Webb will be launched on an Ariane 5 rocket. The launch vehicle is part of the European contribution to the mission. The Ariane 5 is the world's most reliable launch vehicle capable of delivering Webb to its destination in space. The European Space Agency (ESA) has agreed to provide an Ariane 5 launcher and associated launch services to NASA for Webb. The Ariane 5's record for successful launches extends over 11 years and some 57 consecutive launches (as of February 2014).
The Webb will be launched from Arianespace's ELA-3 launch complex at European Spaceport located near Kourou, French Guiana.
The Launch Segment has 3 primary components:
1. Launch Vehicle: an Ariane 5 with the cryogenic upper stage. It will be provided in the single launch configuration, with a long payload fairing providing a maximum 4.57 meter static diameter and useable length of 16.19 meters.
2. Payload Adapter, comprising the Cone 3936 plus ACU 2624 lower cylinder and clamp-band, which provides the separating mechanical and electrical interface between the Webb Observatory and the Launch Vehicle.
3. Launch campaign preparation and launch campaign.
The launch campaign preparation and launch campaign is the mutual responsibility of NASA, ESA, NGAS, and Arianespace.