A Search for Earth-size Planets Borucki – Page 1 Roger Hunter (Ames Research Center) & Kepler Team March 26, 2010

A Search for Earth-size Planets Borucki – Page 2

A Search for Earth-size Planets Borucki – Page 3 CRITICAL QUESTIONS: Are terrestrial planets common or rare? What are their sizes & distances? How often are they in the habitable zone? What is their dependence on stellar properties?

A Search for Earth-size Planets Borucki – Page 4 THE HABITABLE ZONE FOR VARIOUS STELLAR SPECTRAL TYPES

A Search for Earth-size Planets Borucki – Page 5 PLANETS ARE DIFFICULT TO DETECT

A Search for Earth-size Planets Borucki – Page 6 THE SUN IN VISIBLE LIGHT Earths are much easier to find when UV light is blocked. Comparison of an Earth-size planet with star spots and plages. Rapid motion and uniform repetition distinguishes planets from spots.

A Search for Earth-size Planets Borucki – Page 7 Use transit photometry to detect Earth-size planets  0.95 meter aperture provides enough photons  Observe for several years to detect transit patterns  Monitor a single large area on the sky continuously to avoid missing transits  Use heliocentric orbit  Up to 170,000 targets at 30 min cadence & 512 at 1 min INSTRUMENT KEPLER: A Wide Field-of-View Photometer that Monitors ≥100,000 Stars for 3.5 yrs with Enough Precision to Find Earth-size Planets in the Habitable Zone Get statistically valid results by monitoring; 100,000 stars Wide Field-of-view telescope (100 sq deg) Large array of CCD detectors 1.4m Primary Mirror Focus Mechanism (3)‏ Focal Plane Radiator Graphite Metering Structure 95 cm Schmidt Corrector (Fused Silica)‏ Focal Plane w/ 42 Science CCD’s & 4 Fine Guidance Sensors Focal Plane Electronics

A Search for Earth-size Planets Borucki – Page 8 SPACECRAFT & INSTRUMENT Largest focal plane for a NASA flight mission: 94.6 million science pixels 42 science CCDs, 2 channels each 4 fine guidance sensor (FGS) CCDs CCDs controlled at -85C, Readout electronics at room temperature

A Search for Earth-size Planets Borucki – Page 9 LAUNCH ON MARCH 6, 2009

Borucki – Page 10 8 A Search for Habitable Planets STScI SAO Continuously Monitor >100,000 Stars Use a 1 m Schmidt telescope with a FOV >100 deg 2 DGK

A Search for Earth-size Planets Borucki – Page 11 Kepler will discover planets by observing transits A transit occurs when a planet passes in front of its star and blocks part of the star’s light. Earth-size planets produce very small reductions in the star’s brightness (we need to go to space to detect them). –Jupiter would block 1% of the sun’s disk –Earth (or Venus) would block only 0.008% of the sun’s disk (84 parts per million change in brightness) Transit of Venus across the Sun

A Search for Earth-size Planets Borucki – Page 12 KEPLER MISSION DATA FLOW Calibrated Pixels Calibrated Light Curves Raw Pixels Raw Data 12 Deep Space Network Canberra/Madrid/Goldstone Science Operations Center NASA A.R.C. Moffett Field, CA & PLANETS! Mission Operations Center LASP Boulder, CO Space Telescope Science Institute, Baltimore, MD

A Search for Earth-size Planets Borucki – Page 13 OBSERVATIONS 9.7 days of calibration observations of 56,000 bright stars of all types began on 1 May 2009 Science operations began on 12 May with observations of 156,000 mostly dwarf stars plus; –1000 red giants for astrometry/parallax measurements –1700, mostly variable, bright stars for astroseismology at 30 min cadence –450, mostly variable, bright stars for asteroseismology at 1 min cadence Data presented here is based on the first 43 days of observations Over one hundred candidate planets, several hundred eclipsing binaries, and thousands of variable stars are visible in these data.

A Search for Earth-size Planets Borucki – Page 14 HAT-P-7b Ground vs. Space 14 A. Pal et al., 2008