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BRIEF HISTORY OF THE KEPLER MISSIONWilliam Borucki , NASA Ames Research Center
Kepler ScienceConference 2019
Determine if Earths are common or rare in our galaxy.
Provide data needed to design future missions that measure the composition of exoplanet atmospheres to detect biosignatures
SAO
Contributing Organizations:
1965 1970 1975 1980 1985 1995 20051990 2000 2010
Rosenblatt paper on the possibility of detecting exoplanets by searching for transits
Borucki, Scargle, Hudson paper noting stellar variability as fundamental limit
Borucki & Summers paper on methods to detect exoplanets via transits
SSB Report: “In principle, it is possible to search for planets by photometrically monitoring the light from stars, looking for decreases due to partial occultation during the planet transit in front of the stellar disk. A clear identification by this technique appears unlikely.”
Kepler Rejection #1(no suitable detectors)
Kepler Rejection #2(too costly)
Kepler Rejection #3(10,000-star photometry
not demonstrated)
Kepler Rejection #4(precision photometry
not demonstrated)
Transit photometry discovers 1st exoplanet
NASA Approves Kepler for Mission
Development!
Launch
Prime mission
endsDevelopment of earlyphotometers.Workshops held onhigh-precision photometry
Proved that CCDs provided needed precision when systematic errors were corrected
Built an observatory at Lickthat performed automated photometry & detected planets
Built testbed thatdemonstrated 10 ppmprecision
First proposal to funddevelop of high precisionphotometers
First exoplanets found orbiting a normal star.
First exoplanets foundorbiting a neutron star
TIMELINE FOR THE DEVELOPMENT OF THE KEPLER MISSION
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EARLY AMES/NIST PHOTOMETERS WITH QUANTUM-PERFECT DETECTORS
Nat’l Inst. Sci. & Tech./Ames three-channel photometer with silicon-diode detectors.
A photometer fit to the Lick Observatory Twin-Astrograph backplane. Holesare drilled for several FOVs. Detectors or optical fibers are inserted into the holes. Optical fibers bring the stellar fluxes to LN2 –cooled detectors.
Borucki, 2016, Rep. Prog. Phys. 79, 036901
PROOF THAT CCDs HAVE THE 10ppm PRECISION NECESSARY TO DETECT EARTH-SIZE PLANETS
Results from 5 hour integrations for an obsolete front-side-illuminated CCD detector show an average of 11 ppm precision.
(Robinson, Wei, Borucki et al., PASP 107, 1094 (1995)
AN OBSERVATORY BUILT TO DEMONSTRATE THECAPABILITY OF PHOTOMETRY TO DETECT EXOPLANETS
Data showing the transit of exoplanet HD209458 with Vulcan photometer demonstrated that automated transit searches and photometric analysis can detect exoplanets.
Early version of the Vulcan photometer in the Crocker Dome, University of California, Lick Observatory, Mt. Hamilton, CA
Borucki, Batalha, Jenkins, Caldwell et al., 2001, PASP 113, 439
TEST FACILITY BUILT TO DEMONSTRATE 10 PPM PHOTOMETRIC PRECISION & THE DETECTION OF
EARTH-SIZE TRANSITS
Light source with scattering sphere
Plate with holes drilled to simulate stars
Photometer with motion controlsInvar support structure
Controlled temperature chamber
Detection of injected transits for 9th and 12th magnitude “stars”
Koch, Borucki, Witteborn, et al., 2000, Proc. SPIE 4013
SPECIFIC GOALS OF THE MISSION
“The Kepler Mission is specifically designed to survey the extended solar neighborhood to detect and characterize hundreds of Earth-size and larger planets in or near the habitable zone”. • Determine the frequency of 0.8 Earth-radii and larger planets in or
near the habitable zone of a wide variety of stars• Determine the distributions of sizes and orbital semi-major axes of
these planets,• Estimate the frequency and orbital distributions of planets orbiting
multiple-star systems,• Determine the distributions of semi-major axis, albedo, size, mass,
and density of short period giant planets,• Identify additional members of each photometrically discovered
planetary system using complementary techniques, and• Determine the properties of those stars that harbor planetary
systems.
1.4m Primary Mirror
Focal Plane
Radiator
95 cm Schmidt Corrector
Focal Plane w/ 42 Science CCD’s &4 Fine Guidance
Sensors
• Observe for several years to detect transit patterns.
• Monitor a single large area on the sky (105 sq. degrees) continuously to avoid missing transits.
• Use heliocentric orbit to make continuous observations.
•Use a large array of CCD detectors to viewthousands of stars simultaneously.
• 94.6 million science pixels
• 42 science CCDs, 2 channels each
• 4 fine guidance sensor (FGS) CCDs
Courtesy of Ball Aerospace & Tech Corp
THE KEPLER INSTRUMENT: A WIDE FIELD-OF-VIEW PHOTOMETER THAT SIMULTANEOUSLY MONITORS THE
BRIGHTNESS OF 170,000 STARS WITH ENOUGH PRECISION TO FIND EARTH-SIZE PLANETS IN THE HABITABLE ZONE
EDUCATION AND PUBLIC OUTREACH WEREIMPORTANT PARTS OF THE KEPLER MISSION
Outreach to the public
Outreach to the scientific communityParticipating Scientist Program
Expanded the capability of the Science Team & the research areas addressedGuest Observer Program
Identified new areas of scientific research enabled by KeplerHelped science community teams obtain NASA-provided research grantsProvided technical expertise on the scientific exploitation of the Kepler dataDeveloped open-source software tools to aid data reduction and analysisOrganized workshops and tutorials to help make Kepler research accessible.
E. DevoreA Gould
G. Barentsen, C. Hedges, M. Gully Sanitago
Science Office Operations:“Pixels to Planetary Candidates”
Jenkins et al, 2010,, ApJL 713, L87
Raw data
Processed data
Data processing Classification of events
A MAJOR TEAM EFFORT WAS NECESSARY TO VALIDATE AND CONFIRM PLANETARY CANDIDATES
Radial Velocity
Transit Timing Variations
Image Offsets
Phase
Radial Velociyt
Endl, et al., 2011, ApJL 197, 13
Probability due to False Positive Spitzer observations
Cochran et al., 2011, AJSS 197:1F. Fressin & W.Torres
S. Bryson, J. Jenkins
KEPLER RESULTS: PLANET SIZE VS. ORBITAL PERIOD
Notes:1) Many planets with very-short-period orbits2) Many planets are larger than Jupiter3) Most planets are between the sizes of Earth and Neptune.4) Paucity of large planets at short periods5) Region in the lower right shows few small planets at long periods
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PLANETARY SURPRISES
Kepler-36:Two planetswith nearly identical orbits; one rocky & one gaseous
Kepler-47: a planetary system orbiting a double star with one planet in the habitable zone
Kepler-22b: A HZ planet unlike any in our solar system. A water-world?
Orosz et al., 2012, Science 337,1511
Borucki et al, 2012, ApJ 745:120Carter et al., 2012, Science 337:556
SMALL- & MEDIUM-SIZE PLANETS IN THE HZ
Light green optimistic HZ. Dark green conservative HZ.Yellow numbers: confirmed planets. Blue circles: Candidates waiting on further ground-based observations.Left-hand column: star size & color associated with temperature
Batalha, 2015, PNAS 111, 12647
MOST PLANETARY SYSTEMS AREUNLIKE OUR SOLAR SYSTEM
Kepler-444; A Compact Planetary System 6 Billion Years Older Than Earth(Implies rocky planets started forming at the time of galaxy formation and that life might be much more advanced than our own.)
D. C. Fabrycky, personal comm.
Campante et al. 2015 ApJ 799 170
Geert Barentsen, 2019
K2 EXPANDS KEPLER’S SCIENTIFIC CONTRIBUTIONS
Robert H. Goddard Memorial Trophy 2014, National Space ClubLaureate Award Space, 2012 , Aviation Week
Current Achievement, 2015, Smithsonian National Air & Space MuseumMedal, Space Science Award, 2012, Amer. Institute of Aeronautics & Astronautics
New Space Award: Vision to Reality, 2012, Space Frontier Foundation
KEPLER TEAM AWARDS
WHAT HAS KEPLER FOUND?Most stars have planets.Planetary systems have been forming from
the beginning of our galaxy.Earth-size planets are common.Planets unlike any in our Solar System are commonPlanets of all sizes are found in the habitable zone.Other planetary systems are quite unlike ours. Implications: Fermi paradox
WHAT’S NEXT?
CURRENT & FUTURE MISSIONS THAT WILL CONTINUE OUR SEARCH FOR HABITABLE PLANETS
BRIEF HISTORY OF THE KEPLER MISSION�William Borucki , NASA Ames Research CenterTIMELINE FOR THE DEVELOPMENT �OF THE KEPLER MISSIONEARLY AMES/NIST PHOTOMETERS �WITH QUANTUM-PERFECT DETECTORSPROOF THAT CCDs HAVE THE 10ppm PRECISION NECESSARY TO DETECT EARTH-SIZE PLANETSAN OBSERVATORY BUILT TO DEMONSTRATE THE�CAPABILITY OF PHOTOMETRY TO DETECT EXOPLANETSTEST FACILITY BUILT TO DEMONSTRATE 10 PPM PHOTOMETRIC PRECISION & THE DETECTION OF EARTH-SIZE TRANSITSSPECIFIC GOALS OF THE MISSIONTHE KEPLER INSTRUMENT: A WIDE FIELD-OF-VIEW PHOTOMETER THAT SIMULTANEOUSLY MONITORS THE BRIGHTNESS OF 170,000 STARS WITH ENOUGH PRECISION TO FIND EARTH-SIZE PLANETS IN THE HABITABLE ZONE�EDUCATION AND PUBLIC OUTREACH WERE�IMPORTANT PARTS OF THE KEPLER MISSIONScience Office Operations:�“Pixels to Planetary Candidates”�A MAJOR TEAM EFFORT WAS NECESSARY TO VALIDATE AND CONFIRM PLANETARY CANDIDATESKEPLER RESULTS: PLANET SIZE VS. ORBITAL PERIODA THOROUGH CORRECTION FOR BIASES IS NECESSARYPLANETARY SURPRISESSMALL- & MEDIUM-SIZE PLANETS IN THE HZMOST PLANETARY SYSTEMS ARE�UNLIKE OUR SOLAR SYSTEMK2 EXPANDS KEPLER’S �SCIENTIFIC CONTRIBUTIONSKEPLER TEAM AWARDSSlide Number 19CURRENT & FUTURE MISSIONS THAT WILL �CONTINUE OUR SEARCH FOR HABITABLE PLANETS