Webb and Ariane 5: a fit made perfect

The James Webb Space Telescope (Webb) will be the largest, most powerful telescope ever launched into space. As part of an international collaboration agreement, ESA is providing the observatory’s launch service using the Ariane 5 launch vehicle.

Webb’s sunshield ¬– a five-layer, diamond-shaped structure the size of a tennis court – was specially engineered to fold up and fit within the confines of Ariane 5. Fully deployed, the telescope’s sunshield measures 21 meters by 14 meters. When stowed inside the rocket for launch, the folded sunshield will be packaged in a very confined area to accommodate the limited space inside the 5.4-meter diameter rocket fairing. The fairing is the housing that will protect Webb during liftoff and its journey through the atmosphere.

Ariane 5 has been customised to accommodate all the specific requirements of the Webb mission. New hardware ensures that venting ports around the base of the fairing remain fully open. This will minimise the shock of depressurisation when the fairing jettisons away from the launch vehicle.

Some elements of Webb are sensitive to radiation from the Sun and heating by the atmosphere. To protect it after the fairing is jettisoned, Ariane 5 will perform a specially developed rolling manoeuvre to avoid any fixed position of the telescope relative to the Sun.

Additionally, an extra battery is installed on Ariane 5 to allow a boost to the upper stage after release of the telescope, distancing it from Webb.

Working with partners, ESA was responsible for the development and qualification of Ariane 5 adaptations for the Webb mission and for the procurement of the launch service.

Webb is an international partnership between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).