It’s arrived - update at the end of the James Webb Space Telescope’s “29 days on the edge”

At 7.00pm (GMT) today, the James Webb Space Telescope (JWST) fired its thrusters for the third time - its insertion burn. And now it’s safely at the final destination point, known as L2, a million miles from Earth. The “29 days on the edge”, when so much had to go smoothly, are now behind us.

Six of the JWST mirrors after cryogenic testing (Credit: Emmett Given/NASA)

On 8th January, 14 days after JWST was launched, NASA announced: “Webb is fully deployed!” The telescope’s primary mirror structure - made up of 18 hexagonal segments, covered in a thin layer of gold - became fully extended and latched into position.

Earlier, the secondary mirror was deployed, which sits at the end of a 7-metre structure. It had to lock into place to a tolerance of 1.5mm.

Another five months are now needed to perform even more detailed optical mirror alignments, as well as for JWST to further cool down so all of its other instruments can come online. The first images might arrive as early as the latter part of April - although these will probably be blurry and ugly. Jane Rigby, a NASA scientist, says: “It's like we have 18 mirrors that are, right now, little prima donnas, all doing their own thing, singing their own tune in whatever key they're in.” She continued: “We have to make them work like a chorus, and that is a methodical, laborious process.”

By the end of June, everything should be up and running, and the work of JWST can finally begin.

Written by Victoria de las Heras & Cal Stewart, 24th January 2022