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NRC Debates NASA's Plan to Participate in ESA's Euclid

Marcia S. Smith
Posted: 22-Jan-2012
Updated: 22-Jan-2012 05:25 PM

The National Research Council (NRC) is debating the merits of NASA’s current plan for U.S. participation in the European Space Agency’s (ESA’s) Euclid dark energy mission and there is not much time to deliberate.

The NRC Committee on Assessment of a Plan for US Participation in Euclid has been asked by NASA to work at breakneck speed for an NRC study, with its report due on April 30.   That deadline is dictated by when ESA needs to know whether NASA wants a piece of the action on Euclid or not.  If it does, ESA wants a Memorandum of Understanding (MOU) to be signed by April 2012, right when the report is due. 

At a public meeting of the NRC committee on Wednesday, it seemed that many of the committee members were not enthusiastic about NASA’s current plan even though their peers on NASA’s internal astrophysics advisory subcommittee approved of it in November. 

The main concern at the NRC committee was the potential impact of spending any money – even the comparatively small amount NASA is proposing – on Euclid instead of on the Wide-Field InfraRed Survey Telescope (WFIRST) mission.  WFIRST was the top large space mission recommended by the NRC’s 2010 decadal survey on astronomy and astrophysics, New Worlds New Horizons.  That report called for WFIRST to be launched in 2020. 

NRC decadal surveys delineate the key science questions for the next 10 years (a decade) in a particular discipline and recommend projects to answer them.   The astronomy and astrophysics decadal surveys were the first of this type and date back to the 1960s.  Often called “bibles” because their recommendations usually are faithfully followed by NASA (primarily responsible for space-based astronomy) and the National Science Foundation (NSF, which is primarily responsible for ground-based astronomy), they represent a hard-won consensus of that community. 

WFIRST has three scientific goals:  studying dark energy, performing an all-sky infrared survey, and searching for exoplanets.   WFIRST is being delayed, however, because of cost overruns on the James Webb Space Telescope (JWST).   NASA has made clear that JWST is its top science priority and with JWST’s launch date slipping to 2018, significant work on design and development of WFIRST will have to wait until then. 

The U.S. space-based astrophysics community hopes WFIRST will lead to answers about dark energy -- called “dark” because scientists do not know what it is.   What they know is that some force is causing the universe to expand faster than earlier theorized and the term was coined to refer to this mysterious force. 

Ground-based facilities also can be used to investigate dark energy and the NRC decadal survey’s top priority for a ground-based instrument, the Large Synoptic Survey Telescope (LSST), will be used for dark energy research, too.  LSST would be funded by NSF and the Department of Energy (DOE), which is working on solving the dark energy puzzle as well, especially at its Lawrence Berkeley Laboratory (LBL).   LBL’s Saul Perlmutter was one of three scientists to win the 2011 Nobel Prize for Physics for dark energy research, along with Brian Schmidt of Australian National University and Adam Reiss of Johns Hopkins University and the Space Telescope Science Institute.

Many astrophysicists, however, believe that space-based observations will be critical to determining the nature of dark energy.  For the U.S. astrophysics community, WFIRST is their top choice. 

At the NRC meeting on Wednesday,  NASA officials emphasized that the earliest a funding wedge will open up for the design and development of WFIRST will be 2018 with launch expected seven years later – or 2025.    Preliminary studies will be carried out before then, but there are not enough funds to make a concerted start on the project until JWST is nearing launch.   Euclid, however, is scheduled for launch in 2019, opening an avenue for U.S. scientists to obtain space-based data about dark energy sooner than if they wait for WFIRST.   Previous estimates were that WFIRST’s launch would slip to 2022 and the 2025 date seemed to come as a surprise to some of the committee members. 

NASA has been discussing the possibility of U.S. participation in Euclid with ESA for a long time, but the U.S. astrophysics community has not been supportive of significant participation because of the potential impact on WFIRST.   The plan NASA asked this NRC committee to review involves NASA providing a hardware contribution valued at about $20 million in exchange for ESA giving NASA one of the 12 coveted seats on the Euclid science team.   That scientist, called a principal investigator, would be able to bring along 20 co-investigators and an even larger number of “collaborators,” all of whom would have early access to Euclid data.   Otherwise, scientists would have to wait 14 months for “quick look” data and longer for more detailed data. 

ESA’s primary interest in cooperating with NASA is that it dearly wants U.S. near-infrared detectors for Euclid, although NASA officials said that ESA would accept other hardware contributions (filter wheels or reaction wheels were mentioned). 

NASA officials refer to the current plan as the United States having a “10 percent role in Euclid.”   At the NRC meeting, they explained that means NASA would provide the equivalent of 10 percent of the total cost for Euclid’s instruments, not 10 percent of the cost of the Euclid project overall.  There would be no exchange of funds between the agencies.   As noted, NASA ran this 10 percent proposal by its internal astrophysics advisory subcommittee in November and they agreed, but NASA also is seeking input from its external advisers at the NRC to ensure it is acceptable to those responsible for the decadal survey. 

The $20 million NASA estimates for its costs would be needed in the next two fiscal years.  NRC committee members worried, however, about where the $20 million would come from and whether it might be better invested in early work on WFIRST.    When asked what the impact would be on WFIRST’s schedule, Paul Hertz, acting director of NASA’s astrophysics division in the Science Mission Directorate (SMD), said “zero” because the Euclid money is needed in the near term while WFIRST’s development will not begin until about 2018. 

Hertz explained that the plan is to take the $20 million in FY2013 and FY2014 from SMD investments planned for technology development, research and analysis, the Explorer program, and research using balloon-borne instruments. Those four areas also were priorities of the NRC decadal survey and Hertz said NASA will increase funding for each of them.   However, taking out $20 million for Euclid would mean the rate of increase would be slowed. 

Apart from JWST, NASA’s astrophysics budget is about $700 million a year, Hertz said.   The $20 million in question ($10 million a year for two years) may seem a small portion of that, but the NRC committee members clearly were worried about which accounts would be cut to pay for Euclid and whether the U.S. astrophysics community would be getting a fair return on the investment. 

NASA’s message was that it is fact that Euclid will launch before WFIRST and the primary determinants for WFIRST are when funding is available to build it and how the field of dark energy research evolves in the meantime. 

NASA is required by law to ask the NRC to perform a “mid-term review” for each decadal survey half way through the decade that it covers.  The mid-term review for the New Worlds, New Horizons Decadal Survey will be due around 2015.  Hertz said NASA will ask the NRC to relook at WFIRST at that time to see if changes should be made based on what has been discovered using ground-based instruments and what is expected to be accomplished with Euclid.    An NRC committee member said he was worried that WFIRST was in a “holding pattern” until the mid-term review.  Hertz agreed that it is, but added that it is true whether or not NASA participates in Euclid.  He assured the committee that NASA would not do anything that would slip WFIRST in favor of participating in Euclid.

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