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