By Wes Traub
The uplifting science message from Astro2010 is that exoplanet science is earmarked for a major space mission in the 2020s, on the condition that the exoplanet community can agree on a single mission concept by about 2015.
We should take this message literally, and treat it seriously. I suggest that this task is our single most important activity before 2015. To help do this, the ExoPAG Executive Committee has been tasked by the Astrophysics Subcommittee, and has agreed to the task, to act as a forum for discussion and planning. The task is now ours as a community, because the ExoPAG itself is by definition the entire exoplanet community. The ExoPAG will begin planning how to respond to Astro2010 at its upcoming meeting, Saturday and Sunday, 8-9 January 2011, at the winter AAS in Seattle. Everyone in the exoplanet community with an opinion on how this activity should be structured should attend this ExoPAG meeting.
Jim Kasting, the ExoPAG chair, suggests the following schedule for this long-term activity:
(a) Formulate study groups and assign tasks, by mid-2011.
(b) Report on 2020s mission science goals and instrumentation options, by mid-2012.
(c) Report on mission technology, engineering, and verification challenges, mid-2013.
(d) Present detailed DRM for mission, early 2014.
As we study the candidate missions, what criteria should guide our winnowing process? The President of the AAS, Debra Elmegreen, in the October 2010 AAS Newsletter, lists these attributes of a mission:
(1) Scientific merit
(2) Technical readiness
(4) Affordable cost
(5) Tolerable risk
We will need all of these attributes to succeed. The question we must ask of each proposed mission concept is, how will it rank in each category as we enter 2014? I suggest that we formally rank the candidate concepts on these criteria.
Many of us have said that we need much more funding for technology development before we can make these decisions. I submit that we must make our decision by 2015 based on what we will know by that time, plus our experience from past projects, our gut feel, as it were. We should plan to do this within a minimal funding envelope. The alternative is to give up on the 2020s and start planning for the 2030s.
Astro2010 stated that "if the scientific groundwork has been laid and the design requirements for an imaging mission have become clear by the second half of this decade, a technology down-select should be made". At that point increased funding is recommended for the 2015-2020 period, on the order of $100-200 million, for "mission specific technology".
Finally, recall that if there is a major exoplanet mission in the 2020s, it will probably be a flagship (strategic) mission, and not a PI-class mission. If it is a strategic mission, each of us will be invited to bid for roles in it, as instrument builders and science investigators.
In the end we will all benefit from the success of a single concept. We can then look forward to the day when we can start doing some real science with the exoplanet mission of the 2020s.
This initial 5-year process begins now, with the January ExoPAG meeting. We should all plan to participate in this and the subsequent meetings and planning sessions. A necessary but not sufficient condition for success is that we work together in good spirit, with the common goal of flying a direct detection exoplanet mission in the 2020s.