KEPLER William Borucki, PI Solar System Exploration Subcommittee Sante Fe, New Mexico February 14-15, 2005
Science Team William J. Borucki, PI, and David Koch, Deputy PI Theoretical Studies • Alan Boss, Carneige Institute Wash. • Jack Lissauer, NASA Ames Mission Operations • Donald Brownlee, U. of Washington • Yoji Kondo, NASA GSGC General Overview • John Caldwell, York U. • David Morrison, NASA Ames • Tobias Owen, Hawaii • Harold Reitsema, Ball Aerospace Co. • Jill Tarter, SETI Institute Education and Public Outreach • Edna DeVore, SETI Institute • Alan Gould, Lawrence Hall of Science Stellar Occultations & High-Precision CCD Photometry • Timothy Brown, HAO, UCAR • Edward Dunham, Lowell Obs. • John Geary, SAO • Ronald Gilliland, STScI • Steve Howell, U. Ariz • Jon M. Jenkins, SETI Institute Doppler Velocity Planet Searches • William Cochran, UTexas • David Latham, CfA, SAO • Geoff Marcy, U. Cal., Berkeley Stellar Variability • Gibor Basri, U. Cal., Berkeley • Andrea Dupree, CfA, SAO • Dmiter Sasselov, CfA, SAO
KEY QUESTIONS: • Are terrestrial planets common or rare? • How many are in the habitable zone? • What are their sizes & distances? • Dependence on stellar properties
Scientific Goals • Determine the frequency of terrestrial and larger planets in or near the habitable zone of a wide variety of stellar spectral types • Determine the distribution of sizes and semi-major axes of these planets • Identify additional members of each photometrically discovered planetary system using complementary techniques • Determine the distributions of semi-major axis, albedo, size, and density of short-period giant planets • Estimate the frequency of planets orbiting multiple star systems • Determine the properties of those stars that harbor planetary systems
Mission Design KEPLER: A Wide FOV Telescope that Monitors 100,000 Stars for 4 years with Enough Precision to Find Earth-size Planets in the HZ • Use transit photometry to detect Earth-size planets • 0.95 meter aperture provides enough photons • Observe for several years to detect the pattern of transits • Monitor stars continuously to avoid missing transits • Use heliocentric orbit • Get statistically valid results by monitoring 100,000 stars • Use wide field of view telescope • Use a large array of CCD detectors 21 CCD Modules are the Heart of the Kepler Mission
DISCOVERY MISSION # 10 Goal: Determine the frequency of Earth-size & larger planets in the HZ of a variety of star types Expected science results; hundreds of Earth-size and larger planets if they are common Science Team; 27 from US, Europe, & Canada Single science instrument: Photometer (0.95m aperture, 42 CCDs, 420-890 nm, passive cooling, focusable primary) Launch date: October 2007 Heliocentric Earth-Trailing Orbit Operational life: 4 years
COMPARISON OF SOLAR SYSTEM TO OTHER PLANETARY SYSTEMS Theory of Formation of SS expected to produce inner terrestrial planets, outer giants, circular orbits. Observations show that a large fraction of stars have giant planets in inner orbits with high eccentricity Implications are that planetary systems can be very different from SS. SS must have had special circumstances
Signal Detectability SNR = (Ntran)1/2 (Rp/R*)2 / [(i2+ v2)+ 1/F]1/2. Where Ntran is the number of transits observed, Rp is the radius of the planet, R* is the radius of the star, F is the stellar flux measured in photoelectrons, and (i2+v2) is the signal variance due to instrument noise and stellar variability.
MERIT FUNCTION (MF) Quantifies science value as f(instrument & mission properties) Merit Function properties • Models of planetary systems, instrument specs., detection approach, catalog of all target stars & their properties • Score is 100 based on currently predicted instrument perform. • 60 pts for planets in HZ, 30 pts for planets outside HZ, 10 pts for p-modes • Small planets have higher value than bigger (40,20,5,1) • Outer planets have higher value than inner planets (r2) • Adjustable parameters for instrument specs & performance, mission parameters, and surprises of nature
SUMMARY • Graceful degradation • Greatest sensitivity • Mission lifetime • CDPP • Four year mission provides comprehensive determination of frequency of Earth-size and larger planets
Validation of Discoveries • SNR > 7 to rule out statistical fluctuations • Three or more transits to confirm orbital characteristics • Light curve depth, shape, and duration • Image subtraction to identify signals from background stars • Radial velocity Medium resolution to rule out stellar companions High resolution to measure mass of giant planets • High spatial resolution to identify extremely close bkgd stars
Educational & Public Outreach • Lesson plans • Planetarium programs • Amateur obs, • KeplerCam
PHASE B WORK: PRELIMINARY DESIGN, RISK MITIGATION, & LONG LEAD ITEMS Table G-9. Our Initial Risk Assessment/Mitigation Top Risks Database Index Risk Item Mitigation Actions Risk Type Likeliness Impact Risk Factor 1 CCD procurement delivery schedule Develop device specification that permit high yields (Don't need SOA performance). Parallel procurement from two vendors. Early delivery of Engineering Model CCDs from both vendors with an option to procure all CCDs from any single vendor after EM assessment. Schedule/ Cost Moderate (2) High (4) 8 2 CCD Module / electronics packaging, metrology and thermal control in an FPA this size. Extrapolation of present IR&D activity that addresses packaging of electronics and CCD focal planes. Early build and test of Pathfinder FPA using EM CCDs. Completion of Pathfinder before detail design and fabrication of Flight FPA. Extensive thermal model analysis using TSS and TAK III, updated with test data as available. Technical Moderate (2) Significant (3) 6 3 Optics procurement Early completion of optics design and analysis to support preparation of specifications for early procurement. Schedule Moderate (2) Moderate (2) 4 4 Science Requirements and Mission Requirements Definition Identify all specifications, ICDs, and plans which must be complete to support program schedule. Complete sign-off of SRD before ATP of Phase B and sign-off of MRD 2 months after ATP. Schedule Moderate (2) Moderate (2) 4
SCHEDULE & MISSION STATUS Phase C/D work has started. JPL management team is integrated into Kepler team. 17 flight-grade CCD detectors have been received. Optics are being polished. FY’05 budget reduction will delay the October 2007 launch. Bill Borucki
MISSION COST HISTORY Proposed in 2000 for 2005 launch at $299M Concept study for 2006 launch ($ for NIAT, inflation, and increase in booster cost) Kepler selected but required to slip the launch to 2007 launch and add JPL $40M cost increase Change to full-cost accounting adds $20M Mission cost at $467M FY’05 funding reduction causes additional delay and cost increase
FOLLOW UP OBSERVATIONS For false positive elimination and understanding of the Kepler planetary candidates: 1. 300 m/s RV measurements, mr=9-16, avg of 2.5 spectra each Terrestrial planets Case 1, no terrestrial planets ~140 false positives (105 go away with DIA after 4 years) ~131 hr on 2m telescope = ~ 22 nights @ $1500/night -> $33K this price depends on being able to buy 1/2 nights or only using time in June-Aug. Case 2, ~2160 terrestrial planets found ~2300 candidates ~2155 hr on 2m telescope = ~ 359 nights @ $1500/night -> $538K Giant planets ~610 candidates ~572 hr on 2m telescope = ~95 nights @ $1500/night -> $142K 2. AO images of 300 candidates mr=9-16 from 1st 90 days ~300 stars ~79 hr = ~13 nights usually need bigger telescope (>= 4m) to get the AO instruments For characterization to understand the sample of planet bearing stars and their planetary systems: 3. Further characterization of the stars R= spectra of 300 selected candidates mr=9-12 or brighter, 1 spectrum each ~xx hr on 2 m telescope = ~xx nights = xx/4 nights/year ~9 Kepler observers -> xx/4/9 nights/yr/observer 4. To search for giant members of system with a terrestrial planet 10 m/s RV measurements of 100 selected candidates, mr=9-12 or brighter, 12 spectra each ~950 hr on 10m telescope = ~158 nights = 40 nights/yr ~4 Kepler observers -> 10 nights/yr/observer 5. .Further characterization is left to the community.