December 24 Confirmed as Target Launch Date for JWST

This morning Arianespace and NASA officially confirmed that the James Webb Space Telescope is now set for launch at 7:20 am ET on December 24. The agency has been working a communications problem between the spacecraft and its Ariane 5 rocket, but that now is resolved and the spacecraft is encapsulated in the Ariane 5’s fairing. The next major milestone will be the Launch Readiness Review three days before liftoff.

NASA revealed on Monday that a “communication issue between the observatory and the launch vehicle” would delay the launch from December 22 to December 24 and promised an update by Friday.

During the day, NASA Administrator Bill Nelson was quoted by the Associated Press as saying launch would take place on December 24 and the Space Telescope Science Institute, which will operate JWST and is hosting reporters and guests on launch day, sent an email confirming that plan.

But there was no official word from the principals involved in getting the telescope ready that the spacecraft was actually encapsulated in the rocket’s fairing, the point at which the launch date was expected to be confirmed since other problems might emerge. Once the fairing is sealed, it would be extremely difficult to access the spacecraft again so it is a considered a major milestone in launch preparations.

JWST is a joint program among NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA). ESA is providing the launch at no cost to NASA on Europe’s Ariane rocket, owned and operated by the French company Arianespace, from its launch site in Kourou, French Guiana on the northeast coast of South America.

During an ESA pre-launch media teleconference Thursday, ESA’s Director of Space Transportation Daniel Neuenschwander and Thomas Zurbuchen, head of NASA’s Science Mission Directorate, described the communications problem as stemming from a faulty cable. Zurbuchen said they believed they had found and fixed the problem, but final “aliveness” tests needed to be completed before the observatory was encapsulated.

Neuenschwander, Zurbuchen, ESA Director General Josef Aschbacher, ESA Director of Science Günter Hasinger, and Arianespace CEO Stéphane Israël did not make any public statements until very late Friday.  Finally, Israël tweeted that they were still working on encapsulation and the launch date would be confirmed this morning.

Final encapsulation operations ongoing.
Need a few more hours to complete them.

Target launch date is December 24 at 12:20 am UTC.
Confirmation Saturday.

Go @NASAWebb/@ESA_Webb! Go #Ariane5! Go! ??#WebbFliesAriane #VA256 pic.twitter.com/15wvWpaD3R

— Stéphane Israël (@arianespaceceo) December 17, 2021

True to his word, he tweeted this morning that December 24 is confirmed as the target launch date.

Encapsulation – ✅@Arianespace confirms December 24 as our target launch date for @NASAWebb/@ESA_Webb! #WebbFliesAriane #VA256 https://t.co/ItdMC85iNW

— Stéphane Israël (@arianespaceceo) December 18, 2021

All that remains to be done before launch now is on rocket side. Every rocket typically goes through a Launch Readiness Review (LRR) several days prior to liftoff to make sure evertyhing is in order. Neuenschwander said that will happen three days before liftoff in this case, which would be December 21.

Weather can also be a factor, so nothing is 100 percent certain until the rocket lifts off the pad.  Hopefully that will indeed be at 7:20 am Eastern Standard Time on December 24, 2021.