Planck will be launched in March 2007 by an Ariane-5 launcher together with ESA's Herschel Space Telescope (formerly called FIRST (Far Infrared and Submillimetre Telescope) observatory). Both satellites will separate shortly after launch and proceed to different orbits.
The Ariane-5 launcher will inject Planck into a transfer trajectory, and after about four to six months the satellite will reach its final orbit 1.5 million kilometres away from the Earth. The satellite will circle around a virtual point in space called the 2nd Lagrangian point of the Earth-Moon-Sun system (or L2 for short), a very good place from which to avoid the undesirable emission of heat from the Earth, the Moon and the Sun -which would cause too much interference in the measurements. As seen from L2, all these hot 'objects' are located behind the instrument.