Planck was carried into space on 14 May 2009, at 13:12:02 UTC, by an Ariane 5 ECA launcher, from the Guiana Space Centre, Kourou, French Guiana. Planck was launched together with ESA's Herschel spacecraft, in the launch configuration as depicted on the right. The two spacecraft separated within 30 minutes after launch and proceeded independently to different orbits about the second Lagrange point of the Sun-Earth system (L2).

The Ariane 5 ECA launcher injected first Herschel and then Planck into their individual transfer trajectories bound for L2. Upon separation, Planck was spin-stabilized.

About six weeks after launch, following a few trajectory correction manoeuvres, Planck will enter its operational orbit, a small Lissajous orbit around L2, 1.5 million kilometres away from the Earth.

Right: Planck (lower, covered by the SYLDA 5 support structure) and Herschel (upper) in their dual launch configuration under the Ariane 5 ECA fairing.