The James Webb Space Telescope was fuelled inside the payload preparation facility at Europe’s Spaceport in French Guiana ahead of its launch on Ariane 5. Credit: ESA/CNES/Arianespace
The James Webb Space Telescope was fuelled inside the payload preparation facility at Europe’s Spaceport in French Guiana ahead of its launch on Ariane 5.
Webb’s thrusters will use this propellant to make critical course-corrections after separation from Ariane 5, to maintain its prescribed orbit about one and a half million kilometers from Earth, and to repoint the observatory and manage its momentum during operations.
Fuelling any satellite is a particularly delicate operation requiring setup of the equipment and connections, fuelling, and then pressurization.
Webb’s propellant tanks were filled separately with 79.5 l of dinitrogen tetroxide oxidizer and 159 l hydrazine. Oxidizer improves the burn efficiency of the hydrazine fuel.
These propellants are extremely toxic so only a few specialists wearing Self-Contained Atmospheric Protective Ensemble, or ‘scape’ suits, remained in the dedicated fuelling hall for fuelling which took 10 days and ended on 3 December.
The next steps will start soon for ‘combined operations’. This is when specialists working separately to prepare Webb and Ariane 5 will come together as one team. They will place Webb atop its Ariane 5 launch vehicle and encapsulate it inside Ariane 5’s fairing.
Then, no longer visible, Webb, joined with its Ariane 5 launch vehicle will be transferred to the Final Assembly building for the final preparations before launch.
Webb will be the largest, most powerful telescope ever launched into space. As part of an international collaboration agreement, ESA is providing the telescope’s launch service using the Ariane 5 launch vehicle. 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 by Arianespace.
Webb and Ariane 5: a fit made perfect. Ariane 5 has been customized 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 minimize the shock of depressurization 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 maneuver 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. Credit: ESA
Webb is an international partnership between NASA, ESA and the Canadian Space Agency (CSA).