Planck mission

Article By:

Demianski, Marek Department of Astronomy, Williams College, Williamstown, Massachusetts.

Last reviewed:2014

DOI:https://doi.org/10.1036/1097-8542.YB140223

The Planck mission is a satellite mission to explore the cosmic microwave background radiation (CMB). The discovery of this radiation in 1964 opened up a new era in observational cosmology. It was soon confirmed that CMB photons almost exactly reproduce the blackbody spectrum corresponding to a temperature of 2.7 K, confirming their cosmological origin as remnants of the very early big bang phase of the evolution of the universe, when it was very dense and very hot. Early in 1992, the Cosmic Background Explorer (COBE) satellite, designed by NASA, detected for the first time small temperature anisotropies at a level of ΔT/T ∼ 10⁻⁵. These small variations carry important information about the distribution of matter and radiation when the photons decoupled from hot matter some 380,000 years after the big bang. Late in June 2001, NASA launched another specially designed satellite, the Wilkinson Microwave Anisotropy Probe (WMAP), and placed it at the second Lagrange (L2) point of the Sun-Earth system to measure the temperature anisotropy of the CMB with much increased accuracy. The WMAP satellite was equipped with several bolometers operating at five different frequencies spanning the range from 23 to 94 GHz, and a special optical system for differential measurements of the sky temperature. The WMAP satellite produced a detailed map of temperature anisotropies that enabled the determination with high precision of several parameters that specify the basic properties of the universe, and independently confirmed the existence of dark matter and dark energy.

The content above is only an excerpt.