Report from NASA’s ExoPAG(Exoplanet Exploration Program

Analysis Group)

James Kasting

ExoPAG Chair

05-07-2008

AstrophysicsDivision What is the ExoPAG?

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.

D. Hudgins, April, 2009

05-07-2008

AstrophysicsDivision What is the ExoPAG?

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

D. Hudgins, April, 2009

Current ExoPAG Steering Current ExoPAG Steering Committee membersCommittee members

1.1. Tom Greene (Ames)—coronagraphs/JWSTTom Greene (Ames)—coronagraphs/JWST2.2. Dave Bennett (Notre Dame)--gravitational microlensingDave Bennett (Notre Dame)--gravitational microlensing3.3. Charlie Noecker (JPL)--everything, including technologyCharlie Noecker (JPL)--everything, including technology4.4. Dan Coulter (JPL)—technology/coronagraphsDan Coulter (JPL)—technology/coronagraphs5.5. Bruce Macintosh (Lawrence Livermore)--Ground-based Bruce Macintosh (Lawrence Livermore)--Ground-based

AO/direct imagingAO/direct imaging6.6. Brad Hansen (UCLA)--theory and measurementsBrad Hansen (UCLA)--theory and measurements7.7. Lisa Kaltenegger (Max Planck Lisa Kaltenegger (Max Planck

Institute)—interferometry/astrobiologyInstitute)—interferometry/astrobiology8.8. Alycia Weinberger (Carnegie Inst.)--circumstellar Alycia Weinberger (Carnegie Inst.)--circumstellar

disks/astrometrydisks/astrometry9.9. Aki Roberge (Goddard)—debris disks/zodiacal dust/New Aki Roberge (Goddard)—debris disks/zodiacal dust/New

Worlds ObserverWorlds 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 up1. Direct imaging flagship mission

requirements2. 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

• 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 life on such planets• The ExoPAG is hoping to help NASA decide how to choose between these mission concepts

TPF-I/Darwin

TPF-C

TPF-O

NASA’s Terrestrial Planet Finderconcepts

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 ATLASTspace 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) – missionconcept 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

http://www.nmm.ac.uk/uploads/jpg/kepler.jpg

• 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

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

Exozodi detection levels for variousground- and space-based platforms(Courtesy: Aki Roberge. Available inupcoming SAG1 report.)

Habitablezone

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 weekend1. TESS—Transiting Exoplanet Survey Satellite2. FINESSE—Fast INfrared Exoplanet Spectroscopy

Survey Explorer3. EXCEDE—Exoplanetary Circumstellar Environments

and Disk Explorer (technology development only)

Conclusions

• Characterizing planets in the habitable zones of 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