NASA’s Sounding Rocket Capabilities
The NASA Sounding Rocket Program (SRP) provides the design, fabrication, integration, test, and launch facilities necessary to execute scientific investigations from near-space as well as mature new technologies for space systems. The NASA Heliophysics Division directly funds the operation of the sounding rocket infrastructure. The funding to operate the sounding rockets comes from three key sources at NASA—the heliospheric, astrophysics, and planetary divisions—each contributing to the entire program through different mechanisms. These divisions utilize research and analysis (R&A) programs to provide funding for scientific investigators through a traditional competitive selection process. Organizations outside NASA gain access to the SRP capabilities through reimbursable contracts. The unique capabilities of the SRP, i.e., a wide range of altitudes, fast turn around, low cost, and access to wavelengths that are blocked by the lower atmosphere, enable the scientific study of otherwise inaccessible environments and phenomena. The SRP does this while supporting NASA’s orbital programs through technology development, workforce training, and suborbital missions that carry out important calibration and validation of instruments.
The combined funding streams support investigations in geospace science, high-energy astrophysics, ultraviolet astrophysics, solar physics, planetary atmospheres, plasma research, and technology maturation. Currently more than 34 universities and research laboratories in the space science community exploit the SRP to conduct scientific observations from the mesosphere (50 km) to exosphere (>1,000 km).
The sounding rocket program has a rich history of establishing directions for NASA and often contributing key technology for new major missions and maturing enabling technologies for future flight (e.g., Table 4.1 and Figure 4.1, which shows the launch of a sounding rocket carrying an inflatable re-entry vehicle experiment payload). The XQC (x-ray quantum calorimeter) sounding rocket experiment developed by the University of Wisconsin acquired the first high-resolution x-ray spectrum of the diffuse x-ray background. The high spectral resolution (see Figure 4.2) provided critical insight into many long-standing questions about the soft x-ray background by making accessible for the first time the plasma diagnostics necessary to understand the emission.
Analysis of this spectrum demonstrated that the x-ray emission was largely galactic, originating from 1 million to 3 million K gas in the galaxy. This high-temperature gas can have profound impacts on galactic evolution. Despite the impact of this hot gas, insufficient data exists to constrain even the filling factor of this gas within our own galaxy. The XQC answered fundamental questions about the nature of this gas, including that the previously detected emission was in fact largely galactic in origin; demonstrated that the Fe is largely missing from the galactic
TABLE 4.1 Links Between Sounding Rockets and Major NASA Orbital Missions
hot gas; and provided the first detection of the long-sought Fe M-lines. The detector technology developed by the sounding rocket program is being migrated onto the next generation of x-ray missions for NASA, the European Space Agency, and the Japan Aerospace Exploration Agency.
I think it is important to educate the next generation of technically literate space scientists. It is also important to allow them to fail, so that they can learn something. Does their work have to be scientifically and technically meaningful? Well, people naturally want to do meaningful work, but the cost of potential failure shouldn’t outweigh the joint benefit of returned science, technological development, and training.
Observations from space can be expensive, so you need institutional arrangements between scientists, government, and industry to provide low-cost building blocks, essentially 2 × 4s, from which to construct inexpensive payloads. This is what the sounding rocket program does: provide standardized launch and support systems from which to build payloads around.
However, the current sounding rocket technology has not changed much over the past 50 years from what we used to develop the first orbiting x-ray observatory Uhuru. Our subsequent successes have raised the bar, making scientifically meaningful work from sounding rockets a challenge. The current institutional arrangements should be expanded, building on commercial innovations in payload delivery to permit the next generation to pursue meaningful science and technology innovations during their training.
—Riccardo Giacconi, 2002 Nobel Laureate in Physics for his pathbreaking work in x-ray astronomy
Solar physics is rife with examples of sounding rocket instruments making first-of-a-kind measurements that ultimately mature into major missions that address questions of solar structure and the physics of the corona and chromosphere, and provide critical measurements about the solar irradiance that are vital inputs to our understanding of climatology. Under-flights, where a sounding rocket observation is made in coordination with a satellite, have provided crucial calibration and validation data for the solar constant, atmospheric constituents, and airglow measurements made by orbital instrumentation. The technologies developed for observing the Sun—EUV multi-layer normal incidence optics, intensified charge-coupled device detectors for the EUV, grazing incidence telescopes—were all used in numerous orbital missions including SOHO, TRACE, STEREO, SDO, and Hinode.
I submitted my first rocket proposal to NASA while still a grad student in 1964 at the suggestion of Henry Smith, then Chief of Solar Physics at NASA HQ. My first flight on a spinning Aerobee Hi in 1968 deployed the largest area proportional counters flown up to that time, to observe the high-energy tail of the quiet Sun x-ray spectrum as well as the spectrum of the Crab Nebula. It was the experience gained in solar rocketry that ultimately resulted in successful solar space experiments on OSO-8, the Solar Max Mission, and YOHKOH. Even if every rocket flight didn’t produce great discoveries, the big scientific payoffs of the satellite instruments wouldn’t have been possible, for me, without them. Thanks, NASA, for the opportunities.
—Loren W. Acton, Astronaut/Payload Specialist for STS-51-F
Sounding rockets provide an excellent means of testing new ideas that require exposure to the space environment and views of the sky without the absorbing layer of Earth’s atmosphere with a rapid turn around compared to satellite programs, which require years to develop. The shorter development time is also important for the training of graduate students, who can hope to carry out a thesis project from concept to data acquisition and analysis during their tenure. The lower investment of time and money in sounding rocket-borne experiments enables more risk taking, i.e., exploratory investigations that can result in new directions of research. An example of this was the discovery of cosmic x-ray sources in 1962 by a sounding rocket experiment. Many early discoveries of solar flare phenomena were made using sounding rockets.
—Gordon Gamire, Evan Pugh Professor, Department of Astronomy and Astrophysics, Pennsylvania State University
The study of auroral phenomena with sounding rockets has a particularly rich history because sounding rockets permit observations at altitudes and other observing conditions unavailable to other platforms (see Figure 4.3). Early sounding rockets (1960s and 1970s) probed altitudes up to 500 km and discovered that the driving source of auroral light is from keV beams of electrons propagating downward into Earth’s atmosphere, and opened the way for understanding the interaction of Earth’s magnetic field with the solar wind. When new rockets capable of achieving altitudes up to 1,500 km became available, whole new classes of auroral physics became accessible for study, including field-aligned electron bursts, ion conics, and large-amplitude Alfvén waves. Ultimately the discoveries made using sounding rockets formed the basis for the FAST satellite, with a complement of rocket-
developed in situ instruments (e.g., “Top Hat” electrostatic detectors, plasma wave interferometers, and so on). The FAST leadership all had extensive heritage with prior sounding rockets, bringing their knowledge and expertise forward to orbital missions.
The SRP is managed using a government-owned, contractor-operated (GOCO) model, whereby management of the infrastructure is led by the NASA Sounding Rocket Program Office and the execution of the individual rocket missions is managed by the competitively selected NASA Sounding Rocket Operations Contract(or) (NSROC), currently held by Northup Grumman. The NSROC model is a performance-based contract where cost plus award/incentive fees are awarded based on the complexity of each individual mission. The cost model used in developing the NSROC assumes 20 flights per year over a 10-year period of performance, with an agreed upon distribution of mission complexities that reflect the breadth of user requirements.
The GOCO model is intended to encourage the commercial contractor to increase the efficiency of the SRP and thus realize a profit. As part of this model, the NSROC contractor is encouraged to seek funding sources outside NASA, referred to as “reimbursable contracts,” to augment the operational costs and increase profits. Reimbursable contracts provide organizations outside NASA (commercial organizations, the Department of Defense, and so on) with access to sounding rockets for exploring new technologies, such as atmospheric re-entry vehicles, high-speed propulsion, target vehicles, and so on. The intent is to engage the aerospace industry to backfill the shortfalls in NASA funding of the SRP. However, the success of this approach is not obvious.
Executing a successful scientific mission requires a coordinated effort between the experimental and the NSROC teams to design the mission and supporting hardware, integrate and test the payload, and ultimately launch the instrument. The nature of a sounding rocket mission requires that the SRP maintain engineering teams capable of supporting thermal analysis, power, telemetry, attitude determination and control, mechanical design, and rocket systems. Finally, the SRP must maintain, operate, or augment the launch facilities across the globe that provide access to specific observing conditions and phenomena.
The breadth of the scientific investigations conducted from sounding rocket platforms requires a similarly diverse technology base. Geospace payloads typically make extensive use of deployable sensors and daughter payloads, relying on coarse attitude control via magnetometers, and typically reach the highest altitudes (~1,000 km) among sounding rocket missions. Recently NASA developed and successfully demonstrated the capability for tailored trajectories, which allow instruments to fly in controlled orientations relative to Earth’s surface. Astrophysics, planetary, and solar payloads require arc-second pointing accuracy using gyroscopes and star-trackers, maximizing observing time above 100 km, and payload recovery to support post-flight calibration and/or reflight after refinement of the instruments based on the data obtained from the launch. These flights are limited in apogee by the lack of a heavy launch capability and limitations in the existing parachute recovery system. Sounding rockets are also used to execute sample and return flights, collecting atmospheric samples over a range of attitudes and atmospheric conditions for subsequent laboratory analysis and comparison with observations from orbital platforms. These missions require longer durations at lower apogees and slower rockets to narrow the range of altitudes represented by an atmospheric sample and instrument recovery.
Assembly, integration, and test (AI&T) of all new sounding rockets first occurs at the NASA Wallops Flight Facility (WFF) in Virginia, which provides the test and fabrication facilities configured specifically to support sounding rockets. Sounding rocket payloads undergo a test program that closely mimics the test philosophies and processes used for orbital missions, which provides unique educational and training opportunities.
A variety of launch vehicles is available to the scientific investigator. Figure 4.4 presents the range of altitudes, mass, and observing time available with the NASA-provided catalog of vehicles. The launch capabilities generally chosen by the investigators to execute their scientific investigation are highlighted. It is worth noting that there is a general lack of capability for putting higher-mass payloads (>1,000 lb) into high altitudes (>1,200 km), which would provide a significant increase in observing time.
The SRP uses surplus military motors in the rocket stacks wherever possible, reducing the cost. These decommissioned military motors cannot be sold, but are available at no charge to other government agencies. With appropriate inspection, refurbishment, and outfitting these motors are usable for sounding rockets and have a demonstrated high success rate (>97 percent). The SRP is required to procure commercial rocket motors for the upper stages of some rockets, as no option for utilizing government surplus currently exists.
Supporting the entire program are national and international launch facilities distributed across the globe, providing access to key phenomena and environmental conditions. National launch facilities are located at WFF (Virginia), Poker Flat Research Range (Alaska), and White Sands Missile Range (New Mexico). WFF provides access to mid-latitudes and can support high-altitude flights, where recovery is not necessarily required. Poker Flat is typically used to reach the auroral oval and supports high-altitude flights and tailored trajectories (i.e., trajectories designed to follow specific flight paths relative to Earth’s surface). White Sands Missile Range is the preferred launch site for missions that require recovery, often to support post-flight calibrations or to refurbish and re-launch the instrument.
International facilities are located in Norway (Svalbard, Andøya), Sweden (Esrange), Australia (Woomera), and Marshall islands (Kwajalein). They are usually utilized in campaign mode, where multiple and/or simultaneous missions are mandatory, to elucidate critical scientific findings in order to justify the effort and cost. The Norway and Sweden launch sites provide access to the auroral oval and offer a wide range of mission-supporting ground-
based instrumentation for conducting simultaneous atmospheric measurements during flight. The Australia site allows for observing southern hemisphere targets and has an extremely large launch range also suitable for testing propulsion and re-entry technology. The Kwajalein site supports high-altitude flights and access to the equatorial regions for geospace investigations. Generally speaking, the international facilities are not standalone facilities, but require extensive field deployment of NASA hardware, such as telemetry ground systems, in order to communicate with the rocket in flight. There does not appear to be significant overlap in the observing regimes provided by the national and international facilities, so a loss of any one facility would translate into a loss of capability.
STATUS—EROSION OF A NATIONAL ASSET
The sounding rocket program supports leading-edge opportunities for scientific research in geospace and solar research, where in situ measurements at altitudes unreachable by other platforms and solar fluxes unobservable from Earth’s surface afford a wealth of opportunity for investigating new phenomena and developing instrumentation. There are currently 12 solar/heliospheric research groups and 9 active groups executing geospace-related missions using sounding rockets. Astrophysics has 13 active rocket groups across the ultraviolet and x-ray communities, developing new instruments for unique observations.
From a historical perspective the program today conducts ~30 percent fewer missions than it did 20 years ago. As shown in Figure 4.5, the decrease in core launch rate has occurred most notably in the past decade. In response to concern about the health of the astrophysics rocket program, NASA formed the Astrophysics Sounding Rocket Assessment Team (ASRAT) specifically to address the decline in the astrophysics rocket program. The ASRAT wrote a white paper entitled “Reinvigorating the Astrophysics Sounding Rocket Program: Strategic Investment
in the Future of Space Astronomy”1 that was submitted to the Astro2010 Astronomy and Astrophysics Decadal Survey. The paper highlighted a pervasive decline in the astrophysics sounding rocket flight rate. The committee notes that the drop in the flight rate of astrophysics missions is essentially identical to a program-wide decrease in the flight rate as discussed prominently in the NRC report Building a Better NASA Workforce: Meeting the Workforce Needs for the National Vision for Space Exploration (NRC, 2007). The inescapable conclusion is that there is a common root-cause for the decline in the flight rate across all sounding rocket disciplines.
The question is obvious: How did this decline come to be in what was once a vibrant and productive source of seed corn for NASA technology, science, and engineering talent? A lack of strategic vision combined with a series of incremental programmatic changes over the last 10 years has steadily eroded the vitality of the SRP as a whole.
First, there is no set of consistent standards communicated across the science disciplines as part of the competitive selection process in relation to the importance of the SRP to NASA’s larger mission. Rocket selections are conducted by individual NASA divisions using different criteria and under different review structures. Clearly, selection within a division is appropriate given the diverse nature of the science objectives, but the lack of guidance from NASA on the selection criteria for sounding rockets leaves the program open to external attack and attrition.
This has been noted in the past: The Sun to the Earth—and Beyond: A Decadal Research Strategy in Solar and Space Physics (NRC, 2003) stated:
In recent years, for a variety of reasons that appear to have included program management and resource allocation decisions, the number of rocket flight opportunities has been decreasing. Illustratively, in FY 2001 fewer than half as many NASA sounding rockets were launched as in the 1980s and 1990s, when there were, on average, 25 launches every year. This decrease in flight opportunities does not appear to have been based on any comprehensive assessment of the program’s scientific merits or its opportunities or on peer-reviewed determinations of the adequate size of the program. (p. 152)
Second, 11 years ago NASA restructured the sounding rocket program to follow the GOCO model (see the June 2009 report of the Sounding Rocket Working Group;2 this is also discussed further below). Third, the transition to the GOCO model was followed 5 years later with the transition within NASA to full cost accounting, which cut deeply across NASA.
The combination of an uncoordinated selection process and decreased R&A funding levels has eroded the vitality of the SRP. This is evident in the flight rate, which on average was less than the GOCO contracted rate; over the last 10 years the SRP flew an average of 17 flights per year for core missions (science, educational, technology), an average of 22 flights per year in total (core missions plus reimbursable contract), and 2 remote campaigns. This flight rate for core missions is more than 30 percent lower than the average flight rate in the decade preceding NSROC, when the average annual flight rate was 28 with nearly annual remote campaigns.3 The NSROC contract is in year 11 of a 10-year contract. NSROC II is under development at the time of this report and is being built around a model of 24 core mission flights per year, still less than the rate routinely achieved prior to NSROC.
Regarding metrics to measure program success, the suborbital programs fall in the category of long-range research and development. For such programs, appropriate metrics are extremely difficult to define because the true impact of the results may not be appreciated or recognized on the short-range time scales within which managers or administrators must judge and be judged. The long-range health of the U.S. space program 20 years from now is the true metric by which to evaluate today’s suborbital program.
—W. Sanders, University of Wisconsin
The NASA stated position that access to near-space is a “need-based” capability provided to the scientific community4 puts the existence of the sounding rocket program at risk. Fewer rocket programs are selected, because of the structure of the review process and lack of R&A funding. Without the science-driven need, the funding of the sounding rocket infrastructure has been similarly reduced. This reduces the number of launches that need to be supported, which limits the number of investigative programs that can be supported, and so on. This spiraling resource reduction has continued to erode the SRP to the point that it may soon no longer be viable. Once the sounding rocket capability is lost, the infrastructure would likely be too costly to reconstitute and a national capability will be lost.
Eroding Workforce Development
A similar erosion of expertise within NASA underlies the withering of the rocket program. Prior to NSROC, the sounding rocket organizations at NASA Goddard Space Flight Center and WFF were composed primarily of NASA employees supported by contractor personnel. The core of the sounding rocket engineering effort and program execution was conducted with personnel from within the NASA organization, providing a “womb-to-tomb” experience. Subcontractor support comprised various engineering disciplines, technicians, machinists, and logistic support that complemented the government organization. The leadership provided by NASA employees maintained within NASA the experience base necessary for implementing flight programs, providing continuity through the maintenance of institutional knowledge. This critical knowledge and experience naturally migrated up through NASA management as personnel moved up through the organizational structure.
The competitive nature of the GOCO model is at direct odds with maturation of the experienced NASA work-
The NASA Sounding Rocket Working Group is an advisory panel composed of active sounding rocket PIs. This group meets twice a year to monitor the program and provide guidance to NASA and NSROC on where improvements are necessary. A full set of the findings from 1994 onward can be found at http://rscience.gsfc.nasa.gov/srwg.html. The most recent findings (June 2009) are consistent with the findings of this committee.
Provided by the NASA Sounding Rocket Program Office and NASA Headquarters.
NASA presentation to the Committee on NASA’s Suborbital Research Capabilities, May 20, 2009.
force necessary to execute future missions. Personnel and skill sets are viewed as commodities to be managed for profit with no consideration for national needs. The GOCO model weakens a critical training avenue for NASA personnel to deepen their experience with flight systems and support future orbital missions.
Finding: The implementation of the GOCO model has effectively throttled a primary artery for growing and maintaining an experienced NASA workforce, concentrating the “womb-to-tomb” experience in a contractor workforce not required to look out for the best interests of NASA.
Finding: The committee finds that the GOCO model for executing the sounding rocket program has not realized the anticipated increases in efficiency or strengthened the infrastructure. Quite the opposite is true; the flight rate has dropped by more than 30 percent and the cost-reimbursable contracts are now required for day-to-day survival, not the promised avenue for expanding capabilities. This places the whole program at serious risk.
Sounding Rocket Element of Recommendations 1, 2, and 3: Given that the sounding rocket program has experienced a decline in the flight rate of scientific missions since the inception of the GOCO model, NASA should provide an assessment of the current GOCO model and its impact on the sounding rocket program over the initial 10 years. This assessment must address issues of cost efficiency and benefit to the program, resiliency to fluctuations in the number of reimbursable contracts, and migration of flight experience into the NASA culture.
The sounding rocket program continues to be a model for training the next generation of experimental scientists and engineers at the post-graduate, graduate, and college level. Sounding rocket launches provide hands-on flight program experience to students and entry-level employees. A typical sounding rocket mission follows the same lifecycle as any major aerospace mission, passing through early concept reviews, detailed design, fabrication, assembly and test, launch, and data analysis. The graduate student or junior engineer is expected to assume the role of the experiment lead for the entire payload. In this all-encompassing role the student learns all aspects of executing a science mission, working with the SRP and NSROC professionals through all phases of the mission on time scales of 1 to 3 years. Also, while failure is never envisioned in a rocket or other suborbital project, failures do occur. They can provide a valuable learning experience. Suborbital projects are small enough in scale to allow for an occasional failure, the learning derived from it, and a second trial. Experience like this cannot be replicated within the time frame of a major NASA mission, which can take more than a decade to execute. This “in the trenches” experience (see Figure 4.6) is an unparalleled training ground that has generated some of the most successful leaders in scientific aerospace today.5
Additionally, the SRP Office leads and/or supports a series of educational opportunities that expose high school and college students and teachers to scientific research and engineering through a series of hands-on programs.6 A combination of programs and flight opportunities actively engage students with hands-on work and are designed to follow the typical NASA/aerospace lifecycle of a program using standard engineering practices to guide the experience.
At the university level, the SRP Office executes educational experiences tailored to institutional needs. On the small scale, the Student Educational Rocketry Initiative (SERI) is designed to utilize commercially available, amateur rockets to give students from colleges and small universities hands-on experience building simpler rockets and purchasing avionics that are ultimately launched from WFF. At a more sophisticated level, WFF supports the RockOn! workshops (I in 2008, II in 2009, and III scheduled for 2010), which provide identical, kit-based experiments (accelerometer, Geiger counter, simple flight computer) to the participants to assemble, test, launch, and
For an incomplete yet impressive list correlating rocket experience with lead participation in NASA missions, see http://www.pha.jhu.edu/~stephan/asrat/missionexptablev2.pdf.
NASA SRPO presentation to the Committee on NASA’s Suborbital Research Capabilities, May 20, 2009.
analyze flight data over the course of a week (see Figure 4.7). Finally, the SRP Office recently initiated a pilot project with the Jet Propulsion Laboratory called the Hands-On Project Experience (HOPE) program, which is designed to give junior engineers from NASA centers access to sounding rockets to develop and test new technology while also broadening their experience base (launch is planned for June 2010).
Finally, the NSROC contractor itself provides a more traditional avenue for educational opportunities and engagement with students through co-op and summer internships. To date over 100 students have participated and 14 have become full-time NSROC employees: notably not NASA employees. According to the SRPO, NSROC is beginning to develop an internal systems engineering function within its organization. This is an excellent step forward that will provide a path for junior engineers to begin to broaden their experience beyond their specific discipline.
Finding: The proactive approach followed by the SRP Office and the NSROC contractor should be held up as a model educational outreach program and supported in every way possible as it directly addresses the wider need of NASA to develop strong engineering and scientific leadership for the future. Continued degradation in the SRP funding puts this highly successful program at risk.
Conspicuously absent in the data collected during the committee’s investigation was any indication of a large-scale, coordinated effort on the part of NASA to engage the SRP to provide a path for professional growth for its employees. The SRP education and public outreach (EPO) effort by NASA policy focuses on K-12 and
university-level education. This is a vital path for educating the general public and provides a beginning career in aerospace. However, once started, there is little mentoring to guide the career development of a young NASA engineer. (Additional discussion of education and training is provided in Chapter 6.)
Finding: The committee finds that NASA under-utilizes the SRP as a method for employee training. With development times of 1 to 3 years, the sounding rocket program is a more efficient training environment than the 5 to 10 years required to develop an orbital mission. The shorter lifecycle of a sounding rocket exposes junior engineers and experimental scientists to the mission lifecycle and the systems engineering discipline in a timely fashion that allows them to carry that experience forward to larger-scale orbital programs.
The SRPO and NSROC contactors have slowly but steadily improved telemetry bandwidth and ADCS capabilities, but not enough to break open new avenues of research. The SRPO is developing new launch vehicle configurations (Terrier-Improved Malemute and Mesospheric Sounder) to support mesospheric studies and did present rudimentary plans for heavy lift capabilities (~1,000 lb to 1,000 km), but no concrete plans are in place at this time. There are also plans being discussed to procure an alternative booster to the Black Brant that could provide additional capability in mass or possibly diameter, but the plans are too immature to make any definitive statements about the impacts.
The SRP is in the process of making a variety of infrastructure upgrades to launch facilities. These include
consolidating the LC-35 and LC-36 (LC = Launch Complex) facilities at White Sands Missile Range in addition to adding an addition for hardware storage to the LC-36 vehicle assembly building. At Poker Flat Research Range there are plans to move some operations functions out of the blockhouse and into a yet to be built science facility.
Finding: The infrastructure improvements being conducted by the SRP are not major improvements or new capabilities, but rather enhancements to existing facilities.
A sounding rocket experiment is designed around a few basic parameters: flight duration and altitude, payload volume and mass, data collection time, and telemetry bandwidth. Within these constraints it is the experimental scientists’ challenge to develop an instrument and mission profile capable of executing the proposed scientific investigation. As the trade space defined by these parameters expands, so do the opportunities for discovery. However, as pointed out by R. Giacconi (see quote in Section 4.1), “current sounding rocket technology has not changed much over the past 50 years. …”
The SRP Office is working on the concept of a long-duration or Orbital Sounding Rocket (OSR), which would place an existing, flight qualified sounding rocket experiment with enhanced support systems on-orbit for hours to tens of days. Extended observing times of this scale far exceed the canonical 10× improvement typically quoted to justify new missions. Such an increase in capability would be revolutionary in the rocket community and generate new scientific discoveries, similar in scale to what the long- and ultralong-duration balloon flights did for balloon-borne science.
The concept of an OSR was also identified by the ASRAT team, which wrote a separate document describing the ground-breaking science that would be enabled by an orbital sounding rocket platform. These science missions address fundamental goals in the NASA strategic plan. They include mapping of the ultraviolet emission from the IGM to understand the formation of galaxies through the coalescence of baryonic matter, spectroscopy of the x-ray background to probe the structure of this illusive component of galactic structure, and technology paths for imaging of extra-solar planets from a sounding rocket platform.7
The OSR mission is conceptualized to bridge the programmatic gap between the low-cost ($1 million to $2 million) sounding rocket missions and the NASA Small Explorer (SMEX) mission at >$100 million. The OSR concept would provide a mission scale on the order of $15 million and open new scientific frontiers that are more appropriately executed as focused investigations rather than as part of major, facility-class missions. Expanding the operational parameter space is clearly cost-constrained, as the sounding rocket program has just barely enough to maintain the current capabilities and restock depleted motor stores.
The committee did have some limited insight into launch options associated with the Missile Defense Agency. The MDA and the Air Force are using surplus motor stages from the Minuteman, Peacekeeper, and Trident C4 programs. These motors are used in varying configurations from single to multiple stages, as well as air launched, which could provide for experiments to be conducted in geographic regions without launch sites. The motors have been configured for short- and long-range suborbital missions as well as to provide a low-Earth-orbit satellite launch capability. This may provide an additional avenue for acquiring new rocket motors with enhanced capabilities.
Finding: The OSR is currently a conceptual design. Without significant financial and programmatic commitment from NASA it is unlikely that such a groundbreaking capability will ever be matured beyond conceptual design.
Sounding Rocket Element of Recommendation 4: NASA should execute a thorough conceptual study of an OSR-type capability to evaluate the technical feasibility, define requirements, and assess programmatic resources necessary to implement this type of program.
The full paper, “Development of an Orbital Sounding Rocket Program,” is available at http://www.galex.caltech.edu/ASRAT/index.php/Main_Page.