Issue 14 - October 2014

Direct Imaging Study Teams
Direct Imaging Missions at a Moderate Cost
By Keith Warfield, NASA Jet Propulsion Laboratory
Probe Study Office Manager

NASA’s two Science and Technology Definition Teams (STDTs) are nearing completion of their respective “probe-scale” mission concepts. In May 2013, NASA selected the two STDTs to develop space mission concepts capable of directly imaging planets orbiting nearby stars at a cost below $1B - “probe-class.” One team is studying a concept using a telescope and coronagraph and is being led by Karl Stapelfeldt of the NASA Goddard Space Flight Center. The other team is exploring a concept based on a spacecraft carrying a telescope and imager and flying in formation with a second spacecraft carrying an occulting starshade. That team is being led by Sara Seager of the Massachusetts Institute of Technology.

The STDTs have made considerable progress over this past year, much of which has been summarized in their Interim Reports released in April. To meet the challenging cost limit set by NASA, both designs are utilizing proven designs wherever possible. The coronagraph concept borrows heavily from the successful (and sub-$1B) Kepler mission, while the starshade concept uses elements from Kepler and commercial communications satellite designs. The starshade concept will also look into the feasibility and cost of a “follow-on” starshade mission to future space telescope missions such as Wide-Field Infrared Survey Telescope-Astrophysics Focused Telescope Assets (WFIRST/AFTA). Both concepts have been submitted for preliminary Cost and Technical Evaluation (CATE) review. The coronagraph concept’s initial CATE estimate has been received and is close to meeting the $1B cost goal. The design is being adjusted based on these results. The initial starshade CATE is pending at this time.

Final reports on both concepts are due to NASA by the end of this coming January, with public release following shortly after the delivery to NASA. Final CATEs will be delivered to NASA in February. Both STDTs will give publicly available briefings on the concepts to the Committee on Astronomy and Astrophysics (CAA) of the National Research Council at the CAA’s spring meeting.

You can read more about how these studies fit into the “big picture” in the 2012 NASA Astrophysics Implementation Plan. The work of the STDTs is of critical importance to both the CAA’s mid-decade review and the coming Decadal Survey process. The studies will guide direct imaging technology development work and will define comparative design points for future Survey concepts.

More information on the STDTs and the probe-class direct imaging concepts - including team membership and the concept Interim Reports - can be found on the ExEP website at Final reports and other publicly releasable information on the studies will be added to the site as the studies conclude in early 2015.