning, data different from that for prior Suzaku processing and analysis. devices. Modeling suggests that QE requirement can be met, but testing has not been performed. HXT-optics Swift, Highly nested, graded Basic processes 5 3-4 II InFocus, multilayer coated mirrors demonstrated, but not to HEFT, for 10-40 keV (InFocus, the requirements of Con- HERO HEFT). Electroformed X. Two processes being thin Ni shells (HERO, developed under funding Swift). Thermally formed outside of the Con-X segmented glass mirrors. program. HXT- Swift, Number and size of Improved shielding design 5.5 4 II detector InFocus, pixels, basic fabrication and fabrication. HEFT, processes, data processing HERO and analysis. NOTE: Acronyms are defined in Appendix G. TABLE 3.6â Key Parameters of Each Spectroscopic X-ray Telescope (SXT) Flight Mirror Assembly (FMA) Parameter Value Band pass 0.3-10 keV Angular resolution 12.5 arcsec half power diameter Effective area at 1.25 keV (on-axis) 4,610 cm2 Field of view â¥7 arcmin diameter Optical design Segmented Wolter I Diameter (largest/smallest mirror surface) 1.3 m/0.3 m Mirror segment material Thermally formed Schott Desag D263 glass Number of mirror segments per FMA 10 (outer); 5 (inner) Number of mirror pairs per module 97 (outer); 66 (inner) Largest mirror segment surface area 0.08 m2 The FMA consists of 15 modules: 5 identical inner modules subtending a 72Â° arc and 10 identical outer modules subtending a 36Â° arc. The complete FMA will contain 2,600 mirror segments. The mirror segments will be assembled from thermally formed glass substrates coated with an iridium reflecting surface. Fabrication of all of these mirror segments, verification of their optical performance, and proper mounting and alignment of the segments will be challenging. The mission team argues that the SXT design is based on materials that are highly reflective (iridium) and that the wedge mandrels are producible and readily procured. Mirror accommodation studies are on record going back to 2005 for launch on a single Delta IV Heavy and in 2006 for a single Atlas V. A mirror fabrication study was undertaken by Swales Corporation in March 2003. According to the mission team, the report concluded that
MISSION READINESS AND COST ASSESSMENT 77 TABLE 3.7â Key Studies Performed on the Spectroscopic X-ray Telescope (SXT) Flight Mirror Assembly Date Study Title Results 2003 Alternative mirror prescription Apparently concluded that the Wolter Type I design was the best for the mission. 2003 Impact of mirror focus correction Evaluated limits of allowable focus correction achieved by warping the thin mirrors on imaging performance to change their cone angle. Warping worked. March 2003 Fabrication study by Swales Concluded that the telescope could be built within the programâs allocated time. Corporation October Delta IV heavy mirror design Achieved comparable effective area performance with multiple mirror 2005 study configurations demonstrating the robustness of the design. August 2006 Off-axis mirror performance Designâs off-axis performance is acceptable. September Design for 3 and 4 SXT single Evaluated multiple three- and four-mirror designs, concluded that a four-mirror 2006 spacecraft Atlas V launch design could be accommodated on the Atlas V with the added advantage that fewer mandrels and mirror surfaces were required over the three-mirror configuration. TABLE 3.8â HXT Mirror Performance Requirements Parameter Value Band-pass 6-40 keV Effective area 150 cm2 Angular resolution 30 arcsec half power diameter âthe telescope could be built in the required time interval based on the mission level schedule.â In August 2006, a performance evaluation was conducted on the off-axis performance and found that there was little degradation in performance of the proposed design off-axis to meet a performance goal of 15 arcsec. Table 3.7 summarizes all of the studies and evaluations performed on the SXT. According to the mission team, the FMA defines the critical path of the project. The assembly will be de- signed, fabricated, and assembled by industry through a competitive procurement. Although a good deal of detailed planning for the FMA has been performed by the mission team, it is not obvious how much of this planning will transfer to the contractor that will be selected to produce the FMA. While the Con-X plan calls for involving the contractor in the final phase of technology development, procurement regulations could make this difficult. It is also unclear how well the considerable experience of the Con-X team in designing the FMA components will transfer to the selected contractor. The planned time for the development of the SXT FMA is stated to be approximately 3.5 years. The performance requirements for each of the two HXT mirrors are given in Table 3.8. According to information provided to the committee, the feasibility of imaging hard x-rays has been demon- strated by multiple balloon programs (e.g., International Focusing Optics Collaboration for micro-Crab Sensitivity [InFOCUS], High-Energy Replicated Optics [HERO], and High Energy Focusing Telescope [HEFT]). A technol- ogy readiness implementation plan was written in 2003 and updated after the decision was made to shift to the Atlas 5 ELV. An RFI was issued by the mission team in October 2006 for instrument concepts for a hard x-ray telescope. No other information was found in documentation provided to the committee on the Con-X teamâs plans for production of the HXT. Constellation X-Ray Observatory team response to the committeeâs Request for Information (see Appendix E in this report), January â 2007.
78 NASAâS BEYOND EINSTEIN PROGRAM The SXT instrument depends on the availability of the X-Ray Microcalorimeter Spectrometer (XMS). The mission team states that a major benchmark for the XMS was the flight of the Suzaku observatory in 2005. Mi- crocalorimeters have been in use for x-ray spectroscopy since 2002, when the first such detector was flown on a sounding rocket for measuring the diffuse x-ray background.10 The Con-X team has fabricated and demonstrated the performance of an 8 Ã 8 transition edge sensor (TES) array with 250 m pixels. For flight, a 32 Ã 32 array is required. A major challenge is the readout electronics associated with the detectors. In particular, sampling speed and the requirement for a very low noise figure are key design drivers for the readout electronics. Con-X has technology readiness challenges with all of the devices listed in Table 3.5 with TRLs of 5 or lower. Of particular concern, however, is the development of the microcalorimeters, since the success of the mission is dependent on these detectors. The mission team states that it believes that its top mission risks are (1) mirror angular resolution, (2) XMS field of view, and (3) XGS/HXT accommodations. Con-X Technical Challenges: Spacecraft The SXT and HXT instruments drive multiple spacecraft design and performance requirements. Table 3.9 shows the instrument accommodation requirements on the spacecraft and, where appropriate, impacts associated with instrument accommodation. Con-X Technical Challenges: Operations Constellation-X operates as a queue-scheduled observatory, pointing at selected targets in the most time-ef- ficient way consistent with science and observatory constraints. Each of the Con-X instruments has a science and engineering mode of operation. For the X-ray Microcalorimeter Spectrometer, the instrument science modes include submodes to allow the adiabatic demagnetization refrigerator (ADR) to reach operating temperature and a second mode to maintain the operating temperature while acquiring science data. There are no other XMS sci- ence modes. For the X-ray Grating Spectrometer (XGS), science modes include (1) timed exposure (TE): photons are col- lected in a frame for a selectable exposure time before being read out, and (2) continuous clocking (CC): where the charge-coupled device (CCD) is read out continuously; each output pixel represents the integrated flux received as the charge crosses the array. The instrument also has diagnostic, calibration, and engineering modes. For the Hard X-ray Telescope instrument, the operating modes include imaging, calibration, and engineering modes of operation. The application of Chandra experience provides confidence that the Con-X operations will not be a particular challenge. Con-X Technical Margins The Con-X mission has adequate technical margins in most areas. The Con-X mission includes 30 percent contingency on its mass estimate and about 1 percent margin on the launch vehicle performance. The 1 percent mass margin for the launch vehicle may not be sufficient for the project. Given that important aspects of the Con-X instrument design are still being evaluated and that ongoing trade studies could result in an increase in mass, overall mass management for Con-X is critical. Particularly, the Con-X team identified XGS and HXT accommodation as an open trade that could result in increased mass. While descoping options have been identified, they would entail significant science loss. Alternatively, Con-X could choose a larger launch vehicle to increase its margin, but at a higher cost. Continued close management of weight growth is necessary for a program at this stage. D. McCammon, R. Almy, E. Apodaca, W. Bergmann Tiest, W. Cui, S. Deiker, M. Galeazzi, M. Juda, A. Lesser, T. Mihara, J.P. Morgenthaler, 10â W.T. Sanders, J. Zhang, E. Figueroa-Feliciano, R.L. Kelley, S.H. Moseley, R.F. Mushotzky, F.S. Porter, C.K. Stahle, and A.E. Szymkowiak, 2002, A high spectral resolution observation of the soft x-ray diffuse background with thermal detectors, Astrophys. J. 576:188-203.
MISSION READINESS AND COST ASSESSMENT 79 TABLE 3.9â Con-X Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude Pointing Pitch: 10 arcsec None; well within the state of the art for a determination Roll: 30 arcsec conventional spacecraft design and control Yaw: 10 arcsec Tracking 1 arcsec/100 microseconds Unknown Jitter <2 arcsec/13.8 milliseconds No challenge Power Orbital average Approx. 2,345 W Array size and battery size Worst case 3,351 W peak Drives solar array size Data storage Orbital average 18 GB No challenge; systems commercially available Command and CPU Not specified Unknown data handling I/O Not specified Unknown Structure â Approx. 1,000 kg payload with 30% contingency. Leaves only 88 kg margin on Atlas V 551. Approx. 2,398 kg bus with 30% contingency, Appears to be a problem. 335 kg propellant with 30% contingency Thermal FMA 10Â°C to +30Â°C 3.5 m2 of radiator area required to maintain payload operating temperatures. Worst XMS â30Â°C to 70Â°C case 2,500 W required for survival heaters. Multiple local thermal controls required to XGS Varies with component maintain detectors and optics at different temperatures. Wide range of operating and HXT â100Â°C to +30Â°C for detector survival temperatures. Radio-frequency Downlink 3.5 Mbps No challenge communications Uplink Minimal No challenge Alignment â Multiple requirements from 10 arcsec up No challenge NOTE: Acronyms are defined in Appendix G. Con-X Management Challenges The Con-X team is led by GSFC, with the mission scientist at the Smithsonian Astrophysical Observatory (SAO). There are no special project management challenges for Con-X. The team has little dependence on non- U.S. team members. In addition, the team has worked together for several years, and any institutional interface issues have long since been resolved. The schedules supplied to the committee were technology development schedules. No overall mission devel- opment schedule was provided. Since the spacecraft bus is well within the state of the art, it seems reasonable to assume that the mission critical path will be through the SXT and associated detector assembly.
80 NASAâS BEYOND EINSTEIN PROGRAM Inflation Probes CIP Mission CIP Technical Challenges: Instrumentâ The Cosmic Inflation Probe (CIP) mission generally makes use of avail- able technologies or technologies being developed for other programs (e.g., the James Webb Space Telescope [JWST]). There are no significant technology challenges for CIP, although work remains to be done to see if the detector noise figure is adequate at the planned higher operating temperature. The technology readiness of the CIP mission is illustrated by Table 3.10. CIP uses an all-reflective three-mirror anastigmatic optical design. The optical figure of the required compo- nents is within the state of the art and should present no special challenges. The detector uses the Teledyne Hawaii-2RG HgCdTe detectors currently planned for JWST, operating at a somewhat higher temperature. The major outstanding issue is whether the dark current level is acceptable at the higher temperature. The vendor (Teledyne Brown) is planning to test the dark current levels at the higher tempera- ture using JWST hardware and, assuming that the levels are acceptable (predicted from early laboratory tests), the degree of difficulty should be low (DoD = I-II). The current TRL is judged to be 4, but this should rise rapidly following the JWST hardware testing. The spectrometerâs focal plane array (FPA) and ASIC are below TRL 6 (TRL judged to be 5), but both are similar to JWST equipment and neither should have a DoD of more than I, assuming that JWST development is successful. Additional development of the grating technology would be beneficial. CIP Technical Challenges: Spacecraftâ There are no unusual or challenging accommodation requirements for CIP relative to the spacecraft. Spacecraft accommodation requirements for the CIP mission are listed in Table 3.11. CIP Technical Challenges: Operationsâ CIP will conduct operations at Lagrange Point 2 (L2) for 3 years in order to meet mission baseline requirements. The mission team provided very little by way of operations information. As a redshift survey mission, its operations are expected to be similar to other survey missions in complexity. Since TABLE 3.10â CIP Technology Readiness Summary Heritage TRL DoD Changes from Previous Committee Committee Element Mission Similarities Mission/Comment Project Rating Rating Rating Detectors JWST/ Basic Uses 8k Ã 8k Teledyne Hawaii- 6 (at completion 4 I-II NIRSpec, design and 2RG HgCdTe detectors. CIP of noise NIRCAM, construction will operate at a warmer characterization) and FGS temperature than JWST. Will need characterization of noise at higher temperature. Optics ATT/ Similar Uses all reflective three-mirror 6-7 6 Not JWST, material and anastigmatic (TMA) at f/14.4. applicable NextView configuration Spectrometer XSS-11 Similar to Uses slitless concentric wide FOV 5-6 5 I the Offner imaging grating spectrometer. magnification The focal plane array and ASIC all-reflective are similar to components being imaging developed for JWST, and the relay other components appear to be at TRL 6. NOTE: Acronyms are defined in Appendix G.
MISSION READINESS AND COST ASSESSMENT 81 TABLE 3.11â CIP Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude Pointing 2.5 arcsec/control No challenge determination 2 arcsec knowledge and control Tracking Not specified Unknown Jitter 10 arcsec/500 s No challenge Power Orbital average 540 W EOL No challenge 190 W payload 653 W EOL capabilityâ100 W EOL margin Worst case Not specified Unknown Data storage â 20 GB No challenge Structure Payload 929 kg No challenge Bus 357 kg plus propulsion module of 122 kg No challenge Total/margin 1,655 kg/246 kg. 17.5% above allocated mass. None; acceptable margins Thermal â Passive with blankets and heaters No challenge Radio frequency Uplink 2 kbps at S band No challenge communications Downlink 100.5 Mbps at Ka band No challenge Alignment â Not specified Unknown Propulsion â 1,956.3 m/s Drives mass and complexity of observatory NOTE: Acronyms are defined in Appendix G. CIP uses passive cooling techniques, its operations are somewhat less complex than missions consuming cryogens with ever-changing center of gravity and balance issues. Flight operations of CIP should present no special chal- lenges. Downlink data rates are somewhat high but well within the current state of the art. CIP Technical Marginsâ The CIP mission team provided a complete package of information that addressed each of the major technical areas. The team allocated adequate technical margins in most areas but did not provide margins for attitude control and data link. Given that the required performance in these areas is not stressing the state of the art, it does not raise significant risk issues. CIP Management Challengesâ The CIP mission is led by a principal investigator from the Harvard-Smithsonian Center for Astrophysics. Team members include scientists from the University of Texas, the California Institute of Technology, the Jet Propulsion Laboratory (JPL), Lockheed Martin, ITT Space Systems, and Teledyne Scientific and Imaging. CIP is managed by the Smithsonian Astrophysical Observatory, with strong support from Lockheed Martin. Since there is no significant dependence on non-U.S. team members to contribute resources, there are no apparent project management challenges other than the schedule, described below. The proposed schedule shows a PDR in the first quarter of 2010 and a launch in the second quarter of 2013. This is an extremely aggressive schedule, but the mission team claims that it has 5 months of schedule reserve. The schedule to the proposed launch date will be a challenge.
82 NASAâS BEYOND EINSTEIN PROGRAM CMBPol Mission CMBPol Technical Challenges: Instrumentâ The microwave optics for the Cosmic Microwave Background Polar- imeter (CMBPol) use a variable-delay polarization modulator (VPM) and a folding mirror to control the entry of stray light into the cooled detector array. The components appear to be standard microwave technology, but there is concern with noise in the detectors and readout electronics as well as some concern with the ability to couple the polarized optical signals. Project documentation indicates that similar VPMs (operating at higher and lower frequencies) have been prototyped at GSFC and are under evaluation. Based on this statement, the committee estimates the TRL to be 2-3, but the DoD cannot be judged without more information. The technology readiness for the CMBPol mission is shown in Table 3.12. The detectors are the same TES detectors proposed for the other Inflation Probe microwave instruments. GSFC has experience with these detectors on previous missions. CMBPolâs challenge will be to keep the noise low enough to make the measurement. There appears to have been a good deal of thought put into the detailed design and fabrication of the microwave strip line circuitry and the TES detectors and readout electronics. The CMBPol team has expressed some concern about the detailed design of the detector system, using the words ârequires very innovative designâ in describing the work to be done. This is an area in which an investment of time and money could potentially be put to good use. The TRL and DoD cannot be assessed on the basis of the information provided. CMBPol Technical Challenges: Spacecraftâ A summary of the CMBPol mission spacecraft accommodation requirements is shown in Table 3.13. Not much was presented to the committee by way of spacecraft accommo- dation information. TABLE 3.12â CMBPol Technology Readiness Summary Heritage TRL DoD Changes from Previous Project Committee Committee Element Mission Similarities Mission/Comment Rating Rating Rating Cryocooler Unknown, but refers Unknown Unknown Not Not enough Not enough to a pulse tube provided information information cooler developed by to assess to assess Lockheed Martin. Detectors TES used in ACT, Unknown Requires 1,000 TES detectors Not 2-3 Not enough GBT cooled to 100 mK. Requires provided information 80 dB of noise reduction. to assess Uses superconducting SQUID multiplexer/readout electronics. Feed horn Unknown, but this is Unknown Uses Platelet feed horn array. Not Not enough Not enough array standard microwave Conventional microwave provided information information technique. technology. to assess to assess Optics HHT Unknown Uses variable-delay polarization Not Not enough Not enough modulator as first element for provided information information control of stray light. Folding to assess to assess mirror transfers radiation to detector array. Issues with polarization. Noted that prototypes operating at different frequencies have been built at GSFC. NOTE: Acronyms are defined in Appendix G.
MISSION READINESS AND COST ASSESSMENT 83 TABLE 3.13â CMBPol Spacecraft Accommodation Requirements System Subsystem Performance Impact Requirements Attitude determination and control Pointing Not provided Unknown Tracking Not provided Unknown Jitter Not provided Unknown Power Orbital average Not provided Unknown Worst case Not provided Unknown Data storage Payload Not provided Unknown Structure Payload Not provided Unknown Bus Not provided Unknown Total Not provided Unknown Thermal â Not provided Unknown Radio frequency communications Downlink 1 Gb per orbit Unknown Uplink Not provided Unknown Alignment â Not provided Unknown Propulsion â Not provided Unknown CMBPol Technical Challenges: Operationsâ CMBPol is a slowly spinning all-sky survey mission. Very little was presented to the committee by way of details on flight operations for this mission. The material submitted states that the mission is still in conceptual development, so it is not surprising that operational details were not provided. CMBPol Technical Marginsâ Insufficient information concerning the spacecraft and mission concept was provided to the committee to allow an assessment of the technical margins of the CMBPol concept. CMBPol Management Challengesâ CMBPol was presented as a mission concept only; no detailed schedule was made available. The mission team is led by a principal investigator at NASA GSFC, with team members from the University of Pennsylvania, the University of Chicago, Princeton University, Harvard University, the University of Toronto, and the University of California, Los Angeles. CMBPol Unique Challengesâ The dearth of information on CMBPol and the absence of any statement invoking proprietary concerns indicate that it is in the very early stages of concept development. The committee assesses that CMBPol faces a major challenge and is very unlikely to be ready for mission development in 2009. EPIC-F Mission EPIC-F Technical Challenge: Instrumentsâ Antenna development for the FPA appears to be the major technology issue for the Experimental Probe of Inflationary Cosmology (EPIC-F) at this point. Integration of the cryogenic optics with the detector system to achieve the required low noise operation will also be challenging. The technol- ogy readiness summary for the EPIC-F mission is shown in Table 3.14. Project documentation indicates that the wave plate technology planned for use in the microwave optics of EPIC-F has been matured to TRL 6 in ground testing. The information provided in the mission teamâs response to the committeeâs RFI suggests significant heritage, but this is not described. Without more information it is not
84 NASAâS BEYOND EINSTEIN PROGRAM TABLE 3.14â EPIC-F Technology Readiness Summary Heritage TRL DoD Project Committee Committee Element Mission Similarity Changes/Comments Rating Rating Rating Focal plane array components (NTD Ge bolometers) NTD Planck and Noted as identical to None 8 >6a N/A thermistors and Herschel those of Planck and JFET readouts Herschel Antennas Ground Basic technology Different (wider) 4 3-4 I-II demonstrations design frequency range required. Wide-field BICEP Noted as identical BICEP was ground tested 6 6 N/A refractor at the South Pole. Wave plate technologies Wave plate SCUBA, HHT, Not provided Noted that half-wave 6 5-6 I optics MAXIPOL, plates have significant others ground testing. Cryogenic Spitzer Apparently identical Noted that the stepper 9 >6 N/A stepper drive motor has been flight tested on Spitzer. Liquid helium Spitzer, ISO, Based on Spitzer Not enough information 9 >6 N/A cryostat Herschel design provided, but likely close enough to Spitzer design to make this low risk. Sub-K cooler: Suzaku Project documentation Little information 9 >6 N/A single-shot ADR indicates that this is provided. the same as flown on Suzaku. Deployable JWST Similar technology Less complex (3-layer, 8 4-5 4 I-II sunshield meter) than JWST (5-layer, 22 meter). All components should be at high TRL (project indicates 9). Toroidal-beam Multiple Components are No integrated 4-5 3-4 I-II downlink proven technologies. demonstration. antenna NOTE: HHT, Heinrich Hertz Telescope; N/A, not applicable. Other acronyms are defined in Appendix G. a A rating of TRL >6 reflects a lack of information about the exact application and environment for those items relative to their claimed flight heritage. possible to put this technology at TRL 6, but the engineering and demonstration should be straightforward; the DoD is estimated at I. The basic principles for the antennas have been demonstrated, but EPIC-F requires a wider frequency range than has been demonstrated in the past. Laboratory experiments are promising, but both environ- mental and system testing are required.
MISSION READINESS AND COST ASSESSMENT 85 The neutron transmutation doped (NTD) Ge bolometric detectors are not considered to be a serious challenge. Previous missions have used these detectors. Packaging may be a challenge for all missions planning on using these detectors to keep the noise to an acceptable level. The deployable sunshield will require careful design and testing. It is similar to but much smaller than the one being developed for JWST. While the TRL is relatively low (TRL = 4), the engineering should be straightforward; the DoD is judged to be I-II. Similarly, the downlink antenna is a new design, but all of the components are of very high TRL. Because there has not been an integrated test, the TRL is judged to be low, but no major obstacles are anticipated for the development effort; the DoD should be between I and II. EPIC-F Technical Challenges: Spacecraftâ Spacecraft accommodation requirements for the EPIC-F mission are listed in Table 3.15. The spacecraft requirements for this mission appear to be modest and are not expected to be a challenge. EPIC-F Technical Challenges: Operationsâ The six cooled telescopes that form the heart of EPIC-F are mounted to a spinning platform orbiting at L2 and use the spinning motion of the spacecraft to scan 50 percent of the sky on a daily basis, although 6 months of operation are required to complete a full-sky map. Owing to the consump- tion of cryogens and the operation of the active and passive cooling systems and the spinning motion of the bus, EPIC-F is likely to be somewhat complex to operate and to be operator labor-intensive. The low data rate require- ment is a plus in reducing complexity. TABLE 3.15â EPIC-F Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude determination and Pointing 1Â° control, 30 arcsec knowledge No challenge control Tracking None Not applicable Jitter Stability of spin axis assumed to be No challenge 1Â° Power â 272 W payload with 43% contingency GaAs triple junction cells, good margins. 981 W bus with 43% contingency Data storage â 2 GB No challenge Structure Payload 898 kg with 43% contingency No challenge Bus 713 bus dry mass with 43% No challenge for the planned Atlas V contingency; appears to be 1,783 wet 401 of Delta IV 4040 ElV mass of the total observatory Total/margin 1,783 with 43% margin. No challenge, good mass margin ELV launch capability margin 95% for Atlas 401, 56% for Delta IV 4040 Thermal â Unknown Unknown Radio-frequency communications Uplink Unknown Unknown Downlink 500 kbps No challenge Alignment â Unknown Unknown Propulsion Delta-v 215 m/s, 172 kg propellant No challenge NOTE: Acronyms are defined in Appendix G.
86 NASAâS BEYOND EINSTEIN PROGRAM EPIC-F Technical Marginsâ The EPIC-F mission team provided a fairly complete description of its concept and showed good technical margins, although no margins were provided for attitude control and data communica- tions. In addition, the sensitivity needed for the instrument is significantly greater than was required for previous instruments and will present a very significant technical challenge to meet. EPIC-F Management Challengesâ The EPIC-F team is led by a principal investigator from the California Insti- tute of Technology, with team members from JPL; the University of California, Berkeley; the Lawrence Berkeley National Laboratory (LBNL); the University of Chicago; the University of Colorado; the University of California, Davis; Cardiff University; and several other institutions. The EPIC-F project will be managed by JPL and is cer- tainly within the experience base of missions led by JPL in the past. It was not possible for the committee to tell if there is a significant dependence on non-U.S. team members to be critical resources. A strong and experienced project manager will be needed to manage this large team. No mission-level schedule was submitted by the EPIC-F team. Based on the phasing included in the cost estimate, the mission team has approximately a 60-month Phase B/C/D schedule. This schedule seems reasonable based on the complexity of the mission and the current TRL levels of the critical technologies. The mission team claims to have extended Phase C/D to allow more time to develop the cryogenic instrument. According to the EPIC-F team, âThe instrument schedule was developed in analogy with phase C/D plans for similar missions, WISE [Wide-field Infrared Survey Explorer] and Spitzer, and is longer than the planned phase C/D for either mission, but shorter than the actual phase C/D of Spitzer.â 11 The development of the cryogenics payload will be the most significant schedule challenge for the mission, along with the integration of the payload with the commercial spacecraft bus. EPIC-F Unique Challengesâ Liquid helium dewars have been used on previous spacecraft and should be reliable enough to meet the 2-year mission life expectancy but will remain a special challenge for EPIC. According to responses provided by the EPIC-F team concerning risk management, âA demonstration of the EPIC instrument is now being developed for a balloon experiment named Spider, led by EPIC team members Lange, Bock, Golwala and Irwin, that incorporates 6 refracting telescopes with aperture-filling half wave plates, and focal planes of antenna-coupled TES bolometers. Spider will use a spinning observing strategy in a 20-day flight to demonstrate the essential operations planned for EPIC, although at reduced sensitivity and observation time.â12 This should be an excellent risk-reduction activity, especially with regard to the cryogenic instrument performance and operating time validation. EPIC-I Mission EPIC-I Technical Challenges: Instrumentâ The Einstein Polarization Interferometer for Cosmology (EPIC-I) mission team is proposing corrugated horn antennas similar to those flown on the Cosmic Background Explorer (COBE). An ortho-mode transducer and Fizeau combiner are described very briefly, but there is not enough infor- mation to allow the committee to assess the TRL or DoD of the components or an integrated system. If the horns are nearly identical to those on COBE, the TRL would be above 6. The mission team has also identified alternate phase modulator technologies. The fact that phase modulator technology is listed as number 1 on its list of primary technical issues indicates that the TRL is significantly below the TRL 6 at which the team rated it. A technology readiness summary for the EPIC-I mission is presented in Table 3.16. The detectors proposed are bolometers with cryogenics provided by a superfluid liquid helium cryostat and a single-shot ADR. As with the horns, the bolometers could be at high TRL if they are truly very close to the NTD Ge devices used for Planck and Herschel or to the TES devices from the Submillimeter Common User Bolometer Array (SCUBA) and the Green Bank Telescope (GBT). The actual âheritageâ is not described. The most up-to-date EPIC-F team response to Risk Questions from the committee, p. 2. 11â EPIC-F team response to Risk Questions from the committee, p. 3. 12â
MISSION READINESS AND COST ASSESSMENT 87 TABLE 3.16â EPIC-I Technology Readiness Summary Heritage TRL DoD Changes from Previous Project Committee Committee Element Mission Similarities Mission/Comment Rating Rating Rating Feed horns COBE, COBE flew Orthomode transducers 9 (?) for Not enough Not enough WMAP corrugated for the required antennas and information information horn antennas; frequencies have âprobably 6â provided to provided to WMAP been built, but little for the phase assess assess devices below information is given. modulators 100 GHz Detectors Planck, Not provided Proposing cooled 8 or 6 Not enough Not enough Herschel or bolometers; high information information SCUBA, Technology Readiness provided to provided to GBT Level assumed due to assess assess past flight heritage, but little information provided. Phase Ground-based Ferrite core Alternative phase 6 for ferrite Not enough Not enough modulator BICEP modulator technologies core version information information and MBI (i.e., MEMS switches provided to provided to instruments or varactor-diode assess assess controlled nonlinear transmission lines) possible. Cooling Spitzer, ISO, Not provided Proposing a helium 9 Not enough Not enough technology Herschel, cryostat and a single- information information COBE, shot ADR. Not enough provided to provided to Suzaku information provided to assess assess assess. NOTE: Acronyms are defined in Appendix G. RFI response references a ground-based testbed (main beam interference [MBI]) for testing EPIC-I technologies, but no details are provided. If the cryogenic technologies (helium cryostat and ADR) are close clones of devices already flown their TRLs would be high, but insufficient information is provided. The fact that cryogenics is listed as number 2 on the mission teamâs list of primary technical issues indicates that the heritage may not be close enough for high-TRL/low-DoD ratings. While the information provided shows that EPIC-I has made significant progress in mission redesign, there is not enough engineering information provided to allow the committee to assess the technologies accurately. EPIC-I Technical Challenges: Spacecraftâ EPIC-I plans to use a spacecraft that is similar structurally to the Co- riolis, Swift, and GeoEye-1. The configuration is similar to the COBE configuration, with sunshields protecting the instrument, spinning, in a Sun-synchronous orbit. The avionics architecture and subsystems will be the same as for the Gamma-ray Large Area Space Telescope (GLAST) spacecraft with minor changes to match the EPIC- I requirements. All changes represent a reduction of requirements relative to GLAST. There are no significant spacecraft challenges for the EPIC-I mission. Spacecraft accommodation requirements for the EPIC-I mission are listed in Table 3.17. EPIC-I Technical Challenges: Operationsâ The EPIC-I mission team provided very little information concern- ing flight operations. The committee assumes that a cryogenically cooled spinning spacecraft will have the same balance issues and center of gravity issues similar to other missions of this type.
88 NASAâS BEYOND EINSTEIN PROGRAM TABLE 3.17â EPIC-I Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude determination Pointing 3 arcmin control, 1 arcmin knowledge, 1 RPM No challenge and control spin about the boresight Tracking None Not applicable Jitter Not stated Unknown Power â 250 W payload with 25% contingency, Six solar array surfaces on three wings. 533 W total with 16.5% contingency, 24% margin Sun synchronous orbit, adequate margin. Data storage â 0.5 GB No challenge, 2 GB capacity Structure Payload 1,590 kg with 25% contingency No challenge Bus 674 kg bus dry mass with 13% contingency No challenge for the planned Atlas V 401. Total/margin 2,261 kg dry with 22% margin None, good mass margin ELV launch capability margin 184% for Atlas 401 Thermal â Cold biased passive with heaters. Payload Minor challenge in the thermal thermally isolated from bus isolation. Has been done before. Radio frequency Uplink S band 2 kbps No challenge communications Downlink 8 Mbps science, X-band No challenge 32 kbps housekeeping, S band Alignment â Spin balanced No challenge Propulsion Delta-V 233 m/s, 324 kg propellant No challenge for 2-yr lifetime capability is 283 m/s with 21% contingency. NOTE: Acronyms are defined in Appendix G. EPIC-I Technical Marginsâ The EPIC-I concept appears to have adequate technical margins. Mass margin, in particular, is more than adequate at 184 percent, given the use of the Atlas 401 launch vehicle (under the assump- tion that the Delta II will not be available). EPIC-I Management Challengesâ The EPIC-I team is led by a principal investigator from the University of Wis- consin-Madison. The teamâs industrial partner is General Dynamics, and team members include those from Cardiff University, the University of Richmond, and Brown University. Ball Aerospace is also involved in development of the instrument. Inadequate information was provided to allow the committee to assess any schedule management challenges for EPIC-I. EPIC-I Unique Challengesâ The use of a cryogenic dewar (and the associated thermal isolation requirements) is the major accommodation challenge faced by EPIC-I. This is within the state of the art, though, and is not a major driver for the mission.
MISSION READINESS AND COST ASSESSMENT 89 TABLE 3.18â ADEPT Technology Readiness Summary Heritage TRL DoD Change from Previous Project Committee Committee Element Mission Similarities Mission/Comments Rating Rating Rating Optics NextView Basic design Uses 1.3 m telescope. High Not enough Not enough 1.3-2.0 Î¼m slitless information information spectrometer. provided to assess provided to assess Detectors Multiple Basic design Uses 2 Î¼m 2k Ã 2k Hawaii High Not enough Not enough HgCdTe detectors with 2 Î¼m information information cutoff. Has to have the cutoff provided to assess provided to assess wavelength modified for ADEPT. Optics GeoEye I Optical design Uses 1.3 m, f/12 telescope, High Not enough Not enough scaled up from GeoEye. information information provided to assess provided to assess Spectrometer Unknown Unknown Operates in the 1.3-2.0 High Not enough Not enough micron, Ha range. information information provided to assess provided to assess NOTE: Acronyms are defined in Appendix G. Joint Dark Energy Missions ADEPT Mission The Advanced Dark Energy Physics Telescope (ADEPT) mission team did not provide detailed technical or programmatic information. The team citied concerns about proprietary information and competition sensitivity as its reason for doing so. ADEPT Technical Challenges: Instrumentâ It was stated by the ADEPT mission team that the mission will be based on technologies developed for missions such as Swift and GeoEye. Project documentation13 states that âwhile there are differences, ADEPT has many similarities to the GeoEye-1 mission, which provides extensive heritage for ADEPT. In some areas ADEPT is somewhat simpler, and in some areas it is more complex, but comparisons are useful and warranted.â The information provided was not sufficient for the committee to perform realistic as- sessments of TRL or DoD. From the general statements made, ADEPT appears similar in complexity to the other JDEM missions. The technology readiness of the ADEPT mission is summarized in Table 3.18. The mission team states that it will be using a Hawaii HgCdTe 2k Ã 2k infrared detector sensor. The cutoff frequency will be modified for ADEPT to 2 Î¼m. There is some challenge to this modification, but there are ongo- ing programs that should demonstrate even lower cutoff frequencies. ADEPT Technical Challenges: Spacecraftâ Not enough information was provided to allow the committee to judge the challenges faced by the ADEPT spacecraft. Spacecraft accommodation requirements for ADEPT are shown in Table 3.19. JDEM/ADEPT team response to the committeeâs Request for Information (see Appendix E in this report), January 2007. 13â
90 NASAâS BEYOND EINSTEIN PROGRAM TABLE 3.19â ADEPT Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude Pointing Not specified Unknown determination and control Tracking Not specified Unknown Jitter Not specified Unknown Power Payload Not specified Unknown Bus Not specified Unknown Data storage â Not specified Unknown Structure Payload 695 kg No challenge Bus 1,260 kg No challenge Total/ 1,955 kg No challenge margin Thermal â Not specified Unknown Radio- Uplink 2 kbps command at S band No challenge frequency communications Downlink 8.5 Mbps No challenge Alignment â Not specified Unknown Propulsion â Not specified Unknown NOTE: Acronyms are defined in Appendix G. ADEPT Technical Challenges: Operationsâ ADEPT redshift survey operations involve agile reorientation of the telescope on a regular basis to acquire targets of opportunity. The Swift mission has the same requirement and has been able to meet the requirement without stressing the attitude control system (ACS). The ACS is not thruster- based and thus does not consume fuel in the process of reorienting the telescope. This design has a considerable design and mission-life advantage over conventional propellant-based technology. Although very little information was provided concerning flight operations, the operational aspects of ADEPT seem to be no more complicated than those of Swift. ADEPT Technical Marginsâ The mission team did not provide sufficient information concerning the spacecraft and mission concept to allow the committee to assess the technical margins of the ADEPT concept. ADEPT Management Challengesâ No information was submitted that allowed the committee to assess the ADEPT teamâs organization or schedule management. DESTINY Mission DESTINY Technical Challenges: Instrumentâ The only identified challenges in the Dark Energy Space Telescope (DESTINY) technologies are in the precision pointing and stabilization, identified by the mission team as chal- lenges. The summary of the technology readiness of the DESTINY mission is shown in Table 3.20.
MISSION READINESS AND COST ASSESSMENT 91 TABLE 3.20â DESTINY Technology Readiness Heritage TRL DoD Changes from Previous Project Committee Committee Element Mission Similarities Mission/Comment Rating Rating Rating Three-mirror IKONOS-1 Optical design Scale size 7 7 N/A astigmatic telescope and components 1.65 m primary HST Size of mirror Slightly smaller than that on 7 7 N/A mirror the HST Spacecraft bus Spitzer 3-axis bus Different ELV, different thermal 7 7 N/A carrying a large environment, vibration isolated telescope reaction control wheels. Detectors HST Similar Different cutoff wavelength of 6 5 II JWST material and the HgCdTe detector material NIRSpec configuration NOTE: N/A, not applicable. Acronyms are defined in Appendix G. The optics required for DESTINY are within the state of the art for size, prescription, and precision. Employ- ing a 1.65 m primary mirror with the required optical figure, the optics for DESTINY can be built without any special challenge. The proposed detectors are 2k Ã 2k Hawaii-2RG devices. While the Single Channel Analyzers are very simi- lar to devices on JWST, there are differences, most notably the cutoff wavelength. The new cutoff material has been demonstrated for the Hubble Space Telescope (HST) program, and this development will be leveraged in the DESTINY program. The DESTINY team is looking at investments required at Teledyne-Brown (the detector manufacturer) beyond those being made by JWST; the team noted that a prototype FPA was being developed. The information provided was not sufficient for the committee to judge the TRL to be 6. Substantial, ongoing invest- ment efforts suggest that the DoD for the DESTINY application should be low (DoD = II). Destiny Technical Challenges: Spacecraftâ The only challenge for the spacecraft is in the area of pointing and stabilization, and it depends in large part on the performance of the camera fine-guidance subsystem. There was not enough information provided to the committee for judging the merit of the fine-guidance subsystem. Spacecraft requirements generated by the DESTINY science payload are listed in Table 3.21. DESTINY Technical Challenges: Operationsâ Based on a 1.65 m telescope operating at L2, DESTINY will survey 1,000 square degrees of the sky in the near-infrared (NIR), performing a weak-lensing survey of candidate super- nova (SN) Ia objects. The detectors are passively cooled, and the spacecraft is not spinning. Attitude control uses reaction wheels and not thrusters, thus eliminating the operational challenge of managing consumables. The mission appears to have good heritage, and from what was presented to the committee, it should be simple to operate. DESTINY Technical Marginsâ The DESTINY mission concept proposed had adequate technical margins for size, weight, power, and other performance parameters, with the exception of pointing stability and control, where it is unclear whether the proposed concept will perform adequately. Specifically, there are concerns with jitter from propellant slosh and other systematics that could present a problem for pointing repeatability. To prove out the proposed pointing and control concept, additional analysis will need to be completed to provide a more thorough understanding of these issues. DESTINY Management Challengesâ The DESTINY mission is led by a principal investigator from the National Optical Astronomy Observatory and the NASA GSFC. Team members are based at the Space Telescope Science
92 NASAâS BEYOND EINSTEIN PROGRAM TABLE 3.21â DESTINY Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude Pointing 3 Ã 10â6 deg Handled by camera fine pointing subsystem. determination Uses image differencing for fine pointing. and control Tracking Not specified Unknown Jitter 3 Ã 10â9 deg/s Uses rates from IMU but controlled by camera fine point system. Power Obital average 785 W (with 30% contingency) for the payload, Drives array size but is not a challenge. 451.6 W (with 30% contingency) for spacecraft bus Worst case 988.4 W (with 30% contingency) for spacecraft Drives array size but is not a challenge. bus Data storage â 62.5 GB Cost Structure Payload 1,784 kg (with 30% contingency) for payload, No particular impact or challenge, although 1,798-2,059 kg for spacecraft bus. discipline will have to be followed in 9-28% mass margin above contingency managing mass. depending on which bus design is used Thermal â Allocated 104 W for operational heater control No challenge Radio frequency Uplink 2 kbps No challenge communications Downlink 28 Mbps at Ka band for science downlink No challenge Alignment â Not specified Unknown Propulsion â 150 m/s, 182 kg propellant No challenge NOTE: Acronyms are defined in Appendix G. Institute; Harvard University; Texas A&M University; the University of California, Davis; Michigan State Uni- versity; the University of Chicago; and the Carnegie Observatories. Assuming that the current team responsibilities remain the same, there are no obvious management challenges to the DESTINY mission. There is no significant dependence on non-U.S. team members for contributions of funding or equipment. The size of the team is not particularly large and should be manageable with established management processes. The mission team provided very little schedule information. It states that only 5 years are required from start to launch readiness, but there is no support for this claim. Since there is very little in the way of new technology, this claim of 5 years for development is possible. DESTINY Unique Challengesâ The only special challenge discussed by the DESTINY team is the risk associated with pointing repeatable to 0.05 pixels or 0.01 arcsec. Pointing at this accuracy is handled by the fine-guidance system but is a design driver. SNAP Mission SNAP Technical Challenges: Instrumentâ SNAP key technologies are either mature (TRL 6 or greater) or pro- gressing toward TRL 6 in well-planned steps. A technology readiness summary of the SNAP mission is shown in Table 3.22.
MISSION READINESS AND COST ASSESSMENT 93 TABLE 3.22â SNAP Technology Readiness Summary Heritage TRL DoD Changes from Previous Project Committee Committee Element Mission Similarities Mission/Comment Rating Rating Rating Telescope HST, Components, design Uses an annular field, Korsch 9 >6 N/A Classified type 1.8 m, f/12 lightweight IKONOS telescope with three-mirror anastigmatic design. Uses Zerodur or ULE composite mirrors and composite metering for low CTE properties. Si Sensor HST/ Manufacturing CCDs are innovative n-type 6 6 N/A WFC3 processes high-resistivity devices produced by LNBL; they have undergone extensive testing to demonstrate that they exceed specifications. Si NeXT, Manufacturing Two ASICs are required and 5 4-5 I-II CCD Bepi- processes one has been demonstrated. electronics Colombo The most recent SNAP inputs indicate that the other (the clocking chip, or CLIC) is currently undergoing testing. No integrated demonstration has been performed. MCT sensor JWST, Commercial product. Uses 36 Raytheon- or Rockwell- 6 6 N/A WFC3 Same device as supplied 1,700 nm cutoff JWST HgCdTe for IR. MCT JWST Based on Will be used without 6 6 N/A electronics SIDECARâs ASIC modification for SNAP. Focal plane JWST/ Optical layout, Requires l/dl = 70-100 resolving 6 4-5 II plate NIRSpec materials power over the 0.4 to 1.7 micron Spitzer band-pass to measure the SiII line to +400 km/s. Prism-based design. Spectrographic JWST Design Innovative design developed for 5 5 I-II image slicer the JWST NIRCAM instrument. Literature cites prototype testing in a relevant environment but gives no detail. Spacecraft Spitzer, Standard structure Requires no new technology 9 >6 N/A structure other and subsystems or developmentâstandard and other components with flight heritage. components Ka-band None Components Transmitter will be assembled 7 4-5 I-II transmitter from flight-proven components, but no integrated demonstration indicated. NOTE: N/A, not applicable; SIDECAR, system image, digitizing, enhancing, controlling, and retrieving. Other acronyms are defined in Appendix G.
94 NASAâS BEYOND EINSTEIN PROGRAM SNAP plans to use a 1.8 m composite telescope. The telescope will have a large FOV and is designed with care for thermal and optical performance. The weak-lensing experiment is highly dependent on the optical perfor- mance of the telescope. The telescope development is seen as a straightforward engineering effort with no obvious challenges (TRL = 7) and is within the experience gained on multiple other programs. SNAP uses two types of detectors: an LBNL-supplied, radiation-hardened CCD and a Rockwell- or Raytheon- supplied mercury cadmium telluride (MCT) IR detector. The Department of Energy (DOE) has made significant investments in detector development (both Si CCD and HgCdTe [MCT]). The MCT cutoff of 1.7 microns is below space-proven technology, but development efforts have been highly successful. The JWST and HST Wide Field Camera 3 programs are developing the manufacturing base that they will need to ensure availability. The CCDs are a custom item developed by LBNL for the Department of Defense (DOD). The performance of the CCD meets requirements, and relevant testing has been done on flight-like parts. The ability of LBNL to produce the required number of CCDs in the needed time frame is a concern, and LBNLâs latest literature indicates that it is transfer- ring processing technology to DALSA Semiconductor for routine processing. The development of the ASICs (two needed) for the CCDs is progressing. A prototype of the clocking chip has been manufactured and was to start testing in April 2007. The ADC has been produced and tested. The committee rated the CCD electronics at a TRL of 4-5 because the testing of the prototype and integrated testing had not been performed; there should be no extraordinary challenges, however, and the DoD should be low (I-II). MCT detectors with the required cutoff and quantum efficiency (QE) have been demonstrated under DOE funding, although little discussion of the testing (e.g., length) is provided. The required ASIC has been developed for JWST, so the MCT should be at the claimed rating of 6 (assuming that the material testing was comprehensive and of the required fidelity). Assuming that funding can be provided in the needed time frame, these devices should not be a challenge. It should be noted that fully integrated demonstrations of the sensors systems have not been completed. The readout electronics for both detectors are claimed to be radiation-hard and with adequate performance to meet mission objectives. The performance of the integrated instrument could be a challenge to maintain low noise levels over temperature. The planned focal plane plate will be âroughly twice as large as prior cryogenic flight focal planes in terms of pixel complementâ14 and will require development efforts. Therefore, the committee rated it at a TRL of 4-5 rather than the 6 given by the mission team. It appears that the mission team has researched the development effort and that the materials and engineering processes should be available for the development effort, so the committee rated the DoD at II. All components in the spectrograph are standard and should pose no development risk with the exception of the Image Slicer (IS). There is heritage from JWST (Near-Infrared Camera), but very little detail was provided on the prototype or testing (e.g., how close is the prototype to the SNAP design and what specific testing has it undergone?). If the prototype is a very close match and the testing was high fidelity with respect to SNAP requirements, then the TRL should be 6. The discussion (on page 31) in the mission teamâs response to the committeeâs RFI (IS TRL = 6) is not consistent with the rating (TRL = 5) provided in Table 9 on the same page of the response, and not enough information is provided to make the distinction. If the IS is at TRL 5, the DoD should not be high (DoD = I to II) based on its similarity to that on JWST. Finally, the Ka-band transmitter calls for the use of all flight-proven parts. Similar transmitters have flown but not with the required wideband mixer. Wideband mixers have flown but not for the same application. In this case, components have been widely demonstrated, and other programs (the Solar Dynamics Observatory and the Lunar Reconnaissance Orbiter) will fly similar hardware (few details on the latter were provided). The development and testing of an integrated unit were not described, so the TRL is judged to be between 4 and 5. The engineering should be straightforward, and the DoD is judged to be low (I-II). The Ka-band resource availability of the Deep Space Network could be a problem for SNAP. SNAP Technical Challenges: Spacecraftâ Only in the areas of ACS performance and downlink data rates might there may be some challenges with the spacecraft. Spacecraft accommodation requirements for the SNAP mission are shown in Table 3.23. 14 SNAP team response to the committeeâs Request for Information (see Appendix E in this report), January 2007.
MISSION READINESS AND COST ASSESSMENT 95 TABLE 3.23â SNAP Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude determination Pointing 3 arcsec No challenge and control Tracking 6 deg/min No challenge Jitter 0.02 arcsec/1,000 s Complexity Power Payload 270 W/30% contingency No challenge Bus/total 343 bus/613 W total with 30% contingency No challenge Data storage â 137.5 GB Cost Structure Payload 985 kg/30% contingency No challenge Bus 493 kg dry with 25% contingency No challenge Total/margin 1,571 kg with 28.3% contingency. 747 kg total LV mass margin No challenge Thermal â Adiabatic interface between spacecraft and instrumentânegotiated Unknown maximum allowable heat transfer from spacecraft to instrument Radio-frequency Uplink 2 kbps No challenge communications Downlink 150 Mbps with 50% contingency Unknown Alignment Telescope Active alignment system Complexity, reliability Propulsion â 93 kg propellant No challenge NOTE: Acronyms are defined in Appendix G. SNAP Technical Challenges: Operationsâ SNAP is a very well developed mission requiring only passive cooling for its detectors, fixed solar array, and an achievable pointing accuracy performance. SNAP will perform a weak- lensing sky survey over about 1,000 square degrees in a time frame of about 1 year. The mission performance requirements are exceptionally well developed. SNAP presents no special operational issues. Observing targets will be selected and command sets uploaded periodically to schedule pointing and observing time for specific targets. SNAP Technical Marginsâ The SNAP mission team provided significant detail on its proposed concept and showed adequate technical margins in all areas. SNAP Management Challengesâ The SNAP mission will be co-led by principal investigators from the LBNL and includes members from the University of California, Berkeley; LBNL; the California Institute of Technology; Fermi National Laboratory; the University of Maryland; the University of Michigan; the University of Pennsylvania; Laboratoire dâAstrophysique de Marseille (France); Institut National de Physique NuclÃ©aire et de Physique des Particules (France); and several other institutions. The project will be managed by the University of California, Berkeley. Managing the SNAP project that has international partners providing key spectrometer hardware could prove to be a challenge. The proposed schedule shows 4.75 years from the PDR to launch. This is barely adequate development time for a mission of this complexity. The committee could not tell from the materials provided how much reserve
96 NASAâS BEYOND EINSTEIN PROGRAM was included in the schedule. Schedule management should not be a challenge unless problems develop with the instrument. The spacecraft should not be a problem, although ACS performance is quite demanding. LISA Mission LISA Technical Challenges: Instrumentâ The optical materials, components, and techniques used in LISA have significant heritage, and the LISA Pathfinder (LP) optical system (while different in design) will provide significant confidence in the system.15 The LP engineering model (EM) has already undergone extensive testing. Development of the optical system appears to be a straightforward engineering effort with a very high probability of success. The LISA Pathfinder is on track to launch in late 2009, with 70 percent of the hardware to be delivered in 2007. The assessed TRL and DoD levels for the key technologies to be demonstrated by the LISA Pathfinder are shown in Table 3.24, which contains a summary of LISA technology readiness issues. 16 The phase measurement system (PMS) for LISA employs both a photo receiver and a phase meter. Other missions have used architectures similar to the one planned for LISA, and ongoing breadboard testing of both components has been successful to date. An integrated prototype development effort is planned, and the current schedule indicates that TRL 5 and 6 for the integrated system will be attained in 2009 and 2010, respectively (assuming success). While the current TRL is low, an adequately funded development effort should be relatively straightforward (DoD = II). The micronewton thrusters are the most challenging technology being developed by the LISA team. Three different thruster types are being evaluated for LISA: (1) Colloid Micronewton Thrusters (CMTs), (2) Indium Needle Field Emission Electric Propulsion (In-FEEP) devices, and (3) Cesium Field Emission Electric Propulsion (Cs-FEEP) devices. While all of these have demonstrated the performance characteristics (thrust level and low noise) required for the LISA mission, none has demonstrated the very taxing lifetime requirement stated in LISA documentation (>50,000 hours). In the United States, a CMT design has been developed and will fly as part of the LISA Pathfinder mission. In the course of its development, multiple 3,000 hour endurance tests were performed, and three life-limiting issues were identified and resulted in design changes. In Europe, designs of both FEEP thrusters are being tested, and one will be chosen for demonstration on LISA Pathfinder. While various FEEP components and/or systems have accumulated thousands of hours of testing, program documentation indicates that the longest end-to-end testing is less than 10 percent of the required lifetime. The micronewton thrusters must work for LISA to be successful. The lack of endurance testing, the inability to perform qualification-level testing prior to the 2009 time frame (from a time perspective), and the problems encountered to date indicate that this is a significant risk area with a high degree of difficulty. While the mission team is working on three alternatives, adding alternate implementations (e.g., the addition of more thrusters to mitigate life requirements) to its planning would enhance the missionâs viability. Three separate techniques are being considered for laser frequency noise suppression. These are (1) laser pre- stabilization (PS), (2) arm locking (AL), and (3) time delayed interferometry (TDI). All three have promise: PS demonstrations have exceeded LISA requirements in laboratory demonstrations, AL is routinely used in ground- based systems, and computer simulations have shown that TDI should work. The documentation provided does not indicate the fidelity of the demonstrations with respect to LISA. Both AL and TDI system-level testing is ongoing, but again, the relation of these tests to LISA is not explained. While it is not expected that the ultimate development will have a high DoD (estimated at DoD = II), the TRL is 3-4. LISA Technical Challenges: Spacecraftâ The LISA spacecraft has been described as a âscience craft,â as the spacecraft bus is built up around the interferometer. Table 3.25 lists the LISA spacecraft accommodation require- ments and issues. The LISA optical components are documented in multiple documents: Gaussian Optics Design Rules (LISA-ASD-3001), Opto-Mechani- 15â cal Payload Design (LISA-ASD-TN-3002), Telescope Design and Tradeoffs (LISA-ASD-TN-3003), and Optical Analysis and Beam Warrior (LISA-ASD-TN-3004). The committee treated LISA as an integrated NASA-ESA project and thus did not distinguish between NASA and ESA technologies. 16â
MISSION READINESS AND COST ASSESSMENT 97 TABLE 3.24â LISA Technology Readiness Summary Heritage TRL DoD Changes from Previous Project Committee Committee Element Mission Similarities Mission/Comments Rating Rating Rating Gravitational GRACE Common design features, EM being built for LISA 4 4 III-IV reference but has a weaker coupling Pathfinder. Currently at CDR sensor to the spacecraft. LISA level. Extensive laboratory system requirements are testing of EM to date. more demanding than those of GRACE. Micronewton LISA Will fly two types of ST-7 will demonstrate 4-5 3-4 IV thrusters Pathfinder thrusters on Pathfinder. functionality but not life. Extensive laboratory testing of units for periods typically less than 15% of required lifetimes. Optical None Project claims that multiple Not enough information 6 4-5 II assembly stated commercial mechanisms provided to judgeâif pointing are meeting requirements, commercial units are to be mechanism but the project is also used, then TRL is likely high, working on an alternate but if a new architecture to the baseline pointing employing a new concept architecture and concepts is selected, then the TRL is for new mechanisms. reduced. Point ahead None Not applicable This is a critical component 3 3 II-III actuator stated with tight operational tolerances (e.g., no motion at the picometer level); ESA has a planned development program with breadboard- level testing. DRS control GPB; LISA Pathfinder will Simulations have 6 5 II-III laws LISA demonstrate functionality. demonstrated that DRS Pathfinder controls can be implemented for LISA, and LISA Pathfinder will demonstrate the required technology. Laser system TerraSAR; Laser will fly on The EM master laser 4-6 4 II-III NFIRE TerraSAR, and the system developed for LISA is to fly as a secondary Pathfinder puts this payload on NFIRE. component at TRL 6. A space-qualified fiber amplifer with a broadband electro-optic modulator is currently being tested. An end-to-end EM system is under development, and a qualification program is in place to bring the system to TRL 6 in 2010. continued
98 NASAâS BEYOND EINSTEIN PROGRAM TABLE 3.24â Continued Heritage TRL DoD Changes from Previous Project Committee Committee Element Mission Similarities Mission/Comments Rating Rating Rating Laser None Not applicable Three techniques (pre- 4 3-4 II frequency claimed stabilization [PS], arm noise locking, and time delayed suppression interferometry) are discussed. PS exceeding LISA requirements has been demonstrated, AL is stated to be a standard technique for ground-based interferometry, and TDI computer simulations indicate that the technique should work. Systems-level tests are in progress. Phase GRACE; Baseline architecture Breadboard component 3 3 II Measurement (Blackjack similar to GPS and testing is promising so System GPS GRACE. far. System verification is (PMS) receiver); planned for increasing TRL LISA to 5 by 2009 and 6 by 2010. Pathfinder The LISA Pathfinder system is different from the LISA system, but the demonstration will be highly relevant. Optical LISA LISA Pathfinder will System design is well 5-6 5 II system Pathfinder qualify components. advanced and employs well- developed components. The LP system is similar to the LISA system; the LP EM unit has undergone extensive, successful testing. NOTE: Acronyms are defined in Appendix G. LISA Technical Challenges: Operationsâ The three LISA spacecraft will be separated by 5 million kilometers in flight. In order to begin operations as a space-based interferometer, the three spacecraft will have to find each other and orient their lasers correctly. Maintaining signal to noise over this arm length and being able to extract phase information from signals with such low amplitude will be extremely challenging. Maintaining the proof mass in the right position will also be challenging. Noise sources ranging from solar pressure, solar wind buffet- ing, Earth-Moon gravity, and numerous interfering sources could also challenge the LISA measurement. While the operations of LISA have been very carefully considered and advanced plans are thorough and reasonable, this type of space operation has never been done before. LISA Technical Marginsâ The LISA project has completed numerous detailed engineering studies to back up the design and had adequate technical margins in all areas, except with the micronewton thruster performance and lifetime. The micro-Newton thrusters required for the LISA program have not demonstrated an adequate lifetime to show margin. The requirement is for 55,000 hours of operation to meet the LISA mission life. 17 However, the LISA team response to the committeeâs Request for Information (see Appendix E in this report). 17â
MISSION READINESS AND COST ASSESSMENT 99 TABLE 3.25â LISA Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude Pointing Not specified for ACS, precision Significant for the DRS. Spacecraft bus requirements determination pointing handled by Disturbance are stated to be achievable with conventional and control Reduction System (DRS) technologies. Tracking Not specified for ACS, precision pointing handled by DRS Jitter Not specified Power Orbital average 253 W (payload) Drives array area but can be met with standard GaAs 381 W spacecraft bus cell technology. Worst case 766 W, 30% contingency No challenge Data storage â Approximately 32 MB No challenge Structure Bus 314 kg Only leaves 271 kg total mass margin on Atlas V 531. Payload 259 kg Prop module 259 kg Dry mass/space 832 kg Propellant 474 kg Wet mass/space 1,556 kg LV adapter 200 kg Total 4,868 kg for 3/wet spacecraft Thermal â 10â3 K/Hz1/2 at 1 mHz thermal noise Unknown Radio- Downlink 90 kbps at Ka band No challenge frequency communications Uplink 2 kbps at Ka band No challenge Alignment â 1 mrad telescope to optical bench No challenge Propulsion â 1,169 m/s, 474 kg propellant Size, complexity, mass. NOTE: Acronyms are defined in Appendix G. currently demonstrated lifetime is on the order of 8,000 hours. While the LISA team has identified risk-mitigation plans, including maintaining multiple suppliers, ground tests, and flight tests on the LISA Pathfinder, it remains a significant issue for the success of the mission that will require time to resolve. In addition, thermal control of the thermal noise is likely to be troublesome and could drive resources. LISA Management Challengesâ LISA is a joint NASA-European Space Agency (ESA) project, based on a Sep- tember 2001 Letter of Agreement and an August 2004 Formulation Phase Agreement between the two agencies. A Joint Project Management Office for LISA was established in 2001, with NASA and ESA project managers and project scientists, who work in close collaboration. In addition, there are integrated technical and engineering teams working jointly on such technologies as the disturbance reduction system and the interferometry measure-
100 NASAâS BEYOND EINSTEIN PROGRAM ment system. Although ESA is the lead agency in developing Pathfinder there is significant NASA participation (under the NASA designation ST-7). There is considerable overlap between the technical and engineering teams building Pathfinder and those working on LISA. The project presented a well-organized team with good depth in each technical discipline. The LISA mission is planned to be co-funded by NASA and ESA and is thus dependent on each partner to maintain its contribution level and annual profile through the life of the project. As estimated by the project, the expected magnitude of the ESA contribution is approximately $440 million, in addition to funding the LISA Path- finder mission, so ESAâs participation is vital. For the LISA mission itself, ESA supplies the propulsion module that puts each spacecraft into its proper orbit, candidate micro-thrusters, and parts of the interferometry system. Managing the partnership between ESA and NASA is a major challenge, especially under the constraints imposed by high visibility and International Traffic in Arms Regulation (ITAR). Leading to a launch in the first quarter of 2016, as shown in the LISA teamâs schedule, the LISA missionâs critical path appears to be through the development of the micronewton thrusters and the phase measurement systems. The thrusterâs performance should be confirmed by the second quarter of 2010, which is in advance of the missionâs PDR by about 9 months. If there are serious performance issues with the thrusters, 9 months is not adequate time to recover and requalify in time to hold the missionâs launch date. Slipping schedule could cost about $1 million per month, according to the spending plan provided to the committee. 18 This seems underestimated, but the last 4 years before launch are about this same rate of spending. LISA Unique Challengesâ The LISA mission is a very difficult mission to implement, and to succeed it will depend on all of the technology development activities going on during pre-Phase A and the LISA Pathfinder mission. The ability to operate a space-based interferometer involving three spacecraft for 5 years with an arm length of millions of kilometers is a daunting technical challenge in such areas as attitude control, phase measurement, laser performance, and flight operations. The mission teamâs suggested mitigations are (1) reduce the arm lengths and (2) reduce the mission lifetime. The first suggestion appears to be a descoping option to reduce performance risk with no associated cost savings, while the second is a descoping option to reduce cost. The reduction of lifetime could save approximately $25 million to $28 million per year. This is a challenge for LISA owing to the fact that it takes all three sciencecraft to perform the mission, and there is essentially nothing to descope during development as there is with a multisensor, multi-instrument mission. If LISA experiences significant cost problems in PhaseÂ C, there is little by way of descoping options to help, and NASA will face the decision of absorbing the overrun or canceling the mission. A post-Pathfinder mission review and recosting seems the best way to ensure that the operaÂ tional flight system can be built to meet science performance requirements within cost and schedule. MISSION COST ASSESSMENTS Overview In response to an expected NASA âfunding wedgeâ that is to open in fiscal year (FY) 2009, NASA and DOE requested that the National Research Council (NRC) assess the Beyond Einstein mission areas and recommend one for first launch and development. To ensure cost realism, the NRCâs Space Studies Board and Board on Phys- ics and Astronomy, in consultation with NASA and DOE, identified the need for independent cost and schedule realism assessments for the 11 Beyond Einstein mission concepts. The purpose of the these assessments was to understand the projectsâ cost estimates using a consistent methodology based on previous missions of similar scope and complexity. The committeeâs goal was to provide a realistic expectation of the cost range for each mission. Assessment Process, Criteria, and Considerations The methodology employed to assess cost realism is as follows: LISA team response to the committeeâs Request for Information (see Appendix E in this report). 18â
MISSION READINESS AND COST ASSESSMENT 101 1. Acquire and normalize data for the individual mission concepts. 2. Perform independent estimates of probable costs and development time to undertake the individual mis- sion concepts. 3. Compare individual estimates with a complexity-based model to aggregate individual mission concepts into a range of cost for the Beyond Einstein mission areas. 4. Develop a budget profile for the committeeâs recommended mission sequence and compare it with the expected funding wedge to assess affordability and mission-ordering options. Data Acquisition and Normalization The first step in the process was to gather mission, instrument, technology, and spacecraft design data for each of the concepts to be considered, so as to have a common basis for assessment. Commonality was particularly important in this case, as there were broad variations in the level of detail and fidelity available or in what the advocates were willing to share. Some concepts were relatively mature, while others were closer to a conceptual paper. The committee sought to normalize these concepts to the extent possible to set a common ground rules and characteristics for comparison. The basic information required for estimating probable cost and cost ranges for each mission area was acquired by requesting information from the individual mission concept advocates through a Request for Information (RFI) process (see Appendix E in this report). The mission teams provided the commit- tee with responses to the RFI and other public documents, presentation material from various public engagements and workshops, and other material describing the proposed mission concepts. In cases where restrictions on the distribution of the RFI data applied, the committee did not make use of the RFI responses. Spacecraft, instrument, and technology data for each of the concepts were gathered at the highest level of definition consistent with Âbeing able to have a common basis for relative assessments of cost and schedule. An implicit assumption is that the proposed concepts are feasible. As the Beyond Einstein mission concepts are at significantly different levels of definition, technology readiness, and development, the independent estimates involved normalizing these disparities to provide a common basis of comparison. In select cases the scarcity of data precluded an in-depth assessment of a specific mission. However, in all cases for the Beyond Einstein Probes there was sufficient information to assess more than one mission concept for each of the mission areas. An influential variable in the probable cost estima- tion methodology is the heritage/percent new design and TRL. TRL was assessed using the risk rating approach described in the previous section. Estimation of Cost and Development Time The methods and tools employed in the estimation of cost and development time were appropriate for con- ceptual-level assessments. Several parametric estimating tools and empirical databases of technical and program- matic information were used to independently estimate probable costs and schedule for the 11 mission concepts. QuickCost, a model developed by the Science Applications International Corporation (SAIC) for NASA, was the principal tool in this study.19 QuickCost only requires objective information at the top level. This tends to level the playing field by obviating the need for the missions that are less well defined to provide information that is not yet mature. QuickCost was cross-checked with the NASA Air Force Cost Model (NAFCOM), another NASA cost model in common use in the aerospace sector. Probable cost estimates are in terms of NASA âfull costs,â including an allowance for NASA (or DOE) civil service labor cost, contractor fee, and other institutional costs such as center management and operations, general and administrative, and overhead. Parametric models were calibrated to a set of past missions suggested by the committee as specific analogies described in the previous section. For each mission, the instrument and spacecraft bus TRLs were assessed (using the standard NASA TRL ratings), as well as the technology development degree of difficulty, and were translated into cost factors. Probable cost estimates were developed for each Â mission SAIC, under contract to the NRC, provided the committee with cost-estimating expertise and tools to assist in the assessment of probable 19â cost ranges for the candidate Beyond Einstein missions.
102 NASAâS BEYOND EINSTEIN PROGRAM c Â andidate.20 In doing so, cost models were used to develop the cost estimates for preliminary design (Phase B), through full-scale development and production (Phase C/D). Comparisons to costs for similar missions were used to develop estimates of the cost for conceptual design (Phase A) and mission operations and data analysis (PhaseÂ E). Launch cost is a point estimate associated with the use of an evolved expendable launch vehicle (EELV) heavy or EELV medium, as dictated by the missionâs launch mass and orbit destination. Comparison of Cost and Schedule Estimates with Historical Data A critical question assessed by the committee is the question of when performance requirements reach a thresh- old at which they are no longer achievable within the allocated resources. To address this issue, the Complexity- Based Risk Assessment (CoBRA) model, developed by the Aerospace Corporation, was used as an independent cross-check on the project estimates and parametric model results. The goal is to understand how technical and programmatic complexity relates to cost and schedule at the system level. The complexity index is derived on the basis of performance, mass, power, destination, and technology choices, to arrive at a broad representation of the system for purposes of comparison. In examining previously built systems, cost data are generally not publicly available at the subsystem level; therefore, a system-level assessment is desirable and appropriate. CoBRA integrates a broad array of technical parameters through a ranking algorithm to derive a complexity index for a given mission compared against an empirical database of missions previously flown or in development. The complexity indices are plotted versus cost and schedule to show overall trends and a range of cost and schedule. The mission team estimates (as avail- able) and the independent parametric estimates of probable cost and schedule were overlaid against prior mission actual cost and schedule to assess the adequacy of resources and associated risk relative to missions of similar complexity. Using an aggregation of the various sources of estimates, a range of costs for each of the mission areas was defined. Development of Funding Profiles Using the ranges of cost and schedule for each mission area, funding profiles were developed for each mission. The funding profiles were assessed relative to available or projected budgets of NASA, DOE, and other sponsors (i.e., non-NASA/DOE partners) to determine the affordability of different scenarios. Two cases involve substantial potential contributions from agencies outside of NASA: LISA (ESA contribution estimated at $500 million 21) and JDEM (DOE contribution estimated at $400 million22). It was assumed that the DOE JDEM contribution would apply to SNAP, ADEPT, DESTINY, or any other JDEM mission that NASA and DOE elected to move forward with. It was also assumed that Phase A and B are covered by the FY 2007 to FY 2009/FY 2010 Beyond Einstein funding wedge. For the budget comparisons, life-cycle cost (LCC) at 70 percent confidence was used (including 20â Both QuickCost and NAFCOM generate cumulative probability-density functions for cost such that a confidence level (percentile) may be chosen. To align with recent NASA policy, 70th percentile costs are reported here. According to the March 14, 2007, note from Thomas Prince, California Institute of Technology, to the committee, entitled âSummary of 21â LISA Status in ESA Cosmic Visionâ: Given the high priority of LISA to the ESA program (as emphasized in the [Science Program Commit- tee] recommendation), given the significant investment in LISA Pathfinder (which will launch in late 2009), and given that LISA has been in the formulation phase since 2005, it is widely viewed that LISA will be chosen to go forward into the definition phase. It will be the only Cosmic Vision program mission to have gone through a full formulation phase at the time of the decision about proceeding into the definition phase. It should also be noted that as a Cosmic Vision program mission, the investment by ESA in LISA can be increased from the current 340 million euro to 650 million euro. Kathy Turner, Office of High Energy Physics, Department of Energy, âNote to BEPAC Regarding DOEâs JDEM Plans,â March 30, 2007, 22â e-mail communication: âWithin the Office of High Energy Physics (OHEP), the out-year plan for the research portion of the budget will con- tinue to support the dark energy program and is where the funds for JDEM would be provided. For out-year planning purposes, we have been using a DOE contribution to the total project cost of approximately $400 million. The FY 2007 budget and the Presidentâs Budget Request for FYÂ 2008 have allocated resources for continuing our dark energy program, including funding for SNAP R&D. In addition, funding for FY 2007 in the amount of Âapproximately $3 million and requested funding for FY 2008 of approximately $6 million will provide competitively selected R&D funding for both midterm and longer-term ground- and/or space-based dark energy concepts.â
MISSION READINESS AND COST ASSESSMENT 103 design, development, test, and evaluation [DDT&E]; production; launch; and mission operations and data analysis [MO&DA]). Results Mission Concept Cost Estimates Table 3.26 provides a summary of the independent cost estimates for the 11 Beyond Einstein mission concepts assessed by the committee. All of the costs are in real-year dollars except where noted otherwise. 23 DDT&E plus production (Phase C/D) is given in the first row. Launch services are assumed to be either $200 million for an EELV medium or $300 million for an EELV heavy. These two rows total to the mission acquisition cost. MO&DA is combined with acquisition cost to give the LCC (Phase C/D/E). For reference, the LCC as it was estimated by the advocates for each project is provided. Other metrics of interest are Phase B/C/D costs and schedule, which in this case are converted to FY 2007 dollars to allow direct comparison with the CoBRA plots. In all cases, the independent estimates were substantially higher than the project estimates. The range of cost results is shown in Figure 3.1; however, for purposes of the comparative and budget analysis that follows, the committee uses 70th percentile estimates in accordance with recent NASA policy. Comparison with Historical Data To understand how technical implementation relates to budget, a complexity index was derived, based on performance, mass, power, and technology choices. Data were assembled for a majority of robotic space missions launched over the past nearly two decades (1989 to 2007). The basis for the relationships is a database of tech- nical specifications, costs, development time, mass properties, and operational status for more than 120 robotic space missions that fall into three general categories: (1) NASA planetary and near-Earth spacecraft, (2) NASA Earth-orbiting satellites, and (3) other U.S. government, non-NASA satellite missions serving as a baseline for comparison. Only robotic spacecraft missions that meet certain criteria and constraints were considered. Large (e.g., Hubble/Cassini-class), medium (e.g., Spitzer/New Frontiers-class), and small missions (e.g., Kepler/Discovery- class or smaller) were included. Missions that are nearing launch or have been launched but have yet to complete a significant portion of their science missions are included, but it is noted that success has yet to be determined. No human-rated systems or launch systems were considered. The complexity index uses a matrix of technical factors to place in rank order a new system relative to a baseline data set. Complexity drivers include more than 30 objective technical parameters (mass, power, perfor- mance, design life, pointing accuracy/control, downlink data rate, technology choices, propulsion, mechanisms, software/data management, and so on). All parameters are demonstrable parameters dictated by project, mission, or system requirements. In this case, the âdevelopmentâ costs and schedule (Phases B/C/D) were considered excluding launch and MO&DA (Phase E). The total flight system development costs (payload instruments and spacecraft bus, excluding launch and operations) and development times (period of time from contract start until ready for launch) are the independent variables against which complexity is compared. From the information in Table 3.26, total development costs (Phase B/C/D) were derived in current-year dollars (millions of FY 2007 dollars). The resultant comparison of the Beyond Einstein missions against the empirical data set is shown in Fig- ures 3.2 and 3.3. The first thing to note is general agreement between the independent probable cost estimates and the historical actuals (cost and schedule). Note also that âin-developmentâ (not yet launched) missions are shown for purposes of comparison; however, the regression curves are derived from the âsuccessfulâ missions (launched and met or having exceeded science goals). There are four âbinsâ of complexity beginning with JDEM on the low Inflation is taken into account using the standard NASA inflation index. 23â
104 NASAâS BEYOND EINSTEIN PROGRAM TABLE 3.26â Summary of Committee Cost Estimate Results (in millions of real-year dollars, except where noted) Black Hole Einstein Great Joint Dark Energy Mission Finder Probe Inflation Probe Observatories DESTINY ADEPT SNAP CASTER EXIST CIP CMBPol EPIC-F EPIC-I LISA Con-X DDT&E + production $1,132 a $973 $1,116 $1,588 $1,290 $876 $910 $980 $1,030 $2,318 $2,059 (excluding Phase A/B) at 70% confidence Launch services $200 $200 $200 $300 $300 $200 $200 $200 $200 $300 $300 Partnering credits (DOE ($400) ($400) ($400) $0 $0 $0 $0 $0 $0 ($500) $0 for JDEM; ESA for LISA) Acquisition subtotal $932 $773 $916 $1,888 $1,590 $1,076 $1,110 $1,180 $1,230 $2,118 $2,359 MO&DA $198 $293 $410 $584 $389 $260 $103 $111 $57 $641 $695 Life cycle cost at 70% $1,130a $1,066 $1,326 $2,472 $1,978 $1,336 $1,213 $1,290 $1,287 $2,759 $3.054 confidence Mission team estimated $834 <$1,000b $724 $993 $1,095 $683 $700? $800 ? $2,045 $2,162 life cycle costâfor reference Estimated Phase C/D 69 63 63 76 69 60 62 62 63 73 77 duration (months) NAFCOM DDT&E + N/A N/A N/A N/A N/A $762 N/A $910 N/A $1,861 $1,630 production (excluding Phase A/B) at 70% confidenceâfor reference DDT&E + production in $1,085 $933 $1,070 $1,523 $1,237 $840 $872 $939 $987 $2,223 $1,974 2007$ including Phase B/C/D for COBRA comparison Estimated Phase B/C/D 81 75 75 88 81 72 74 74 75 91 95 duration (months) including Phase B for COBRA comparison Dry mass (kg) model input 2,551a 1,800 1,571 13,740 9,000? 1,409 1,600? 1,611 1,810 1,282 5,882 (provided by the mission teams) NOTE: N/A, not applicable. Other acronyms are defined in Appendix G. a Following the release of the report, the DESTINY principal investigator notified the committee that his team misunderstood the committeeâs request for the payload dry mass, and that the correct figure is 1,784 kg. If this revised figure were to be used in place of the one originally supplied to the committee, the cost estimate in this table for the DESTINY mission would be reduced by approximately 15 percent. This revised number would not change the $1 billion estimated cost which was used to characterize JDEM for the committeeâs budget analysis, and would have no impact on any of the committeeâs conclusions, findings, or recommendations. b In the prepublication copy of this report, the â<â sign was accidentally omitted from the table. continued
MISSION READINESS AND COST ASSESSMENT 105 TABLE 3.26â Continued Row 1 (DDT&E + production [excluding Phase A/B] at 70% confidence): This row contains the QuickCost cost model independent estimates for the development and production cost of each mission. It does not reflect partnering credits. The numbers in this row include sufficient reserve to achieve the NASA standard 70% confidence level. Row 2 (Launch services): This row contains the independent estimate of what the launch costs will be for each mission. Row 3 (Partnering credits [DOE for JDEM; ESA for LISA]): The study assumed that DOE participation in JDEM will be on the order of $400 million and that ESA participation in LISA will be on the order of $500 million. These values were subtracted from the development cost in the table (as a cash contribution) because the budget analysis that uses the resultant numbers is performed against theÂ committeeâs extrapolation of the resources available to NASA through FY 2020. Row 4 (Acquisition subtotal): This row is a subtotal of rows 1, 2, and 3. Row 5 (MO&DA): This row contains the QuickCost independent estimate of the mission operations and data analysis costs associated with operating the mission control function and data archiving over the operating life cycle of the mission. The Beyond Einstein missions varied in the number of years included in the operating life cycle. The Phase E (MO&DA) costs in this row reflect the number of operating years as defined by the projects themselves in briefings to the committee. Row 6 (Life cycle cost at 70% confidence): This row is a sum of rows 4 and 5. Because the number predominately includes cost model 70% confidence-level values, it is labeled 70% confidence. This row does not include costs for any necessary work in Phase A or B. Row 7 (Mission team estimated life cycle costâfor reference): This row represents the life cycle costs as estimated by the mission teams themselves and briefed to the committee. It is included as a comparison to the independent Phase C/D/E estimate in row 6. The mission teams provided cost information in accordance with the RFI (see Appendix E) in real-year dollars, and these figures include costs to partner agencies where applicable (JDEM and LISA). Row 8 (Estimated Phase C/D duration [months]): The value in this row is the QuickCost cost model predicted duration of full-scale development in months. This value is included in the table because it is used as the time period over which to phase the development cost in the budget analysis. Row 9 (NAFCOM DDT&E + production [excluding Phase A/B] at 70% confidenceâfor reference): The NAFCOM results for four missions are documented in row 9 as a cross-check. The costs in row 2 are comparable in content to the costs in row 1. The NAFCOM results are somewhat lower than the QuickCost results but are within an acceptable statistical spread. Row 10 (DDT&E + production in 2007$ including Phase B/C/D for COBRA comparison): Several discussions and plots of output from the Aerospace Corporationâs COBRA model are included in the report. The COBRA modelâs output is structured differently from that of QuickCost; it includes costs for Phases B, C, and D and provides them in FY2007 dollars. Row 10 converts the QuickCost output in row 1 so that it is comparable to COBRA results reported elsewhere in the report by adding Phase B costs and converting to FY2007 dollars. Row 11 (Estimated Phase B/C/D duration [months] including Phase B for COBRA comparison): Several discussions and plots of output from the Aerospace Corporationâs COBRA model are included in the report. The COBRA modelâs output is structured differently from that of QuickCost; it includes costs for Phases B, C, and D. Row 11 expands the full-scale duration estimate in row 8 to include Phase B in order to be comparable to COBRA results. Row 12 (Dry mass [kg] model input): Because mass is a principal independent variable in all the cost models used in this study, it is noted in row 12. The mass values were taken from the mission team briefings given to the committee. Mass is useful in understanding some of the differences in cost. However, since the cost models used other independent variables in addition to mass, it is not fully explanatory. Other variables such as the engineering and manufacturing complexity of the missions can drive cost as much or more than mass.
106 NASAâS BEYOND EINSTEIN PROGRAM 3,500 50% Confidence 60% Confidence 3,000 70% Confidence Project Estimate 2,500 Millions of Real-Year Dollars 2,000 1,500 1,000 500 0 Y N -X T R SA IP ) T AP ol ) PL IS W TI TE EP on BP C LI ES EX (U SN (J C AS AD M D IC IC C C EP Mission EP FIGURE 3.1â Ranges of estimated life-cycle costs to NASA. NOTE: Acronyms are defined in Appendix G. 3-1 end and culminating with the large observatories (LISA and Con-X) as most complex. Approximate development cost (Phase B/C/D) and schedule regimes are as follows for the Beyond Einstein mission areas: â¢ Large Observatories (LISA and Con-X): $2 billion; 8 years â¢ BHFP (EXIST, CASTER): $1.5 billion; 7 years â¢ JDEM (SNAP, ADEPT, DESTINY): $1 billion; 6 years â¢ IP (CIP, CMBPol, EPIC-F, EPIC-I): $1 billion; 6 years Note that the inclusion of launch service ($200 million or $300 million) and MO&DA (which varies, but is on the order of $25 million per year) is above and beyond the development cost numbers noted above. Budget Analysis Once the cost and schedule estimates of each individual Beyond Einstein mission were completed, the costs were time-phased against the required schedule span. The committee compared the resulting time-phased cost to the expected available budgets for these missions as currently understood by the NASA advanced budget plan- ning process. The Beyond Einstein funding wedge is part of the NASA Science Mission Directorate budget. The science budget further subdivides into themes, and Beyond Einstein is part of the astrophysics theme, which also includes general astronomy and astrophysics missions such as the James Webb Space Telescope. At the time of this study,
MISSION READINESS AND COST ASSESSMENT 107 System Cost as Function of Com plexity Development Cost (Project) Successful Missions y = 5.6292e6.3348x R2 = 0.9014 In-Development Missions Development Cost (Estimate) 10000 Large Obs BHFP JDEM Cost (FY07$M) 1000 IP LISA Con-X 100 EXI ST CASTER EPIC-F, CIP EPIC-Bock, CIP SNAP, DESTINY 10 30% 40% 50% 60% 70% 80% 90% 100% Com plexity Index FIGURE 3.2â Comparison of project cost estimates and independent cost estimates to NASA. NOTE: Acronyms are defined in Appendix G. 3.2 the Beyond Einstein funding wedge was established through FY 2012. Obviously the budgets for Beyond Einstein that might be available after the FY 2012 budget horizon are not known with certainty. However, it is plausible to extend the FY 2006-FY 2012 budget trajectory into the future using a curve function that assumes neither dramatic increases nor decreases from the FY 2006-FY 2012 trend. Figure 3.4 does that by assuming that the FY 2011- FYÂ 2012 interval slope ($211 million/$157 million, or a 34 percent increase) will continue into the future but will be dampened to more reasonable growth after FY 2013 equal to the square root of the previous yearâs increase. As can be seen in the figure, this assumption yields an out-year budget curve that extends the general curvature of the FY 2011-FY 2012 interval but with a moderately decreasing slope. Using this assumption allowed the committeeâs budget analysis to make rational observations about likely starting dates and affordable development intervals of the Beyond Einstein budget scenarios. For the budget analysis, the committee compared the time-phased cost of various missions to NASA with the available NASA budget. Figure 3.5 shows the 11 Beyond Einstein mission concepts with their nominal time lines shown in comparison against the funding wedge. LISA and the JDEM mission budget profiles were prorated to account for the ESA and DOE contributions, respectively. These contributions were not taken into account when developing the mission cost estimates, but are applied in the budget analysis when comparing the mission cost profile to the available budget.
108 NASAâS BEYOND EINSTEIN PROGRAM Schedule as Function of Com plexity Development Time (Project) Successful y = 89.813x +10.842 To-be-determined R2 = 0.7542 Development Time (Estimate) 132 120 Development Time (months) 108 96 Large Obs BHFP 84 BHF JDEM 72 IP LISA 60 LISA Con-X 48 EXIST 36 CASTER EPIC-F, CIP 24 EPIC-BockCIP , 12 SNAP, DESTINY 0 30% 40% 50% 60% 70% 80% 90% 100% Com plexity Index FIGURE 3.3â Comparison of project and independent schedule estimates. NOTE: Acronyms are defined in Appendix G. 700 3-3 600 500 Millions of Real-Year Dollars âReasonableâ exponential dampened growth 400 Inflation only after FY17 300 200 100 NASA budget through FY12 0 FY06 FY07 FY08 FY09 FY10 FY11 FY12 FY13 FY14 FY15 FY16 FY17 FY18 FY19 FY20 FY21 FY22 FY23 FY24 FY25 Fiscal Year FIGURE 3.4â NASAâs assumed Beyond Einstein funding wedge, FY 2006-FY 2025. 3-4
MISSION READINESS AND COST ASSESSMENT 109 600 500 Wedge Destiny Millions of Real-Year Dollars 400 ADEPT SNAP CASTER EXIST 300 CIP CMBPol EPIC-F 200 EPIC-I LISA Con-X 100 0 FY06 FY07 FY08 FY09 FY10 FY11 FY12 FY13 FY14 FY15 FY16 FY17 FY18 FY19 FY20 Fiscal Year FIGURE 3.5â Cost to NASA of Beyond Einstein mission concepts compared to the NASA budget wedge. 3-5 NASAâs Beyond Einstein funding wedge through FY 2009 is inadequate to prepare any Beyond Einstein mission for an FY 2009 start without a significant increase in the funding wedge or substantial investment from outside NASA. The JDEM missions (SNAP, ADEPT, and DESTINY) are the notable exceptions compatible with the NASA budget wedge because of the DOE contribution. The available FY 2006-FY 2009 funds total about $60 million. Most NASA science missions spend an amount equal to about 10 percent of their Phase C/D full- scale development (not including launch services) on Phase A/B activities to reach PDR, at which point they are confirmed by NASA management for a new start. In addition, the FY 2009 funding level of $37 million is inadequate to start a billion-dollar-class mission. The first-year funding for such a mission would more normally be $100 million or more. SUMMARY The realism of technology and management plans and of cost estimates is a primary consideration called for in the committeeâs statement of task. The assessment of the five Beyond Einstein mission areas is necessarily comparative. Three specific criteria are used for the assessment: technical readiness, management readiness, and cost realism: â¢ Technical readiness elements are the instrument, spacecraft, operations, and technical margins; â¢ Management readiness elements include team organization, schedule, and other special challenges; and â¢ Cost realism was done as an independent estimation of the probable cost.
110 NASAâS BEYOND EINSTEIN PROGRAM Technical Readiness Black Hole Finder Probes CASTERâ There are multiple technical readiness issues with CASTER. The instrument uses new and unproven technologies, the spacecraft design is at a conceptual stage, and it is not clear that any existing launch vehicle can accommodate the CASTER size, length, and associated high-center-of-gravity location. Specifically, more time is needed to develop the detector, the scintillator, and the collimator shielding technique. To achieve the re- quired sensitivity, CASTER will require a very large number of detector modules. Achieving the necessary yield of detectors to meet CASTERâs requirements will be a significant manufacturing and production challenge. The CASTER team proposes to use photo-multiplier tubes (PMTs) as the readout sensor. While PMTs have been used many times in space applications, the Burle Planacon tube selected for CASTER is not flight-rated, and there is no flight experience with this device. Similarly, the lanthanum bromide (LaBr 3) scintillators have no flight heritage and are in an early state of development. A significant effort will be required to bring both the PMT and LaBr3 technologies to the level of maturity necessary, TRL 6, to begin a mission. Additional technology issues include detector shielding and the opaqueness of the coded-aperture mask needed to meet angular resolution requirements at energies up to 600 keV; both the detector shielding and the coded-ap- erture mask will be difficult to manufacture. The requirements placed on the coded-aperture mask are severe and more challenging than those of any coded-aperture mask flown to date. The proposed CASTER spacecraft design is at a preliminary stage. The CASTER observatory, which includes the instrument and the spacecraft, is extremely heavy; the structure will present a serious technical challenge to design. In addition, the mass of the CASTER observatory requires the use of the largest U.S. launch vehicle, and even then, it cannot be placed in the desired equatorial orbit. EXISTâ The proposed EXIST spacecraft is in the conceptual stage with some basic design trade studies completed. Several of the key instrument technologies are judged to be at TRLs well below 6, and so significant technology development work (high- and low-energy detectors, coded-aperture mask, shielding/anticoincidence system) will be required before EXIST is ready to progress to mission development. The optics for EXIST are in the coded- aperture masks and, while laboratory prototypes have been demonstrated, significant development efforts are still anticipatedâthat is, the pinhole pattern and the actual laminate construction of the masks for the two telescopes will require significant development. The cadmium-zinc-telluride/application-specific integrated circuit (CZT/ASIC) and silicon detector/readout electronics have heritage from other programs, but the technology development is more complicated than what has been demonstrated in the past, and packaging will be challenging. The packaging of the detector assemblies will be challenging, and the manufacturing of the large number of subsystems will also be a challenge. In addition, the Fast On-board Burst Alert System has to be developed and debugged, and will be a driver for the spacecraft attitude determination and control system. Constellation-X The proposed Constellation-X mission is the result of detailed studies and design work. Every major element of the Con-X instruments is at a TRL of 5 or lower, which presents major technology development challenges for the mission. The Con-X observatory employs two telescope systems: the Spectroscopic X-ray Telescope and the Hard X-ray Telescope. The Flight Mirror Assembly optics used in the SXT is driven in large part by the need for large collecting area and high angular resolution. The fabrication of the 10,000 mirror segments, verification of their optical performance, and proper mounting and alignment of the segments to meet Con-X requirements will be challenging. Although significant detailed planning for the FMA has been performed, it is not obvious how much of this planning and the experience of the Con-X mission team members will transfer to the contractor that will be selected to produce the FMA. The SXT instrument, and therefore mission success, depends on the availability of the X-Ray Microcalorimeter Spectrometer. A major XMS challenge is the readout electronics associated with
MISSION READINESS AND COST ASSESSMENT 111 the detectors. In particular, sampling speed combined with the requirement for a very low noise figure are key design drivers for the readout electronics. The SXT and HXT instruments drive multiple spacecraft design and performance requirements, for example, attitude determination and control, data storage, and thermal considerations. The Con-X mission has adequate technical margins in most areas. However, the level of maturity of the FMA and the potential increase in mass to address issues in accommodating the XGS and HXT are a concern. The 1 percent mass margin for the proposed launch vehicle on Con-X may not be sufficient for the project. Inflation Probes CIPâ The Cosmic Inflation Probe mission team provided a complete description of its proposed implementation and, in general, makes use of available technologies or technologies being developed for other programs. There are no serious technology readiness issues for CIP, although work remains to be done to determine whether the detector noise figure is adequate at the planned higher operating temperature. The CIP detector uses the same Teledyne Hawaii-2RG HgCdTe detectors currently planned for JWST, but CIP will be operating the detectors at a somewhat higher temperature. The major outstanding issue is whether the dark current level is acceptable at the higher temperature. There are no unusual or unduly challenging requirements for the CIP spacecraft. The CIP project allocated adequate technical margins in most areas, but did not provide margins for attitude control and data link; however, these areas are not stressing the state of the art and do not raise significant risk issues. CMBPolâ The Cosmic Microwave Background Polarimeter mission team provided a concept for its proposed instrument to measure the polarization of the cosmic background, but little detail was provided on the implemen- tation of its spacecraft and the overall mission, although it appears to be based on NASAâs Cosmic Background Explorer mission. The CMBPol instrument uses a variable-delay polarization modulator and a folding mirror to control the entry of stray light into the cooled detector array; similar VPMs have been prototyped at GSFC and are under evaluation, but none has flown in space. The detector challenge will be to keep the noise low enough to provide the sensitivity necessary to measure the polarization of the cosmic microwave background. There is concern about the detailed design of the detector system, particularly the signal-to-noise ratio, and this is an area where an investment of time and money could potentially be put to good use. EPIC-Fâ The Experimental Probe of Inflationary Cosmology mission team provided a fairly complete description of its instrument, mission, and spacecraft. The primary area of technical concern is with the instrument. Antenna development for the focal plane array is the major technology issue, as well as integration of the cryogenic optics with the detector system to achieve the required low noise operation. The wave plate technology planned for use in the microwave optics of EPIC-F has been matured to TRL 6 in ground testing. The NTD Ge bolometric detectors are not considered to be a serious challenge; however, packaging may be a challenge for all missions planning on using these detectors to keep the noise to an acceptable level. The deployable sunshield will require careful design and testing. It is similar to but much smaller than the one being developed for JWST. The spacecraft requirements for EPIC-F appear to be modest and are not expected to be a challenge. EPIC-F showed good technical margins, although no margins were provided for attitude control and data communications. In addition, the sensitivity needed for the instrument is significantly greater than that needed for previous instru- ments and will present a very significant technical challenge to meet. EPIC-Iâ Insufficient information concerning the spacecraft and mission concept was provided for the committee to adequately evaluate the technical readiness of the Einstein Polarization Interferometer for Cosmology.
112 NASAâS BEYOND EINSTEIN PROGRAM The project is proposing corrugated horn antennas similar to those flown on COBE. Similar heritage could be made for the bolometers if they are truly close to the NTD Ge devices used for Planck and Herschel or TES devices from SCUBA and GBT. Joint Dark Energy Missions ADEPTâ The Advanced Dark Energy Physics Telescope mission team provided insufficient information for the committee to adequately evaluate the technical readiness of the proposed mission. The mission will be based on technologies developed for missions such as Swift and the commercial GeoEye imaging spacecraft. They will be using the same Hawaii HgCdTe 2k Ã 2k infrared detectors that JWST uses, but with the cutoff frequency modified to 2 Î¼m. There is some challenge to this modification, but there are ongoing programs that should demonstrate even lower cutoff frequencies. DESTINYâ The Dark Energy Space Telescope mission team provided a complete description of its proposed mis- sion with broad use of proven technologies. Key technologies for the instrument and spacecraft were rated at TRL 6 or higher, with the exception of the detectors, which were rated at TRL 5 by the committee. The optics required for DESTINY is within the state of the art for size, prescription, and precision. Employ- ing a 1.65 m primary mirror, the optics for DESTINY can be built without any special challenge. The proposed detectors are 2k Ã 2k Hawaii-2RG devices. While the sensor chip assemblies are very similar to devices on JWST, there are differences, most notably the cutoff wavelength. The only challenge for the spacecraft is in the area of pointing and stabilization, and depends in large part on the performance of the camera fine-guidance subsystem. SNAPâ The Supernova Acceleration Probe mission team provided extensive details on its planned approach, with adequate technical margins in all areas. SNAP technologies are either mature or progressing toward TRL 6 in well-planned steps. SNAP uses two types of detectors, a Lawrence Berkeley National Laboratory-supplied, radiation-hardened charge-coupled device and a Rockwell- or Raytheon-supplied mercury-cadmium-telluride infrared detector. The ability of LBNL to produce the required number of CCDs in the needed time frame is a concern. The performance of the integrated instrument could be a challenge to maintain low noise levels over temperature. The focal plane plate is about twice the size of existing devices and could present a challenge. All components in the spectrograph are standard and should pose no development risk with the exception of the Image Slicer. LISA The Laser Interferometer Space Antenna mission team provided extensive details on the proposed mission. The LISA system will be very challenging to implement, in large part because many of the key technologies are at low TRL levels. These include the Gravitational Reference Sensor, optical systems, laser systems, phase measurement systems, laser frequency noise suppression systems, and micronewton thrusters. The LISA team, however, has laid out a comprehensive plan to mature these key technologies prior to initiating full-scale development for LISA. These plans include the LISA Pathfinder demonstration mission, which will serve to reduce risk and demonstrate on-orbit performance of most of the key technologies. The optical materials, components, and techniques used in LISA have significant heritage. The LISA Pathfinder optical system (while different in design) will provide significant confidence in the system. The phase measurement system for LISA employs both a photo receiver and a phase meter. Other missions have used similar architectures to the one planned for LISA, and ongoing breadboard testing of both components has been successful to date. The micronewton thrusters are the most challenging technology development being addressed by the LISA team. The micronewton thrusters must work for the entire life of the mission for LISA to be successful. The lack of endurance testing, the inability to perform qualification-level testing prior to the 2009 time frame (just from
MISSION READINESS AND COST ASSESSMENT 113 a time perspective), and the problems encountered to date indicate that this is a significant risk area with a high degree of difficulty. Three separate techniques are being considered for laser frequency noise suppression. The LISA spacecraft has been described as a âscience craft,â which is an accurate description, as the spacecraft bus is built up around the interferometer. The three LISA spacecraft will be separated by 5 million kilometers in flight. Maintaining signal to noise over this arm length and being able to extract phase information from signals with such low amplitude will be extremely challenging. Maintaining the proof mass in the right position will also be challenging, but the initial acquisition, alignment and tracking will be extremely challenging. Management Readiness Management readiness elements included team organization, schedule, and other special challenges. Not all of these criteria were discussed by the individual mission teams. A summary of the key points that were presented by the mission teams is included here. Black Hole Finder Probes CASTERâ The CASTER team is a modest-sized team and is well within the experience base of the Southwest Research Institute to manage. There is no known significant foreign contribution planned for CASTER, thus less- ening ITAR problems and eliminating the missionâs vulnerability to priority changes of foreign governments. The CASTER mission schedule proposes to launch 4.5 years after Preliminary Design Review, which is tight even if progress is made by the mission in raising the Technology Readiness Levels of the elements. The challenging part of the proposed schedule will be to complete the technology development and detector production activities. EXISTâ It is assumed that the mission will be managed by NASAâs Goddard Space Flight Center, because GSFC has been deeply involved with EXIST for the past few years. The proposed schedule of 4.25 years from PDR to launch is quite tight, given the extent of the detector production effort and the roll-up of instrument assembly into an observatory. Con-Xâ The Con-X team is led by GSFC, with the mission scientist at the Smithsonian Astrophysical Observatory (SAO). There are no special project management challenges for Con-X. The schedules supplied to the committee focused primarily on technology development schedules. Inflation Probes CIPâ CIP is managed by SAO, with strong support from Lockheed Martin. The proposed schedule shows a PDR in the first quarter of 2010 and a launch in the second quarter of 2013, which is an extremely aggressive schedule. CMBPolâ The CMBPol mission was presented as a concept only, and no detailed schedule was made available. EPIC-Fâ The EPIC-F project will be managed by the Jet Propulsion Laboratory and is certainly within the experi- ence base of missions led by JPL in the past. The EPIC-F team has proposed a 60 month development schedule, which is reasonable based on the complexity of the mission and the current TRLs of the critical technologies. The development of the cryogenics payload will be the most significant schedule challenge for EPIC-F, along with integration of the payload with the commercial spacecraft bus. EPIC-Iâ The EPIC-I team is led by the University of Wisconsin-Madison with the industrial partners General Dynamics and Ball Aerospace. No information regarding schedule was provided.
114 NASAâS BEYOND EINSTEIN PROGRAM Joint Dark Energy Missions ADEPTâ ADEPT has a diverse science team from a number of organizations. There was no other information presented relative to team organization and operations. DESTINYâ Assuming that the team responsibilities remain unchanged, there are no obvious management chal- lenges to the DESTINY mission. There was very little schedule information provided by the DESTINY team. SNAPâ Managing the SNAP project that has international partners as well as two U.S. government centers (GSFC and LBNL) could prove to be a challenge. The proposed schedule shows 4.75 years from the PDR to launch, which is barely adequate development time for a mission of this complexity. LISAâ The LISA mission is to be co-funded by NASA and the European Space Agency and is thus dependent on the willingness of each agency to maintain its contribution level and profile through the life of the project. Managing the partnership between ESA and NASA is a major challenge, especially under the constraints imposed by high visibility and ITAR. The LISA missionâs critical path is through the development of the micronewton thrusters and the phase measurement systems. LISA did present a very well-organized team with good depth in each technical discipline. Cost Assessment Using a consistent methodology, an independent estimate was performed for the purpose of comparison with previous missions of similar scope and complexity in order to provide a realistic expectation of the cost range for each mission concept. While not exacting, relative assessment and comparison with project estimates as available indicates higher costs and longer schedules than previously estimated for each mission. The committee developed a set of most probable budget profiles for the candidate Beyond Einstein missions. Although some came closer to the Beyond Einstein budget profile than others, the committee concludes that there are realistic options for NASA to initiate JDEM and LISA with or without its partners. As one option, the commit- tee assessed funding profiles against the available NASA funding wedge, taking into account non-NASA budget contributions. While the Beyond Einstein funding wedge is inadequate to develop any Beyond Einstein mission on its nominal schedule, contributions from non-NASA partners, as is the case for JDEM and LISA, could alleviate budget stresses but would require additional management, commitments, and coordination. Furthermore, mission development could be slowed to adhere to the available budget, with the effect of delaying launch.