1. A Search for Habitable Planets Kepler Mission A S EARCH FOR H ABITABLE P LANETS (Earth-size Planets in the Habitable Zone) Janice Voss NASA Ames Research Center

2. A Search for Habitable Planets 2 K EY F EATURES 1. Habitable zone =>temperature =>water 2. Planet size =>mass =>atmosphere Reference: Rare Earth, Ward and Brownlee, Copernicus (Springer-Verlag) ISBN 0-387- 98701

3. A Search for Habitable Planets 3 P LANET S IZE A FECTS H ABITABILITY Too small (about <0.5 M  ): Surface gravity g=0.8 G Can’t hold onto a life sustaining atmosphere (Mercury, Mars) Too big (about >10 M  ): Surface gravity g=2.2 G Can hold onto the very abundant light gases (H 2 and He) and turn into a gas giant (Jupiter, Saturn, Uranus, Neptune) (Surface gravity proportional to radius) Copyright Lynnette Cook

4. A Search for Habitable Planets 4 P LANETS IN O UR S OLAR S YSTEM Terrestrials Gas giants Mercury Venus Earth MarsJupiterSaturnUranus Neptune Pluto mass0.0550.821.000.11318951417.0002 radius0.380.951.000.5311.29.44.03.90.18 area0.150.901.000.281268916150.03 volume0.060.851.000.15140884464590.006 density0.980.951.000.710.240.120.240.320.20 (all values are relative to Earth)

5. A Search for Habitable Planets 5 T HE H ABITABLE Z ONE FOR V ARIOUS S TELLAR T YPES The Habitable Zone (HZ) in green is the distance from a star where liquid water is expected to exist on the planets surface. (Kasting, Whitmire and Reynolds, 1993)

6. A Search for Habitable Planets 6 T ECHNIQUES FOR F INDING E XTRASOLAR P LANETS MethodYieldMass LimitStatus Pulsar Timingm/M ;  LunarSuccessful (3) Radial Velocitym sini ;  UranusSuccessful (~120) Astrometrym ;  D s ; a Ground: TelescopeJupiterOngoing Ground: Interferometersub-JupiterIn development Space: InterferometerUranusBeing studied Transit PhotometryA ;  sini=1 Ground sub-JupiterHD209458, OGLE TR- 56 Space VenusPlanned Kepler Reflection Photometry: albedo*A ;  SpaceSaturnPlanned Kepler Microlensing: f(m,M,r,D s,D L ) Groundsub-UranusOn-going Direct Imagingalbedo*A ;  D s ; a ; M GroundSaturnBeing studied SpaceEarthBeing studied (Source: J. Lissauer)

7. A Search for Habitable Planets 7 S EARCH R ESULTS The first 50 known extrasolar planets are shown along with the planets in our solar system. The limit for planet detection using Doppler spectroscopy is shown. The range of habitable planets (0.5 to 10 M  ) in the HZ is shown in green.

8. A Search for Habitable Planets 8 U SING P HOTOMETRY TO D ETECT E ARTH- S IZE P LANETS The relative change in brightness (  L / L) is equal to the relative areas (A planet /A star ) To measure 0.01% must get above the Earth’s atmosphere Method is robust but you must be patient: Require at least 3 transits preferably 4 with same brightness change, duration (how long the star is dimmer) and period (time between dimmings) Jupiter: 1% area of the Sun (1/100) Earth or Venus 0.01% area of the Sun (1/10,000)

9. A Search for Habitable Planets 9 Kepler P HOTOMETER Photometer = CCDs sensors+ Telescope Kepler will be 9 th largest Schmidt ever built

10. A Search for Habitable Planets 10 Proto Type CCDs Views of a prototype module composed of two CCDs mounted to a common carrier Each CCD is 2200 columns by 1024 rows, thinned, back-illuminated, anti-reflection coated, 4-phase devices manufactured by e2v. Each CCD has two outputs with the serial channel on the long edge. The pixels are 27  m square, corresponding to 3.98 arcsec on the sky.

11. A Search for Habitable Planets 11 E ARTH- T RAILING H ELIOCENTRIC O RBIT Delta II 2925-10L

12. A Search for Habitable Planets 12 F IELD OF V IEW IN C YGNUS A region of the extended solar neighborhood in the Cygnus-Lyra regions along the Orion arm of our galaxy has been chosen.

13. A Search for Habitable Planets 13 The minimum detectable planet size versus planetary orbital period for a 12 th magnitude solar-like star (G2), a CDPP of 20 ppm and >4 grazing transits. (Ref: Koch et al,, Overview and Status of the Kepler Mission, SPIE Conf 5487,p1491-1500 Optical, Infrared, and Millimeter Space Telescopes, J. Mather ed., Glasgow, Scotland, 2004) K EPLER C APABILITIES

14. A Search for Habitable Planets 14 E XPECTED R ESULTS Hypothesis: all dwarf stars have planets and monitor 100,000 dwarf stars for 4 years Transits of terrestrial planets: About 50 planets if most have R~1.0 R  (M~1.0 M   ) About 185 planets if most have R~1.3 R  (M~2.2 M  ) About 640 planets if most have R ~2.2 R  (M~10 M  ) About 70 cases (12%) of 2 or more planets per system Transits of thousands of terrestrial planets: If most have orbits much less than 1 AU Modulation of reflected light of giant inner planets: About 870 planets with periods ≤1 week, 35 with transits Albedos for 100 giants planets also seen in transit Transits of giant planets: About 135 inner-orbit planet detections Densities for about 35 giants planets from radial velocity data About 30 outer-orbit planet detections Results expected will most likely be a mix of the above

15. A Search for Habitable Planets S CHEDULE AND R ESULTS 15

16. A Search for Habitable Planets 16 S CIENCE T EAM William Borucki, Principal Investigator, NASA Ames Research Center David Koch, Deputy Principal Investigator, NASA Ames Research Center Co-Investigator’s Working Group G. BasriUC-Berkeley T. BrownHAO/NCAR W. CochranMcDonald Obs./U. Texas E. DeVoreSETI Institute E. DunhamLowell Observatory J. GearySAO R. GillilandSTScI A. GouldLawrence Hall of Sci/UC-B J. JenkinsSETI Institute Y. KondoNASA/GSFC D. LathamSAO J. LissauerNASA/ARC Science Working Group A. BossCarnegie Institute of Washington D. BrownleeUniversity of Washington J. CaldwellYork University A. DupreeSAO S. HowellPlanetary Science Institute G. MarcyUC-Berkeley D. MorrisonNASA/ARC T. OwenUniversity of Hawaii H. ReitsemaBall Aerospace D. SasselovSAO J. TarterSETI Institute M ANAGEMENT T EAM Chet Sasaki, Project Manager at Jet Propulsion Lab Larry Webster, Deputy Project Manager at NASA Ames Research Center Len Andreozzi, Program Manager Ball Aerospace, Boulder, CO

17. A Search for Habitable Planets S UMMARY The Kepler Mission will: Observe more than 100,000 dwarf stars continuously for 4 to 6+ years with a precision capable of detecting Earths in the habitable zone The Kepler Mission can discover: Planet sizes from that of Mars to greater than Jupiter Orbital periods from days up to two years About 600 terrestrial planetary systems if most have 1 AU orbits About 1000 inner-orbit giant planets based on already known frequency Can expect 100s to 1000s of ??? size planets depending on frequency ??? and orbit ??? A NULL result would also be very significant ! ! ! Results begin 3 months after launch in Oct. 2007 and continue for 4 to 6+ years More info at http://Kepler.NASA.gov 17