page_title: Kepler space telescope
section_title: Operational timeline
hierarchical_section_title: Kepler space telescope / Spacecraft design / Operational timeline
caption_attribution_description: English: Ignition of a Delta II 7925-10L rocket with the the Kepler space telescope on Board Deutsch: Zündung der Triebwerke einer Delta II 7925-10L Rakete mit dem Kepler Weltraumteleskop an Bord Polski: Moment startu rakiety nośnej Delta II 7925-10L z sondą kosmiczną Kepler
context_page_description: The Kepler space telescope is a retired space telescope launched by NASA to discover Earth-size planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched on March 7, 2009, into an Earth-trailing heliocentric orbit. The principal investigator was William J. Borucki. After nine 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 estimate how many of 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 are 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 can be detected. During its over nine and a half years of service, Kepler observed 530,506 stars and detected 2,662 planets.
context_section_description: 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 gimbal-led design to one fixed to the frame of the spacecraft to reduce 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 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 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, 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 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—an example of such a downlink was on November 22–23, 2010.
caption: Kepler's launch on March 7, 2009
exif: {"Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS3 Macintosh", "Image DateTime": "2009:03:07 23:58:48", "Image ExifOffset": "164", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "302", "Thumbnail JPEGInterchangeFormatLength": "2691", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "1500", "EXIF ExifImageLength": "2301"}