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Nasa ’s Beyond Einstein Program: An Architecture for Implementation 3 Mission Readiness and Cost Assessment INTRODUCTION AND OVERVIEW The “realism of preliminary technology and management plans, and cost estimates” 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 assessment: mission readiness and cost. The Committee on NASA’s 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.1 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, “mission development” 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 “Technology Readiness and Degree of Difficulty”). 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 “to 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.”2 1 The terms “margins,” “allocations,” “reserves,” and “contingencies” are used consistent with definitions in recent announcements of opportunity, such as: “NASA Announcement of Opportunity, Mars Scout 2006 and Missions of Opportunity, May 1, 2006, Appendix B, Section G, #13.” 2 National Research Council, A Performance Assessment of NASA’s Astrophysics Program, The National Academies Press, Washington, D.C., 2007, p. 42.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation 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 committee’s 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 assessments (see the list of definitions below).3 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.4 The simplified 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 “flight-qualified” through test and demonstration (ground or flight). TRL 9. Actual system “flight-proven” through successful mission operations. 3 NASA, NASA System Engineering Processes and Requirements, NPR 7123.1A, March 26, 2007. Available at http:\\nodis3.gsfc.nasa.gov. 4 Ibid.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation 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).5,6 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 members’ 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: 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 probability of success in achieving technical objectives in later systems applications. Moderate degree of difficulty anticipated in achieving R&D objectives for this technology; a single technological 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. 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. Very high degree of difficulty anticipated in achieving R&D objectives for this technology; multiple technological 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. 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 mission’s probable cost. The schedule assessment for each mission concept is contained in the individual discussions in the section below (“Mission Readiness Assessments”), while the cost assessments for each mission concept are given in the next major section (“Mission Cost Assessments”). Consistent methodologies were used to independently estimate cost and development time for the 11 Beyond Einstein mission concepts and to compare them with previous 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 team’s own proposed plans were considered. The committee also assessed life-cycle costs and potential funding profiles against the available NASA Beyond Einstein funding wedge7 and non-NASA budget contributions as part of the considerations in making its recommendations. 5 James Bilbro and Robert Sackheim, “Managing a Technology Development Program,” paper presented at the Workshop on Process for Assessing Technology Maturity and Determining Requirements for Successful Infusion into Programs, September 2003. 6 John C. Mankins, “Research and Development Degree of Difficulty (R&D3)” White Paper, Advanced Projects Office, Office of Space Flight, NASA Headquarters, Washington, D.C., March 10, 1998. 7 NASA’s FY 2007 budget request projected NASA’s level of support for Beyond Einstein missions covering the years FY 2007 through 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 “Beyond Einstein funding wedge.”
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation MISSION READINESS ASSESSMENTS Black Hole Finder Probes CASTER Mission CASTER Technical Challenges: Instrument There are multiple technology readiness issues with the Coded Aperture 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: “We currently have no experience with this device.” 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: “A program to fabricate and test … would raise the TRL of this device to 5 or perhaps 6,” 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 × 8 detectors in each detector module, with 16 detector modules per “detector tile” 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 states8 that “the 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).” 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 LaBr3-based scintillators to TRL 6 from the committee’s 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: Spacecraft The CASTER observatory is extremely heavy and has a unique configuration, 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: Operations In order to achieve the science goals discussed in Chapter 2, the spacecraft will primarily operate in a scanning mode. For CASTER’s 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 ±20°, 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 8 Mark McConnell, University of New Hampshire, “CASTER, A Candidate Concept for the Black Hole Finder Probe,” presentation to the committee, January 30, 2007.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation TABLE 3.1 CASTER Technology Readiness Summary Heritage TRL DoD Element Mission Similarity Changes from Previous Mission/Comment Program Rating Committee Rating Committee Rating Detectors and light sensors None known N/A Baseline approach identified: current laboratory prototype uses a Planacon tube by Burle Industries. Alternative is a Hamamatsu flat panel PMT. 3 2-3 II-III Scintillator Some use in medical industry, no known flight heritage N/A Lanthanum bromide (LaBr3) scintillator material has been developed and shows promise, but testing is in early stages. 4 2-3 III Coded aperture Swift, SIGMA Basic design Smaller and thicker mask than Swift. Complex mask and program literature indicate that the mask pattern has not been specified. Not stated 2-3 II-III Collimator shield None known N/A Baseline design chosen and trade studies appear to be in early stages. Not stated 2-3 II-III 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 team’s experience using neural network algorithms for the processing of event location data from the Compton Gamma Ray Observatory’s 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 team’s experience provides confidence that it will be done successfully. CASTER Technical Margins 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 instrument and spacecraft. The CASTER team’s 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 0° 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 passages 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
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation TABLE 3.2 CASTER Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude determination and control Pointing About 1° control, about 5 arcmin knowledge No challenge Tracking 0.5 deg/min No known requirement Jitter/stability 1 deg/s No challenge Power Orbital average 1,370 W, payload 550 W, spacecraft 480 W contingency Drives array size Worst case 2,240 W—total bus Array size Data storage — 6.4 GB (4 orbits) No challenge Structure Payload 2,500 kg Extremely large vehicles, very heavy launch loads; only notional illustrations shown on arrangement of payload in spacecraft bus Spacecraft 2,290 kg Contingency 8,950 kg Total 13,740 kg Margin 6,860 kg Thermal — Not specified Unknown Radio-frequency communications Downlink Average data rate: 2.2 Mbps 200 Mbps downlink via TRDSS Ka band Unknown if this rate is available Uplink Not specified Unknown Alignment — Not specified Unknown Propulsion Delta-V Required delta-v (velocity increment) is unknown; 800 kg propellant allocated in mass tables. Unknown NOTE: Acronyms are defined in Appendix G. vehicle would be able to reach an inclination of 15° with zero mass margin and could comfortably reach a 28° inclination with more than 50 percent margin. It is possible that a non-U.S. launch vehicle could have the capability 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 Challenges 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 mission’s 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.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation CASTER Unique Challenges 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: Instrument The High Energy Telescope (HET) cadmium-zinc-telluride/application-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 existing systems. The mission team’s response to the committee’s RFI notes that “some development is underway through a separate NASA Phase 1 SBIR.” 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 3.3 EXIST Technology Readiness Summary Heritage TRL DoD Element Mission Similarities Changes from Previous Mission/Comment Project Rating Committee Rating Committee Rating High-energy detectors (19 telescopes) ProtoEXIST imager—balloon. Swift/BAT Basic design, materials Coded mask telescopes and shielding: components demonstrated in laboratory; the departure from the current state 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. 5-6 3-4 II Low-energy detectors (32 telescopes) Commercial product Unknown Uses Si detectors for the Low Energy Telescope (LET). Larger pixels, spectrographic readout of each pixel. Prototype developed under SBIR by Black Forrest Engineering. 3 3 II Coded-aperture telescope SIGMA—Russian INTEGRALESA Unknown 5 mm tungsten mask for the High Energy Telescope (HET). New laminate required for pinhole pattern. <4 3 II-III Shielding/anti-coincidence system None Not applicable Uses cesium iodide (CsI) scintillators with PMTs and light pipes around CZT detectors. <4 3 II NOTE: Acronyms are defined in Appendix G.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation 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 committee’s 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 determination and control (AD&C) system. EXIST Technical Challenges: Spacecraft Spacecraft accommodation requirements for EXIST are listed in Table 3.4. EXIST Technical Challenges: Operations 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 3.4 EXIST Spacecraft Accommodation Requirements System Subsystem Performance Requirements Impact Attitude determination and control Pointing 1 arcmin control 5 arcsec knowledge No challenge Tracking 15° nodding Unknown Jitter ~15° nodding scan No challenge Power Orbital average 1,912 W payload with 30% contingency 957 W bus with 9% contingency 2,869 W with 22.1% contingency Drives array size Worst case 1,912 W Array size Data Storage — 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 — Not specified Unknown Radio-frequency communications Downlink 5 Mbps science data rate 200 Mbps via TDRSS TDRSS access time required. Uplink TDRSS No challenge Alignment — None No challenge Propulsion Delta-V 260 m/s for orbit maintenance and disposal. Pressurized bipropellant design. Mass, cost, safety NOTE: Acronyms are defined in Appendix G.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation subtelescopes, respectively, and each subtelescope of the HET and LET has 21° × 21° and 16° × 16° 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 “nodding” motion with amplitude +/−15° 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 collecting 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 assurance 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 Margins 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 (0° inclination). However, because of the performance limits on available launch vehicles, the EXIST mission will be flown in a 20° inclination orbit. EXIST Management Challenges 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 Center (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 Challenges 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 development. 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.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation TABLE 3.5 Con-X Technology Readiness Summary Heritage TRL DoD Element Mission Similarities Changes from Previous Mission/Comment Project Rating Committee Rating Committee Rating SXT FMA mirror fabrication Einstein, ROSAT, ASCA, Chandra, XMM-Newton, HEFT, Suzaku Wolter Type I optics, thin mirror segments (ASCA, Suzaku), mass production (ASCA, Suzaku), mandrel fabrication (XMM-Newton), hundreds of co-aligned mirror segments (ASCA, Suzaku), moderate angular resolution (XMM-Newton), areal density (Suzaku, HEFT). Combine angular resolution demonstrated by XMM-Newton with number of mirror segments and a real density demonstrated on Suzaku and HEFT. 4 3-4 II SXT FMA mirror assembly Chandra Many more mirror segments than Chandra but alignment budget less demanding. Over 2,000 individual segments to be aligned. Two methods being evaluated. 3 3 III-IV XMS-microcalorimeter XQC suborbital payload, Suzaku-XRS Microcalorimeter technology, wafer processing, operating temperature, ADR technology, data processing. Increased pixel count, multiplexed readout, cryogen-free operation. 4 4 II XMS-ADR XQC suborbital payload, Suzaku-XRS Same basic technologies as XRS-ADR. Con-X requires broader operating range and increased cooling capacity because of the larger arrays. Continuous operation is anticipated. Multistage ADR, passive heat switches, somewhat more complex control algorithm. Multiple component demonstrations completed. 4-5 4-5 II XMS-cryo cooler Under development for JWST Low vibration, minimum power. Possibly use 3He instead of 4He to achieve lower operating temperatures. Joint development effort with JWST and TPF: three alternatives being pursued. 5 4-5 II XGS-grating Sounding rockets, Einstein, Exosat, Chandra, XMM-Newton Basic fabrication techniques, alignment tolerances, number of grating elements, data analysis. Both line density and facet size are increased compared to prior applications. Required technology advances (line density, facet size) have been demonstrated separately; a flight prototype is to be developed and tested in 2008. 4 4 II
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation Heritage TRL DoD Element Mission Similarities Changes from Previous Mission/Comment Project Rating Committee Rating Committee Rating XGS-CCDs ASCA, Chandra, XMM-Newton, Suzaku Number and size of basic fabrication processes, backside thinning, data processing and analysis. Low-energy QE requires backside processing different from that for prior devices. Modeling suggests that QE requirement can be met, but testing has not been performed. 4 3-4 II HXT-optics Swift, InFocus, HEFT, HERO Highly nested, graded multilayer coated mirrors for 10-40 keV (InFocus, HEFT). Electroformed thin Ni shells (HERO, Swift). Thermally formed segmented glass mirrors. Basic processes demonstrated, but not to the requirements of Con-X. Two processes being developed under funding outside of the Con-X program. 5 3-4 II HXT-detector Swift, InFocus, HEFT, HERO Number and size of pixels, basic fabrication processes, data processing and analysis. Improved shielding design and fabrication. 5.5 4 II NOTE: Acronyms are defined in Appendix G. TABLE 3.6 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 ≥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 72° arc and 10 identical outer modules subtending a 36° 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
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation TABLE 3.26 Summary of Committee Cost Estimate Results (in millions of real-year dollars, except where noted) Joint Dark Energy Mission Black Hole Finder Probe Inflation Probe Einstein Great Observatories DESTINY ADEPT SNAP CASTER EXIST CIP CMBPol EPIC-F EPIC-I LISA Con-X DDT&E + production (excluding Phase A/B) at 70% confidence $1,132a $973 $1,116 $1,588 $1,290 $876 $910 $980 $1,030 $2,318 $2,059 Launch services $200 $200 $200 $300 $300 $200 $200 $200 $200 $300 $300 Partnering credits (DOE for JDEM; ESA for LISA) ($400) ($400) ($400) $0 $0 $0 $0 $0 $0 ($500) $0 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% confidence $1,130a $1,066 $1,326 $2,472 $1,978 $1,336 $1,213 $1,290 $1,287 $2,759 4 Mission team estimated life cycle cost—for reference $834 <$1,000b $724 $993 $1,095 $683 $700? $800 ? $2,045 $2,162 Estimated Phase C/D duration (months) 69 63 63 76 69 60 62 62 63 73 77 NAFCOM DDT&E + production (excluding Phase A/B) at 70% confidence—for reference N/A N/A N/A N/A N/A $762 N/A $910 N/A $1,861 $1,630 DDT&E + production in 2007$ including Phase B/C/D for COBRA comparison $1,085 $933 $1,070 $1,523 $1,237 $840 $872 $939 $987 $2,223 $1,974 Estimated Phase B/C/D duration (months) including Phase B for COBRA comparison 81 75 75 88 81 72 74 74 75 91 95 Dry mass (kg) model input (provided by the mission teams) 2,551a 1,800 1,571 13,740 9,000? 1,409 1,600? 1,611 1,810 1,282 5,882 NOTE: N/A, not applicable. Other acronyms are defined in Appendix G. aFollowing the release of the report, the DESTINY principal investigator notified the committee that his team misunderstood the committee’s 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 committee’s budget analysis, and would have no impact on any of the committee’s conclusions, findings, or recommendations. bIn the prepublication copy of this report, the “<” sign was accidentally omitted from the table.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation 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 thecommittee’s 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 cost—for 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% confidence—for 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 Corporation’s COBRA model are included in the report. The COBRA model’s 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 Corporation’s COBRA model are included in the report. The COBRA model’s 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.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation FIGURE 3.1 Ranges of estimated life-cycle costs to NASA. NOTE: Acronyms are defined in Appendix G. 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: Large Observatories (LISA and Con-X): $2 billion; 8 years BHFP (EXIST, CASTER): $1.5 billion; 7 years JDEM (SNAP, ADEPT, DESTINY): $1 billion; 6 years 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 planning 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,
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation FIGURE 3.2 Comparison of project cost estimates and independent cost estimates to NASA. NOTE: Acronyms are defined in Appendix G. 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-FY 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 year’s 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 committee’s 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.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation FIGURE 3.3 Comparison of project and independent schedule estimates. NOTE: Acronyms are defined in Appendix G. FIGURE 3.4 NASA’s assumed Beyond Einstein funding wedge, FY 2006-FY 2025.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation FIGURE 3.5 Cost to NASA of Beyond Einstein mission concepts compared to the NASA budget wedge. NASA’s 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 committee’s 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: Technical readiness elements are the instrument, spacecraft, operations, and technical margins; Management readiness elements include team organization, schedule, and other special challenges; and Cost realism was done as an independent estimation of the probable cost.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation Technical Readiness Black Hole Finder Probes CASTER 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 required sensitivity, CASTER will require a very large number of detector modules. Achieving the necessary yield of detectors to meet CASTER’s 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 (LaBr3) 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-aperture 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. EXIST 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 anticipated—that 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
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation 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 CIP 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. CMBPol 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 implementation of its spacecraft and the overall mission, although it appears to be based on NASA’s 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-F 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 instruments and will present a very significant technical challenge to meet. EPIC-I 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.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation 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 ADEPT 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 × 2k infrared detectors that JWST uses, but with the cutoff frequency modified to 2 µm. There is some challenge to this modification, but there are ongoing programs that should demonstrate even lower cutoff frequencies. DESTINY The Dark Energy Space Telescope mission team provided a complete description of its proposed mission 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. Employing a 1.65 m primary mirror, the optics for DESTINY can be built without any special challenge. The proposed detectors are 2k × 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. SNAP 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
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation 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 “science craft,” 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 CASTER 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 lessening ITAR problems and eliminating the mission’s 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. EXIST It is assumed that the mission will be managed by NASA’s 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-X 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 CIP 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. CMBPol The CMBPol mission was presented as a concept only, and no detailed schedule was made available. EPIC-F The EPIC-F project will be managed by the Jet Propulsion Laboratory and is certainly within the experience 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-I 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.
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Nasa ’s Beyond Einstein Program: An Architecture for Implementation Joint Dark Energy Missions ADEPT ADEPT has a diverse science team from a number of organizations. There was no other information presented relative to team organization and operations. DESTINY Assuming that the team responsibilities remain unchanged, there are no obvious management challenges to the DESTINY mission. There was very little schedule information provided by the DESTINY team. SNAP 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. LISA 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 mission’s 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 committee 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.