UPDATE: NAC Astrophysicists Take Cautious Stance on U.S. Participation in ESA's Euclid

UPDATE (September 28, 2010): This issue was discussed extensively at the NAC Science Committee meeting today. The committee decided to forward a recommendation to the full NAC, which meets next week in Palmdale, CA, that NASA should keep open the option of a possible partnership with ESA on Euclid, and if ESA does select Euclid to proceed next summer, NASA’s goal then should be negotiation of a joint ESA/NASA program that meets the science goals of both Euclid and WFIRST either as a combined mission or two complementary missions.

ORiGINAL STORY (September 27, 2010)

The NASA Advisory Council’s (NAC’s) astrophysics subcommittee (APS) took a cautious position on the possibility of NASA participating in the European Space Agency’s (ESA’s) Euclid dark energy mission after two days of intense debate (see our two earlier stories). Euclid is one of three missions competing for two slots in ESA’s science mission program; a decision will be made next summer. The National Research Council’s Astro2010 Decadal Survey recommended a U.S. mission, WFIRST, that would also study dark energy among other pursuits. NASA asked for input from the U.S. astrophysics community, through APS, on the extent to which the two agencies could work together.

In a report to its parent NAC Science Committee, which meets tomorrow by teleconference, the APS conveyed that it supports NASA’s plan to continue discussions with ESA about a possible partnership on Euclid, but it was “primarily to keep the Euclid option open at this time, not endorsement of proceeding to a legally binding Memorandum of Understanding (MOU).” The APS also “indicated a preference that the US share of Euclid be kept at the present 20% level, rather than being raised to 33% as proposed….” (emphasis in original).

The subcommittee was responding to briefings it received from NASA and the NRC about priorities for space-based astrophysics in the next decade. The Astro 2010 Decadal Survey, entitled New Worlds New Horizons (NWNH), recommended the Wide Field InfraRed Survey Telecope (WFIRST) as the top priority for large space-based astrophysics missions in the next 10 years. WFIRST would investigate dark energy, search for exoplanets, and conduct an all-sky infrared survey. Euclid would study only dark energy. The question then is whether the two agencies should work together, with NASA participating in Euclid and ESA participating in WFIRST.

Much is at stake. NASA officials made clear that WFIRST is not likely to launch until at least 2022, while Euclid would launch in 2018 if it is approved by ESA. The APS subcommittee’s letter said that meant “Euclid would … spend 3-4 years making measurements similar to some of those planned for WFIRST, effectively skimming the cream off the dark energy pail.”

Money is another issue. NASA estimates that it would cost $260 million over 10 years for NASA to participate in Euclid at the 33 percent level most recently discussed between the two agencies. The subcommittee asked what NASA astrophysics opportunities would be foresaken to pay for that, and whether having two dark energy missions (Euclid and WFIRST) would create an imbalance in the astrophysics portfolio.

Nonetheless, APS noted that if ESA contributed a like amount to WFIRST and the arrangement therefore was revenue neutral, “[p]articipation in Euclid would then be the first element in a US near-infrared space telescope program leading to WFIRST. Continuing this partnership with ESA on the Euclid and potentially WFIRST missions would fulfill a NASA objective of pursuing a new era of international cooperation in space.”

Thus, they decided to keep their options open by supporting NASA’s plan to proceed with negotiations on U.S. participation in Euclid, but at the lower 20 percent level instead of 33 percent. They also chided NASA for giving them so lilttle time to consider the issues: “In the future, questions to be asked of the APS about such important issues should be provided to the APS in advance of the meeting, so APS members have time to provide thoughtful advice, and, when needed, consult with their colleagues in the community.” (emphasis in original)

The NAC Science Committee teleconference meeting tomorrow is open to the public. It begins at 8:30 am EDT. Dial-in information is available in the Federal Register notice.