COBE

Explorer 66, Cosmic Background Explorer

Mission Profile

COBE (Cosmic Background Explorer, Explorer 66) was NASA's pioneering space observatory launched on 18 November 1989 aboard a Delta rocket to map the cosmic microwave background radiation with unprecedented precision and characterize the infrared emission of the Milky Way and extragalactic sources. COBE's three instruments — DIRBE, DMR, and FIRAS — made two fundamental discoveries: the CMB has a perfect blackbody spectrum at 2.725 K, confirming the Big Bang, and it exhibits tiny temperature anisotropies at the level of one part in 100,000, the primordial seeds of all cosmic structure. These discoveries, announced in 1992, confirmed the fundamental predictions of Big Bang cosmology and earned COBE Principal Investigators John Mather and George Smoot the 2006 Nobel Prize in Physics. COBE's maps directly motivated the subsequent WMAP and Planck missions with far greater sensitivity.