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Two Stellar Teams, One Interstellar Goal: Direct Detection
By Steve Unwin

Two Science and Technology Definition Teams (STDTs) have been selected by NASA to develop “probe-scale” mission concepts. In space astronomy, the term “probe” refers to the total cost of the mission (not to exceed $1B). The two teams are chartered to develop and deliver mission concepts that use direct imaging for detection and spectroscopy of exoplanets orbiting nearby stars. One team, led by Karl Stapelfeldt of NASA’s Goddard Space Flight Center, will study a concept based on a telescope with an internal coronagraph to generate the ultra-high-contrast images needed for planet detection. The second team, led by Sara Seager of MIT, will study a pair of spacecraft flying in formation - a telescope and an external occulter (starshade). The two teams were selected in May 2013 and have met by telecon; a joint in-person meeting of the teams is planned for early July.

These studies will take about 18 months, with final reports due to NASA HQ in January 2015. The Exoplanet Exploration Program is very excited that these studies are underway, and looks forward to working closely with the STDTs as they develop the science case and the instrument designs for the mission concepts. Supporting the STDTs will be a major activity for the Program. A Study Office has been set up by the Program led by Keith Warfield of JPL, who is assembling a Design Team to work closely with each of the two STDTS to provide technical analysis as requested, including instrument design, performance modeling, and cost estimates. During the studies, the draft concepts will be provided to JPL's Team X, which will conduct a technical and cost assessment to make sure that the concepts meet the “probe-scale” constraint. At the very end of the studies, a Cost Appraisal and Technical Evaluation (CATE) will be performed by an independent contractor.

You can read more about how these studies fit into the “big picture” in the recent NASA Astrophysics Implementation Plan. A key event is the mid-Decade review by the Committee on Astronomy and Astrophysics (CAA) of the National Research Council at about the mid-point between Decadal Surveys. The work of the STDTs is of critical importance to this process. A probe-scale exoplanet mission could begin development late in the decade if recommended by the CAA and selected by NASA. It would also be a stepping stone toward a future large space telescope mission designed to gather spectra of Earth-like planets in the habitable zones of sunlike stars, a key goal in the search for life beyond the solar system.

There are pages devoted to the STDTs on the ExEP website at, where you can find the team membership lists and the charter that governs their work. As the studies progress, we will add updates and news. Public versions of the final reports should be available in mid-2015.