While astronomers are both excited and concerned about the deployment of the James Webb Space Telescope, the liftoff is simply the start of the mission’s most dangerous stage. After a one-day delay due to weather on December 21, NASA and other mission partners indicated on December 22 that they were still on track for a December 25 deployment of JWST on the Ariane 5 from the French Guiana facility. On December 23, the rocket will be rolled out of its assembly building and onto the launch pad.
On December 25, liftoff is slated for between 7:20 to 7:52 a.m. Eastern. JWST will split from the rocket’s upper stage 27 minutes after the liftoff if all goes according to plan.
While the launch of a spacecraft is usually the most dangerous portion of the mission, it will be nothing compared to what JWST will face. JWST will have to accomplish a number of first-of-its-kind sophisticated deployments and movements once it splits from the upper stage, despite the fact that it is flying on the rocket which has been in operation for over two decades, with its recent catastrophic deployment failure in 2002.
The initial deployment occurs 33 minutes after the liftoff when the solar panel is released. After that, it will perform its first-ever midcourse correction burn, known as MCC-1a, which will occur 12.5 hours after the liftoff. Those two occurrences are the most time-precise for the mission, according to Greg Robinson, program director of JWST at NASA Headquarters, who spoke with reporters on December 21. “Everything else is flexible,” he continued, “but for the time being, we’re clearly planning for a notional schedule.”
The sunshield is supposed to be deployed three days after launch, according to the official plan. The sunshield will be folded into two pallets on each side of the spaceship when they swing down. Covers safeguarding the sunshield material were released two days later, followed by the release of two booms to expand the sunshield to full proportions a day later. Over the next two days, the sunshield’s five Kapton layers, that are aluminum-coated and are tensioned into place, finishing the sunshield deployment 8 days after launch.
When a tripod supporting the small secondary mirror stretches into place 10 days after liftoff, a telescope mirror is deployed. Two wings, each bearing three of the primary mirror’s 18 segments, subsequently lock into position, completing the telescope’s deployment 13 days after launch.
Following those deployments, months of work will be required to position the telescope mirrors as well as commission the equipment as they cool to operating temperatures, which is a process that will take six months to complete. JWST will enter its last halo orbit around the Earth-sun L-2 Lagrange point, about 1.5 million kilometers (kms) from Earth and 29 days after the launch.