Herschel/Planck Program-From Complex Mission Design to Verification and Operations

Two astrophysics missions, Herschel, an observatory mission and Planck, a survey mission, are combined into one program within the long-term science program "Cosmic Vision" of the European Space Agency (ESA). This paper reviews the scientific and mission requirements together with the payload and spacecraft design, and it highlights the adopted model and verification approach and operational aspects of the two spacecraft. Herschel will target the largely unexplored infrared and sub-millimeter part of the electromagnetic spectrum from 60 to 670 microns with three scientific instruments. Planck will systematically image the whole sky with two scientific instruments simultaneously in nine frequency channels between 30 and 900 GHz to unravel the temperature fluctuations of the cosmic background radiation. For both satellites, which will be launched from the European Space Port in Kourou (French Guiana) on a single Ariane 5 launcher in the first half of 2008, the orbits will be Lissajous orbits around the 2^nd Lagrange Point L2 of the Earth-Sun system.