page_title: Cosmic Background Explorer
section_title: History
hierarchical_section_title: Cosmic Background Explorer / History
caption_attribution_description: Čeština: Start družice COBE, 18. listopad 1989, Vandenberg Air Force Base. English: Launch of the COBE spacecraft November 18, 1989. The launch of the only Delta 5920 with the Cosmic Background Explorer. Русский: Запуск спутника COBE, 18 ноября 1989 года. தமிழ்: Launch of the COBE spacecraft November 18, 1989.
context_page_description: The Cosmic Background Explorer, also referred to as Explorer 66, was a satellite dedicated to cosmology, which operated from 1989 to 1993. Its goals were to investigate the cosmic microwave background radiation of the universe and provide measurements that would help shape our understanding of the cosmos.
  COBE's measurements provided two key pieces of evidence that supported the Big Bang theory of the universe: that the CMB has a near-perfect black-body spectrum, and that it has very faint anisotropies. Two of COBE's principal investigators, George Smoot and John Mather, received the Nobel Prize in Physics in 2006 for their work on the project. According to the Nobel Prize committee, "the COBE-project can also be regarded as the starting point for cosmology
  as a precision science".
  COBE was followed by two more advanced spacecraft: the Wilkinson Microwave Anisotropy Probe operated from 2001-2010 and the Planck spacecraft from 2009–2013.
context_section_description: In 1974, NASA issued an Announcement of Opportunity for astronomical missions that would use a small- or medium-sized Explorer spacecraft.  Out of the 121 proposals received, three dealt with studying the cosmological background radiation. Though these proposals lost out to the Infrared Astronomical Satellite (IRAS), their strength made NASA further explore the idea. In 1976, NASA formed a committee of members from each of 1974's three proposal teams to put together their ideas for such a satellite. A year later, this committee suggested a polar-orbiting satellite called COBE to be launched by either a Delta rocket or the Space Shuttle. It would contain the following instruments:
  NASA accepted the proposal provided that the costs be kept under $30 million, excluding launcher and data analysis.  Due to cost overruns in the Explorer program due to IRAS, work on constructing the satellite at Goddard Space Flight Center (GSFC) did not begin until 1981.  To save costs, the infrared detectors and liquid helium dewar on COBE would be similar to those used on IRAS.
  COBE was originally planned to be launched on a Space Shuttle mission STS-82-B in 1988 from Vandenberg Air Force Base, but the Challenger explosion delayed this plan when the Shuttles were grounded. NASA kept COBE's engineers from going to other space agencies to launch COBE, but eventually, a redesigned COBE was placed into sun-synchronous orbit on November 18, 1989 aboard a Delta rocket. A team of American scientists announced, on April 23, 1992 that they had found the primordial "seeds" (CMBE anisotropy) in data from COBE. The announcement was reported worldwide as a fundamental scientific discovery and ran on the front page of The New York Times.
  The Nobel Prize in Physics for 2006 was jointly awarded to John C. Mather, NASA Goddard Space Flight Center, and George F. Smoot, University of California, Berkeley, "for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation."
caption: Launch of the COBE spacecraft November 18, 1989.
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