Life in the Milky Way:Panel Discussion

Wesley A. TraubChief Scientist, NASA’s Exoplanet Exploration Program

Jet Propulsion Laboratory,California Institute of Technology

Ozma 50 Workshop, Green Bank, West Virginia

13 Sept. 2010

Our Big Questions for Exoplanets• What kind of signs of life should we be looking for? • Where and how should we look?• What is our strategy for finding signs of life beyond the Solar System?

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Three Direct Images To Date

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Ref.: Fomalhaut, Kalas et al., 2009HR8799, Marois et al., 2009 also Serabyn & Mawet 2010Beta Pic, Lagrange et al., 2010

Exoplanet prospects, near and far

Kepler transits/seismology 500 to 2000 pc distant

156,000 stars14 to 16 mag0.24% of sky

Expect 400 Earths (1/star)

CoRoT transits/seismology 400 to 2000 pc distant

~40,000 stars13 to 15 mag0.01% of sky

SIM Lite astrometry 5 to 25 pc distant~70 to 2100 stars

3 to 7 mag100% of sky

Expect 70 Earths (1/star)

+TPF-C/O/I direct imaging

Color & spectrum all planetsSigns of life

PLATO transits/seismology 100-400 pc distant

250,000 stars10 to 13 mag

8% of skyExpect 400 Earths (1/star)

WFIRST gravitational microlensing 1000 to 10,000 pc distant

Prospects for finding and characterizing exoplanets

• Current missions: CoRoT and Kepler for transits

- Telling us frequency of terrestrial planets, from close-in to habitable zones

• Also: Spitzer (warm) and HST

- Giving us transit visible and infrared spectra of giant planets

• Planned missions: JWST

- Possible transit spectra of super-Earth planets

• Recommended mission: WFIRST for exoplanets (and dark energy)

- Gravitational lensing gives mass and snapshot of orbit

• Future possibility: Exoplanet mission

- To be decided around mid-decade, and launched in 2020s,

could be coronagraph imager for exoplanet discovery and characterization

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