Status Report

NASA Advisory Council SSAC Origins Subcommittee Minutes 16-17 Oct 2000

By SpaceRef Editor
October 17, 2000
Filed under ,

Letter to SEC Director Dr. Anne Kinney from Dr. Alan Dressler, Chair of OS

Dear Dr. Kinney,

The Origins Subcommittee (OS) met at NASA Headquarters October 16-17, 2000. We thank you for bringing us up to date with developments in the Origins theme since our July meeting, particularly matters concerning HST and the upcoming ST-3 mission.Ê We are also grateful to Ed Weiler for providing a broad overview of OSS activities and passing on the good news about the budget that has come down from Conference in the Congress.Ê At the same time, both of you stressed that the projections of cost growth for many major missions challenge our ability to accomplish the goals of the NASA Strategic Plan at the hoped-for pace. We recognize this challenge and hope to do our part in keeping the Origins theme on track towards its goals, consistent with realities of schedule and budget.

WF-3 — the Wide-Field Camera for the Hubble Space Telescope.Ê In your opening remarks you reviewed the present situation concerning the development of WF-3 that was a focus of attention at our last meeting.Ê One particular comment that caught our attention was the idea that, if de-scopes are necessary for WF-3 to meet its $75M budget cap, the UV/Vis channel might be dropped in favor of the IR channel. You will recall that in our letter to you last June the OS advised that dropping the IR channel might be the better way to go if a de-scope is necessary, given the promise of NGST to far exceed this capability.Ê We stressed instead the importance of keeping the broad scientific capability of CCD’s in the context of the deteriorating performance of ACS that is expected after the first five years of its life. Regardless of the wisdom of that recommendation, the OS would like to know more about the process and criteria for a decision on the de-scope should that prove necessary.

SIRTF –Ê Space Infrared Telescope Facility.Ê We are grateful that Mike Werner briefed us on the SIRTF mission.Ê The OS acknowledges the necessity of a schedule slip in the launch of SIRTF to July 2002; of course, we hope that all steps be taken to avoid further delays and associated costs. Despite the regrettable schedule slip, the OS is pleased with the progress SIRTF has made, especially the high level of readiness being achieved in the important areas.Ê We were also glad to hear of the impressive success of the Legacy Program as indicated by the great over-subscription rate for the telescope time offered. ÊSIRTF seems to be well on track to become the major new scientific wellspring of the Origins program.Ê The OS congratulates the SIRTF team on the excellent job they are doing.

SIM — Space Interferometry Mission.Ê We heard presentations from the SIM Program Manager (Tom Fraschetti), the SIM Project Scientist (Mike Shao), and the NASA Origins Program Financial Officer (Lia LaPiana) concerning the project’s current management, technological, and financial status.Ê Tom Fraschetti outlined the conclusions of the Langley Independent Assessment (IA) team concerning the feasibility of SIM’s original technological goals and costs, and described the developing partnership between the IA and SIM teams to address the specifics of the IA report.Ê

We learned that present cost estimates for the implementation phase of SIM are running well ahead of early estimates, in excess of $1B, and although the highest numbers may be overly pessimistic, it is likely that the true cost will significantly exceed what OSS can afford for SIM in the context of a healthy and diverse Origins program.

Mike Shao updated us on technical progress in the components and systems for SIM, and Lia LaPiana presented the updated NASA Origins Program management rules, cost stipulations, and performance requirements for SIM.Ê Ms. LaPiana reported that (1) the SIM Science Team would be selected in October, (2) an internal review of new concepts and cost estimates was proceeding, (3) the SIM project and Science Team will establish a “skunk works”” to study alternate (presumably lower-cost) designs, and (4) an External Review Board chartered by Code S will look at the scientific merit of proposed redesigns and concepts, with the plan that Code S will decide in April 2001 if any of the proposals are both viable and affordable.Ê We understand that Ms. LaPiana expects these actions to result in a delay of 6 to 12 months beyond the original June 2001 date in the implementation of Phase B.

The OS is impressed with the technological advances that the SIM Project has demonstrated, the rapid pace of component development and testing, and the variety of cutting-edge technologies being developed on the way to achieving SIM’s demanding performance goals.Ê We agree that projected cost growth suggests that a less ambitious SIM may emerge in the next year, and we feel that it is vital to assess whether that mission will still have a compelling science case that fits naturally within the NASA Origins Program portfolio.

We expect the final judgement on this to be made by others, for example, the new Science Team that is being assembled.Ê We have, however, discussed the situation and offer our opinion in the hope that it might be useful.Ê A principal driver for SIM has been the demonstration of Michelson interferometry in space.Ê In addition, two major science drivers are:Ê 1) the discovery of planets and 2) a more general astrophysics program of stellar and galactic precision measurements.Ê The latter has broad support in the astronomical community, for it will firmly establish the galactic distance scale, test the central tenets of stellar evolution theory, measure the galactic gravitational potential and halo star kinematics out to unprecedented distances, and determine the proper motions and ages of globular clusters. Some of these goals could be threatened by a de-scope, but we believe that only a modest improvement in the level of performance already achieved will accomplish much of the original program in general astrophysics.Ê Indeed, the wide-angle capability quoted by Mike Shao for the “current” SIM (~32 microarcseconds) is within a factor of 2 to 3 of the floor level requirements for all of the wide-angle astrometric projects promoted by the SIMSWG.

Planet discovery in particular is a central theme of the Origins Program: SIM is seen as not only a technical but a scientific precursor to TPF.Ê The ~7 microarcsecond narrowÊangle accuracy quoted by Shao is at the SIMSWG “recommended” level for giant planet and brown dwarf detection and is within about a factor of two of the SIMSWG “recommended” level for both giant terrestrial planet and ice giant (e.g., Uranus and Neptune) detection. Giant planets have always been the natural technological and scientific stepping stone to the terrestrial planets.Ê SIM’s capabilities in this regard will complement and vastly extend the radial velocity studies that are being carried out with ground-based telescopes. Our preliminary conclusion is that the science that could be accomplished at the present state of SIM technology is still at the forefront of astronomical and planetary research and satisfies many of SIM’s original objectives.

Because of the large constituency for SIM science among astronomers, we recommend that the NRC Committee on Astronomy and Astrophysics (CAA) be kept informed of the progress of reviewing and perhaps rethinking the SIM mission. The OS thinks it essential that the scientific rationale for SIM put forward by the Bahcall Decadal Survey (and reaffirmed by the Taylor/McKee Decadal Survey) be contained within the new mission if community support for SIM is to continue — good communication with the CAA can ensure that this is the case.

SIM is a crucial Origins mission for both technology demonstration and advancement of science; in particular, it serves as a bridge to TPF and terrestrial planet detection and characterization.Ê As such, the SIM team must achieve the proper balance of capability and technological readiness to permit its developement and successful flight in this decade.

Planet Finder Program.Ê We were very interested in Origins Program Manager Mike Devirian’s presentation on the establishment of the Planet Finder Program at JPL.Ê We understand that the creation of this structure is mandated by NASA HQ’s decision to outsource program management to the individual NASA centers.Ê ÊThe OS agrees that the synergy between missions with such close science and technology objectives can be effectively exploited within one management structure. We were reassured to learn that, although this management structure exists entirely within JPL, the Planet Finder Program will vigorously promote open, peer-reviewed competition for future instruments and missions falling within its purview.Ê

The establishment of the Interferometry Science Center in close connection with the Infrared Procesing and Analysis Center (IPAC) will allow the infrarstructure, community support, and data archive experience of IPAC to be fully utilized in the program. The OS is especially pleased to see that the program already has an active education/public outreach effort, including fellowships and a summer school.

NGST — Next Generation Space Telescope.Ê The OS recognizes that NGST presents significant technical challenges, and thanks the NGST Project for their presentation on Nexus.Ê We are glad to see that a process is in place to, among other things, address the issues of serious concern about Nexus we expressed in our June 26, 2000 letter to you.Ê Specifically, the OS is very supportive of the Tiger Team and External Review activities that will be assessing the need for a flight test of critical NGST technologies as proposed in the form of Nexus. We thank Bernie Seery and the NGST Project for keeping the OS informed, and look forward to a thorough discussion of the Nexus and NGST,Ê including the report of the External Review, at our next meeting.

Origins Technology.Ê The OS received a comprehensive, impressive briefing on technologies for Origins missions. Richard Capps presentation emphasized the interdependence of ST-3, SIM, NGST, and TPF in terms of technology development and the increased risk and difficulty shouldÊ one of the earlier missions not be flown.Ê Rich Burg went through the NGST technical hurdles one by one, emphasizing the challenges but also the substantial progress that is being made in all areas.Ê (The one exception, the slow progress on the manufacture of micro-mirror/micro-shutter masks for the spectrograph, concerns us as it does Dr. Burg, since multi-object spectroscopy is a key part of the NGST mission.)ÊÊ Dan Coulter described for us the process now underway to expand thinking on TPF through four pre-Phase A architecture studies carried out by teams involving both industry and universities.ÊÊ Juan Roman reported on the Large Telescope Systems Initiative with its emphasis on lighter mirrors, cryo-coolers, advanced wavefront metrology and control, and new energy-resolving detectors. The scope of all this technological effort is truly dazzling, and the OS is encouraged by the degree to which this effort is focused on Origins missions, and the way that technology is being shared between projects –Ê these have been critical goals of the reorganized technology development program and it is very encouraging to see that they are being effectively pursued.

Interferometry with the Large Binocular Telescope (LBT).Ê The OS thanks Roger Angel for providing a lucid, compelling description of Fizeau interferometry and its proposed implementation on LBT in furthering Origins science goals, in particular, the survey of exo-zodi dust disks around stars that are potential targets for TPF.Ê In addition to the substantial benefit of providing an independent and possibly superior approach to that of the Keck (Michelson) Interferometer, the OS was persuaded that the larger field enabled by the Fizeau approach could eventually prove important to a wide range of astrophysical research areas, and we are therefore enthusiastic about its continued development.ÊÊ With the tight budget constraints of the Origins theme, support for this research needs to be weighed, of course, within the context of the overall Program.Ê The OS recommends that, if the U. of Arizona effort to build a cryogenic beam combiner for the LBT is to be supported, the proposal first be subjected to a standard technical review including evaluation of schedule and budget. We understand that NASA already has a commitment from the University of Arizona for 20 nights a year observing time for 8 years nights on the LBT as a result of the support the project has already received.Ê The discussion we heard left considerable confusion about who has access to those nights, how the time is to be allocated, and what science will be supported.Ê If it would be of help to you, the OS would be happy to hear a more detailed discussion and offer advice regarding the scientific potential of different arrangements.

Research & Analysis.Ê Guenter Riegler’s report on the progress of implementing the 9 Science Cluster concept for Reseach and Analysis funding was well received by the OS, which has been a strong supporter of the idea from its inception.Ê The upcoming Senior Review is, of course, a key step in developing a system that can evolve as scientific priorities change.

We raised with Guenter the question about grant size, particularly because we have heard about the difficulty of supporting such activities as astrobiology laboratories with the present average grant size of $60K.Ê Guenter told us that increasing the average grant size is one of Ed Weiler’s priorities, and that he himself would like to see signficantly larger grants, at the level of a few hundred thousand dollars, when the science justifies the need.Ê We hope to watch with you the evolution of this sytem and look forward to further reports from Dr. Riegler.

Supporting Origins Goals with Ground-Based Facilities.Ê Discussions at this meeting reminded us of the continuing possibility of valuable contributions to Origins missions from ground-based telescope observations.Ê Both you and Ed Weiler made clear your reluctance to encourage proposals to NASA for further investments in ground-based facilities.Ê However, we remain concerned that valuable opportunities could be missed.Ê Lia LaPiana reminded us that there has been a NSF/NASA working group that could in principle develop criteria to help decide how the Agency and the Foundation can best share the responsibility for achieving scientific goals of the Origins program that have received the support of the Space Studies Board and the NASA Strategic Plan.Ê We recommend that this working group be reconvened and urge that it consider how meritorious cost-effective programs to do Origins research with ground-based telescopes can be supported.

We look forward to seeing you at our next meeting in Pasadena, March 6 and 7, 2001.


Alan Dressler, for the Origins Subcommittee

SpaceRef staff editor.