Webb Telescope Now Fuelled Up as Much-Anticipated Launch Approaches

Webb Telescope Now Fuelled Up as Much-Anticipated Launch Approaches
The Webb space telescope inside the payload preparation facility at Europe's Spaceport in French Guiana on on Nov. 26, 2021. (Photo: ESA/CNES/Arianespace)

Wearing protective suits to guard against toxic chemicals, a small team of mission specialists has completed the 10-day fuelling of the upcoming Webb space telescope. For what seems like the first time ever, the long-delayed mission is actually starting to feel real.

Fuelling was completed on December 3 at the payload preparation facility at Europe’s Spaceport in French Guiana, according to a European Space Agency press release. It’s a major milestone, as all that’s left is for mission specialists to mount the telescope atop an Ariane 5 rocket, make some final adjustments, and then roll it out to the launch pad.

At the risk of jinxing this international project, things are finally starting to feel a bit normal. The project has been beset by problems, so the fuelling, because it happened without incident, seems like a small victory unto itself. And in fact, fuelling was only allowed to happen after NASA investigators determined that Webb wasn’t damaged during a processing incident that caused a vibration to course through the entire structure.

The specialists who performed the fuelling had to wear Self-Contained Atmospheric Protective Ensemble (SCAPE) suits, to protect them from the very toxic propellants: dinitrogen tetroxide oxidizer and hydrazine.

Webb is a telescope, but it’s also a spacecraft. The next-gen observatory, built by NASA, ESA, and the Canadian Space Agency, will need propellant to make important course-corrections following separation from the Ariane 5 rocket. Unlike its predecessor, the Hubble Space Telescope, Webb will not perform its work in low Earth orbit. The sensitive infrared telescope needs a super-cold environment, so it’s being sent some 1.5 million kilometres to the second Lagrange point, or L2. This special orbit around the Sun will keep Webb cold and in line with Earth. A sunshield will protect its instruments from excessive light and heat.

Webb will also need propellant for conducting normal operations, such as repointing the observatory and managing its momentum in space. Webb will finally get to work approximately six months after launch, at which time we’ll finally witness the power of this fully armed and operational battle station, er, infrared telescope. Like Hubble, Webb will perform sweeping observations of the solar system, Milky Way, and distant galaxies, but it will be far more powerful and likely to reveal hidden details, such as the oldest galaxies in the universe and the atmospheric composition of far-away exoplanets.

The next step is to place Webb on top of Ariane 5 and secure it within the rocket’s faring. From there, the rocket will be transported to the Final Assembly Building for the final tweaks needed before launch. We’re only weeks away now, and soon it’ll be just a few days, then hours, and finally minutes. Seems unreal, but we honestly won’t believe anything until we see this rocket headed skywards.