From: NASA Advisory Council
Posted: Friday, July 13, 2001
Letter to Origins Director Dr. Anne Kinney from Dr. Alan Dressler, Chair of OS
Dear Dr. Kinney,
The Origins Subcommittee (OS) met at NASA HQ on July 11-13, including a joint session with the Structure and Evolution of the Universe Subcommittee (SEUS) on the afternoon of July 11th. One of the topics of this joint session was the reorganization of Code-S, and in this connection, the members of the OS congratulate you on your appointment as Director of the new Astronomy and Physics Division. We look forward to advising you in the context of this larger, more challenging role of coordinating the entire suite of astrophysics missions and activities. The OS joins with the SEUS in acknowledging the years of excellent leadership by Alan Bunner, most recently in his role as SEU theme director.
We very much appreciated your briefing about the state of the Origins theme, specifically the questions raised at our last meeting. We were pleased to hear that technical milestones for SIM have been added as a pre-requisite for entering Phases B and C-D and concur in your decision to continue with Starlight as a vital development path toward the leading conceptual design for TPF. Your report on the Origins budget indicated that the program as now structured fits within budget allocations and projections, which is good news indeed. Ed Weiler’s briefing left us with a similarly encouraging view of the health of the entire Space Science Enterprise.
We were also grateful to Chas Beichman for bringing us up-to-date on the work of the Astrobiology Task Force. Even though astrobiology has become the principal responsibility of the Solar System Exploration division, the OS wants to be kept informed about progress in this exciting NASA initiative, and in particular to ensure that the interests of astrophysics in astrobiology research, such as atmospheric bio-signatures (for TPF), receive continuing attention and support.
Our joint discussion included, at your request, some consideration of the Subcommittee structure after the reorganization. We all seem to agree that --- at least through the period of strategic planning when new roadmaps will be produced for the two themes --- itis essential that the Subcommittees retain their separate identities. However, we are also aware that it would be counterproductive for the OS and SEUS to provide you with contradictory advice. We therefore are proposing to conduct parallel two-day meetings of the OS and SEUS over the next two years, with at least one joint OS-SEUS session with briefings and discussions of matters of common interest. From these combined sessions we intend to provide you always with consistent advice. We will continue to review OS and SEUS missions separately; however, over time, each Subcommittee intends to brief the other on its theme’s missions and solicit opinions as will be helpful. We hope that this transition period with two separate but somewhat overlapping Subcommittees will demonstrate whether this is a useful, stable structure, or alternatively suggest a future restructuring that could serve you more effectively. The OS believes that this will depend to an important extent on the success of securing funding for the Cosmic Journeys line, but, in any event, both Subcommittees are convinced of the importance of the two themes in the future of our programs and want to do what we can to keep the themes focused, vital, and productive.
NVO - National Virtual Observatory
With the OS and SEUS in joint session, OS member George Helou introduced a discussion of the proposed National Virtual Observatory (NVO), the only ranked small program of the McKee-Taylor Decadal (Astronomy & Astrophysics Survey Committee) report. Helou’s brief review of present NASA archives, data systems, and tools was followed by a description by Bob Hanisch of an NVO development and implementation proposal to the NSF Information Technology Research program, and a report by Joe Bredekamp of plans being developed at NASA HQ. Because of the priority given to NVO in the Decadal report and its potential importance to a wide range of Code S missions, the OS recommends that Code S move ahead with a plan for implementing an initial stage of NVO as soon as possible, and in particular to quickly identify funding options. We support the goal of the Decadal report to make this a joint NASA/NSF program, but emphasize that the potential benefits should encourage NASA to begin implementation of NVO regardless of progress on the NSF side.
Space Science Research and Analysis Programs
The results of the recent “Assessment of NASA’s Space Science Research and Analysis Program” by a specially convened committee were summarized by Guenter Riegler. It is clear from their report that the committee carried out their task with great care and effort. While finding the overall quality of the R&A Program high, they recognized that it is substantially oversubscribed; the pressure to accommodate more programs results in shrinking grant size and/or narrowing focus. The oversubscription has grown over the last decade as the OSS program content has increased in size over while the funding for the R&A program has remained flat. The committee made several specific recommendations to ameliorate these problems and we encourage NASA to adopt as many of these as possible. In particular, we strongly endorse the committee’s recommendation that the R&A program be augmented to provide “the proper level of science support for utilizing the results of missions and prepare for future missions.” We note in particular the recommendation to augment group grants in the Astrophysics Theory Program (ATP) and suggest that the effectiveness of group grants be considered for the other clusters and encouraged as appropriate
SIM - Space Interferometry Mission
The OS heard from SIM Project Manager Tom Fraschetti concerning the current status of the project, now that the Shared Baseline concept has been accepted. This simpler design, which eliminates the large metrology kite and uses shared siderostats, has been costed both by the Independent Assessment team and by the project itself at $932M, a substantial reduction in cost. Nevertheless, Shared Baseline SIM retains ~90% of the original SIM science goals; in particular, the performance goal of 4 microarcsecs will enable most of the wide-angle science supported by a large fraction of the astronomical community. The series of technical milestones mandated by Headquarters as a requirement to proceed from Phase A to B to C/D addresses well the concerns that we raised at our last meeting, described to you in our letter of March 15, 2001.
The OS also heard from Joe Wampler, the chair of the SIM External Review Board. The Board endorsed the Shared Baseline concept as the appropriate new path, complimented the JPL team for doing an outstanding job, concluding that the Project is on track to achieve the floor recommendation of 3 microarcsecs for narrow-angle measurement. This capability should enable the detection of 3 Earth-mass planets around the closest stars, however, the Board noted that a higher precision of 1 microarcsecond will probably be necessary to detect Earth-mass planets around stars beyond 3 parsecs.
The OS took note of the fact that the rescoped SIM still preserves a unique single-pointing capability (one to two orders of magnitude better than FAME). Because of this, SIM will be the only astrometry mission in the near-term that can detect and measure the masses of large terrestrial planets. SIM’s potential to detect giant planets at large separations is also unmatched. Hence, SIM retains its status as a key component of the Origins program. The OS joins the External Review Board in commending the project for its continuing excellence as it strives to achieve its very difficult development goals.
SIRTF - Space Infrared Telescope Facility
Dave Gallagher provided an update on SIRTF’s progress toward its planned July, 2002 launch. We were glad to hear that the problem encountered last December during cryogenic operation has been understood and that the cool down has now been successfully completed. We concur with the Project’s recommendation, and your decision, to proceed with the present “long-low” IRS filter in spite of its 30% degradation in transmission as a result of thermal cycling. We support the decision to replace this filter only if it is necessary to open the dewar for other reasons, and were pleased to hear that a review team has concluded that a structural failure of this filter on orbit would not impact the other science instruments.
NGST - Next Generation Space Telescope
The OS thanks Eric Smith, NGST deputy project scientist, for a comprehensive NGST update. It was gratifying to learn that the telescope has passed all science review hurdles, and that negotiations with CSA and ESA have resulted in a plan for international participation. The RFP and a draft of the instrument AO will be released soon. The OS was particularly pleased to hear that the scientific importance of the Mid-IR Instrument is appreciated, and that a Mid-Infrared Steering Committee with international membership has been established to formulate the science requirements for this instrument.
Eric Smith also presented the proposed organization for providing science input and oversight to the NGST Project. The proposed structure has a science working group or committee at each level, attached to each of the Program Scientist, the Project Scientist, and the ISIM (Integrated Science Instrument Module) and OTE (Optical Telescope Element) Project Scientists. The OS commends the Project on addressing the issue of science oversight early in the planning for the mission. The proposed organization is responsive to the need for a close integration of science with design and development at various levels in the project. It could potentially accommodate multiple interactions on different time-scales, independent of the timing of major meetings by the Science Working Group (SWG). A particular concern of ours, that the Project Scientist chairs the Science Working Group, appears to be addressed in a web document referenced by Eric Smith, www.ngst.nasa.gov/public/unconfigured/doc_0867/rev_03/SWGCharter.pdf,which clarifies that this is to be the case. However, we also note that the proposed organizational structure creates the need for frequent interactions among the various science committees to keep the science input synchronized, and we are concerned that it appears to create distinctions between members of the SWG, for instance, placing the Facility and Telescope Scientists in at least two places on the Organizational structure. There also seems to be a real risk of divergence between the scientific input and oversight for the ISIM and the OTE. The OS hopes that these concerns will be kept in mind as the organization develops. In particular, the need for frequent interactions could be accommodated by the addition of subcommittees or focus groups. We believe it is important to document the roles and responsibilities of the various entities in the science oversight organization as soon as possible.
Marcia Rieke presented a review of recent activities of the ISWG. Overall, it appears that while the NGST rescope has cost some science at short wavelengths, long wavelength science has not been significantly compromised. The ISWG has informed NASA Headquarters that the rescoped NGST will still achieve its primary scientific objectives, as the OS also concluded in its March 2001 letter to you.
We discussed the issue raised by the ISWG of the ability of NGST to track solar system targets. The Infrared Space Observatory (ISO) detected mineralogical features in one comet that are strikingly similar to those seen in circumstellar disks, implying that observations of comets within the context of what we learn from disks around other stars may enable us to better understand the formation of our own planetary system. The ISWG has therefore suggested that a modest tracking requirement be explored for NGST to enable it to observe active comets in the outer solar system. The OS concurs that this possibility should be examined, and implemented if there are not significant impacts on cost and schedule.
The OS understands that, in order to reduce scheduling risks, it has been decided that the Mid-Infrared Instrument (MIRI) is to be developed as a facility-class instrument managed by a NASA Center. The resulting loss of competition is unfortunate, and the OS strongly believes that whoever is chosen to be the MIRI Project Scientist should have a vested scientific interest and be a full member of the US MIRI science team.
The OS heard from Marcia Rieke about the ISWG’s review of the development program for a MEMs device for the NIR spectrograph for NGST. We join with them in re-emphasizing the clear preference that arose from the Ad Hoc Science Work Group for this addressable multi-aperture technology over integral field units, an approach previously preferred by ESA. Given the tight schedule and technical challenge of achieving a flight-qualified micro-mirror or micro-shutter devices for NGST, we think it very important to review the science drivers that previously led to the preference for MEMs over IFUs. We understand that the ISWG will take this matter up at its August meeting and we look forward to reviewing their discussion at the next OS meeting and advising you as appropriate.
The MEMs issue highlights a concern about the dissolution of the ISWG when the forthcoming AO is released. Undoubtedly there will be matters like this which would benefit from continued input from the scientific community in the interim period before the constitution of the new science working group. The OS believes that it would be highly desirable to continue a group of non-proposing scientists as an interim working group to follow progress on the MEMs and like matters that affect scientific capabilities.
TPF - Terrestrial Planet Finder
The OS was impressed by the amount of progress on TPF reported to us by Chas Beichman. Despite the budget cuts of the past few years, the scope of the mission has not been reduced and more architecture concepts are now being investigated. There also seems to be significant progress in hardware demonstrations. We are especially pleased that NASA HQ has recently released the “Extra-Solar Planets Advanced Mission Concepts” NRA calling for new mission concepts as TPF precursors, as described to us by Phil Crane. There is some concern that due to descopes with SIM and NGST several of the critical technologies, such as lightweight mirrors and low temperature cryocoolers, respectively, must be developed by the TPF team. There is also a concern that the final architecture decision will be made before missions like Kepler (or others) have better characterized extrasolar planetary systems. We all hope that such instruments as the Keck Interferometer and the LBT may help with this, but the concern remains that the architecture decision may be strongly dependent on what may continue to be poorly understood characteristics of extrasolar systems. It is essential that we continue to address this question.
The OS appreciates Mark Colavita’s status report on the Keck interferometer project. The acquisition of first fringes for the Keck-Keck interferometer is a major milestone for the project. The OS is pleased to hear that commissioning science using visibility interferometry may begin in early 2002. Much work remains before the Keck-Keck is routinely used for nulling interferometry at 10 microns and differential interferometry at the shorter wavelengths. Since both capabilities are necessary to achieve major Origins scientific goals, the OS strongly endorses this effort and requests that we be kept abreast of progress in these areas.
FAME - Full-sky Astrometric Mapping Explorer
The OS thanks Ken Johnston, the FAME PI, for telling us about progress on FAME, and commends him for investigating a rescoping of this mission to avoid a substantial cost overrun at its upcoming PDR. FAME exceeds the scientific capabilities of prior astrometric missions (e.g. Hipparcos) by such a large factor that even with reductions in its capabilities it would still retain the essential scientific value of the mission. A mission that delivers positions even at a level of 100 micro-arcsec for tens of million of stars with the same sensitivity (V=9 at the best accuracy, V=15 at 500 micro-arcsec) would be an order of magnitude jump over Hipparcos, and would, for example, probe the Galaxy's thick disk. FAME's data are also very important for establishing the astrometric grid required by SIM.
SOFIA - Stratospheric Observatory for Infrared Astronomy
We thank you for bringing us up-to-date on the restructuring efforts in the SOFIA program. The OS is pleased that our previous recommendations regarding this program have been followed. In particular, the budget problems have been solved within the Project by using the first year of operating funds as the source for additional construction funds. We feel that the recommendations of the Independent Management Review, which include increased oversight of the Project by ARC and descopes of first light requirements to enable an early operations start, will put the SOFIA Project on a path for success. An independent review of the AIRES instrument has recently been held; the review recommended cancellation of this instrument due to cost overruns and technical problems. The OS notes that the AIRES instrument provides a capability that is not available on any other NASA mission and is central to SOFIA's scientific mission. Assuming the recommendation is followed, we strongly endorse a plan to pursue the eventual construction of such an instrument through an open AO. Finally, on several previous occasions, the OS has asked for a review of the science data system, including analysis tools, distribution and archiving. The Project has been too busy grappling with more serious programmatic issues to provide such a review. However, we note that requirements for this data system will be defined in the Science Phasing Review to be held this Fall. We therefore request an update on the Project’s progress, including the data system, at the next OS meeting in November 2001.
Education and Public Outreach
It was gratifying to hear of further developments in Education and Public Outreach associated with the Origins program. Ian Griffin’s descriptions of the Space Science Education Resource Directory and the Origins Forum, a program to increase connectivity between the education and science communities, were very encouraging regarding progress in bringing the excitement of space science to a much wider public audience. We also thank Rolf Danner for describing plans for a new public outreach program emphasizing the Navigator program at JPL and look forward to hearing future reports on these efforts.
Alan Dressler, for the Origins Subcommittee
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