B
Summary of the Workshop

The panel held a workshop on November 7, 2010, in Irvine California, at which a number of presentations were made as described in Appendix A. Below is a brief overview of each presentation at the workshop. To focus the presentations and in the interest of efficient data gathering, the panel prepared guiding questions, which were delivered to the speakers prior to the workshop. These questions are reproduced alongside a short summary of each speaker’s presentation. Additional questions not listed below were asked during the actual meeting. Speakers’ viewgraphs are available, as provided, upon request through the NRC’s Public Access Records Office.1

William Colglazier, executive officer of the National Research Council (NRC), opened the meeting by outlining the nature of the request to the NRC for this study from the Office of Science and Technology Policy. He thanked the panel for addressing this challenging task on such a rapid schedule. He noted that the U.S. government is looking forward to the panel’s perspective on the NASA proposal to participate in the European Space Agency’s (ESA’s) Euclid mission.

Adam Burrows and Charles Kennel, co-chairs of the panel, provided some opening remarks and described the issues on which the panel wanted to focus. They noted the tight meeting agenda and asked speakers to be efficient in their presentations and to leave time for questions. They concluded by remarking that both the Board on Physics and Astronomy and the Space Studies Board—of which they are chairs, respectively—had just earlier that morning been discussing the need for NRC stewardship of the space sciences decadal surveys, including the astronomy and astrophysics survey, and that this rapid panel and workshop activity only underscored that need.

Alexandre Réfrégier of the Service d’Astrophysique, Saclay, and principal investigator for Euclid, had been asked to answer the following questions:

• What are Euclid’s primary (or Level 1) science requirements?

• To what extent is U.S. technical involvement needed to deliver Euclid science?

• To what extent is Euclid’s science complementary to and/or synergistic with the science envisioned for WFIRST?

• Given the NWNH recommendation and a potential NASA partnership, is there any consideration being given to scaling Euclid back to an optical-only mission, with the expectation that a WFIRST mission would carry out the infrared complement?

• How might the Euclid design and mission be modified to incorporate microlensing?

Dr. Réfrégier delivered a presentation via teleconference entitled “Euclid: Mapping the Geometry of the Dark Universe.” He outlined the outstanding questions in cosmology and then described the Euclid mission as being driven by science concerning the nature of the dark energy, the nature of the dark matter, initial conditions (inflation physics), and modifications to gravity. He remarked that U.S. involvement is very welcome but not necessary for Euclid to proceed and that Euclid has involved U.S. scientists from the project’s beginning, so continued involvement would allow U.S. scientists to participate in the project in a more formal way and give more programmatic margins to optimize the mission. He then described the Euclid mission baseline and technical specifications, as well as its figures of merit (FOMs). He also

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1 The National Research Council’s Public Access Records Office provides access to project materials available to the public. It can be accessed at http://www8.nationalacademies.org/cp/.



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B Summary of the Workshop The panel held a workshop on November 7, 2010, in Irvine California, at which a number of presentations were made as described in Appendix A. Below is a brief overview of each presentation at the workshop. To focus the presentations and in the interest of efficient data gathering, the panel prepared guiding questions, which were delivered to the speakers prior to the workshop. These questions are reproduced alongside a short summary of each speaker’s presentation. Additional questions not listed below were asked during the actual meeting. Speakers’ viewgraphs are available, as provided, upon request through the NRC’s Public Access Records Office.1 William Colglazier, executive officer of the National Research Council (NRC), opened the meeting by outlining the nature of the request to the NRC for this study from the Office of Science and Technology Policy. He thanked the panel for addressing this challenging task on such a rapid schedule. He noted that the U.S. government is looking forward to the panel’s perspective on the NASA proposal to participate in the European Space Agency’s (ESA’s) Euclid mission. Adam Burrows and Charles Kennel, co-chairs of the panel, provided some opening remarks and described the issues on which the panel wanted to focus. They noted the tight meeting agenda and asked speakers to be efficient in their presentations and to leave time for questions. They concluded by remarking that both the Board on Physics and Astronomy and the Space Studies Board—of which they are chairs, respectively—had just earlier that morning been discussing the need for NRC stewardship of the space sciences decadal surveys, including the astronomy and astrophysics survey, and that this rapid panel and workshop activity only underscored that need. Alexandre Réfrégier of the Service d’Astrophysique, Saclay, and principal investigator for Euclid, had been asked to answer the following questions: • What are Euclid’s primary (or Level 1) science requirements? • To what extent is U.S. technical involvement needed to deliver Euclid science? • To what extent is Euclid’s science complementary to and/or synergistic with the science envisioned for WFIRST? • Given the NWNH recommendation and a potential NASA partnership, is there any consideration being given to scaling Euclid back to an optical-only mission, with the expectation that a WFIRST mission would carry out the infrared complement? • How might the Euclid design and mission be modified to incorporate microlensing? Dr. Réfrégier delivered a presentation via teleconference entitled “Euclid: Mapping the Geometry of the Dark Universe.” He outlined the outstanding questions in cosmology and then described the Euclid mission as being driven by science concerning the nature of the dark energy, the nature of the dark matter, initial conditions (inflation physics), and modifications to gravity. He remarked that U.S. involvement is very welcome but not necessary for Euclid to proceed and that Euclid has involved U.S. scientists from the project’s beginning, so continued involvement would allow U.S. scientists to participate in the project in a more formal way and give more programmatic margins to optimize the mission. He then described the Euclid mission baseline and technical specifications, as well as its figures of merit (FOMs). He also 1 The National Research Council’s Public Access Records Office provides access to project materials available to the public. It can be accessed at http://www8.nationalacademies.org/cp/. 16

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noted its anticipated synergies with other facilities and “legacy” through archival means and said that, depending on WFIRST’s actual manifestation, there may be a lot of scope for making Euclid and WFIRST’s science complementary. He said that the incorporation of microlensing would be possible from a hardware point of view and is being discussed, but the current nominal survey baseline does not include it. Finally, he provided the current Euclid mission schedule, which foresees launch in 2018, contingent on its selection in the M(edium)-class mission decision expected mid-2011. Fabio Favata, head of the ESA Science Planning and Community Coordination Office, was given the following questions prior to his talk: • What is ESA’s reaction to the statement on Euclid in NWNH: “Collaboration on a combined mission with the United States playing a leading role should be considered so long as the committee’s recommended [NWNH] science program is preserved and overall cost savings result.”? • Is there any flexibility in the plans for the science of the Euclid mission? Could it be restructured to include all three components of a WFIRST mission (specifically, for dark energy: weak lensing, BAO, and SNe; exoplanets via microlensing; and a guest investigator survey mode)? • What approach is ESA taking to secure independent cost and schedule estimates for the Euclid mission? • What is the current status of independent cost estimates for Euclid, and how confident is ESA that Euclid can stay within the €470 million cost ceiling? • What is ESA’s schedule for delivery of Euclid science, and to what extent does that schedule depend on U.S. involvement? Dr. Favata delivered a presentation via teleconference on ESA program planning with respect to Euclid. He outlined the ESA long-term science program planning process and described the “Cosmic Vision 2015-2025”2 process, which resulted in the identification of four Grand Themes.3 He went on to discuss the Cosmic Vision 2015-2025 budget consideration and allocation process and the mission types and management processes created within the science program. He also outlined the Cosmic Vision project selection process and the current status of the process. He mentioned that Euclid will have to undergo selection in the M-class selection process next year and that Euclid is competing with two strong competitors. He said that at this stage in the competition, no significant changes to Euclid’s configuration that would impact the project’s readiness for the selection process would be possible. He noted that after the competition the agency could consider it if it had international partnerships. He said there was no consideration being given to scaling Euclid back to an optical-only mission, given an expectation that a WFIRST mission would carry out the infrared complement. Should there be a partnership with the United States then ESA could consider a different scenario after the Euclid selection; however, this would need to go through the usual ESA advisory structure process. At the time of Dr. Favata’s presentation to the panel, NASA has not communicated any final decision on Euclid, and ESA is continuing with Euclid as is. He noted it would be very difficult to modify the mission significantly at this stage and keep with the launch date of 2018. Jon Morse, director of the NASA Astrophysics Division, and Fabio Favata, ESA, next took questions pertaining to ongoing NASA-ESA discussions regarding Euclid and a possible NASA minority partnership in the Euclid project and perhaps a reciprocal ESA involvement in the WFIRST program. They were given the following questions prior to their appearance: • When is the deadline for NASA and ESA to firm their commitments to Euclid? • How would a 1-year delay (or more) in a U.S. decision to join Euclid impact NASA’s and ESA’s decision on the mission and its scope? 2 See http://sci.esa.int/science-e/www/area/index.cfm?fareaid=100. 3 See European Space Agency Publication BR-247. 17

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• Do you think it is possible to join Euclid in a leadership role, with all three components (exoplanets, guest investigator survey mode, and dark energy) included in the mission? • In what way is possible U.S. participation in Euclid seen as a part of a new era of wider U.S./European collaboration in space astrophysics? Dr. Favata remarked that a U.S. commitment to Euclid, if made, should come as soon as possible. Dr. Morse said that ESA has suggested to NASA that ideally, it should hold its competition and announce the U.S. science team in late January 2011 if it plans to name scientists to the Euclid science team. Dr. Morse said that the situation with JWST, the FY 2011 budget, and the FY 2012 president’s budget request will be clearer before June 2011. Dr. Morse commented that ESA has said that its deadline for committing to a 20 percent U.S. participation in Euclid would be spring 2011, to ensure proper evaluation in the ESA Cosmic Vision downselect process. NASA does not finalize its FY 2012 budget until mid- December 2011; if NASA were to make an announcement on Euclid in late January or early February 2011, it would need to incorporate them into the FY 2012 budget. He added that this is why the rapid schedule was needed for this panel to give its input to the agencies by mid-December 2010. Dr. Favata later remarked via e-mail that “[ESA] believe[s] that to implement Euclid for a launch in 2018 ESA will need to start implementation phase in the third quarter of 2011. Hence by the middle of 2011 all contributions to the missions will need to be defined.” The panel heard from Steve Kahn, Stanford University, the deputy project director for the Large Synoptic Survey Telescope (LSST) and a co-investigator of Euclid from the U.S. community. The following questions were given to him prior to the meeting: • What do you see as the advantages for U.S. scientists and science of possible U.S. participation in Euclid? • What are the scientific redundancies between Euclid and LSST? • To what extent might LSST and other synergistic programs depend on Euclid capabilities, and vice versa? Specifically, in what ways are they mutually dependent? • What does LSST need from WFIRST to optimize their joint scientific return? • Do DOE laboratories have technical contributions or hardware development activities that would benefit WFIRST? • What is the level of enthusiasm in the DOE science community for participation in WFIRST? Dr. Kahn emphasized that U.S. researchers have played important roles in Euclid’s scientific and technical development since the mission’s beginning. He then spoke about the relationship between Euclid and LSST, noting that LSST and Euclid are complementary. In particular, “each data set [from Euclid and LSST] will individually constrain the properties of dark energy at unprecedented levels.” Dr. Kahn also said that “LSST can achieve its scientific goals with respect to dark energy without relying on data from any other experiment or facility.” Moving on to the relationship between LSST and WFIRST, he remarked that “LSST could benefit from complementary observations by WFIRST, depending on how WFIRST is designed.” Dr. Kahn believed that DOE laboratories have technical contributions or hardware development activities that would benefit WFIRST, as evidenced by the role that Lawrence Berkeley National Laboratory, SLAC National Accelerator Laboratory, and Fermi National Accelerator Laboratory have played in past astrophysics concepts and experiments such as the Supernova/Acceleration Probe, Joint Dark Energy Mission (JDEM), and the Fermi Gamma Ray Space Telescope. He thought relevant elements of the DOE science community would be “eager to participate” in WFIRST science and hardware. He wondered what additional benefit the U.S. community might derive from an increased share in Euclid beyond the proposed 20 percent, and concluded by stating that dark energy is a rich topic with many distinct analyses that can be used to constrain parameters. David Weinberg, Ohio State University, discussed the relative scientific reach of WFIRST and Euclid. He was given the following questions prior to the meeting: 18

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• JDEM Omega, the dark energy mission developed by a U.S. science definition team, and Euclid have different designs and emphasize different wavebands. Could you comment on the relative strengths and weaknesses of the two approaches? • Is there a scientific rationale for the United States both to invest in Euclid and to pursue WFIRST, assuming it launches 5 years after Euclid? • Measuring weak lensing of distant galaxies constrains both models of dark energy and possible departures from the predictions of general relativity of gravity’s behavior over the largest scales. LSST—the highest ranked ground-based facility in NWNH—is to make crucial observations of weak lensing. How important is WFIRST’s near-IR photometry of vast galaxy samples to the success of the LSST effort? Dr. Weinberg discussed the capabilities of WFIRST and how its three survey methods— supernovae, baryon acoustic oscillations, and weak lensing—would make substantial contributions to dark energy science. He also noted that WFIRST “would have a broad impact on high priority science” because it had the insight to combine several activity proposals with different science ambitions but similar technology requirements into one mission. He also noted that WFIRST’s IR capability would make a “critical contribution to each of the three leading methods” and that those IR observations are only possible from space. Dr. Weinberg remarked that the absence of a wide-field IR space mission would result in a several-fold to 10-fold decrease in dark energy discovery potential, and that “the LSST weak lensing survey will be systematics-limited by photo-z uncertainties at a level well above its statistical uncertainties.” He then described Euclid’s space-based optical weak lensing experiment as “powerful,” and remarked that Euclid and LSST are complementary because of their ability to provide cross-checks on measurements. He also said that Euclid’s IR capabilities, while able to make contributions to dark energy science, will not be able to match WFIRST, nor can they achieve WFIRST’s expected contributions to the three measurement methods identified earlier. Concluding, Dr. Weinberg outlined several best- and worst-case scenarios with respect to various Euclid and WFIRST outcomes. He also opined that “it may be hard to maintain U.S. community support for WFIRST following Euclid-IR, even though WFIRST is a factor of several more powerful, and that this problem gets worse if WFIRST slips later and is seen to be cutting into flexibility for the next decade.” Roger Blandford, Stanford University, and Chair of Astro2010, then described the NWNH survey process and its science objectives for the 2012-2021 decade. He was given the following questions prior to the meeting: • The top NWNH recommendations in large ground and space projects have a dark energy component. Can you explain the intended scientific and programmatic synergy between LSST and WFIRST and any time-critical elements? • How important is the timely execution of a microlensing survey to the overall NWNH strategy for exoplanets? • What is the major science to be achieved by the infrared surveys that motivated the NWNH recommendation for WFIRST and how time-critical is it? • How might NASA decisions on Euclid affect WFIRST science, as well as non-WFIRST science complementary to and/or synergistic with WFIRST science? • More broadly, how might early U.S. participation in Euclid affect other initiatives and recommendations of NWNH, as well as its overall integrated program? Dr. Blandford described the budgetary context presented to and used by the survey committee, as well the cost, risk, and technical evaluation process that the survey committee implemented. He discussed the report’s emphasis on balancing the program and briefly listed the large-class space-based priorities. He also discussed the WFIRST mission and its complementarity with LSST, as well as the importance of 19

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WFIRST to dark energy science and the science enabled by WFIRST’s microlensing and IR surveys. He noted that “LSST and WFIRST combine to measure properties of dark energy,” that “multiple techniques are needed to explore the physics of dark energy over the full range of redshift, and that “combined observations improve accuracy and control systematics.” Also, since Kepler and WFIRST are complementary, Dr. Blandford stated that the timely execution of a microlensing survey is important to the overall NWNH strategy for exoplanets. He added that the IR surveys enabled by WFIRST will contribute much to galactic and extragalactic astronomy, and the guest investigator program will add “much discovery space.” With the exception of the coordinated monitoring programs, he did not believe most of this survey-enabled science is time-critical. On the proposed NASA participation in Euclid, Dr. Blandford thought a “comprehensive joint program could get the science faster and cheaper and retain strong U.S. presence in fields it currently leads” and that “[a] Euclid, with or without NASA, that executes much of the WFIRST science program on schedule will likely obviate a later WFIRST mission under constrained economic circumstances with possible consequences.” He noted the “danger of surrendering U.S. leadership in dark energy and exoplanets.” Going on, Dr. Blandford commented that a minority role in Euclid is not among NWNH recommendations. If, alternatively, “Euclid (with U.S. participation) only executes some of the program and there is a clear commitment to start WFIRST at a later date, then this will significantly impact the implementation of the second ranked Explorer augmentation and the integrated and time-critical mission development recommendations on LISA, IXO, the [New Worlds Technology Development Program], [NWNH’s Inflation Probe Technology Development Program], and ‘small’ programs.” He added that no U.S. space mission has been started to exploit either the discovery of exoplanets in 1995 and of cosmic acceleration in 1998. Dr. Blandford stated that “Euclid is primarily a cosmology mission” and currently has more ambitious instrumentation than does WFIRST. Jon Morse, NASA Astrophysics, gave the next talk. He had been presented with the following questions prior to the meeting: • What is the present budget outlook for NASA Astrophysics? How is it expected to change? How does it impact the suite of large, medium, and small missions and activities recommended in NWNH? • If we are involved with Euclid and it does only the dark energy component, how would this impact the goals of a WFIRST mission that would come later? • If we join Euclid at the 20 percent level now, even if it were cost-neutral, how would that expenditure affect the implementation of the Explorer recommendation, LISA and IXO, and the new medium and small priorities articulated in NWNH? • Please describe the funding profile (particularly in the years before the JWST launch) that you imagine for a 20 percent U.S. share of Euclid and compare it with what would be required to (1) build WFIRST for a 2020 launch or (2) build it later in the next decade? Dr. Morse stated that the budget profile and schedule for JWST dominate considerations of when WFIRST development may begin, adding that, as communicated to the Astro2010 decadal survey committee and acknowledged in the report, significant funds for the next astronomy flagship mission will not become available until after JWST launches. In his talk, Dr. Morse emphasized that participation in Euclid by NASA may be the only way, under the reduced future funds anticipated due to a JWST launch delay, the U.S. astronomy community might participate during this decade in large-area, space-based dark-energy studies. He said that NASA has discussed with ESA participating in Euclid in a cost-neutral way, such that ESA would contribute toward WFIRST an amount equal to whatever NASA spends on Euclid. Dr. Morse said that the current participation level on Euclid is planned at 20 percent of the estimated mission development cost, based on ESA’s invitation to NASA in early 2010 and recent feedback from NASA’s advisory committees. While that expenditure would defer some WFIRST planning activities beyond the launch of JWST, the resulting delay to the WFIRST launch would be small. 20

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The panel heard that NASA had issued a “dear colleague” letter inviting participation in a science definition team as a first step in the WFIRST program. The panel also heard that, since WFIRST would follow JWST, a launch of the top-priority large space mission from NWNH would happen no earlier than 2022 under current projections. NASA has also made a call for U.S. scientists to participate in the Euclid science team, but the call reserves the right of the agency to defer or terminate any investigations dependent on “the outcome of decisions informed by an assessment of the proposed ESA-NASA Euclid collaboration.”4 Project offices have been established for the Euclid and WFIRST projects. Dr. Morse stated that NASA is working on its initial response to all of the decadal survey priorities as part of the next budget cycle and will communicate the response in the February 2011 release of the FY 2012 president’s budget request. The panel heard brief remarks from William F. Brinkman, DOE Science, Dennis Kovar, DOE High Energy Physics (HEP), and Vern Pankonin, NSF Astronomy. They were given the following questions prior to the meeting: • What are NSF and DOE plans for implementing LSST and other programs synergistic with WFIRST science? • Does the DOE see any role for it in Euclid? • Could DOE comment on its position concerning possible contributions of either hardware or scientific personnel to WFIRST? The panel heard that with the termination of the JDEM, DOE is no longer currently involved in a space-based dark energy project. On Euclid, DOE stated that it sees no role for it in Euclid, though “DOE HEP will support our scientists on the Euclid science team (if selected), and if our community proposes an effort on Euclid, we will then investigate participation, depending on funding availability.” On WFIRST, DOE HEP said it “will support our scientists on the WFIRST Science Definition Team (if selected),” and that, “after the WFIRST concept is developed, DOE HEP will explore possible contributions if appropriate (consistent with Particle Astrophysics Scientific Assessment Group criteria) and depending on funding availability.” DOE does remain a partner in the decadal survey’s priority large, ground-based activity, LSST. NSF gave a brief update on LSST progress toward a construction start in 2014 at the very earliest. On November 5, 2010, the NSF Directorate for Mathematical and Physical Sciences Advisory Committee unanimously recommended LSST to advance to preliminary design review. DOE and NSF are working to coordinate their schedules and funding for LSST. Carl Wieman, associate director for science at OSTP, made several comments to conclude the day’s open session activities. Dr. Wieman was provided the following questions prior to the meeting: • What are the motivations for this NRC activity? • How can the panel help the [Obama] administration? • What is OSTP’s view of the possibility that the entire NASA program could be dependent in large measure on international collaboration? Dr. Wieman remarked that OSTP’s motivation in requesting this panel to conduct this study was to preserve the integrity of the decadal survey process and to obtain NRC advice on NWNH recommendations in light of the present budget reality. He recognized the unprecedented community effort that the most recent survey represents. He also looked forward to receiving the panel’s analysis of the various options for implementing the NWNH recommendations as laid out in the panel’s charge. When asked if he is comfortable with having all major NASA missions be international collaborations, Dr. Wieman replied that, while it is not the preferred option, international collaboration on NASA astronomy missions may be the only choice available in the near future given the current budget environment. Dr. 4 NASA, “Solicitation for NASA Science Team Members for ESA’s Euclid Mission,” Solicitation Number NNH11ZDA006J, October 7, 2010. 21

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Wieman mentioned that OSTP wants more resources available for astrophysics in a larger fiscal environment. He said that OSTP sees the gains in the FY 2011 topline budget (assuming it is passed and signed as requested) difficult to sustain in the current fiscal environment. He noted that it is not realistic to expect significant adjustment for astrophysics in the future. OMB and OSTP concurred with NASA’s assessment that JWST’s problems will make a WFIRST launch unlikely in the early 2020s. Also, they agree with NASA that funding for Euclid at the 20 percent level would not substantially impact either JWST or WFIRST launch dates, though it would impact other activities. He asked for this report to be ready by mid-December so it could inform the final stages of the budget process leading up to the president’s FY 2012 budget request due to be released in early February 2011. 22