The James Webb Space Telescope was launched on an Ariane 5 rocket. The launch vehicle and launch site were part of the European Space Agency's contribution to the mission. The Ariane 5 is one of the world's most reliable launch vehicles and was chosen for a combination of reliability (it was the only launch vehicle that met NASA's requirements for launching a mission like Webb) and for the value it brought via our international partnership. Read more about why the Ariane 5 was chosen.
Webb was launched from Arianespace's ELA-3 launch complex at Europe's Spaceport located near Kourou, French Guiana. It is beneficial for launch sites to be located near the equator - the spin of the Earth can help give an additional push. The surface of the Earth at the equator is moving at 1670 km/hr.
The Launch Segment has 3 primary components:
1. Launch Vehicle: an Ariane 5 with the cryogenic upper stage 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: comprised of the Cone 3936 plus the ACU 2624 lower cylinder and clamp-band, which provided 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 were the mutual responsibility of NASA, ESA, Northrop Grumman and ArianeSpace.