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Learn about NASA's ExoPAG, a forum that solicits community input for the development and execution of the Exoplanet Exploration Program. The ExoPAG conducts analyses, provides science and technology inputs, evaluates mission capabilities, reviews goals, and prioritizes focus areas.
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Report from NASA’s ExoPAG(Exoplanet Exploration Program Analysis Group) James Kasting ExoPAG Chair
What is the ExoPAG? D. Hudgins, April, 2009 The ExoPAG is designed be an open, community-based forum for soliciting and coordinating community input into the development and execution of NASA’s Exoplanet Exploration Program (ExEP). To carry out its role, the ExoPAG will: • Conduct analyses of ExEP planning and activities under auspices of NAC; • Provide science and technology inputs to the Astrophysics Subcommittee (APS) for propagation to the Agency through the NASA advisory structure • Evaluate capabilities of potential missions w/r/t ExEP science goals; • Regularly review ExEP goals, objectives, investigations and required measurements against the current state-of-the-art, drawing on the widest possible community input; • Articulate and prioritize focus areas for technology development; and • Provide recommendations on related activities such as ground-based observing, theory and modeling programs, and community engagement. • Provide a forum for maintaining regular, unfettered communication with program stakeholders in government, academia, and industry.
What is the ExoPAG? D. Hudgins, April, 2009 Structure and function of the ExoPAG: • Chair appointed from APS membership (J. Kasting); • Chair supported by Executive Secretary (HQ ExEP PS, D. Hudgins) and Executive Committee; • nominations solicited through open “Dear Colleague” letter to community • members serve rolling 3-year terms • constituted to achieve functional balance between observers, theorists, and technologists, as well as scientific balance across fields of astrophysics, (exo)planetary science, and astrobiology; • Meetings held biannually with schedule set by Chair in consultation with EC; • Tasking from SMD, NAC Science Committee, or Astrophysics Subcommittee • Results of ExoPAG meetings and analyses reported to the Astrophysics Subcommittee
Current ExoPAG Steering Committee members Tom Greene (Ames)—coronagraphs/JWST Dave Bennett (Notre Dame)--gravitational microlensing Charlie Noecker (JPL)--everything, including technology Dan Coulter (JPL)—technology/coronagraphs Bruce Macintosh (Lawrence Livermore)--Ground-based AO/direct imaging Brad Hansen (UCLA)--theory and measurements Lisa Kaltenegger (Max Planck Institute)—interferometry/astrobiology Alycia Weinberger (Carnegie Inst.)--circumstellar disks/astrometry Aki Roberge (Goddard)—debris disks/zodiacal dust/New Worlds Observer
ExoPAG activities • 5 meetings held since January, 2010 • ExoPAG5 held this past weekend • Roughly 40-80 participants at each meeting • Two joint meetings with COPAG, described further below • Study Analysis Groups (SAGs) set up • Direct imaging flagship mission requirements • Exozodiacal dust studies
Main focus to this point • Planning for a future, flagship-class, direct imaging mission to find and characterize other Earth-like planets • Technology development for such a New Worlds/New Horizons mission was a high-priority recommendation of the Astro2010 Decadal Survey
TPF-C TPF-I/Darwin • There are at least three concepts • for a large, space-based tele- • scope that could directly image • Earth-size planets around other • stars • These missions would also look for • spectroscopic biomarkers (O2, O3, CH4) • and try to infer the presence or absence • of lifeon such planets • The ExoPAG is hoping to help NASA • decide how to choose between these • mission concepts TPF-O NASA’s Terrestrial Planet Finder concepts
Collaboration with COPAG • COPAG is also interested in large, UV/optical space telescopes • Some in that community are thinking really big (8-16 m aperture) • But see below.. • Question: Are UV-capable coatings compatible with a TPF-like direct imaging mission? 16-m version of the proposed ATLAST space telescope (M. Postman, STScI)
Flagship mission requirements SAG • A fairly complete set of science requirements for a direct imaging mission was developed for the 2005 version of TPF-C • Is the same set of requirements applicable to an occulter mission? • No.. • How does the mission design depend on Earth and exozodi brightness? TPF-C (internal coronagraph) – mission concept circa 2005
Earth • Astronomers describe planetary habitability in terms of a factor called Earth—the fraction of stars that have at least one planet in their habitable zone • This is what we need to know in order to design a space telescope to look for such planets around nearby stars
Kepler Mission • This space-based telescope • will point at a patch of the • Milky Way and monitor the • brightness of ~160,000 stars, • looking for transits of Earth- • sized (and other) planets • 105 precision photometry • 0.95-m aperture capable • of detecting Earths • Launched: March 5, 2009 http://www.nmm.ac.uk/uploads/jpg/kepler.jpg
Measuring exozodi brightness • The other key parameter for designing a TPF telescope is the exozodi brightness • High brightness need a larger telescope to distinguish the planet from the dust • LBTI (the Large Binary Telescope Interfero-meter) is the key instrument for measuring this background Habitable zone Exozodi detection levels for various ground- and space-based platforms (Courtesy: Aki Roberge. Available in upcoming SAG1 report.)
Smaller probe-class missions • A key concern, given the current (bleak) budget environment, is that there may not be enough money for a flagship mission in the 2020-2030 time frame • Consequently, the ExoPAG is also studying probe-class missions (<$1B and $1B-$2B) • We heard talks from 3 proposed Explorer missions at ExoPAG5 this past weekend • TESS—Transiting Exoplanet Survey Satellite • FINESSE—Fast INfrared Exoplanet Spectroscopy Survey Explorer • EXCEDE—Exoplanetary Circumstellar Environments and Disk Explorer (technology development only)
Conclusions • Characterizing planets in the habitable zonesof nearby stars requires a large, space-based direct imaging mission • This remains the top priority for ExoPAG • SAG reports on flagship mission requirements and exozodi dust levels will be available soon • Collaboration with other interest groups (e.g., COPAG) is being actively encouraged • Smaller probe-class exoplanet missions are also of interest and may have to sustain us in the near term • We welcome comments and participation from all members of the astronomical community