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Kepler

Artist's impression of the Kepler telescope

Mission type Space observatory

Operator NASA / LASP

COSPAR ID 2009­011A

SATCAT 34380

Website kepler.nasa.gov(http://kepler.nasa.gov/)

Mission duration Planned: 3.5 yearsElapsed: 6 years, 7 months and20 days

Spacecraft properties

Manufacturer Ball Aerospace & Technologies

Launch mass 1,052.4 kg (2,320 lb)[1]

Dry mass 1,040.7 kg (2,294 lb)[1]

Payload mass 478 kg (1,054 lb)[1]

Dimensions 4.7 m × 2.7 m (15.4 ft × 8.9 ft)[1]

Power 1100 watts[1]

Start of mission

Launch date March 7, 2009, 03:49:57 UTC[2]

Rocket Delta II (7925­10L)

Kepler (spacecraft)From Wikipedia, the free encyclopedia

This article is about the NASA space telescope. For the European cargo spacecraft, see JohannesKepler ATV. For the telescope invented by Johannes Kepler, see Keplerian Telescope. For other uses,see Kepler (disambiguation).

Kepler is a space observatory launched by NASAto discover Earth­like planets orbiting otherstars.[5] The spacecraft, named after theRenaissance astronomer Johannes Kepler,[6] waslaunched on March 7, 2009.[7]

Designed to survey a portion of our region of theMilky Way to discover dozens of Earth­sizeextrasolar planets in or near the habitable zone andestimate how many of the billions of stars in theMilky Way have such planets,[8][9][10] Kepler'ssole instrument is a photometer that continuallymonitors the brightness of over 145,000 mainsequence stars in a fixed field of view.[11] Thisdata is transmitted to Earth, then analyzed todetect periodic dimming caused by extrasolarplanets that cross in front of their host star.

Kepler is part of NASA's Discovery Program ofrelatively low­cost, focused primary sciencemissions. The telescope's construction and initialoperation were managed by NASA's JetPropulsion Laboratory, with Ball Aerospaceresponsible for developing the Kepler flightsystem. The Ames Research Center is responsiblefor the ground system development, missionoperations since December 2009, and scientificdata analysis. The initial planned lifetime was 3.5years,[12] but greater­than­expected noise in thedata, from both the stars and the spacecraft, meantadditional time was needed to fulfill all missiongoals. Initially, in 2012, the mission was expectedto be extended until 2016,[13] but on July 14, 2012,one of the spacecraft's four reaction wheels usedfor pointing the spacecraft stopped turning, andcompleting the mission would only be possible ifall other reaction wheels remained reliable.[14]

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Launch site CCAFS SLC­17BCape Canaveral, FL

Contractor United Launch Alliance

Entered service May 12, 2009, 09:01 UTC

Orbital parameters

Reference system Heliocentric

Regime Earth­trailing

Semi­major axis 1.0132 AU[3]

Eccentricity 0.036091[3]

Perihelion 0.97667 AU[3]

Apohelion 1.0498 AU[3]

Inclination 0.44745 degrees[3]

Period 372.53 days[3]

Argument ofperihelion

2.9411 degrees[3]

Mean anomaly 41.177 degrees[3]

Mean motion 0.96635 deg/day[3]

Epoch March 13, 2015 (J2000: 2457094.5)[3]

Main telescope

Type Schmidt

Diameter 0.95 m (3.1 ft)

Collecting area 0.708 m2 (7.62 sq ft)[A]

Wavelengths 430–890 nm[3]

Transponders

Bandwidth X band up: 7.8 bps­2 kbps[3]

X band down: 10 bps­16 kbps[3]

Ka band down: Up to 4.3 Mbps[3]

Then, on May 11, 2013, a second reaction wheelfailed, disabling the collection of science data[15]

and threatening the continuation of the mission.[16]

On August 15, 2013, NASA announced that theyhad given up trying to fix the two failed reactionwheels. This meant the current mission needed tobe modified, but it did not necessarily mean theend of planet­hunting. NASA had asked the spacescience community to propose alternative missionplans "potentially including an exoplanet search,using the remaining two good reaction wheels andthrusters".[17][18][19][20] On November 18, 2013,the K2 "Second Light" proposal was reported. Thiswould include utilizing the disabled Kepler in away that could detect habitable planets aroundsmaller, dimmer red dwarfs.[21][22][23][24] On May16, 2014, NASA announced the approval of theK2 extension.[25]

As of January 2015, Kepler and its follow­upobservations had found 1,013 confirmedexoplanets in about 440 stellar systems, along witha further 3,199 unconfirmed planetcandidates.[B][26][27] Four planets have beenconfirmed through Kepler 's K2 mission.[28] InNovember 2013, astronomers reported, based onKepler space mission data, that there could be asmany as 40 billion Earth­sized planets orbiting inthe habitable zones of Sun­like stars and reddwarfs within the Milky Way.[29][30][31] It isestimated that 11 billion of these planets may beorbiting Sun­like stars.[32] The nearest such planetmay be 3.7 parsecs (12 ly) away, according to thescientists.[29][30] On January 6, 2015, NASAannounced the 1000th confirmed exoplanetdiscovered by the Kepler Space Telescope. Fourof the newly confirmed exoplanets were found toorbit within habitable zones of their related stars:three of the four, Kepler­438b, Kepler­442b andKepler­452b, are near­Earth­size and likely rocky;the fourth, Kepler­440b, is a super­Earth.[33]

Contents1 Spacecraft

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1 Spacecraft1.1 Camera1.2 Primary mirror1.3 Performance1.4 Spacecraft orbit and orientation1.5 Spacecraft operations1.6 Spacecraft history

2 Field of view3 Objectives and methods4 Planet finding process

4.1 Finding planet candidates4.2 Confirming planet candidates

5 Mission results to date5.1 20095.2 20105.3 20115.4 20125.5 20135.6 20145.7 2015

6 Mission status6.1 Extension6.2 Reaction wheel issues6.3 Second Light (K2)

7 Data releases7.1 Follow­ups by others7.2 Citizen scientist participation

8 Confirmed exoplanets9 Kepler Input Catalog10 See also11 Notes12 References13 External links

Spacecraft

The spacecraft has a mass of 1,039 kilograms (2,291 lb) and contains a 1.4­meter (55 in) primary mirrorfeeding an aperture of 0.95­meter (37.4 in) – at the time of its launch this was the largest mirror on anytelescope outside Earth orbit.[34] The spacecraft has a 115 deg2 (about 12­degree diameter) field of view(FOV), roughly equivalent to the size of one's fist held at arm's length. Of this, 105 deg2 is of sciencequality, with less than 11% vignetting. The photometer has a soft focus to provide excellent photometry,rather than sharp images. The mission goal is a combined differential photometric precision (CDPP) of 20ppm for a m(V)=12 solar­like star for a 6.5­hour integration, though the observations so far have fallenshort of this objective (see mission status). An Earth­like transit produces a brightness change of 84 ppmand lasts for thirteen hours when it crosses the center of the star.

Camera

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Kepler in Astrotech's HazardousProcessing Facility

Kepler 's image sensor array. Thearray is curved to account for Petzvalfield curvature.

Comparison of primary mirror sizesfor the Kepler spacecraft and othernotable optical telescopes.

The focal plane of the spacecraft's camera is made out of 42 CCDs at 2200x1024 pixels, which made it atthe time the largest camera yet launched into space, possessing a total resolution of 95 megapixels.[35][36]

The array is cooled by heat pipes connected to an external radiator.[37] The CCDs are read out every sixseconds (to limit saturation) and co­added on board for 58.89 seconds for short cadence targets, and 1765.5seconds (29.4 minutes) for long cadence targets. Due to the larger bandwidth requirements for the former,these are limited in number to 512 compared to 170,000 for long cadence. However, even though at launchKepler had the highest data rate of any NASA mission, the 29­minute sums of all 95 million pixelsconstitute more data than can be stored and sent back to Earth. Therefore, the science team has pre­selectedthe relevant pixels associated with each star of interest, amounting to about 6 percent of the pixels (5.4megapixels). The data from these pixels is then requantized, compressed and stored, along with otherauxiliary data, in the on­board 16 gigabyte solid­state recorder. Data that is stored and downlinked includes

science stars, p­mode stars,smear, black level,background and full field­of­view images.[37][38]

Primary mirror

The Kepler primary mirror is1.4 meters (4.6 ft) indiameter, the largest mirrorlocated outside Earth orbit.Manufactured by glass

maker Corning using ultra­low expansion (ULE) glass, the mirror isspecifically designed to have a mass only 14% that of a solid mirrorof the same size.[39][40] In order to produce a space telescope systemwith sufficient sensitivity to detect relatively small planets, as theypass in front of stars, a very high reflectance coating on the primarymirror was required. Using ion assisted evaporation, Surface OpticsCorp. applied a protective 9­layer silver coating to enhancereflection and a dielectric interference coating to minimize theformation of color centers and atmospheric moistureabsorption.[41][42]

Performance

In terms of photometric performance, Kepler is working well, muchbetter than any Earth­bound telescope, but still short of the designgoals. The objective was a combined differential photometricprecision (CDPP) of 20 parts per million (PPM) on a magnitude 12star for a 6.5­hour integration. This estimate was developedallowing 10 ppm for stellar variability, roughly the value for theSun. The obtained accuracy for this observation has a wide range,depending on the star and position on the focal plane, with a medianof 29 ppm. Most of the additional noise appears to be due to a

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Kepler 's search volume, in the contextof the Milky Way galaxy.

larger­than­expected variability in the stars themselves (19.5 ppm as opposed to the assumed 10.0 ppm),with the rest due to instrumental noise sources slightly larger than predicted.[43] Work is ongoing to betterunderstand, and perhaps calibrate out, instrument noise.[44]

Since the signal from an Earth­size planet is so close to the noise level (only 80 ppm), the increased noisemeans each individual transit is only a 2.7 σ event, instead of the intended 4 σ. This, in turn, means moretransits must be observed to be sure of a detection. Scientific estimates indicated that a mission lasting 7 to8 years, as opposed to the originally planned 3.5 years, would be needed to find all transiting Earth­sizedplanets.[45] On April 4, 2012, the Kepler mission was approved for extension through the fiscal year2016,[13][46] but this also depended on all remaining reaction wheels staying healthy, which turned out notto be the case (see Spacecraft history below).

Spacecraft orbit and orientation

Kepler orbits the Sun,[47][48] which avoids Earth occultations, straylight, and gravitational perturbations and torques inherent in anEarth orbit. The photometer points to a field in the northernconstellations of Cygnus, Lyra and Draco, which is well out of theecliptic plane, so that sunlight never enters the photometer as thespacecraft orbits.[37]

This is also the direction of the Solar System's motion around thecenter of the galaxy. Thus, the stars which Kepler observes areroughly the same distance from the galactic center as the SolarSystem, and also close to the galactic plane. This fact is important ifposition in the galaxy is related to habitability, as suggested by theRare Earth hypothesis.

NASA has characterised Kepler 's orbit as "Earth­trailing".[49] With an orbital period of 372.5 days, Keplerslowly falls further behind Earth.

Spacecraft operations

Kepler is operated out of Boulder, Colorado, by the Laboratory for Atmospheric and Space Physics (LASP)under contract to Ball Aerospace & Technologies. The spacecraft's solar array is rotated to face the Sun atthe solstices and equinoxes, so as to optimize the amount of sunlight falling on the solar array and to keepthe heat radiator pointing towards deep space.[37] Together, LASP and Ball Aerospace control thespacecraft from a mission operations center located on the research campus of the University of Colorado.LASP performs essential mission planning and the initial collection and distribution of the science data.The mission's initial life­cycle cost was estimated at US$600 million, including funding for 3.5 years ofoperation.[37] In 2012, NASA announced that the Kepler mission would be funded until 2016.[13]

Communications

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Kepler 's orbit. The spacecraft's solararray is adjusted at solstices andequinoxes.

NASA contacts the spacecraft using the X band communication linktwice a week for command and status updates. Scientific data aredownloaded once a month using the Ka band link at a maximumdata transfer rate of approximately 550 KBps. The Kepler spacecraftconducts its own partial analysis on board and only transmitsscientific data deemed necessary to the mission in order to conservebandwidth.[50]

Data management

Science data telemetry collected during mission operations at LASPis sent for processing to the Kepler Data Management Center(DMC) which is located at the Space Telescope Science Institute onthe campus of Johns Hopkins University in Baltimore, Maryland.The science data telemetry is decoded and processed intouncalibrated FITS­format science data products by the DMC, which are then passed along to the ScienceOperations Center (SOC) at NASA Ames Research Center, for calibration and final processing. The SOC atNASA Ames Research Center (ARC) develops and operates the tools needed to process scientific data foruse by the Kepler Science Office (SO). Accordingly, the SOC develops the pipeline data processingsoftware based on scientific algorithms developed by the SO. During operations, the SOC:

1. Receives calibrated pixel data from the DMC2. Applies the analysis algorithms to produce light curves for each star3. Performs transit searches for detection of planets (threshold­crossing events, or TCEs)4. Performs data validation of candidate planets by evaluating various data products for consistency as a

way to eliminate false positive detections

The SOC also evaluates the photometric performance on an ongoing basis and provides the performancemetrics to the SO and Mission Management Office. Finally, the SOC develops and maintains the project’sscientific databases, including catalogs and processed data. The SOC finally returns calibrated data productsand scientific results back to the DMC for long­term archiving, and distribution to astronomers around theworld through the Multimission Archive at STScI (MAST).

Spacecraft history

In January 2006, the project's launch was delayed eight months because of budget cuts and consolidation atNASA.[51] It was delayed again by four months in March 2006 due to fiscal problems.[51] At this time, thehigh­gain antenna was changed from a gimbal­led design to one fixed to the frame of the spacecraft toreduce cost and complexity, at the cost of one observation day per month.

The Kepler observatory was launched on March 7, 2009, at 03:49:57 UTC aboard a Delta II rocket fromCape Canaveral Air Force Station, Florida.[2][7] The launch was a success and all three stages werecompleted by 04:55 UTC. The cover of the telescope was jettisoned on April 7, 2009, and the first lightimages were taken on the next day.[52][53]

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Kepler 's launch on March 7, 2009

Diagram showing the interior ofKepler

A 2004 conceptual drawing of Kepler

On April 20, 2009, it was announced that the Kepler science team had concluded that further refinement ofthe focus would dramatically increase the scientific return.[54] On April 23, 2009, it was announced that thefocus had been successfully optimized by moving the primary mirror 40 micrometers (1.6 thousandths of aninch) towards the focal plane and tilting the primary mirror 0.0072 degree.[55]

On May 13, 2009, at 00:01 UTC, Kepler successfully completed its commissioning phase and began itssearch for planets around other stars.[56][57]

On June 19, 2009, the spacecraft successfully sent its first science data to Earth. It was discovered thatKepler had entered safe mode on June 15. A second safe mode event occurred on July 2. In both cases theevent was triggered by a processor reset. The spacecraft resumed normal operation on July 3 and thescience data that had been collected since June 19 was downlinked that day.[58] On October 14, 2009, the

cause of these safing eventswas determined to be a lowvoltage power supply thatprovides power to theRAD750 processor.[59] OnJanuary 12, 2010, oneportion of the focal planetransmitted anomalous data,suggesting a problem withfocal plane MOD­3 module,covering two out of Kepler 's42 CCDs. As of October2010, the module wasdescribed as "failed", but thecoverage still exceeded thescience goals.[60]

Kepler downlinked roughlytwelve gigabytes of data[61]

about once per month[62]—an example of such a

downlink was on November 22–23, 2010.[63]

On July 14, 2012, one of the four reaction wheels used for finepointing of the spacecraft failed.[64] While Kepler requires only three reaction wheels to accurately aim thetelescope, another failure would leave the spacecraft unable to continue in its mission.[65]

On January 17, 2013, NASA announced that one of the three remaining reaction wheels showed increasedfriction, and that Kepler would discontinue operation for ten days as a possible way of solving the problem.If this second wheel should also fail, the Kepler mission would be over.[66][67] On January 29, 2013, NASAreported the successful return to normal science collection mode,[68] though the reaction wheel still exhibitselevated and erratic friction levels.[69]

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On May 11, 2013, another reaction wheel failed, and the spacecraft was put in point rest state (PRS) byMay 15, 2013.[15] In PRS, the spacecraft uses a combination of thrusters and solar pressure to controlpointing.[15] The fuel use is low, which allows time to attempt recovery of the spacecraft.[15]

The spacecraft automatically went into a thruster­controlled safe mode with the solar panels facing the Sunand with an intermittent communication link with the Earth. In this state the fuel would last for severalmonths. Commands were sent to the spacecraft to put it into Point Rest State. This state reduced fuelconsumption ­ fuel reserves would last for several years in this state. This state also makes communicationpossible at any time. Work was started on the possibility of getting at least one reaction wheel workingagain.[70][71]

In July 2013, the spacecraft remained in point rest state while recovery efforts were planned.[72] By August15, 2013, attempts to resolve issues with two of the four reaction wheels failed.[17][18][19] An engineeringreport was ordered to assess the spacecraft's remaining capabilities.[17]

Field of view

Kepler has a fixed field of view (FOV) against the sky. The diagram to the right shows the celestialcoordinates and where the detector fields are located, along with the locations of a few bright stars withcelestial north at the top left corner. The mission website has a calculator (http://kepler.nasa.gov/cgi­bin/ra2pix.pl) that will determine if a given object falls in the FOV, and if so, where it will appear in thephoto detector output data stream. Data on extrasolar planet candidates is submitted to the Kepler Follow­up Program, or KFOP, to conduct follow­up observations.

Kepler 's field of view covers 115 square degrees, around 0.25 percent of the sky, or "about two scoops ofthe Big Dipper". Thus, it would require around 400 Kepler­like telescopes to cover the whole sky.[73] TheKepler field contains portions of the constellations Cygnus, Lyra, and Draco.

Objectives and methods

The scientific objective of Kepler is to explore the structure and diversity of planetary systems.[74] Thisspacecraft observes a large sample of stars to achieve several key goals:

To determine how many Earth­size and larger planets there are in or near the habitable zone (oftencalled "Goldilocks planets")[75] of a wide variety of spectral types of stars.To determine the range of size and shape of the orbits of these planets.To estimate how many planets there are in multiple­star systems.To determine the range of orbit size, brightness, size, mass and density of short­period giant planets.To identify additional members of each discovered planetary system using other techniques.Determine the properties of those stars that harbor planetary systems.

Most of the extrasolar planets previously detected by other projects were giant planets, mostly the size ofJupiter and bigger. Kepler is designed to look for planets 30 to 600 times less massive, closer to the order ofEarth's mass (Jupiter is 318 times more massive than Earth). The method used, the transit method, involvesobserving repeated transit of planets in front of their stars, which causes a slight reduction in the star'sapparent magnitude, on the order of 0.01% for an Earth­size planet. The degree of this reduction in

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Diagram of Kepler 's investigated areawith celestial coordinatesThe photometer's field of view in the

constellations Cygnus, Lyra andDraco

brightness can be used todeduce the diameter of theplanet, and the intervalbetween transits can be usedto deduce the planet's orbitalperiod, from which estimatesof its orbital semi­major axis(using Kepler's laws) and itstemperature (using models ofstellar radiation) can becalculated.

The probability of a randomplanetary orbit being alongthe line­of­sight to a star isthe diameter of the stardivided by the diameter ofthe orbit.[76] For an Earth­like planet at 1 AU transitinga Sol­like star the probability is 0.47%, or about 1 in 210.[76][C] For

a planet like Venus orbiting a Sol­like star the probability is slightly higher, at 0.65%;[76] such planets couldbe Earth­like if the host star is a late G­type star such as Tau Ceti. If the host star has multiple planets, theprobability of additional detections is higher than the probability of initial detection assuming planets in agiven system tend to orbit in similar planes – an assumption consistent with current models of planetarysystem formation.[76] For instance, if a Kepler­like mission conducted by aliens observed Earth transitingthe Sun, there is a 12% chance that it would also see Venus transiting.[76]

Kepler 's 115­deg2 field of view gives it a much higher probability of detecting Earth­like planets than theHubble Space Telescope, which has a field of view of only 10 sq. arc­minutes. Moreover, Kepler isdedicated to detecting planetary transits, while the Hubble Space Telescope is used to address a wide rangeof scientific questions, and rarely looks continuously at just one starfield. Of the approximately half­millionstars in Kepler 's field of view, around 150,000 stars were selected for observation. More than 90,000 are G­type stars on, or near, the main sequence. Thus, Kepler was designed to be sensitive to wavelengths of 400–865 nm where brightness of those stars peaks. Most of the stars observed by Kepler have apparent visualmagnitude between 14 and 16 but the brightest observed stars have apparent visual magnitude of 8 orlower. Most of the planet candidates were initially not expected to be confirmed due to being too faint forfollow­up observations.[77] All the selected stars are observed simultaneously, with the spacecraftmeasuring variations in their brightness every thirty minutes. This provides a better chance for seeing atransit. The mission was designed to maximize the probability of detecting planets orbiting otherstars.[37][78]

Since Kepler must observe at least three transits to confirm that the dimming of a star was caused by atransiting planet, and since larger planets give a signal that is easier to check, scientists expected the firstreported results to be larger Jupiter­size planets in tight orbits. The first of these were reported after only afew months of operation. Smaller planets, and planets farther from their sun would take longer, anddiscovering planets comparable to Earth were expected to take three years or longer.[47]

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Artist's impression of Kepler

Data collected by Kepler is also being used for studying variable stars of various types and performingasteroseismology,[79] particularly on stars showing solar­like oscillations.[80]

Planet finding process

Finding planet candidates

Once Kepler has collected and sent back the data, raw light curvesare constructed. Brightness values are then adjusted to take thebrightness variations due to the rotation of the spacecraft intoaccount. The next step is processing (folding) light curves into amore easily observable form and letting software select signals thatseem potentially transit­like. At this point, any signal that showspotential transit­like features is called a threshold crossing event.These signals are individually inspected in 2 inspection rounds, withthe first round taking only a few seconds per target. This inspectioneliminates erroneously selected non­signals, signals caused byinstrumental noise and obvious eclipsing binaries.[81]

Threshold crossing events that pass these tests are called Kepler Objects of Interest (KOI), receive a KOIdesignation and are archived. KOIs are inspected more thoroughly in a process called dispositioning. Thosewhich pass the dispositioning are called Kepler planet candidates. The KOI archive is not static, meaningthat a Kepler candidate could end up in the false­positive list upon further inspection. In turn, KOIs thatwere mistakenly classified as false positives could end up back in the candidates list.[82]

Not all the planet candidates go through this process. Circumbinary planets do not show strictly periodictransits, and have to be inspected through other methods. In addition, third­party researchers use differentdata­processing methods, or even search planet candidates from the unprocessed light curve data. As aconsequence, those planets may be missing KOI designation.

Confirming planet candidates

Once suitable candidates have been found from Kepler data, it is necessary to rule out false positives withfollow­up tests.

Usually, Kepler candidates are imaged individually with more­advanced ground­based telescopes in orderto resolve any background objects which could contaminate the brightness signature of the transit signal.[83]Another method to rule out planet candidates is astrometry for which Kepler can collect good data eventhough doing so was not a design goal. While Kepler cannot detect planetary­mass objects with thismethod, it can be used to determine if the transit was caused by a stellar­mass object.[84]

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A photo taken by Kepler with twopoints of interest outlined. Celestialnorth is towards the lower left corner.

Kepler mission ­ new exoplanet candidates ­ as of July 23, 2015.[85]

Through other detection methods

There are a few different exoplanet detection methods which help to rule out false positives by givingfurther proof that a candidate is a real planet. One of the methods, called doppler spectroscopy, requiresfollow­up observations from ground­based telescopes. This method works well if the planet is massive or islocated around a relatively bright star. While current spectrographs are insufficient for confirming planetarycandidates with small masses around relatively dim stars, this method can be used to discover additionalmassive non­transiting planet candidates around targeted stars.

In multiplanetary systems, planets can often be confirmed throughtransit timing variation by looking at the time between successivetransits, which may vary if planets are gravitationally perturbed byeach other. This helps to confirm relatively low­mass planets evenwhen the star is relatively distant. Transit timing variations indicatethat two or more planets belong to the same planetary system. Thereare even cases where a non­transiting planet is also discovered inthis way.[86]

Circumbinary planets show much larger transit timing variationsbetween transits than planets gravitationally disturbed by otherplanets. Their transit duration times also vary significantly. Transittiming and duration variations for circumbinary planets are causedby the orbital motion of the host stars, rather than by otherplanets.[87] In addition, if the planet is massive enough, it can causeslight variations of the host stars' orbital periods. Despite beingharder to find circumbinary planets due to their non­periodictransits, it is much easier to confirm them, as timing patterns of transits cannot be mimicked by an eclipsingbinary or a background star system.[88]

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In addition to transits, planets orbiting around their stars undergo reflected­light variations – like the Moon,they go through phases from full to new and back again. Since Kepler cannot resolve the planet from thestar, it sees only the combined light, and the brightness of the host star seems to change over each orbit in aperiodic manner. Although the effect is small – the photometric precision required to see a close­in giantplanet is about the same as to detect an Earth­sized planet in transit across a solar­type star – Jupiter­sizedplanets with an orbital period of a few days or less are detectable by sensitive space telescopes such asKepler. In the long run, this method may help find more planets than the transit method, because thereflected light variation with orbital phase is largely independent of the planet's orbital inclination, and doesnot require the planet to pass in front of the disk of the star. In addition, the phase function of a giant planetis also a function of its thermal properties and atmosphere, if any. Therefore, the phase curve may constrainother planetary properties, such as the particle size distribution of the atmospheric particles.[89]

Kepler 's photometric precision is often high enough to observe a star's brightness changes caused bydoppler beaming or a star's shape deformation by a companion. These can sometimes be used to rule out hotJupiter candidates as false positives caused by a star or a brown dwarf when these effects are toonoticeable.[90] However, there are some cases where such effects are detected even by planetary­masscompanions such as TrES­2b.[91]

Through validation

If a planet cannot be detected through at least one of the other detection methods, it can be confirmed bydetermining if the possibility of a Kepler candidate being a real planet is significantly larger than any false­positive scenarios combined. One of the first methods was to see if other telescopes can see the transit aswell. The first planet confirmed through this method was Kepler­22b which was also observed with aSpitzer space telescope in addition to analyzing any other false­positive possibilities.[92] Such confirmationis costly, as small planets can generally be detected only with space telescopes.

In 2014, a new confirmation method called "validation by multiplicity" was announced. From the planetspreviously confirmed through various methods, it was found that planets in most planetary systems orbit ina relatively flat plane, similar to the planets found in the Solar System. This means that if a star has multipleplanet candidates, it is very likely a real planetary system.[93] Transit signals still need to meet severalcriteria which rule out false­positive scenarios. For instance, it has to have considerable signal­to­noiseratio, it has at least three observed transits, orbital stability of those systems have to be stable and transitcurve has to have a shape that partly eclipsing binaries could not mimic the transit signal. In addition, itsorbital period needs to be 1.6 days or longer to rule out common false positives caused by eclipsingbinaries.[94] Validation by multiplicity method is very efficient and allows to confirm hundreds of Keplercandidates in a relatively short amount of time.

A new validation method using a tool called PASTIS has been developed. It makes it possible to confirm aplanet even when only a single candidate transit event for the host star has been detected. A drawback ofthis tool is that it requires a relatively high signal­to­noise ratio from Kepler data, so it can mainly confirmonly larger planets or planets around quiet and relatively bright stars. Currently, the analysis of Keplercandidates through this method is underway.[95] PASTIS was first successful for validating the planetKepler­420b.[96]

Mission results to date

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Detail of Kepler 's image of theinvestigated area showing open starcluster NGC 6791. Celestial north istowards the lower left corner.

Detail of Kepler 's image of theinvestigated area. The location ofTrES­2b within this image is shown.Celestial north is towards the lowerleft corner.

The Kepler observatory was in active operation from 2009 through2013, with the first main results announced on January 4, 2010. Asexpected, the initial discoveries were all short­period planets. As themission continued, additional longer­period candidates were found.

2009

NASA held a press conference to discuss early science results of theKepler mission on August 6, 2009.[97] At this press conference, itwas revealed that Kepler had confirmed the existence of thepreviously known transiting exoplanet HAT­P­7b, and wasfunctioning well enough to discover Earth­size planets.[98][99]

Since Kepler 's detection of planets depends on seeing very smallchanges in brightness, stars that vary in brightness all by themselves(variable stars) are not useful in this search.[62] From the first fewmonths of data, Kepler scientists have determined that about 7,500stars from the initial target list are such variable stars. These weredropped from the target list, and replaced by new candidates. OnNovember 4, 2009, the Kepler project publicly released the lightcurves of the dropped stars.[100]

The first six weeks of data revealed five previously unknownplanets, all very close to their stars.[101][102] Among the notableresults are one of the least dense planets yet found,[103] two low­mass white dwarfs[104] that were initially reported as being membersof a new class of stellar objects,[105] and a well­characterized planetorbiting a binary star.

2010

On June 15, 2010, the Kepler mission released data on all but 400 ofthe ~156,000 planetary target stars to the public. 706 targets fromthis first data set have viable exoplanet candidates, with sizesranging from as small as the Earth to larger than Jupiter. Theidentity and characteristics of 306 of the 706 targets were given. Thereleased targets included five candidate multi­planet systems. Data for the remaining 400 targets withplanetary candidates was to be released in February 2011. (For details about this later data release, see theKepler results for 2011 below.) Nonetheless, the Kepler results, based on the candidates in the list releasedin 2010, imply that most candidate planets have radii less than half that of Jupiter. The Kepler results alsoimply that small candidate planets with periods less than thirty days are much more common than largecandidate planets with periods less than thirty days and that the ground­based discoveries are sampling thelarge­size tail of the size distribution.[106] This contradicted older theories which had suggested small andEarth­like planets would be relatively infrequent.[107][108] Based on extrapolations from the Kepler data, anestimate of around 100 million habitable planets in the Milky Way may be realistic.[109] However, somemedia reports of the TED talk have led to the misunderstanding that Kepler had actually found these

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A size comparison of the exoplanetsKepler­20e[116] and Kepler­20f[117]

with Venus and Earth

planets. This was clarified in a letter to the Director of the NASA Ames Research Center, for the KeplerScience Council dated August 2, 2010 states, "Analysis of the current Kepler data does not support theassertion that Kepler has found any Earth­like planets."[110][111][112]

In 2010, Kepler identified two systems containing objects which are smaller and hotter than their parentstars: KOI 74 and KOI 81.[113] These objects are probably low­mass white dwarfs produced by previousepisodes of mass transfer in their systems.[104]

In 2010, the Kepler team released a paper which had data for 312 extrasolar planet candidates from 306separate stars. Only 33.5 days of data were available for most of the candidates.[106] NASA also announceddata for another 400 candidates were being withheld to allow members of the Kepler team to performfollow­up observations.[114] The data for these candidates were made public on February 2, 2011.[115]

2011

On February 2, 2011, the Kepler team announced the results ofanalysis of the data taken between 2 May and September 16,2009.[115] They found 1235 planetary candidates circling 997 hoststars. (The numbers that follow assume the candidates are reallyplanets, though the official papers called them only candidates.Independent analysis indicated that at least 90% of them are realplanets and not false positives).[118] 68 planets were approximatelyEarth­size, 288 super­Earth­size, 662 Neptune­size, 165 Jupiter­size,and 19 up to twice the size of Jupiter. In contrast to previous work,roughly 74% of the planets are smaller than Neptune, most likely asa result of previous work finding large planets more easily thansmaller ones.

That February 2, 2011 release of 1235 extrasolar planet candidates, included 54 that may be in the"habitable zone", including 5 less than twice the size of the Earth.[119][120] There were previously only twoplanets thought to be in the "habitable zone", so these new findings represent an enormous expansion of thepotential number of "Goldilocks planets" (planets of the right temperature to support liquid water).[121] Allof the habitable zone candidates found thus far orbit stars significantly smaller and cooler than the Sun(habitable candidates around Sun­like stars will take several additional years to accumulate the threetransits required for detection).[122] Of all the new planet candidates, 68 are 125% of Earth's size or smaller,or smaller than all previously discovered exoplanets.[120] "Earth­size" and "super­Earth­size" is defined as"less than or equal to 2 Earth radii (Re)" [(or, Rp ≤ 2.0 Re) – Table 5].[115] Six such planet candidates[namely: KOI 326.01 (Rp=0.85), KOI 701.03 (Rp=1.73), KOI 268.01 (Rp=1.75), KOI 1026.01 (Rp=1.77),KOI 854.01 (Rp=1.91), KOI 70.03 (Rp=1.96) – Table 6][115] are in the "habitable zone."[119] A more recentstudy found that one of these candidates (KOI 326.01) is in fact much larger and hotter than firstreported.[123]

The frequency of planet observations was highest for exoplanets two to three times Earth­size, and thendeclined in inverse proportionality to the area of the planet. The best estimate (as of March 2011), afteraccounting for observational biases, was: 5.4% of stars host Earth­size candidates, 6.8% host super­Earth­

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size candidates, 19.3% host Neptune­size candidates, and 2.55% host Jupiter­size or larger candidates.Multi­planet systems are common; 17% of the host stars have multi­candidate systems, and 33.9% of all theplanets are in multiple planet systems.[124]

By December 5, 2011, the Kepler team announced that they had discovered 2,326 planetary candidates, ofwhich 207 are similar in size to Earth, 680 are super­Earth­size, 1,181 are Neptune­size, 203 are Jupiter­size and 55 are larger than Jupiter. Compared to the February 2011 figures, the number of Earth­size andsuper­Earth­size planets increased by 200% and 140% respectively. Moreover, 48 planet candidates werefound in the habitable zones of surveyed stars, marking a decrease from the February figure; this was due tothe more stringent criteria in use in the December data.[125]

On December 20, 2011, the Kepler team announced the discovery of the first Earth­size exoplanets, Kepler­20e[116] and Kepler­20f,[117] orbiting a Sun­like star, Kepler­20.[126]

Based on Kepler 's findings, astronomer Seth Shostak estimated in 2011 that "within a thousand light­yearsof Earth", there are "at least 30,000" habitable planets.[127] Also based on the findings, the Kepler team hasestimated that there are "at least 50 billion planets in the Milky Way", of which "at least 500 million" are inthe habitable zone.[128] In March 2011, astronomers at NASA's Jet Propulsion Laboratory (JPL) reportedthat about "1.4 to 2.7 percent" of all Sun­like stars are expected to have earthlike planets "within thehabitable zones of their stars". This means there are "two billion" of these "Earth analogs" in the MilkyWay alone. The JPL astronomers also noted that there are "50 billion other galaxies", potentially yieldingmore than one sextillion "Earth analog" planets if all galaxies have similar numbers of planets to the MilkyWay.[129]

2012

In January 2012, an international team of astronomers reported that each star in the Milky Way Galaxy mayhost "on average...at least 1.6 planets", suggesting that over 160 billion star­bound planets may exist in theMilky Way.[130][131] Kepler also recorded distant stellar super­flares, some of which are 10,000 times morepowerful than the superlative 1859 Carrington event.[132] The superflares may be triggered by close­orbiting Jupiter­sized planets.[132] The Transit Timing Variation (TTV) technique, which was used todiscover Kepler­9d, gained popularity for confirming exoplanet discoveries.[133] A planet in a system withfour stars was also confirmed, the first time such a system had been discovered.[134]

As of 2012, there were a total of 2,321 candidates.[125][135][136] Of these, 207 are similar in size to Earth,680 are super­Earth­size, 1,181 are Neptune­size, 203 are Jupiter­size and 55 are larger than Jupiter.Moreover, 48 planet candidates were found in the habitable zones of surveyed stars. The Kepler teamestimated that 5.4% of all stars host Earth­size planet candidates, and that 17% of all stars have multipleplanets. In December 2011, two of the Earth­sized candidates, Kepler­20e[116] and Kepler­20f,[117] wereconfirmed as planets orbiting a Sun­like star, Kepler­20.[126][137][138]

2013

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A chart showing Kepler discoveries,in context of all discoveredexoplanets (through 2013), with sometransit probabilities indicated forexample scenarios.

According to a study by Caltech astronomers published in January 2013, the Milky Way Galaxy contains atleast as many planets as it does stars, resulting in 100–400 billion exoplanets.[139][140] The study, based onplanets orbiting the star Kepler­32, suggests that planetary systemsmay be common around stars in the Milky Way. The discovery of461 more candidates was announced on January 7, 2013.[141] Thelonger Kepler watches, the more planets with long periods it candetect.[141]

“ Since the last Kepler catalog was released inFebruary 2012, the number of candidates discoveredin the Kepler data has increased by 20 percent andnow totals 2,740 potential planets orbiting 2,036stars. ­ NASA[141] ”

A candidate, newly announced on January 7, 2013, was Kepler­69c(formerly, KOI­172.02), an Earth­like exoplanet orbiting a starsimilar to the Sun in the habitable zone and possibly a "primecandidate to host alien life".[142]

In April 2013, a white dwarf was discovered bending the light of itscompanion red dwarf in the KOI­256 star system.[143]

In April 2013, NASA announced the discovery of three new Earth­like exoplanets – Kepler­62e, Kepler­62f, and Kepler­69c – in the habitable zones of their respective hoststars, Kepler­62 and Kepler­69. The new exoplanets, which are considered prime candidates for possessingliquid water and thus potentially life, were identified using the Kepler spacecraft.[144][145][146] A more recentanalysis has shown that Kepler­69c is likely more analogous to Venus, and thus unlikely to behabitable.[147]

On May 15, 2013, NASA announced the spacecraft had been crippled by failure of a reaction wheel thatkeeps it pointed in the right direction. A second wheel had previously failed, and the spacecraft requiresthree wheels (out of four total) to be operational for the instrument to function properly. Further testing inJuly and August determined that while Kepler was capable of using its damaged reaction wheels to preventitself from entering safe mode and downlinking previously collected science data it was not capable ofcollecting further science data as previously configured.[148] Scientists working on the Kepler project saidthere was a backlog of data still to be looked at, and that more discoveries would be made in the followingcouple of years, despite the setback.[149]

Although no new science data from Kepler field had been collected since the problem, an additional sixty­three candidates were announced in July 2013 based on the previously collected observations.[72]

In November 2013, the second Kepler science conference was held. The discoveries included the mediansize of planet candidates getting smaller compared to early 2013, preliminary results of the discovery of afew circumbinary planets and planets in the habitable zone.[150]

2014

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Histogram of exoplanet discoveries.The yellow shaded bar shows newlyannounced planets including thoseverified by the multiplicity technique(February 26, 2014).

On February 13, over 530 additional planet candidates wereannounced residing around single planet systems. Several of themwere nearly Earth­sized and located in the habitable zone. Thisnumber was further increased by about 400 in June 2014.[151]

On February 26, scientists announced that data from Kepler hadconfirmed the existence of 715 new exoplanets. A new statisticalmethod of confirmation was used called "verification bymultiplicity" which is based on how many planets around multiplestars were found to be real planets. This allowed much quickerconfirmation of numerous candidates which are part ofmultiplanetary systems. 95% of the discovered exoplanets weresmaller than Neptune and four, including Kepler­296f, were lessthan 2 1/2 the size of Earth and were in habitable zones wheresurface temperatures are suitable for liquid water.[93][152][153][154]

In March, a study found that small planets with orbital periods of less than 1 day are usually accompaniedby at least one additional planet with orbital period of 1–50 days. This study also noted that ultra­shortperiod planets are almost always smaller than 2 Earth radii unless it is a misaligned hot Jupiter.[155]

Kepler data has also helped scientists observe and understand supernovae; measurements were collectedevery half hour so the light curves were especially useful for studying these types of astronomicalevents.[156]

On April 17, the Kepler team announced the discovery of Kepler­186f, the first nearly Earth­sized planetlocated in the habitable zone. This planet orbits around a red dwarf.[157]

In May 2014, campaign fields 0 to 13 were reported and described in detail.[158]

In July 2014, the first discoveries from post­Kepler field data were reported in the form of eclipsingbinaries. Discoveries were derived from a Kepler engineering data set which was collected prior tocampaign 0[159] in preparation to the main K2 mission.[160]

On September 23, 2014, NASA reported that the K2 mission had completed campaign 1,[161] the firstofficial set of science observations, and that campaign 2[162] was underway.[163]

Campaign 3[165] lasted from November 14, 2014 to February 6, 2015 and included "16,375 standard longcadence and 55 standard short cadence targets".[158]

2015

In January 2015, the number of confirmed Kepler planets exceeded 1000. At least two (Kepler­438band Kepler­442b) of the discovered planets announced that month were likely rocky and in thehabitable zone.[33] Also in January 2015, NASA reported that five confirmed sub­earth­sized rockyexoplanets, all smaller than the planet Venus, were found orbiting the 11.2 billion year old starKepler­444, making this star system, at 80% of the age of the universe, the oldest yetdiscovered.[166][167][168]

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Kepler observed KSN 2011b, a Type Iasupernova, in the process of exploding:before, during and after.[164]

Predicted structure of the Milky Waygalaxy overlaid with the originalKepler search space.[178]

In April 2015, campaign 4[169] was reported to lastbetween February 7, 2015, and April 24, 2015, and toinclude observations of nearly 16,000 target stars and twonotable open star clusters, Pleiades and Hyades.[170]In May 2015, Kepler observed a newly discoveredsupernova, KSN 2011b (Type 1a), before, during andafter explosion. Details of the pre­nova moments mayhelp scientists better understand dark energy.[164]On July 24, 2015, NASA announced the discovery ofKepler­452b, a confirmed exoplanet that is near­Earth insize and found orbiting the habitable zone of a Sun­likestar.[171][172] The seventh Kepler planet candidate catalogwas released, containing 4,696 candidates, and increaseof 521 candidates since the previous catalog release in January 2015.[173][174]On September 14, 2015, astronomers reported unusual light fluctuations of KIC 8462852, an F­typemain­sequence star in the constellation Cygnus, as detected by Kepler, while searching forexoplanets. Various explanations have been presented, including comets, asteroids, and an aliencivilization.[175][176][177]

Mission status

Kepler was launched in 2009. It was very successful at finding exoplanets, but failures in two of fourreaction wheels crippled its extended mission in 2013. Without three functioning wheels, the telescopecould not be pointed accurately.

Extension

In April 2012, an independent panel of senior NASA scientistsrecommended that the Kepler mission be continued through 2016.According to the senior review, Kepler observations needed tocontinue until at least 2015 to achieve all the stated scientificgoals.[179] On November 14, 2012, NASA announced thecompletion of Kepler 's primary mission, and the beginning of itsextended mission, which may last as long as four years.[180]

Reaction wheel issues

In July 2012, one of Kepler 's four reaction wheels (wheel 2)failed.[17] On May 11, 2013, a second wheel (wheel 4) failed,threatening the continuation of the mission, as three wheels arenecessary for its planet hunting.[15][16] Kepler has not collectedscience data since May because it is not able to point with sufficientaccuracy.[141] On July 18 and 22 reaction wheels 4 and 2 were testedrespectively; wheel 4 only rotated counter­clockwise but wheel 2 ran in both directions, albeit withsignificantly elevated friction levels.[181] A further test of wheel 4 on July 25 managed to achieve bi­directional rotation.[182] Both wheels, however, exhibited too much friction to be useful.[19] On August 2,

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NASA put out a call for proposals to use the remaining capabilities of Kepler for other scientific missions.Starting on August 8, a full systems evaluation was conducted. It was determined that wheel 2 could notprovide sufficient precision for scientific missions and the spacecraft was returned to a "rest" state toconserve fuel.[17] Wheel 4 was previously ruled out because it exhibited higher friction levels than wheel 2in previous tests.[182] Sending astronauts to fix Kepler is not an option since it orbits the Sun and is millionsof kilometers from Earth.[19]

On August 15, 2013, NASA announced that Kepler would not continue searching for planets using thetransit method after attempts to resolve issues with two of the four reaction wheels failed.[17][18][19] Anengineering report was ordered to assess the spacecraft's capabilities, its two good reaction wheels and itsthrusters.[17] Concurrently, a scientific study was conducted to determine whether enough knowledge canbe obtained from Kepler 's limited scope to justify its $18 million per year cost.

Possible future uses include searching for asteroids and comets, looking for evidence of supernovas, andfinding huge exoplanets through gravitational microlensing.[19] Another proposal is to modify the softwareon Kepler to compensate for the disabled reaction wheels. Instead of the stars being fixed and stable inKepler 's field of view, they will drift. However, software could track this drift and more or less completelyrecover the mission goals despite being unable to hold the stars in a fixed view.[183]

Previously collected data continues to be analyzed.[184] It is expected that around 90% of the 3,548candidate planets previously identified by Kepler will be confirmed when the data analysis is complete, aprocess that will take several years. As of August 2013, 135 of those candidates have been confirmed.[19]

Second Light (K2)

In November 2013, a new mission plan named K2 "Second Light" was presented forconsideration.[22][23][24][185] K2 would involve using Kepler 's remaining capability, photometric precision ofabout 300 parts per million, compared with about 20 parts per million earlier, to collect data for the study of"supernova explosions, star formation and solar­system bodies such as asteroids and comets, ... " and forfinding and studying more exoplanets.[22][23][185] In this proposed mission plan, Kepler would search amuch larger area in the plane of Earth's orbit around the Sun.[22][23][185]

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K2 proposal explained (December 11, 2013).[23]

In early 2014, the spacecraft underwent successful testing for the K2 mission.[186] From March to May2014, data from a new field called Field 0 was collected as a testing run.[187] On May 16, 2014, NASAannounced the approval of extending the Kepler mission to the K2 mission.[25] Kepler 's photometricprecision for the K2 mission was estimated to be 50 ppm on a magnitude 12 star for a 6.5­hourintegration.[188] In February 2014, photometric precision for the K2 mission using two­wheel, fine­pointprecision operations was measured as 44 ppm on magnitude 12 stars for a 6.5­hour integration. The analysisof these measurements by NASA suggests the K2 photometric precision approaches that of the Keplerarchive of three­wheel, fine­point precision data.[189]

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K2 mission timeline (August 8, 2014).[190]

On May 29, 2014, campaign fields 0 to 13 were reported and described in detail.[158]

Field 1 of the K2 mission is set towards the Leo­Virgo region of the sky, while Field 2 is towards the "head"area of Scorpius and includes two globular clusters, Messier 4 and Messier 80,[191] and part of theScorpius–Centaurus Association, which is only about 11 million years old[192] and 120–140 parsecs (380–470 ly) distant[193] with probably over 1,000 members.[194]

On December 18, 2014, NASA announced that the K2 mission had detected its first confirmed exoplanet, asuper­Earth named HIP 116454 b. Its signature was found in a set of engineering data meant to prepare thespacecraft for the full K2 mission. Radial velocity follow­up observations were needed as only a singletransit of the planet was detected.[195]

Data releases

The Kepler team originally promised to release data within one year of observations.[196] However, thisplan was changed after launch, with data being scheduled for release up to three years after itscollection.[197] This resulted in considerable criticism,[198][199][200][201][202] leading the Kepler science teamto release the third quarter of their data one year and nine months after collection.[203] The data throughSeptember 2010 (quarters 4, 5, and 6) was made public in January 2012.[204]

Follow­ups by others

Periodically, the Kepler team releases a list of candidates (Kepler Objects of Interest, or KOIs) to thepublic. Using this information, a team of astronomers collected radial velocity data using the SOPHIEéchelle spectrograph to confirm the existence of the candidate KOI­428b in 2010, later named Kepler­40b.[205] In 2011, the same team confirmed candidate KOI­423b, later named Kepler­39b.[206]

Citizen scientist participation

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Confirmed small exoplanets in habitable zones(Kepler­62e, Kepler­62f, Kepler­186f, Kepler­296e, Kepler­296f, Kepler­438b, Kepler­440b,

Kepler­442b).[33]

Since December 2010, Kepler mission data has been used for the Zooniverse project "Planethunters.org",which allows volunteers to look for transit events in the light curves of Kepler images to identify planetsthat computer algorithms might miss.[207] By June 2011, users had found sixty­nine potential candidatesthat were previously unrecognized by the Kepler mission team.[208] The team has plans to publicly creditamateurs who spot such planets.

In January 2012, the British Broadcasting Corporation (BBC) program Stargazing Live aired a publicappeal for volunteers to analyse Planethunters.org data for potential new exoplanets. This led two amateurastronomers—one in Peterborough, England—to discover a new Neptune­sized exoplanet, to be namedThreapleton Holmes B.[209] One hundred thousand other volunteers are also engaged in the search by lateJanuary, analyzing over one million Kepler images by early 2012.[210]

Confirmed exoplanets

Main article: List of exoplanets discovered usingthe Kepler spacecraftSee also: List of exoplanetary host stars and List ofexoplanets

In addition to discovering hundreds of exoplanetcandidates, the Kepler spacecraft has also reportedtwenty­six exoplanets in eleven systems that have notyet been added to the Extrasolar Planet Database.[211]Exoplanets discovered using Kepler 's data, butconfirmed by outside researchers, include KOI­423b,[206] KOI­428b,[205] KOI­196b,[212] KOI­135b,[213] KOI­204b,[214] KOI­254b,[215] KOI­730,[216]

and Kepler­42 (KOI­961).[217] The "KOI" acronymindicates that the star is a Kepler Object of Interest.

Both Corot[218] and Kepler[99] measured the reflectedlight from planets. However, these planets were already known, because they transit their star. Kepler 's dataallowed the first discovery of planets by this method, Kepler­70b and Kepler­70c.[219]

Kepler Input Catalog

Main article: Kepler Input Catalog

The Kepler Input Catalog (KIC) is a publicly searchable database of roughly 13.2 million targets used forthe Kepler Spectral Classification Program and the Kepler mission.[220][221] The catalog alone is not usedfor finding Kepler targets, because only a portion of the listed stars (about one­third of the catalog) can beobserved by the spacecraft.[220]

See also

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Kepler­22b, the first exoplanet confirmed by Kepler to have an average orbital distance within itsstar's habitable zoneList of exoplanetsList of multiplanetary systems

Related or comparable missions and projects

Automated Planet FinderCOROTDarwinEddingtonExoplanet ArchiveGaiaHATNet ProjectHigh Accuracy Radial Velocity Planet SearcherPlanetQuestPLATOSpace Interferometry MissionSuperWASPTerrestrial Planet FinderTransiting Exoplanet Survey SatelliteTrans­Atlantic Exoplanet Survey

Notes

A. Aperture of 0.95 m yields a light­gathering area of Pi×(0.95/2)2 = 0.708 m2; the 42 CCDs each sized 0.050 m ×0.025m yields a total sensor area of 0.0525 m2:[4]

B. This does not include Kepler candidates without a KOI designation, such as circumbinary planets, or candidatesfound in the Planet Hunters project.

C. This probability only has two significant figures. Thus, it is stated as 1 in 210, not 1 in 212.77

References1. "Kepler: NASA's First Mission Capable of Finding Earth­Size Planets" (PDF). NASA. February 2009. Retrieved

March 13, 2015.2. "KASC Scientific Webpage". Kepler Asteroseismic Science Consortium. Aarhus University. March 14, 2009.

Retrieved March 14, 2009.3. "Kepler (spacecraft)". JPL Horizons On­Line Ephemeris System. NASA/JPL. March 13, 2015. Retrieved

March 13, 2015.4. "Kepler Spacecraft and Instrument". NASA. June 26, 2013. Archived from the original on January 18, 2014.

Retrieved January 18, 2014.5. Koch, David; Gould, Alan (March 2009). "Kepler Mission". NASA. Retrieved March 14, 2009.6. DeVore, Edna (June 9, 2008). "Closing in on Extrasolar Earths". Space.com. Retrieved March 14, 2009.7. NASA Staff. "Kepler Launch". NASA. Retrieved September 18, 2009.8. NASA Staff. "Kepler Mission/QuickGuide". NASA. Retrieved April 20, 2011.9. Overbye, Dennis (May 12, 2013). "Finder of New Worlds". The New York Times. Retrieved May 13, 2014.10. Overbye, Dennis (January 6, 2015). "As Ranks of Goldilocks Planets Grow, Astronomers Consider What’s

Next". The New York Times. Retrieved January 6, 2015.

10/29/2015 Kepler (spacecraft) ­ Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Kepler_(spacecraft) 24/32

11. AAS Staff. "Meeting Program and Block Schedule". American Astronomical Society. Retrieved April 20, 2011. –click the itinerary builder to get to the abstract of "Kepler Planet Detection Mission: Introduction and FirstResults".

12. BBC Staff (March 7, 2009). "Nasa launches Earth hunter probe". BBC News. Retrieved March 14, 2009.13. "NASA Extends Planet­Hunting Kepler Mission Through 2016" (http://www.space.com/15160­alien­planet­

kepler­mission­2016.html). Space.com. April 4, 2012. Retrieved May 2, 2012.14. Stephen Clark (October 16, 2012). "Kepler's exoplanet survey jeopardized by two issues". Spaceflight Now.

Retrieved October 17, 2012.15. NASA ­ Kepler Mission Manager Update (May 21, 2013)

(http://www.nasa.gov/mission_pages/kepler/news/keplerm­20130521.html)16. "Equipment Failure May Cut Kepler Mission Short". The New York Times. May 15, 2013. Retrieved May 15,

2013.17. "NASA Ends Attempts to Fully Recover Kepler Spacecraft, Potential New Missions Considered". August 15,

2013. Retrieved August 15, 2013.18. Overbye, Dennis (August 15, 2013). "NASA’s Kepler Mended, but May Never Fully Recover". The New York

Times. Retrieved August 15, 2013.19. Wall, Mike (August 15, 2013). "Planet­Hunting Days of NASA's Kepler Spacecraft Likely Over". Space.com.

Retrieved August 15, 2013.20. "Kepler: NASA retires prolific telescope from planet­hunting duties". BBC News. August 16, 2013.21. Overbye, Dennis (November 18, 2013). "New Plan for a Disabled Kepler". The New York Times. Retrieved

November 18, 2013.22. Johnson, Michele (November 25, 2013). Johnson, Michele, ed. "A Sunny Outlook for NASA Kepler's Second

Light". NASA Official: Brian Dunbar; Image credits: NASA Ames; NASA Ames/W Stenzel. NASA. Archivedfrom the original on April 17, 2014. Retrieved December 12, 2013.

23. Johnson, Michele (December 11, 2013). Johnson, Michele, ed. "Kepler's Second Light: How K2 Will Work".NASA Official: Brian Dunbar; Image credit: NASA Ames/W Stenzel. NASA. Archived from the original onApril 17, 2014. Retrieved December 12, 2013.

24. Hunter, Roger (December 11, 2013). Johnson, Michele, ed. "Kepler Mission Manager Update: Invited to 2014Senior Review". NASA Official: Brian Dunbar;. NASA. Archived from the original on April 17, 2014. RetrievedDecember 12, 2013.

25. Sobeck, Charlie (May 16, 2014). Johnson, Michele, ed. "Kepler Mission Manager Update: K2 Has BeenApproved!". NASA Official: Brian Dunbar; Image credit(s): NASA Ames/W. Stenzel. NASA. Archived from theoriginal on May 17, 2014. Retrieved May 17, 2014.

26. Wall, Mike (June 14, 2013). "Ailing NASA Telescope Spots 503 New Alien Planet Candidates". Space.com.TechMediaNetwork. Retrieved June 15, 2013.

27. "NASA's Exoplanet Archive KOI table". NASA. Retrieved February 28, 2014.28. Crossfield, Ian J. M.; Petigura, Erik; Schlieder, Joshua; Howard, Andrew W.; Fulton, B. J.; Aller, Kimberly M.;

Ciardi, David R.; Lepine, Sebastien; Barclay, Thomas; de Pater, Imke; de Kleer, Katherine; Quintana, Elisa V.;Christiansen, Jessie L.; Schlafly, Eddie; Kaltenegger, Lisa; Crepp, Justin R.; Henning, Thomas; Obermeier,Christian; Deacon, Niall; Hansen, Brad M. S.; Liu, Michael C.; Greene, Tom; Howell, Steve B.; Barman, Travis;Mordasini, Christoph (January 2015). "A nearby M star with three transiting super­Earths discovered by K2".arXiv:1501.03798 [astro­ph].

29. Overbye, Dennis (November 4, 2013). "Far­Off Planets Like the Earth Dot the Galaxy". The New York Times.Retrieved November 5, 2013.

30. Petigura, Erik A.; Howard, Andrew W.; Marcy, Geoffrey W. (October 31, 2013). "Prevalence of Earth­sizeplanets orbiting Sun­like stars". Proceedings of the National Academy of Sciences of the United States ofAmerica. arXiv:1311.6806. Bibcode:2013PNAS..11019273P. doi:10.1073/pnas.1319909110. RetrievedNovember 5, 2013.

31. Staff (January 7, 2013). "17 Billion Earth­Size Alien Planets Inhabit Milky Way". Space.com. RetrievedJanuary 8, 2013.

32. Khan, Amina (November 4, 2013). "Milky Way may host billions of Earth­size planets". Los Angeles Times.Retrieved November 5, 2013.

10/29/2015 Kepler (spacecraft) ­ Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Kepler_(spacecraft) 25/32

33. Clavin, Whitney; Chou, Felicia; Johnson, Michele (January 6, 2015). "NASA's Kepler Marks 1,000th ExoplanetDiscovery, Uncovers More Small Worlds in Habitable Zones". NASA. Retrieved January 6, 2015.

34. Atkins, William (December 28, 2008). "Exoplanet Search Begins with French Launch of Corot TelescopeSatellite". iTWire. Retrieved May 6, 2009.

35. NASA Staff. "Kepler: Spacecraft and Instrument". NASA. Retrieved May 1, 2009.36. NASA Staff (April 16, 2009). "Kepler's Diamond Mine of Stars". NASA. Retrieved May 1, 2009.37. NASA Staff (February 2009). "Kepler: NASA's First Mission Capable of Finding Earth­Size Planets" (PDF).

NASA. Retrieved March 14, 2009.38. "PyKE Primer ­ 2. Data Resources". NASA. Retrieved March 12, 2014.39. "Kepler Primary Mirror". NASA. Retrieved April 5, 2013.40. "Corning To Build Primary Mirror For Kepler Photometer". Retrieved April 5, 2013.41. Fulton L., Michael; Dummer, Richard S. (2011). "Advanced Large Area Deposition Technology for

Astronomical and Space Applications". Vacuum & Coating Technology (December 2011): 43–47. RetrievedApril 6, 2013.

42. "Ball Aerospace Completes Primary Mirror and Detector Array Assembly Milestones for Kepler Mission".SpaceRef.com (Press release). Ball Aerospace and Technologies. September 25, 2007. Retrieved April 6, 2013.

43. Gilliland, Ronald L.; et al. (2011). "Kepler Mission Stellar and Instrument Noise Properties". arXiv:1107.5207[astro­ph.SR].

44. Caldwell, Douglas A.; van Cleve, Jeffrey E.; Jenkins, Jon M.; Argabright, Vic S.; Kolodziejczak, Jeffery J.;Dunham, Edward W.; Geary, John C.; Tenenbaum, Peter; Chandrasekaran, Hema; Li, Jie; Wu, Hayley; vonWilpert, Jason (2010). Oschmann, Jr, Jacobus M; Clampin, Mark C; MacEwen, Howard A, eds. "KeplerInstrument Performance: An In­Flight Update" (PDF). Proceedings of SPIE. Space Telescopes andInstrumentation 2010: Optical, Infrared, and Millimeter Wave (International Society for Optics and Photonics)7731: 30. Bibcode:2010SPIE.7731E..30C. doi:10.1117/12.856638.

45. Kelly Beatty (September 2011). "Kepler's Dilemma: Not Enough Time". Sky and Telescope.46. News (April 4, 2012). "NASA Approves Kepler Mission Extension". kepler.nasa.gov.47. NASA Staff (March 6, 2009). "Kepler Mission Rockets to Space in Search of Other Earth" (Press release).

NASA. Retrieved March 14, 2009.48. Koch, David; Gould, Alan (March 2009). "Kepler Mission: Launch Vehicle and Orbit". NASA. Archived from

the original on June 22, 2007. Retrieved March 14, 2009.49. "Kepler: Spacecraft and Instrument". NASA. Retrieved December 21, 2011.50. Ng, Jansen (March 8, 2009). "Kepler Mission Sets Out to Find Planets Using CCD Cameras". DailyTech.

Retrieved March 14, 2009.51. Borucki, W. J. (May 22, 2010). "Brief History of the Kepler Mission". NASA. Retrieved April 23, 2011.52. DeVore, Edna (April 9, 2009). "Planet­Hunting Kepler Telescope Lifts Its Lid". Space.com. Retrieved April 14,

2009.53. NASA Staff (April 16, 2009). "NASA's Kepler Captures First Views of Planet­Hunting Territory". NASA.

Retrieved April 16, 2009.54. NASA Staff (April 20, 2009). "04.20.09 – Kepler Mission Manager Update". NASA. Retrieved April 20, 2009.55. NASA Staff (April 23, 2009). "04.23.09 – Kepler Mission Manager Update". NASA. Retrieved April 27, 2009.56. NASA Staff (May 14, 2009). "05.14.09 – Kepler Mission Manager Update". NASA. Retrieved May 16, 2009.57. NASA Staff (May 13, 2009). "Let the Planet Hunt Begin". NASA. Retrieved May 13, 2009.58. NASA Staff (July 7, 2009). "2009 July 7 Mission Manager Update". NASA. Retrieved April 23, 2011.59. NASA Staff (October 14, 2009). "Kepler Mission Manager Update". NASA. Retrieved October 18, 2009.60. NASA Staff (August 23, 2010). "Kepler outlook positive; Followup Observing Program in full swing". Retrieved

April 23, 2011.61. NASA Staff (September 23, 2009). "Kepler Mission Manager Update". NASA. Retrieved September 25, 2009.62. NASA Staff (November 5, 2009). "Kepler Mission Manager Update". NASA. Retrieved November 8, 2009.63. NASA Staff (December 6, 2010). "Data Download; Data Release; 2010 ground­based observing complete; AAS

meeting". Retrieved December 21, 2010.64. Roger Hunter (July 24, 2012). "Kepler Mission Manager Update". NASA.65. Maggie McKee (July 24, 2012). "Kepler glitch may lower odds of finding Earth's twin". New Scientist.66. Hunter, Roger (January 17, 2013). "Kepler Mission Manager Update". NASA. Retrieved January 18, 2013.

10/29/2015 Kepler (spacecraft) ­ Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Kepler_(spacecraft) 26/32

67. Marchis, Franck (January 17, 2013). "Kepler is Sick and Resting: 'Mountain View, we have a problem' ". CosmicDiary. Retrieved January 18, 2013.

68. Hunter, Roger (January 29, 2013). "Kepler Mission Manager Update: Kepler Returns to Science Mode". NASA.Retrieved January 30, 2013.

69. Roger Hunter. "Kepler Mission Manager Update, 29.03.2013". NASA.70. "Kepler Mission Manager Update". NASA. May 15, 2013. Retrieved June 14, 2013.71. "Kepler Mission Manager Update". NASA. May 21, 2013. Retrieved June 14, 2013.72. NASA ­ Kepler Mission Manager Update: Preparing for Recovery (http://www.nasa.gov/content/kepler­mission­

manager­update­preparing­for­recovery/)73. Ball Aerospace & Technologies. "Kepler mission & program information". Ball Aerospace & Technologies.

Retrieved September 18, 2012.74. Koch, David; Gould, Alan (2004). "Overview of the Kepler Mission" (PDF). SPIE. Retrieved December 9, 2010.75. Muir, Hazel (April 25, 2007). " 'Goldilocks' planet may be just right for life". New Scientist. Retrieved April 2,

2009.76. "Kepler Mission: Characteristics of Transits (section "Geometric Probability")". Curators: David Koch, Alan

Gould. NASA. March 2009. Archived from the original on August 25, 2009. Retrieved September 21, 2009.77. Batalha, N. M.; Borucki, W. J.; Koch, D. G.; Bryson, S. T.; Haas, M. R.; et al. (January 3, 2010). "Selection,

Prioritization, and Characteristics of Kepler Target Stars". arXiv:1001.0349 [astro­ph.SR].78. "Kepler Mission: Frequently Asked Questions". Curators: David Koch, Alan Gould. NASA. March 2009.

Archived from the original on August 20, 2007. Retrieved March 14, 2009.79. Grigahcène, A.; et al. (2010). "Hybrid γ Doradus – δ Scuti pulsators: New insights into the physics of the

oscillations from Kepler observations". arXiv:1001.0747 [astro­ph.SR].80. Chaplin, W. J.; et al. (2010). "The asteroseismic potential of Kepler: first results for solar­type stars".

arXiv:1001.0506 [astro­ph.SR].81. http://exoplanetarchive.ipac.caltech.edu/docs/PurposeOfKOITable.html82. Haas, Michael (May 31, 2013). "New NASA Kepler Mission Data" (Interview). NASA Official: Brian Dunbar;

Image credit: NASA Ames/W. Stenzel. NASA. Archived from the original on April 20, 2014. Retrieved April 20,2014.

83. Batalha, Natalie M.; et al. (2010). "Pre­Spectroscopic False Positive Elimination of Kepler Planet Candidates".arXiv:1001.0392 [astro­ph.EP].

84. Monet, David G.; et al. (2010). "Preliminary Astrometric Results from Kepler". arXiv:1001.0305 [astro­ph.IM].85. Johnson, Michele (July 23, 2015). "Kepler Planet Candidates, July 2015". NASA. Retrieved July 24, 2015.86. The Transit Timing Variation (TTV) Planet­finding Technique Begins to Flower

(http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=226)87. Nascimbeni, V.; Piotto, G.; Bedin, L. R.; Damasso, M. (September 29, 2010). "TASTE: The Asiago Survey for

Timing transit variations of Exoplanets". arXiv:1009.5905 [astro­ph.EP].88. Doyle, Laurance R.; Carter, Joshua A.; Fabrycky, Daniel C.; Slawson, Robert W.; Howell, Steve B.; et al.

(September 2011). "Kepler­16: A Transiting Circumbinary Planet". Science 333 (6049): 1602. arXiv:1109.3432.Bibcode:2011Sci...333.1602D. doi:10.1126/science.1210923.

89. Jenkins, J.M.; Laurance R. Doyle (September 20, 2003). "Detecting reflected light from close­in giant planetsusing space­based photometers" (PDF). Astrophysical Journal 1 (595): 429–445. arXiv:astro­ph/0305473.Bibcode:2003ApJ...595..429J. doi:10.1086/377165.

90. Rowe, Jason F.; Bryson, Stephen T.; Marcy, Geoffrey W.; Lissauer, Jack J.; Jontof­Hutter, Daniel; et al.(February 26, 2014). "Validation of Kepler's Multiple Planet Candidates. III: Light Curve Analysis &Announcement of Hundreds of New Multi­planet Systems". arXiv:1402.6534 [astro­ph.EP].

91. Angerhausen, Daniel; DeLarme, Emily; Morse, Jon A. (April 16, 2014). "A comprehensive study of Keplerphase curves and secondary eclipses ­­ temperatures and albedos of confirmed Kepler giant planets".arXiv:1404.4348 [astro­ph.SR].

92. "Kepler 22­b: Earth­like planet confirmed". BBC Online. December 5, 2011. Retrieved December 6, 2011.93. Johnson, Michele; Harrington, J.D. (February 26, 2014). "NASA's Kepler Mission Announces a Planet Bonanza,

715 New Worlds". NASA. Retrieved February 26, 2014.

10/29/2015 Kepler (spacecraft) ­ Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Kepler_(spacecraft) 27/32

94. Lissauer, Jack J.; Marcy, Geoffrey W.; Bryson, Stephen T.; Rowe, Jason F.; Jontof­Hutter, Daniel; Agol, Eric;Borucki, William J.; Carter, Joshua A.; Ford, Eric B.; Gilliland, Ronald L.; Kolbl, Rea; Star, Kimberly M.;Steffen, Jason H.; Torres, Guillermo (February 25, 2014). "Validation of Kepler's Multiple Planet Candidates. II:Refined Statistical Framework and Descriptions of Systems of Special Interest". arXiv:1402.6352 [astro­ph.EP].

95. Díaz, Rodrigo F.; Almenara, José M.; Santerne, Alexandre; Moutou, Claire; Lethuillier, Anthony; Deleuil,Magali (March 26, 2014). "PASTIS: Bayesian Extrasolar Planet Validation. I. General Framework, Models, andPerformance". arXiv:1403.6725 [astro­ph.EP].

96. Santerne, A.; Hébrard, G.; Deleuil, M.; Havel, M.; Correia, A. C. M.; et al. (June 24, 2014). "SOPHIEVelocimetry of Kepler Transit Candidates: XII. KOI­1257 b: A Highly­Eccentric 3­Month Period TransitingExoplanet". arXiv:1406.6172 [astro­ph.EP].

97. NASA Staff (August 3, 2009). "NASA Announces Briefing About Kepler's Early Science Results". NASA.Retrieved April 23, 2011.

98. NASA Staff (August 6, 2009). "NASA's Kepler Spies Changing Phases on a Distant World". NASA. RetrievedAugust 6, 2009.

99. Borucki, W. J.; Koch, D.; Jenkins, J.; Sasselov, D.; Gilliland, R.; Batalha, N.; Latham, D. W.; Caldwell, D.;Basri, G.; Brown, T.; Christensen­Dalsgaard, J.; Cochran, W. D.; Devore, E.; Dunham, E.; Dupree, A. K.;Gautier, T.; Geary, J.; Gould, A.; Howell, S.; Kjeldsen, H.; Lissauer, J.; Marcy, G.; Meibom, S.; Morrison, D.;Tarter, J. (August 7, 2009). "Kepler’s Optical Phase Curve of the Exoplanet HAT­P­7b". Science (Washington,DC: AAAS) 325 (5941): 709. Bibcode:2009Sci...325..709B. doi:10.1126/science.1178312. ISSN 1095­9203.OCLC 1644869. PMID 19661420. Retrieved March 23, 2014. (registration required (help)).

100. NASA Staff (November 4, 2009). "Kepler dropped stars now public". NASA. Retrieved April 23, 2011.101. ScienceNews Staff (January 30, 2010). "Kepler space telescope finds its first extrasolar planets".

Sciencenews.org. Retrieved February 5, 2011.102. MacRobert, Robert (January 4, 2010). "Kepler's First Exoplanet Results – News Blog". Sky & Telescope.

Retrieved April 21, 2011.103. Gilster, Paul (February 2, 2011). "The Remarkable Kepler­11". Tau Zero Foundation. Retrieved April 21, 2011.104. van Kerkwijk, Marten H.; Rappaport, Saul A.; Breton, René P.; Justham, Stephen; Podsiadlowski, Philipp; Han,

Zhanwen (May 20, 2010). "Observations of Doppler Boosting in Kepler Light Curves". The AstrophysicalJournal (IOP Publishing) 715 (1): 51–58. arXiv:1001.4539. Bibcode:2010ApJ...715...51V. doi:10.1088/0004­637X/715/1/51. ISSN 0004­637X.

105. Villard, Ray. "Blazing Stellar Companion Defies Explanation". Discovery.com. Retrieved April 20, 2011.106. Borucki, William J.; et al. (Kepler Team) (2010). "Characteristics of Kepler Planetary Candidates Based on the

First Data Set: The Majority are Found to be Neptune­Size and Smaller". arXiv:1006.2799 [astro­ph.EP].107. Woolfson, M. M. (1993). "The Solar System: Its Origin and Evolution". Journal of the Royal Astronomical

Society 34: 1–20. Bibcode:1993QJRAS..34....1W. Page 18 in particular states that models that required a nearcollision of stars imply about 1% will have planets.

108. Ward, W.R. (1997). "Protoplanet Migration by Nebula Tides" (PDF). Icarus (Elsevier) 126 (2,): 261–281.Bibcode:1997Icar..126..261W. doi:10.1006/icar.1996.5647. Retrieved April 23, 2011.

109. Sasselov, Dimitar (July 2010). "How we found hundreds of Earth­like planets". Ted.com. Retrieved February 5,2011.

110. Dunham, Edward W.; Gautier, Thomas N.; Borucki, William J. (August 3, 2010). "NASA Kepler Science Status:Statement to Ames Center Director". Retrieved April 24, 2011.

111. Steffen, Jason H.; et al. (November 9, 2010). "Five Kepler target stars that show multiple transiting exoplanetcandidates". Astrophysical Journal (IOP Publishing) 725: 1226–1241. arXiv:1006.2763.Bibcode:2010ApJ...725.1226S. doi:10.1088/0004­637X/725/1/1226. ISSN 0004­637X.

112. Prsa, Andrej; Batalha, Natalie M.; Slawson, Robert W.; Doyle, Laurance R.; Welsh, William F.; et al. (January21, 2011). "Kepler Eclipsing Binary Stars. I. Catalog and Principal Characterization of 1879 Eclipsing Binariesin the First Data Release". arXiv:1006.2815 [astro­ph.SR].

10/29/2015 Kepler (spacecraft) ­ Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Kepler_(spacecraft) 28/32

113. Rowe, Jason F.; Borucki, William J.; Koch, David; Howell, Steve B.; Basri, Gibor; Batalha, Natalie; Brown,Timothy M.; Caldwell, Douglas; Cochran, William D.; Dunham, Edward; Dupree, Andrea K.; Fortney, JonathanJ.; Gautier III, Thomas N.; Gilliland, Ronald L.; Jenkins, Jon; Latham, David W.; Lissauer, Jack . J.; Marcy,Geoff; Monet, David G.; Sasselov, Dimitar; Welsh, William F. (2010). "Kepler Observations of Transiting HotCompact Objects". The Astrophysical Journal Letters 713 (2): L150–L154. arXiv:1001.3420.Bibcode:2010ApJ...713L.150R. doi:10.1088/2041­8205/713/2/L150.

114. NASA Staff (May 15, 2010). "Kepler News: First 43 Days of Kepler Data Released". NASA. Retrieved April 24,2011.

115. Borucki, William J.; et al. (2011). "Characteristics of planetary candidates observed by Kepler, II: Analysis ofthe first four months of data". arXiv:1102.0541 [astro­ph.EP].

116. NASA Staff (December 20, 2011). "Kepler: A Search For Habitable Planets – Kepler­20e". NASA. RetrievedDecember 23, 2011.

117. NASA Staff (December 20, 2011). "Kepler: A Search For Habitable Planets – Kepler­20f". NASA. RetrievedDecember 23, 2011.

118. Morton, Timothy D.; Johnson, John Asher (2011). "On the Low False Positive Probabilities of Kepler PlanetCandidates". arXiv:1101.5630 [astro­ph.EP].

119. NASA Staff (February 2, 2011). "NASA Finds Earth­size Planet Candidates in Habitable Zone, Six PlanetSystem". NASA. Retrieved April 24, 2011.

120. Overbye, Dennis (February 2, 2011). "Kepler Planet Hunter Finds 1,200 Possibilities". New York Times.Retrieved April 24, 2011.

121. Borenstein, Seth (February 2, 2011). "NASA spots scores of potentially livable worlds". MSNBC News.Retrieved April 24, 2011.

122. Alexander, Amir (February 3, 2011). "Kepler Discoveries Suggest a Galaxy Rich in Life". The Planetary Society.Retrieved February 4, 2011.

123. Grant, Andrew (March 8, 2011). "Exclusive: "Most Earth­Like" Exoplanet Gets Major Demotion—It Isn'tHabitable". Discover Magazine. Retrieved April 24, 2011.

124. Borucki, William J.; et al. (2011). "Characteristics of planetary candidates observed by Kepler, II: Analysis ofthe first four months of data". The Astrophysical Journal (IOP Publishing) 736: 19. arXiv:1102.0541.Bibcode:2011ApJ...736...19B. doi:10.1088/0004­637X/736/1/19. ISSN 0004­637X.

125. "Kepler­22b, Super­Earth in the habitable zone of a Sun­like Star". NASA. December 5, 2011.126. Johnson, Michele (December 20, 2011). "NASA Discovers First Earth­size Planets Beyond Our Solar System".

NASA. Retrieved December 20, 2011.127. Shostak, Seth (February 3, 2011). "A Bucketful of Worlds". Huffington Post. Retrieved April 24, 2011.128. Borenstein, Seth (February 19, 2011). "Cosmic census finds crowd of planets in our galaxy". Associated Press.

Retrieved April 24, 2011.129. Choi, Charles Q. (March 21, 2011). "New Estimate for Alien Earths: 2 Billion in Our Galaxy Alone".

Space.com. Retrieved April 24, 2011.130. Wall, Mike (January 11, 2012). "160 Billion Alien Planets May Exist in Our Milky WayGalaxy". Space.com.

Retrieved January 11, 2012.131. Cassan, A. (January 11, 2012). "One or more bound planets per Milky Way star from microlensing

observations". Nature 481 (7380): 167–169. arXiv:1202.0903. Bibcode:2012Natur.481..167C.doi:10.1038/nature10684. PMID 22237108. Retrieved January 11, 2012.

132. "Kepler telescope studies star superflares". BBC News. May 17, 2012. Retrieved May 31, 2012.133. The Transit Timing Variation (TTV) Planet­finding Technique Begins to Flower

(http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=226). NASA.gov.134. Planet Hunters Find Circumbinary Planet in 4­Star System – 10.16.2012

(http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=233).135. Govert Schilling (September 12, 2011). " 'Super­Earth' Found in Habitable Zone". AAAS.136. "Released Kepler Planetary Candidates". MAST. February 27, 2012. Retrieved November 26, 2012.137. Hand, Eric (December 20, 2011). "Kepler discovers first Earth­sized exoplanets". Nature.

doi:10.1038/nature.2011.9688.138. Overbye, Dennis (December 20, 2011). "Two Earth­Size Planets Are Discovered". New York Times. Retrieved

December 21, 2011.

10/29/2015 Kepler (spacecraft) ­ Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Kepler_(spacecraft) 29/32

139. Claven, Whitney (January 3, 2013). "Billions and Billions of Planets". NASA. Retrieved January 3, 2013.140. Staff (January 2, 2013). "100 Billion Alien Planets Fill Our Milky Way Galaxy: Study". Space.com. Retrieved

January 3, 2013.141. NASA's Kepler Mission Discovers 461 New Planet Candidates

(http://www.nasa.gov/mission_pages/kepler/news/kepler­461­new­candidates.html)142. Moskowitz, Clara (January 9, 2013). "Most Earth­Like Alien Planet Possibly Found". Space.com. Retrieved

January 9, 2013.143. "Gravity­Bending Find Leads to Kepler Meeting Einstein". NASA. April 4, 2013. Retrieved April 6, 2013.144. Johnson, Michele; Harrington, J.D. (April 18, 2013). "NASA's Kepler Discovers Its Smallest 'Habitable Zone'

Planets to Date". NASA. Retrieved April 18, 2013.145. Overbye, Dennis (April 18, 2013). "2 Good Places to Live, 1,200 Light­Years Away". The New York Times.

Retrieved April 18, 2013.146. "NASA's Kepler Discovers Its Smallest 'Habitable Zone' Planets to Date". YouTube. April 18, 2013. Retrieved

April 19, 2013.147. Kane, Stephen R.; Barclay, Thomas; Gelino, Dawn M. (2013). "A Potential Super­Venus in the Kepler­69

System". The Astrophysical Journal Letters (IOP Publishing) 770 (2): L20. arXiv:1305.2933.Bibcode:2013ApJ...770L..20K. doi:10.1088/2041­8205/770/2/L20. ISSN 2041­8205.

148. "Kepler Mission Manager Update: Pointing Test Results". NASA. August 19, 2013. Retrieved September 9,2013.

149. "Kepler broken ­ mission may be over". 3 News NZ. May 20, 2013.150. http://nexsci.caltech.edu/conferences/KeplerII/agenda.shtml151. "Welcome to the NASA Exoplanet Archive". California Institute of Technology. February 27, 2014. Archived

from the original on February 27, 2014. Retrieved February 27, 2014. "February 13, 2014: The Kepler project hasupdated dispositions for 534 KOIs in the Q1­Q16 KOI activity table. This brings the total number of Keplercandidates and confirmed planets to 3,841. For more information, see the Purpose of KOI Table document andthe interactive tables."

152. Wall, Mike (February 26, 2014). "Population of Known Alien Planets Nearly Doubles as NASA Discovers 715New Worlds". Space.com. Retrieved February 26, 2014.

153. Amos, Jonathan (February 26, 2014). "Kepler telescope bags huge haul of planets". BBC News. RetrievedFebruary 27, 2014.

154. Overbye, Dennis (February 27, 2014). "From Kepler Data, Astronomers Find Galaxy Filled With More butSmaller Worlds". The New York Times. Retrieved February 28, 2014.

155. Sanchis­Ojeda, Roberto; Rappaport, Saul; Winn, Joshua N.; Kotson, Michael C.; Levine, Alan M.; El Mellah,Ileyk (March 10, 2014). "A Study of the Shortest­Period Planets Found With Kepler". arXiv:1403.2379 [astro­ph.EP].

156. Cowen, Ron (January 16, 2014). "Kepler clue to supernova puzzle". Journal (Nature Publishing Group) 505(7483): 274–275. Bibcode:2014Natur.505..274C. doi:10.1038/505274a. ISSN 1476­4687. OCLC 01586310.Archived from the original on February 28, 2014. Retrieved February 28, 2014.

157. Culler, Jessica (April 17, 2014). Jessica Culler, ed. "NASA's Kepler Discovers First Earth­Size Planet In The'Habitable Zone' of Another Star". NASA Official: Brian Dunbar; Image credit(s): 2xNASA Ames/SETIInstitute/JPL­Caltech; NASA Ames. NASA. Archived from the original on April 26, 2014. Retrieved April 26,2014.

158. Barclay, Thomas; Dotson, Jessie (May 29, 2014). "K2 Campaign Fields ­ 0 to 13". NASA. Retrieved April 4,2015.

159. Barclay, Thomas; Dotson, Jessie (May 29, 2014). "K2 Campaign 0 (March 8, 2014 ­ May 30, 2014)". NASA.Retrieved April 4, 2015.

160. http://arxiv.org/abs/1407.3780161. Barclay, Thomas; Dotson, Jessie (May 29, 2014). "K2 Campaign 1 (May 30, 2014 ­ August 21, 2014)". NASA.

Retrieved April 4, 2015.162. Barclay, Thomas; Dotson, Jessie (May 29, 2014). "K2 Campaign 2 (August 22, 2014 ­ November 11, 2014)".

NASA. Retrieved April 4, 2015.163. Sobeck, Charlie (September 23, 2014). "Mission Manager Update: C1 data on the ground; C2 underway". NASA.

Retrieved September 23, 2014.

10/29/2015 Kepler (spacecraft) ­ Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Kepler_(spacecraft) 30/32

164. Johnson, Michele; Chandler, Lynn (May 20, 2015). "NASA Spacecraft Capture Rare, Early Moments of BabySupernovae". NASA. Retrieved May 21, 2015.

165. Barclay, Thomas; Dotson, Jessie (May 29, 2014). "K2 Campaign 3 (November 14, 2014 ­ February 6, 2014)".NASA. Retrieved April 4, 2015.

166. Campante, T. L.; Barclay, T.; Swift, J. J.; Huber, D.; Adibekyan, V. Zh.; et al. (February 2015). "An AncientExtrasolar System with Five Sub­Earth­size Planets". The Astrophysical Journal 799 (2). article 170.arXiv:1501.06227. Bibcode:2015ApJ...799..170C. doi:10.1088/0004­637X/799/2/170.

167. Dunn, Marcia (January 27, 2015). "Astronomers find solar system more than double ours in age". Excite.com.Associated Press. Retrieved January 27, 2015.

168. Atkinson, Nancy (January 27, 2015). "Oldest Planetary System Discovered, Improving the Chances forIntelligent Life Everywhere". Universe Today. Retrieved January 27, 2015.

169. Barclay, Thomas; Dotson, Jessie (May 29, 2014). "K2 Campaign 4 (February 7, 2015 ­ April 24, 2015)". NASA.Retrieved April 4, 2015.

170. Sobeck, Charlie; Johnson, Michele; Dunbar, Brian (April 2, 2015). "Mission Manager Update: K2 in Campaign4". NASA. Retrieved April 4, 2015.

171. Chou, Felicia; Johnson, Michele (July 23, 2015). "NASA's Kepler Mission Discovers Bigger, Older Cousin toEarth" (Press release). NASA. Retrieved July 23, 2015.

172. Jenkins, Jon M.; Twicken, Joseph D.; Batalha, Natalie M.; Caldwell, Douglas A.; Cochran, William D.; et al.(July 2015). "Discovery and Validation of Kepler­452b: A 1.6 R⨁ Super Earth Exoplanet in the Habitable Zoneof a G2 Star". The Astronomical Journal 150 (2): 56. doi:10.1088/0004­6256/150/2/56.

173. Overbye, Dennis (July 23, 2015). "NASA Says Data Reveals an Earth­Like Planet, Kepler 452b". The New YorkTimes. Retrieved July 24, 2015.

174. Johnson, Michele (July 23, 2015). "Kepler Planet Candidates, July 2015". NASA. Retrieved July 24, 2015.175. Kaplan, Sarah (October 15, 2015). "The strange star that has serious scientists talking about an alien

megastructure". The Washington Post (in en­US). ISSN 0190­8286. Retrieved October 15, 2015.176. Andersen, Ross (October 13, 2015). "The Most Mysterious Star in Our Galaxy". The Atlantic. Retrieved

October 13, 2015.177. Boyajian, T.S.; LaCourse, D.M.; Rappaport, S.A.; Fabrycky, D.; Fischer, D.A.; Gandolfi, D.; Kennedy, G.M.;

Liu, M.C.; Moor, A.; Olah, K.; Vida, K.; Wyatt, M.C.; Best, W.M.J.; Ciesla, F.; Csak, B.; Dupuy, T.J.;Handler, G.; Heng, K.; Korhonen, H.; Kovacs, J.; Kozakis, T.; Kriskovics, L.; Schmitt, J.R.; Szabo, Gy.; Szabo,R.; Wang, J.; Goodman, S.; Hoekstra, A.; Jek, K.J. (September 14, 2015). "Planet Hunters X. KIC 8462852­Where's the flux?" (PDF). MNRAS. Retrieved October 13, 2015. (Abstract (http://arxiv.org/abs/1509.03622v1))

178. Kepler Quick Guide (http://kepler.nasa.gov/Mission/QuickGuide/)179. Clark, stephen (April 4, 2012). "Kepler planet­hunting mission extended until 2016". Spaceflight Now. Retrieved

April 4, 2012.180. "Release : 12–394 – NASA's Kepler Completes Prime Mission, Begins Extended Mission". NASA. Retrieved

November 17, 2012.181. "Kepler Mission Manager Update: Initial Recovery Tests". NASA. July 24, 2013. Retrieved September 9, 2013.182. "Kepler Mission Manager Update: Pointing Test". NASA. August 2, 2013. Retrieved August 3, 2013.183. Ofir, Aviv (August 9, 2013). "KeSeF ­ Kepler Self Follow­up Mission". arXiv:1308.2252 [astro­ph.EP].184. "Kepler Mission Manager Update". NASA. June 7, 2013. Retrieved June 14, 2013.185. Wall, Mike (November 5, 2013). "NASA's Hobbled Planet­Hunting Spacecraft May Resume Search for Alien

Worlds". Space.com. Image credit: NASA. TechMediaNetwork. Archived from the original on April 17, 2014.Retrieved April 17, 2014.

186. Hunter, Roger (February 14, 2014). Johnson, Michele, ed. "Kepler Mission Manager Update: K2 spacecraftoperation tests continue". NASA Official: Brian Dunbar; Image Credit: NASA Ames/T. Barclay. NASA.Archived from the original on April 17, 2014. Retrieved April 17, 2014.

187. Bakos, G. Á.; Hartman, J. D.; Bhatti, W.; Bieryla, A.; de Val­Borro, M.; et al. (April 17, 2014). "HAT­P­54b: Ahot jupiter transiting a 0.64 Msun star in field 0 of the K2 mission". arXiv:1404.4417 [astro­ph.EP].

188. Still, Martin, ed. (May 29, 2014). "Kepler Guest Observer Program". NASA Official: Jessie Dotson. NASA.Archived from the original on June 12, 2014. Retrieved June 12, 2014.

189. Still, Martin, ed. (May 29, 2014). "K2 Performance". NASA Official: Jessie Dotson. NASA. Archived from theoriginal on June 12, 2014. Retrieved June 12, 2014.

10/29/2015 Kepler (spacecraft) ­ Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Kepler_(spacecraft) 31/32

190. Staff (August 8, 2014). "Kepler Mission Manager Update: K2 collecting data". NASA. Retrieved August 9, 2014.191. Molnár, L.; Plachy, E.; Szabó, R. (May 29, 2014). "Cepheids and RR Lyrae Stars in the K2 Fields".

arXiv:1405.7690 [astro­ph.SR].192. Mark J. Pecaut, Eric E. Mamajek, & Eric J. Bubar (February 2012). "A Revised Age for Upper Scorpius and the

Star Formation History among the F­type Members of the Scorpius­Centaurus OB Association". AstrophysicalJournal 746 (2): 154. arXiv:1112.1695. Bibcode:2012ApJ...746..154P. doi:10.1088/0004­637X/746/2/154.

193. de Zeeuw, P.T., Hoogerwerf, R., de Bruijne, J.H.J., Brown, A.G.A., & Blaauw, A. (1999). "A HipparcosCensus of Nearby OB Associations". Astronomical Journal 117 (1): 354–399. arXiv:astro­ph/9809227.Bibcode:1999AJ....117..354D. doi:10.1086/300682.

194. Mamajek, E.E., Meyer, M.R., & Liebert, J. (2002). "Post­T Tauri Stars in the Nearest OB Association".Astronomical Journal 124 (3): 1670–1694. arXiv:astro­ph/0205417. Bibcode:2002AJ....124.1670M.doi:10.1086/341952.

195. Chou, Felicia; Johnson, Michele (December 18, 2014). "NASA's Kepler Reborn, Makes First Exoplanet Find ofNew Mission". NASA. Release 14­335. Retrieved December 19, 2014.

196. "Frequently Asked Questions from the Public". Retrieved September 6, 2011. This Kepler FAQ states: "Data foreach 3­month observation period will be made public within one year of the end the observation period".

197. "NASA's Kepler Mission Data Release Schedule". NASA. Retrieved October 18, 2011. On this schedule, the datafrom the quarter ending June 2010 was scheduled to be released in June 2013.

198. Dennis Overbye (June 14, 2010). "In the Hunt for Planets, Who Owns the Data?". New York Times.199. Eric Hand (April 14, 2010). "Telescope team may be allowed to sit on exoplanet data". Nature.200. Alan MacRobert (August 2011). "Kepler's Exoplanets: A Progress Report". S ky and Telescope.201. Alex Brown (March 28–29, 2011). "Minutes of the Kepler Users Panel" (PDF).202. Nicole Gugliucci (June 15, 2010). "KEPLER EXOPLANET CONTROVERSY ERUPTS". Discovery news.203. "NASA's Kepler Mission Announces Next Data Release to Public Archive".204. "Kepler Data Collection and Archive Timeline". Retrieved January 1, 2012.205. Santerne, A.; Diaz, R. F.; Bouchy, F.; Deleuil, M.; Moutou, C.; Hebrard, G.; Eggenberger, A.; Ehrenreich, D.;

Gry, C.; Udry, S. (November 30, 2010). "SOPHIE velocimetry of Kepler transit candidates II. KOI­428b: a hotJupiter transiting a subgiant F­star" (PDF). Astronomy & Astrophysics 528. EDP Sciences. p. A63.arXiv:1101.0196v1. doi:10.1051/0004­6361/201015764. ISSN 0004­6361. Retrieved April 23, 2011.

206. Bouchy, F.; et al. (2011). "SOPHIE velocimetry of Kepler transit candidates III. KOI­423b: An 18 Mjuptransiting companion around an F7IV star". arXiv:1106.3225 [astro­ph.EP].

207. Andrews, Bill (December 20, 2010). "Become a Planet Hunter!". Astronomy. Retrieved April 24, 2011.208. Zooniverse Staff. "Planetometer". Zooniverse. Retrieved June 15, 2011.209. "Amateur stargazers discover new planet". The Daily Telegraph (Telegraph Media Group). January 20, 2012.

Retrieved January 20, 2012.210. "Stargazing viewer in planet coup". BBC News. January 18, 2012. Retrieved January 19, 2012.211. O'Neill, Ian (January 26, 2012). "11 New Alien Solar Systems Crammed with Exoplanets". Discovery News.

Retrieved January 26, 2012.212. cyril DEDIEU. "Star: KOI­196". Extrasolar Planets Encyclopaedia. Retrieved December 21, 2011.213. "Star: KOI­135". Extrasolar Planets Encyclopaedia. Retrieved 2011.214. "Star: KOI­204". Extrasolar Planets Encyclopaedia. Retrieved 2011.215. "Star: KOI­254". Extrasolar Planets Encyclopaedia. Retrieved 2011.216. "Star: KOI­730". Extrasolar Planets Encyclopaedia. Retrieved 2011.217. "Star: KOI­961". Extrasolar Planets Encyclopaedia. Retrieved 2012.218. Snellen, I.A.G.; De Mooij, E.J.W.; Albrecht, S. (2009). "The changing phases of extrasolar planet CoRoT­1b".

Nature 459 (7246): 543–545. arXiv:0904.1208. Bibcode:2009Natur.459..543S. doi:10.1038/nature08045.PMID 19478779.

219. Charpinet, S.; Fontaine, G.; Brassard, P.; Green, E. M.; vanGrootel, V.; Randall, S. K.; Silvotti, R.; Baran, A.S.; øStensen, R. H.; Kawaler, S. D.; Telting, J. H. (December 22, 2011). "A compact system of small planetsaround a former red­giant star". Nature (Nature Publishing Group) 480 (7378): 496–499.Bibcode:2011Natur.480..496C. doi:10.1038/nature10631. ISSN 1476­4687. OCLC 01586310. PMID 22193103.Archived from the original on March 23, 2014. Retrieved March 23, 2014.

220. NASA Staff. "MAST KIC Search Help". Space Telescope Science Institute. Retrieved April 23, 2011.

10/29/2015 Kepler (spacecraft) ­ Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Kepler_(spacecraft) 32/32

Wikimedia Commons hasmedia related to KeplerMission.

221. NASA Staff. "KIC10 Search". Retrieved April 23, 2011.

External links

Official website (http://kepler.nasa.gov) by NASA's AmesResearch CenterKepler website (http://www.nasa.gov/kepler) by NASAKepler (https://twitter.com/NASAKepler) on TwitterKepler Science Center (http://keplerscience.arc.nasa.gov/) by NASA's Ames Research CenterKepler public data archive (http://archive.stsci.edu/kepler/) by the Space Telescope Science InstituteStrömgren Survey for Asteroseismology and Galactic Archaeology(http://www.mso.anu.edu.au/saga/)

Exoplanet catalogs and databases

Extrasolar Planets Encyclopaedia (http://exoplanet.eu/) by the Paris ObservatoryThe Habitable Exoplanets Catalog (http://phl.upr.edu/projects/habitable­exoplanets­catalog) by UPRAreciboNew Worlds Atlas (http://planetquest.jpl.nasa.gov/newworldsatlas) by the NASA/JPL PlanetQuest

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Categories: Kepler (spacecraft) Space probes launched in 2009 Artificial satellites orbiting the SunDiscovery Program Exoplanet search projects NASA space probes Space observatoriesSpacecraft launched by Delta II rockets NASA programs

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