Summary Thoughts - Scientific

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

Jet Propulsion Laboratory, California Institute of Technology

Ozma 50 WorkshopGreen Bank, West Virginia

15 Sept. 2010

SETI

Radio survey• 1-15 GHz, full spectrum, continuous observation• Sounds wise, not precluding any spectral region• “Expect the unexpected” philosophy

Optical survey• Visible or near-infrared• Could detect a beacon• Could have a radio signal in parallel, or be the signal itself

SETU or SETSOL

Direct Imaging of Nearby Exoplanet Systems• Must be in space• Probably optical (possibly infrared)• Could happen in early 2020s• Would give images of planets (Earth-size and larger) and exozodi• Image from HZ to beyond Jupiter• Would give spectrum of each pixel• Detect H20, O2, O3, CO2, CH4, land plants, atmosphere, rotation, etc.

Drake Equation Term ne

Preliminary derivation of ne from Kepler data• 42 days of data published so far• Select subset of exoplanets, complete in the 2-17 day period range• Select Jupiters in this complete sample• Compare to expected number in period & mass/radius range• Get excellent agreement; good sign!

Exoplanet Mass-Radius

Kepl

er, B

oruc

ki e

t al 2

010

Cumming et al 2008

dN/dln(M) ~ M-0.31

Ref.: Seager, Kuchner, et al. 2007

“Jupiters”

“Earths”

“Jupiters”

“Jupiters”“Ice giants” “Earths & SuperEarths”

ne

Preliminary derivation of ne from Kepler data• 42 days of data published so far• Select subset of exoplanets, complete in the 2-17 day period range• Select Jupiters in this complete sample• Compare to expected number in period & mass/radius range• Get excellent agreement; good sign!

• Fit ice-giant trend• Assume smallest radius bin is not complete• Extend trend to 1 Earth radius• Count expected number of 1-2 Earth-radius planets

• Extrapolate to HZ planets (Venus to Mars distances, 1-2 Earth radii)• Compare to sample size• Derive estimated ne, find a large number.