COBEs

COBE stands for Cosmic Background Explorer. The plural form COBEs is uncommon in practice and may be used to refer to the mission together with its instrument suite or, rarely, to multiple projects sharing the acronym; in any case, there has been only one COBE mission. Launched in 1989, COBE was a NASA satellite dedicated to mapping the cosmic microwave background (CMB) and the diffuse infrared background. It carried three instruments: FIRAS, which measured the spectrum of the CMB; DMR, which mapped temperature anisotropies in the CMB; and DIRBE, which surveyed the sky in the infrared to study the diffuse infrared background and foreground emission from dust.

Key results from the mission include FIRAS confirming that the CMB has an almost perfect blackbody spectrum with a temperature of about 2.725 K, with deviations constrained to parts per ten million. DMR detected temperature fluctuations in the CMB at large angular scales, producing the first full-sky map of CMB anisotropies. DIRBE mapped the infrared sky, aiding the separation of foreground dust emission from cosmological signals and contributing to studies of the cosmic infrared background.

Impact and legacy: The COBE results provided strong support for the Big Bang model and for inflationary theory by revealing initial density fluctuations consistent with the formation of large-scale structure. The mission’s work earned John C. Mather and George F. Smoot the 2006 Nobel Prize in Physics. COBE set a standard for precision cosmology and influenced subsequent missions such as WMAP and Planck, continuing to inform models of the early universe.