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62-447: The archive's data include published light curves, images, spectra and parameters, and time-series data from surveys that aim to discover transiting exoplanets. The archive also develops Web-based tools and services to work with the data, particularly the display and analysis of transit data sets from the Kepler mission and COnvection ROtation and planetary Transits (CoRoT) mission, for which

124-424: A random planetary orbit being along the line-of-sight to a star is the diameter of the star divided by the diameter of the orbit. For an Earth-size planet at 1  AU transiting a Sun-like star the probability is 0.47%, or about 1 in 210. For a planet like Venus orbiting a Sun-like star the probability is slightly higher, at 0.65%; If the host star has multiple planets, the probability of additional detections

186-462: A soft focus to provide excellent photometry , rather than sharp images. The mission goal was a combined differential photometric precision (CDPP) of 20 ppm for a m (V)=12 Sun-like star for a 6.5-hour integration, though the observations fell short of this objective (see mission status ). The focal plane of the spacecraft's camera is made out of forty-two 50 × 25 mm (2 × 1 in) CCDs at 2200×1024 pixels each, possessing

248-586: A candidate is a real planet. One of the methods, called doppler spectroscopy , requires follow-up observations from ground-based telescopes. This method works well if the planet is massive or is located around a relatively bright star. While current spectrographs are insufficient for confirming planetary candidates with small masses around relatively dim stars, this method can be used to discover additional massive non-transiting planet candidates around targeted stars. In multiplanetary systems, planets can often be confirmed through transit timing variation by looking at

310-412: A cost of about $ 20 million per year. NASA contacted the spacecraft using the X band communication link twice a week for command and status updates. Scientific data are downloaded once a month using the K a band link at a maximum data transfer rate of approximately 550  kB/s . The high gain antenna is not steerable so data collection is interrupted for a day to reorient the whole spacecraft and

372-416: A dielectric interference coating to minimize the formation of color centers and atmospheric moisture absorption. In terms of photometric performance, Kepler worked well, much better than any Earth-bound telescope, but short of design goals. The objective was a combined differential photometric precision (CDPP) of 20 parts per million (PPM) on a magnitude 12 star for a 6.5-hour integration. This estimate

434-485: A fixed field of view (FOV) against the sky. The diagram to the right shows the celestial coordinates and where the detector fields are located, along with the locations of a few bright stars with celestial north at the top left corner. The mission website has a calculator that will determine if a given object falls in the FOV, and if so, where it will appear in the photo detector output data stream. Data on exoplanet candidates

496-573: A further 3,199 unconfirmed planet candidates. Four planets have been confirmed through Kepler's K2 mission. In November 2013, astronomers estimated, based on Kepler space mission data, that there could be as many as 40 billion rocky Earth-size exoplanets orbiting in the habitable zones of Sun-like stars and red dwarfs within the Milky Way . It is estimated that 11 billion of these planets may be orbiting Sun-like stars. The nearest such planet may be 3.7 parsecs (12  ly ) away, according to

558-461: A large sample of stars to achieve several key goals: Most of the exoplanets previously detected by other projects were giant planets , mostly the size of Jupiter and bigger. Kepler was designed to look for planets 30 to 600 times less massive, closer to the order of Earth's mass (Jupiter is 318 times more massive than Earth). The method used, the transit method , involves observing repeated transit of planets in front of their stars, which causes

620-810: A mass (or minimum mass) equal to or less than 30 Jupiter masses. In addition to providing access to large public data sets, the Exoplanet Archive has developed several tools to work with exoplanet and stellar host data. The Exoplanet Archive serves photometric time-series data from surveys that aim to discover transiting exoplanets, such as the Kepler Mission and CoRoT. The database provides access to over 22 million light curves from space and ground-based exoplanet transit survey programs, including: The Exoplanet Archive offers search and filtering capabilities for exoplanet stellar and planetary properties, Kepler planetary candidates, and time series data sets. All data in

682-448: A mission lasting 7 to 8 years, as opposed to the originally planned 3.5 years, would be needed to find all transiting Earth-sized planets. On April 4, 2012, the Kepler mission was approved for extension through the fiscal year 2016, but this also depended on all remaining reaction wheels staying healthy, which turned out not to be the case (see Reaction wheel issues below). Kepler orbits

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744-650: A much higher probability of detecting Earth-sized planets than the Hubble Space Telescope , which has a field of view of only 10 sq. arc-minutes . Moreover, Kepler is dedicated to detecting planetary transits, while the Hubble Space Telescope is used to address a wide range of scientific questions, and rarely looks continuously at just one starfield. Of the approximately half-million stars in Kepler's field of view, around 150,000 stars were selected for observation. More than 90,000 are G-type stars on, or near,

806-623: A process called dispositioning. Those which pass the dispositioning are called Kepler planet candidates. The KOI archive is not static, meaning that a Kepler candidate could end up in the false-positive list upon further inspection. In turn, KOIs that were mistakenly classified as false positives could end up back in the candidates list. Not all the planet candidates go through this process. Circumbinary planets do not show strictly periodic transits, and have to be inspected through other methods. In addition, third-party researchers use different data-processing methods, or even search planet candidates from

868-463: A second one failed, disabling the collection of science data and threatening the continuation of the mission. On August 15, 2013, NASA announced that they had given up trying to fix the two failed reaction wheels. This meant the current mission needed to be modified, but it did not necessarily mean the end of planet hunting. NASA had asked the space science community to propose alternative mission plans "potentially including an exoplanet search, using

930-424: A second reaction wheel failed on May 11, 2013, ending Kepler's primary mission. The spacecraft was put into safe mode, then from June to August 2013 a series of engineering tests were done to try to recover either failed wheel. By August 15, 2013, it was decided that the wheels were unrecoverable, and an engineering report was ordered to assess the spacecraft's remaining capabilities. This effort ultimately led to

992-592: A signal that is easier to check, scientists expected the first reported results to be larger Jupiter-size planets in tight orbits. The first of these were reported after only a few months of operation. Smaller planets, and planets farther from their sun would take longer, and discovering planets comparable to Earth were expected to take three years or longer. Data collected by Kepler is also being used for studying variable stars of various types and performing asteroseismology , particularly on stars showing solar-like oscillations . Once Kepler has collected and sent back

1054-455: A slight reduction in the star's apparent magnitude , on the order of 0.01% for an Earth-size planet. The degree of this reduction in brightness can be used to deduce the diameter of the planet, and the interval between transits can be used to deduce the planet's orbital period, from which estimates of its orbital semi-major axis (using Kepler's laws ) and its temperature (using models of stellar radiation) can be calculated. The probability of

1116-463: A threshold crossing event. These signals are individually inspected in two inspection rounds, with the first round taking only a few seconds per target. This inspection eliminates erroneously selected non-signals, signals caused by instrumental noise and obvious eclipsing binaries. Threshold crossing events that pass these tests are called Kepler Objects of Interest (KOI), receive a KOI designation and are archived. KOIs are inspected more thoroughly in

1178-423: A total resolution of 94.6 megapixels , which at the time made it the largest camera system launched into space. The array was cooled by heat pipes connected to an external radiator. The CCDs were read out every 6.5 seconds (to limit saturation) and co-added on board for 58.89 seconds for short cadence targets, and 1765.5 seconds (29.4 minutes) for long cadence targets. Due to the larger bandwidth requirements for

1240-445: Is higher than the probability of initial detection assuming planets in a given system tend to orbit in similar planes—an assumption consistent with current models of planetary system formation. For instance, if a Kepler -like mission conducted by aliens observed Earth transiting the Sun, there is a 7% chance that it would also see Venus transiting. Kepler's 115 deg field of view gives it

1302-559: Is submitted to the Kepler Follow-up Program , or KFOP, to conduct follow-up observations. Kepler's field of view covers 115 square degrees , around 0.25 percent of the sky, or "about two scoops of the Big Dipper". Thus, it would require around 400 Kepler-like telescopes to cover the whole sky. The Kepler field contains portions of the constellations Cygnus , Lyra , and Draco . The nearest star system in Kepler's field of view

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1364-401: Is the trinary star system Gliese 1245 , 15 light years from the Sun. The brown dwarf WISE J2000+3629, 22.8 ± 1 light years from the Sun is also in the field of view, but is invisible to Kepler due to emitting light primarily in infrared wavelengths. The scientific objective of the Kepler space telescope was to explore the structure and diversity of planetary systems . This spacecraft observes

1426-753: The Kepler Science Office (SO). Accordingly, the SOC develops the pipeline data processing software based on scientific algorithms developed jointly by the SO and SOC. During operations, the SOC: The SOC also evaluates the photometric performance on an ongoing basis and provides the performance metrics to the SO and Mission Management Office. Finally, the SOC develops and maintains the project's scientific databases, including catalogs and processed data. The SOC finally returns calibrated data products and scientific results back to

1488-432: The high-gain antenna was changed from a design using a gimbal to one fixed to the frame of the spacecraft to reduce cost and complexity, at the cost of one observation day per month. The Ames Research Center was responsible for the ground system development, mission operations since December 2009, and scientific data analysis. The initial planned lifetime was three and a half years, but greater-than-expected noise in

1550-430: 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 visual magnitude between 14 and 16 but the brightest observed stars have apparent visual magnitude of 8 or lower. Most of the planet candidates were initially not expected to be confirmed due to being too faint for follow-up observations. All

1612-463: The "K2" follow-on mission observing different fields near the ecliptic. In January 2006, the project's launch was delayed eight months because of budget cuts and consolidation at NASA. It was delayed again by four months in March 2006 due to fiscal problems. At this time, the high-gain antenna was changed from a gimballed design to one fixed to the frame of the spacecraft to reduce cost and complexity, at

1674-604: The DMC for long-term archiving, and distribution to astronomers around the world through the Multimission Archive at STScI (MAST). On July 14, 2012, one of the four reaction wheels used for fine pointing of the spacecraft failed. While Kepler requires only three reaction wheels to accurately aim the telescope, another failure would leave the spacecraft unable to aim at its original field. After showing some problems in January 2013,

1736-531: The Exoplanet Archive are vetted by a team of astronomers and the original literature references are available. The Exoplanet Archive supports interactive visualization of images, spectra, and time series data and maintains its own stellar cross-identification to minimize ambiguity in multiple star components. Kepler Mission The Kepler space telescope is a defunct space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars . Named after astronomer Johannes Kepler ,

1798-638: The Exoplanet Archive is the U.S. data portal. Other astronomical surveys and telescopes that have contributed data sets to the archive include SuperWASP , HATNet Project , XO , Trans-Atlantic Exoplanet Survey and KELT . According to third-party web analytics provider SimilarWeb , the company's website has over 130,000 visits per month, as of January 2015. The Exoplanet Archive contains objects discovered through all methods ( radial velocity , transits , microlensing , imaging , astrometry , eclipse timing variations , and transit timing variations/TTV ) that have publicly available planetary parameters, with

1860-490: The Sun , which avoids Earth occultations , stray light, and gravitational perturbations and torques inherent in an Earth orbit. NASA has characterized Kepler's orbit as "Earth-trailing". With an orbital period of 372.5 days, Kepler is slowly falling farther behind Earth (about 16 million miles per annum ). As of May 1, 2018 , the distance to Kepler from Earth was about 0.917 AU (137 million km). This means that after about 26 years Kepler will reach

1922-640: The aerospace industry include lubricants, optical systems, star trackers and antennas. As a wholly-owned subsidiary of the Ball Corporation, Ball Aerospace was cited in 2023 as the 54th largest defense contractor in the world. Both parent and subsidiary headquarters are co-located in Broomfield, Colorado. In August 2023, Ball Corporation agreed to divest Ball Aerospace to BAE Systems Inc. for $ 5.6 billion in cash. On February 14, 2024 The companies announced that all regulatory approvals were in place to allow

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1984-623: The billions of stars in the Milky Way have such planets, Kepler's sole scientific instrument is a photometer that continually monitored the brightness of approximately 150,000 main sequence stars in a fixed field of view. These data were transmitted to Earth, then analyzed to detect periodic dimming caused by exoplanets that cross in front of their host star. Only planets whose orbits are seen edge-on from Earth could be detected. Kepler observed 530,506 stars, and had detected 2,778 confirmed planets as of June 16, 2023. The Kepler space telescope

2046-558: The campus of Johns Hopkins University in Baltimore, Maryland . The science data telemetry is decoded and processed into uncalibrated FITS -format science data products by the DMC, which are then passed along to the Science Operations Center (SOC) at NASA Ames Research Center, for calibration and final processing. The SOC at NASA Ames Research Center (ARC) develops and operates the tools needed to process scientific data for use by

2108-421: 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 from Cape Canaveral Air Force Station , Florida. The launch was a success and all three stages were completed by 04:55 UTC. The cover of the telescope was jettisoned on April 7, 2009, and the first light images were taken on the next day. On April 20, 2009, it

2170-408: The data , from both the stars and the spacecraft, meant additional time was needed to fulfill all mission goals. Initially, in 2012, the mission was expected to be extended until 2016, but on July 14, 2012, one of the four reaction wheels used for pointing the spacecraft stopped turning, and completing the mission would only be possible if the other three all remained reliable. Then, on May 11, 2013,

2232-402: The data, raw light curves are constructed. Brightness values are then adjusted to take the brightness variations due to the rotation of the spacecraft into account. The next step is processing (folding) light curves into a more easily observable form and letting software select signals that seem potentially transit-like. At this point, any signal that shows potential transit-like features is called

2294-415: The former, these were limited in number to 512 compared to 170,000 for long cadence. However, even though at launch Kepler had the highest data rate of any NASA mission, the 29-minute sums of all 95 million pixels constituted more data than could be stored and sent back to Earth. Therefore, the science team pre-selected the relevant pixels associated with each star of interest, amounting to about 6 percent of

2356-713: The galaxy. Thus, the stars which Kepler observed are roughly the same distance from the Galactic Center as the Solar System , and also close to the galactic plane . This fact is important if position in the galaxy is related to habitability, as suggested by the Rare Earth hypothesis . Orientation is three-axis stabilized by sensing rotations using fine-guidance sensors located on the instrument focal plane (instead of rate sensing gyroscopes, e.g. as used on Hubble ). and using reaction wheels and hydrazine thrusters to control

2418-573: The high gain antenna for communications to Earth. The Kepler space telescope conducted its own partial analysis on board and only transmitted scientific data deemed necessary to the mission in order to conserve bandwidth. Science data telemetry collected during mission operations at LASP is sent for processing to the Kepler Data Management Center (DMC) which is located at the Space Telescope Science Institute on

2480-430: The mirror is specifically designed to have a mass only 14% that of a solid mirror of the same size. To produce a space telescope system with sufficient sensitivity to detect relatively small planets, as they pass in front of stars, a very high reflectance coating on the primary mirror was required. Using ion assisted evaporation , Surface Optics Corp. applied a protective nine-layer silver coating to enhance reflection and

2542-500: The orientation. Kepler was 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 was rotated to face the Sun at the solstices and equinoxes , so as to optimize the amount of sunlight falling on the solar array and to keep the heat radiator pointing towards deep space. Together, LASP and Ball Aerospace controlled

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2604-504: The other side of the Sun and will get back to the neighborhood of the Earth after 51 years. Until 2013 the photometer pointed to a field in the northern constellations of Cygnus , Lyra and Draco , which is well out of the ecliptic plane, so that sunlight never enters the photometer as the spacecraft orbits. This is also the direction of the Solar System's motion around the center of

2666-471: The pixels (5.4 megapixels). The data from these pixels was then requantized, compressed and stored, along with other auxiliary data, in the on-board 16 gigabyte solid-state recorder. Data that was stored and downlinked includes science stars, p-mode stars , smear, black level, background and full field-of-view images. The Kepler primary mirror is 1.4 meters (4.6 ft) in diameter. Manufactured by glass maker Corning using ultra-low expansion (ULE) glass ,

2728-554: The remaining two good reaction wheels and thrusters". On November 18, 2013, the K2 "Second Light" proposal was reported. This would include utilizing the disabled Kepler in a way that could detect habitable planets around smaller, dimmer red dwarfs . On May 16, 2014, NASA announced the approval of the K2 extension. By January 2015, Kepler and its follow-up observations had found 1,013 confirmed exoplanets in about 440 star systems , along with

2790-420: The rest due to instrumental noise sources slightly larger than predicted. Because decrease in brightness from an Earth-size planet transiting a Sun-like star is so small, only 80 ppm, the increased noise means each individual transit is only a 2.7 σ event, instead of the intended 4 σ. This, in turn, means more transits must be observed to be sure of a detection. Scientific estimates indicated that

2852-436: The same day, bringing an end to its nine-year service. Kepler observed 530,506 stars and discovered 2,662 exoplanets over its lifetime. A newer NASA mission, TESS , launched in 2018, is continuing the search for exoplanets. The telescope has a mass of 1,039 kilograms (2,291 lb) and contains a Schmidt camera with a 0.95-meter (37.4 in) front corrector plate (lens) feeding a 1.4-meter (55 in) primary mirror —at

2914-462: The scientists. On January 6, 2015, NASA announced the 1,000th confirmed exoplanet discovered by the Kepler space telescope. Four of the newly confirmed exoplanets were found to orbit within habitable zones of their related stars : three of the four, Kepler-438b , Kepler-442b and Kepler-452b , are almost Earth-size and likely rocky; the fourth, Kepler-440b , is a super-Earth . On May 10, 2016, NASA verified 1,284 new exoplanets found by Kepler,

2976-439: The selected stars are observed simultaneously, with the spacecraft measuring variations in their brightness every thirty minutes. This provides a better chance for seeing a transit. The mission was designed to maximize the probability of detecting planets orbiting other stars. Because Kepler must observe at least three transits to confirm that the dimming of a star was caused by a transiting planet, and because larger planets give

3038-407: The single largest finding of planets to date. Kepler data have also helped scientists observe and understand supernovae ; measurements were collected every half-hour so the light curves were especially useful for studying these types of astronomical events. On October 30, 2018, after the spacecraft ran out of fuel, NASA announced that the telescope would be retired. The telescope was shut down

3100-465: The spacecraft 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 life-cycle cost was estimated at US$ 600 million, including funding for 3.5 years of operation. In 2012, NASA announced that the Kepler mission would be funded until 2016 at

3162-427: The spacecraft successfully sent its first science data to Earth. It was discovered that Kepler had entered safe mode on June 15. A second safe mode event occurred on July 2. In both cases the event was triggered by a processor reset . The spacecraft resumed normal operation on July 3 and the science data that had been collected since June 19 was downlinked that day. On October 14, 2009, the cause of these safing events

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3224-450: The spacecraft was launched into an Earth-trailing heliocentric orbit . The principal investigator was William J. Borucki . After nine and a half years of operation, the telescope's reaction control system fuel was depleted, and NASA announced its retirement on October 30, 2018. Designed to survey a portion of Earth's region of the Milky Way to discover Earth-size exoplanets in or near habitable zones and to estimate how many of

3286-494: The time between successive transits, which may vary if planets are gravitationally perturbed by each other. This helps to confirm relatively low-mass planets even when the star is relatively distant. Transit timing variations indicate that two or more planets belong to the same planetary system. There are even cases where a non-transiting planet is also discovered in this way. Ball Aerospace %26 Technologies Ball Aerospace & Technologies Corp. , commonly Ball Aerospace ,

3348-472: The time of its launch this was the largest mirror on any telescope outside Earth orbit, though the Herschel Space Observatory took this title a few months later. Its telescope has a 115 deg (about 12-degree diameter) field of view (FoV), roughly equivalent to the size of one's fist held at arm's length. Of this, 105 deg is of science quality, with less than 11% vignetting . The photometer has

3410-437: The transit signal. Another method to rule out planet candidates is astrometry for which Kepler can collect good data even though doing so was not a design goal. While Kepler cannot detect planetary-mass objects with this method, it can be used to determine if the transit was caused by a stellar-mass object. There are a few different exoplanet detection methods which help to rule out false positives by giving further proof that

3472-415: The unprocessed light curve data. As a consequence, those planets may be missing KOI designation. Once suitable candidates have been found from Kepler data, it is necessary to rule out false positives with follow-up tests. Usually, Kepler candidates are imaged individually with more-advanced ground-based telescopes in order to resolve any background objects which could contaminate the brightness signature of

3534-728: Was acquired by BAE Systems Inc. in 2024, and is operated as a new division within BAE called Space & Mission systems. Ball Aerospace began building pointing controls for military rockets in 1956. The aerospace part of the Ball Corporation was then known as Ball Brothers Research Corporation , and later won a contract to build some of NASA 's first spacecraft, the Orbiting Solar Observatory satellites. The company has been responsible for numerous technological and scientific projects and continues to provide aerospace technology to NASA and related industries. Other products and services for

3596-624: Was an American manufacturer of spacecraft, components and instruments for national defense, civil space and commercial space applications. Until 2024, the firm was a wholly owned subsidiary of Ball Corporation , with primary offices in Boulder, Colorado , and facilities in Broomfield and Westminster in Colorado , with smaller offices in New Mexico , Ohio , northern Virginia , Missouri and Maryland . It

3658-546: Was announced that the Kepler science team had concluded that further refinement of the focus would dramatically increase the scientific return. On April 23, 2009, it was announced that the focus had been successfully optimized by moving the primary mirror 40  micrometers (1.6 thousandths of an inch) towards the focal plane and tilting the primary mirror 0.0072 degree. On May 13, 2009, at 00:01 UTC, Kepler successfully completed its commissioning phase and began its search for planets around other stars. On June 19, 2009,

3720-525: Was determined to be a low voltage power supply that provides power to the RAD750 processor. On January 12, 2010, one portion of the focal plane transmitted anomalous data, suggesting a problem with focal plane MOD-3 module, covering two out of Kepler's 42 CCDs . As of October 2010 , the module was described as "failed", but the coverage still exceeded the science goals. Kepler downlinked roughly twelve gigabytes of data about once per month. Kepler has

3782-407: Was developed allowing 10 ppm for stellar variability, roughly the value for the Sun. The obtained accuracy for this observation has a wide range, depending on the star and position on the focal plane, with a median of 29 ppm. Most of the additional noise appears to be due to a larger-than-expected variability in the stars themselves (19.5 ppm as opposed to the assumed 10.0 ppm), with

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3844-467: Was part of NASA's Discovery Program of relatively low-cost science missions. The telescope's construction and initial operation were managed by NASA's Jet Propulsion Laboratory , with Ball Aerospace responsible for developing the Kepler flight system. In January 2006, the project's launch was delayed eight months because of budget cuts and consolidation at NASA. It was delayed again by four months in March 2006 due to fiscal problems. During this time,

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