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Grading NASA's Solar System Exploration Program: A Midterm Report FIGURE 6.1 The Deep Space Network allows NASA to communicate with distant spacecraft. However, future missions will seriously strain its capabilities. SOURCE: NASA.
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Grading NASA's Solar System Exploration Program: A Midterm Report 6 Enabling Technologies Advanced technology to enable planetary exploration missions is addressed in the New Frontiers in the Solar System decadal survey.1 Subjects under the heading of Advanced Technology in that report are (1) technology development, (2) generic technologies, (3) mission-specific technologies, (4) technologies for the following decade, and (5) the Deep Space Network.2 NASA defines technology for future space missions according to technology readiness levels (TRLs) on a scale of 1 to 9. Technologies that have a low TRL rating are the most immature and require the most funding to make them available for incorporation into spacecraft missions. For example, a TRL of 1 means that the basic principle has been observed and reported, whereas a TRL of 9 means that the hardware has actually flown on a mission and proven successful. In the past, NASA has funded technologies at all levels of readiness through different programs. However, in recent years the agency has cut funding, starting with funding for technologies with the lowest levels of readiness and then eventually for those higher up the scale. Today the agency is funding very little technology development except at the highest TRL levels. NASA has ceased sponsoring the development of cutting-edge technology and has made severe cuts to the New Millennium technology development program. Enabling Technologies OVERALL ASSESSMENT: Grade: D Trend: The committee is seriously concerned that NASA has severely cut back its technology development programs, making it extremely difficult for the agency to conduct remaining missions recommended by the decadal survey. Many of the technologies addressed individually in this chapter have received grades as high as they are only because of past progress, but have suffered substantially in recent years. Overall, NASA’s enabling technologies program lacks funding and strategic direction yet is vital to future progress in implementing the decadal survey goals. Because of this, the committee has given the agency a grade of D with a downward trend. Unlike other areas of this report, enabling technologies is one area in which the committee must conclude that the only realistic solution to the lack of progress in technology development is for NASA to reinvigorate its 1 See the section entitled “Advanced Technology” in Chapter 8, “Recommended Flight Investigations and Supporting Ground-Based Activities: 2003-2013,” in National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, The National Academies Press, Washington, D.C., 2003, pp. 202-206. 2 The complex subject of enabling technologies is further discussed by this committee in Appendix C (providing greater detail on technology programs) and Appendix D (providing an explanation of technology readiness levels).
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Grading NASA's Solar System Exploration Program: A Midterm Report technology development program and to create a technology development program that is independent of flight programs. This independence is vital because when flight programs have gone over budget in the past, technology development funding has often been one of the first things to be cut by program managers, thereby creating a situation in which technology development is never properly funded. An independently funded technology development program would be insulated from such pressures. The committee stresses that it is important that safeguards are put in place so that the independence from flight programs does not result in a nonalignment with future mission needs. Recommendation: NASA should develop a strategic plan for technology development and infusion independent of flight programs. In addition, NASA should restore funding to its New Millennium program. TECHNOLOGIES FOR THE FOLLOWING DECADE Low-TRL technology programs are the most conceptual and hence are focused on the long-range technology needs. The Cross-Enterprise Technology Development Program (CETDP) funded many technologies needed for planetary exploration. When NASA formed the Exploration Mission Systems Directorate, the agency moved the CETDP/Space Technology Program to that directorate and reprogrammed the resources ($300 million to $400 million) to exploration needs (i.e., human spaceflight). As a result, NASA no longer has a dedicated major source of funding for long-range technology needs for planetary exploration. Mid-TRL funding in the Science Mission Directorate (SMD) is in three current programs—in Space Propulsion, Radioisotope Power, and the Mars Technology program. All of these programs can address significant needs for mid-TRL technology or advanced development, but all have seen substantial funding reductions in the past 3 years. At high TRLs, spaceflight validation has been important in infusing a number of spaceflight technologies into flight missions. The New Millennium program has played a key role in flight experiments, including subsystem experiments on the ST-6 and ST-8 spacecraft, as well as a system experiment on the ST-5 and ST-7 spacecraft. However, funding reductions in the FY 2008 New Millennium budgets have already delayed the ST-8 flight (testing a lightweight solar array, commercial off-the-shelf processor) and indefinitely postponed the ST-9 project. The committee considers NASA’s recent actions concerning enabling technologies—like its recent actions concerning research and analysis—to be examples of the agency’s making short-term budgetary decisions that threaten the long-term viability of its overall program. Many of the remaining missions recommended in the decadal survey cannot be accomplished only with existing technology. There are enabling components that are required: Venus In Situ Explorer: Multiple technology developments are required; South Pole-Aitken Basin: Guidance and associated autonomy technologies are required; Comet Surface Sample Return: The sample return can be accomplished now, but is too expensive; Jupiter deep atmosphere probes: NASA’s Juno mission accomplishes some of the Jupiter atmosphere science, but the decadal survey calls for probes deep into the atmosphere to provide more details; and Europa Geophysical Explorer: The current Jet Propulsion Laboratory design with eight Multi-Mission Radioisotope Thermoelectric Generators (MMRTGs) cannot be flown by 2020—there is insufficient plutonium fuel to accomplish the mission with MMRTGs. Without the Advanced Stirling Radioisotopic Generators, future missions to the outer solar system become increasingly difficult, if not impossible. The committee is concerned because NASA has not invested in required technology and shows little indication of reversing this trend. If this trend is not reversed immediately, the number and types of missions that the agency will be able to undertake in the future will be severely reduced.
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Grading NASA's Solar System Exploration Program: A Midterm Report TECHNOLOGY DEVELOPMENT New Frontiers Recommendation “The SSE Survey recommends that NASA commit to significant new investments in advanced technology so that future high-priority flight missions can succeed.” (p. 8) The committee has chosen to highlight below 13 separate areas from the decadal survey. Results of Midterm Review Advanced Radioisotope Power Systems Grade: B Trend: The decadal survey noted that advanced radioisotope power systems (RPSs) are required to replace the depleted inventory of first-generation RPSs. Solar power is generally insufficient beyond the asteroid belt, provides limited power for spacecraft systems, and severely limits the lifetime of landed spacecraft. Full qualification and use of the Multi-Mission Radioisotope Thermoelectric Generator on the Mars Science Laboratory scheduled for launch in 2009 provides an advanced system that will be fully qualified for other landers. While the specific power is low, the MMRTG offers a reliable system, and NASA has made significant progress. NASA plans work on Stirling converters, and if this is successful it will reduce the requirement for plutonium on future missions and enable new missions using radioisotope electric propulsion (REP). Results of Midterm Review In-Space Fission-Reactor Power Source—Nuclear-Electric Propulsion Grade: Withdrawn from effort Trend: These decadal survey recommendations were based on the assumption of a continuing nuclear power and propulsion program in NASA under the Prometheus program. With the demise of Prometheus, these recommendations are now moot, although the loss of the technology is regrettable. However, a significant amount of work was accomplished that allows better appreciation of the inherent issues in bringing this technology to fruition. Energy conversion systems for surface power systems are still being worked on as part of the Constellation program; these efforts should be monitored for possible use in future robotic solar system exploration missions. Results of Midterm Review Advanced Ion Engines Grade: A Trend: In 2005, NASA canceled work on the Prometheus program to develop a fission reactor to power spacecraft. Without a nuclear reactor, the only way of continuing to accomplish high (≥3 km/s total in-space) delta-V missions is with solar electric propulsion (SEP), or potentially REP. The 30 cm thruster used for the Deep Space-1 and Dawn spacecraft was not optimized for specific power. The NASA Evolutionary Xenon Thruster (NEXT) and High Voltage Hall Accelerator (HiVHAC; an advanced Hall effect thruster) should contribute to lower mass, lower costs, and lower risks and will help to enable more challenging science missions. Results of Midterm Review Aerocapture Grade: C Trend: While there have been advances in aerocapture, flight qualification is required before its use in planetary missions will be acceptable. Currently the only approach to flight qualification is the New Millennium program. With
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Grading NASA's Solar System Exploration Program: A Midterm Report the budget downturn through FY 2010, there is no mechanism to qualify aerocapture under the current approach prior to the end of 2013. In the absence of a flight test, there should be a detailed study of how far the ongoing testing of thermal protection system concepts for the Crew Exploration Vehicle (CEV) can help qualify the needed systems for aerocapture in robotic exploration of the solar system. Results of Midterm Review Ka-band Communications Grade: A Trend: NASA continues to move toward use of the Ka band as the standard for deep-space communications. Advanced coding and compression for part of the Ka-band architecture are in development, and all Deep Space Network (DSN) 34-meter stations are now upgraded to use Ka band. Future needs have been quantitatively assessed, and a way forward using arrays of small antennas has been articulated. The aging 70-meter antennas are in desperate need of both current maintenance and eventual replacement with Ka band with the same equivalent aperture area. Failure to address the need to maintain and upgrade the DSN could place the entire NASA planetary exploration program in jeopardy of suffering a single-point failure should any 70 meter antenna system fail. Recommendation: NASA should conduct a study of the trade-offs of the cost versus risk of developing a Ka-band array system to handle the required transmissions (uplink and downlink) and determine whether optical communications are required for data delivery during the 2013-2023 time frame. Prior to the next decadal survey, NASA should present the results of such a study to the science community. Results of Midterm Review Optical Communications Grade: F Trend: The development of first-generation optical communications has been put off until 2018. The Deep Space Network Roadmap suggests that an optical communications infrastructure may be operational by 2022. However, the committee was informed that these dates and the system are only notional and that NASA does not have a plan to even select a basic architecture. Optical communications will require technology developments on the spacecraft side (transmitter, receiver, guidance and control, and software developments) as well as infrastructure on the ground side.3 NASA should determine whether optical communications are required for data delivery during the 2013-2023 time frame and scope the technology development, operations, and maintenance required for a notional system. Results of Midterm Review Spacecraft Autonomy Grade: C Trend: The New Millennium ST-6 Autonomous Science Experiment on Tacsat 2 validated orders-of-magnitude increases in science per bits downlinked. The AutoNav technology qualified on Deep Space-1 was used on the impactor on the Deep Impact mission. However, there is no clear path for these focused technologies to have a general impact on subsequent missions. The autonomy program was canceled in 2004 with no funding for further development of either of these focused technologies. The state of the art and realistic expectations need to be well articulated to the science community prior to the next decadal survey. Results of Midterm Review Advanced Avionics Packaging and Miniaturization Grade: B Trend: 3 Unlike the existing Deep Space Network with the receiving stations located on the ground, current concepts for optical communications networks envision receiving spacecraft in Earth orbit; these receiving spacecraft would intercept the beamed information and relay it to the ground.
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Grading NASA's Solar System Exploration Program: A Midterm Report In the recent past, NASA made significant progress on developing advanced avionics packaging and miniaturization. NASA has made progress under previously funded programs, such as X2000, the CETDP, and the Prometheus/Deep Space Avionics program. But with the exception of the Mars Technology Program, most of the funding in these areas has been eliminated. The progress noted above has fed new technologies into many of the current missions, but without these programs many future programs are in jeopardy. The X2000 and Prometheus/ Deep Space Avionics programs were focused on the outer planets and specifically on a Europa mission. If NASA is to comply with the decadal survey recommendation to fund a Europa mission (see Chapter 3 in this report), the agency will have to develop radiation-hardened electronics. There has been no continued development of the CETDP high-temperature/high-pressure/corrosion-resistant technologies required for the Venus In Situ mission. Cold-temperature/thermal cycling electronics are under development as part of the Mars program and should be assessed for any relevance to the Comet Surface Sample Return mission and Titan missions. Results of Midterm Review Instrumentation Miniaturization Grade: C Trend: Programs for support of these developments are in place, but funding has been eroding for non-Mars programs. Four continuing Planetary Science Division research and develpment programs are addressing the instrument technology needs: Planetary Instrument Definition and Development (PIDDP), Mars Instrument Development Project (MIDP), Astrobiology Science and Technology Instrument Development (ASTID), and Astrobiology Science and Technology for Exploring Planets (ASTEP). Only MIDP (Mars) covers mid-TRL technologies; no comparable program exists for non-Mars technology. Reductions in astrobiology funding have impacted both ASTID and ASTEP. How well the developments under MIDP can be leveraged to support non-Mars missions remains to be seen. Instrumentation for the South Pole-Aitken Basin and Comet Surface Sample Return missions is apparently not funded. No instruments for the Venus-environment mission are being supported, nor are instruments for outer-planet entry probe missions. Results of Midterm Review Autonomous Entry and Precision Landing Grade: C Trend: NASA has made progress in the important technology area of autonomous entry and precision landing. The Mars Exploration Rovers used the Descent Image Motion Estimation System to estimate lateral velocity and ensure a safe landing. The Mars Science Laboratory mission will reduce landing uncertainty by autonomously controlling the direction of the lift vector of the entry vehicle and will use Skycrane technology for heavy-vehicle deployment (although hazard avoidance at landing was removed from the mission). Future missions to Mars need more-advanced methods of detecting, avoiding, or tolerating landing hazards, and capabilities that enable “pinpoint landing” within tens of meters to 1 kilometer of a target site. Also, NASA needs to make an assessment of which elements of the Mars Technology Program are enabling for a Mars Sample Return mission. NASA will have to conduct an independent assessment of the analogous technology needs for the Moon, Venus, asteroids, and other targets. Recommendation: NASA should make an assessment of which technologies will be required for Mars Sample Return and conduct an independent assessment of the analogous technology needs for the Moon, Venus, asteroids, and other targets. Results of Midterm Review In-Situ Sample Gathering, Handling, and Analysis Grade: C Trend: While there has been extensive development of Mars technologies in support of the Mars Science Laboratory mission, there are no SMD technology programs for the development of technology needs related to Venus and
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Grading NASA's Solar System Exploration Program: A Midterm Report comets other than through the NASA Small Business Innovation Research program. In addition, planetary protection funding is focused largely on compliance with requirements and not on technology to develop alternative ways of meeting requirements. Lack of attention to development of methods to gather samples without damage and to analyze them for their value may preclude the selection of scientifically compelling samples for any sample return mission, whether to Mars, Venus, asteroids, or comets. There is no obvious initiative in place to continue even the limited Mars-focused component for missions following the Mars Science Laboratory. Results of Midterm Review Autonomous Mobility Grade: C Trend: In the area of surface rover technology, the overarching goal is to increase the navigational range, access, precision, safety, and time efficiency of autonomous mobile Mars surface science exploration. “Mobility” to access regions below the surface is also being pursued using both drills and “robotic moles.” The Mars program is attempting to bring subsurface access to a high TRL for deep drilling to 20 meters, shallow drilling to 0.5 meter, and permafrost drilling. Work on robotic moles has focused on subsurface ice access with cryobots (i.e., robots capable of operating in icy conditions), but these are still at a low level of maturity. With respect to aerial vehicles, the Mars Technology Program is working on Mars balloon technology, but for Titan and Venus there has been no concept development or technology work except through the Small Business Initiative Research program. Work that has been accomplished tends to be Mars-centric, and applicability to the other targets called out in the decadal survey is questionable owing to the environmental differences, for example among Venus, Titan, asteroids, and comets. The Mars-centric nature of the work is good for Mars exploration, but it does not support other developments required to accomplish missions to other targets in the decadal survey. Results of Midterm Review Ascent Vehicles Grade: F Trend: Ascent vehicles are spacecraft designed to lift off a planetary surface in order to bring samples back to Earth. NASA has made little progress on these. The Mars Exploration Program has terminated all work on ascent vehicles for Mars Sample Return. The agency is also not conducting any technology development on the South Pole-Aitken Basin Sample Return ascent vehicle. The agency has also dismissed Venus ascent vehicle requirements and is not pursuing any technology development in this area owing to its high level of difficulty. All activities are shut down with no plans for restarting them, yet this task is on the critical path for all landed sample return missions. THE DEEP SPACE NETWORK New Frontiers Recommendation Results of Midterm Review “The SSE Survey recommends upgrades and increased communications capability for the DSN [Deep Space Network] in order to meet the specific needs for this program of missions throughout the decade, and that this be paid from the technology portion of the Supporting Research and Technology (SR&T) line rather than from the mission budgets.” (p. 206) Grade: B Trend: The decadal survey noted a significant need for upgrading the Deep Space Network to deal with “insufficient communications capability and occasional failure as it ages.” A variety of potential solutions were mentioned, along with the admonition that “any upgrade cannot realistically be charged to the first mission that uses it….”4 The decadal goal is the provision of upgrades and increased communications capability for the DSN to deal with 4 National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, The National Academies Press, Washington, D.C., 2003, p. 206.
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Grading NASA's Solar System Exploration Program: A Midterm Report the missions flown during the decade. NASA’s detailed assessment and plan drawn up by the DSN to deal with current and anticipated DSN traffic constitutes significant progress toward reaching the goal. The committee notes that doing nothing will lead to the failure of the current system. The 70-meter antennas may begin to fail before 2015 in a way that cannot be repaired. Such failure would put at risk continued data collection from the Voyager spacecraft as well as from the New Horizons spacecraft during its 2015 flyby of Pluto. The DSN enables all that the Science Mission Directorate does; the assigned grade and trend are contingent upon following through with a replacement/upgrade plan for the DSN stations. Recommendation: NASA should fund the Small Aperture Receive Array for the Deep Space Network and plan to replace the 70-meter antennas with arrays of small-diameter antennas by 2015. LAUNCH VEHICLE INFRASTRUCTURE Access to space remains a significant cost issue that is getting worse with the phaseout of the Delta II and associated launch complex 17 at the Cape Canaveral Air Force Station (Figure 6.2). This problem was exacerbated when a commercial launch market boom failed to appear in the late 1990s and early part of the new decade. The problem is the large cost of infrastructure maintenance as part of overall launch service costs. NASA’s share of the Expendable Launch Vehicle market is insufficient to drive prices; hence NASA is at the mercy of the same market forces that have driven unit costs up as projected launch rates have decreased. In any event, NASA will have to figure out how to deal with larger and more expensive Delta IVs and Atlas Vs rather than the workhorse Delta II. The committee notes that access to affordable launch vehicles enables all of the Science Mission Directorate’s programs, not only the planetary ones. To deal with this situation, NASA could begin looking for a negotiated contract price for evolved expendable launch vehicles that will guarantee launch prices for the rest of this decade as well as the next. Under public law, and given the requirements for New Frontiers and flagship missions, NASA needs to negotiate appropriate purchases with the United Launch Alliance to fill the gap left by the phaseout of the Delta IIs.
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Grading NASA's Solar System Exploration Program: A Midterm Report FIGURE 6.2 Launch of the Dawn spacecraft aboard a Delta II rocket. The Delta II is slated for retirement by NASA in the next few years. SOURCE: NASA.