Astronomers breathe a sigh of relief after Webb Telescope unfolds its mirror in space

NASA’s Bill Ochs and John Durning bump fists in celebration at the Space Telescope Science Institute after the James Webb Space Telescope’s deployment. (NASA Photo / Bill Ingalls)

Two weeks after its Christmas launch, NASA James Webb Space Telescope It finished unfolding today, delighting astronomers in the process.

The deployment of JWST’s 21.3-foot-wide, 18-segment primary mirror marked the end of the riskiest part of the telescope’s $ 10 billion mission.

You are still more than 300,000 miles from your destination, a gravitational equilibrium point known as L2 that is a million miles from Earth. You still have to fine-tune the orientation of the gold and beryllium segments of the mirror and cool your instruments to a temperature just a few degrees above absolute zero. But mission controllers at the Space Telescope Science Institute were able to mark nearly 300 potential points of failure without issue.

“We have a fully deployed JWST observatory,” said Northrop Grumman’s Paul Reynolds, who led the mission’s deployment operations team, during a widely viewed webcast.

JWST is designed to be 100 times more sensitive than the 32-year-old Hubble Space Telescope, which is near the end of its longer-than-expected lifespan. Once JWST begins science operations, as early as May, it should bring new revelations about mysteries ranging from the habitability of alien planets to the nature of black holes and quasars and the origins of the universe.

Today’s mirror deployment, which came after years of development delays and cost overruns worth billions of dollars, was hailed as a sign of success by astronomers in the field, as well as senior officials from The NASA.

“NASA is a place where the impossible becomes possible,” said Bill Nelson, the agency’s administrator.

Mark McCaughrean, senior adviser for science and exploration at the European Space Agency, referred to Winston Churchill’s aphorisms during the war to describe the moment. “To quote Mr. Churchill, now this is not the end”, McCaughrean tweeted. “It is not even the beginning of the end. But it is, perhaps, the end of the beginning. There are five months of cool down, alignment and commissioning left, hard work for the teams involved, before the science begins. But today is a big step”.

It took two weeks to deploy the primary mirror, and the other components of the JWST, including a lens hood and the secondary mirror assembly, because the telescope was too large to fit in its fully deployed configuration within the nose cone of the European Ariane rocket. 5 in which it was launched.

The sunshade, which consists of five layers of ultra-thin coated plastic, had to be deployed in space to protect the telescope from solar radiation, in what was considered the riskiest part of the deployment. Then the left and right sides of the telescope had to be raised and locked like the sides of a drop table. The left side was placed on Friday and the right side was repaired today.

“This has been possibly the most challenging deployment program NASA has ever conducted,” said NASA mission systems engineer Mike Menzel during a post-deployment briefing at the Space Telescope Science Institute in Baltimore.

The mission team had made contingency plans for possible failures, including a procedure to move the spacecraft in space if necessary. But none of those plans had to be used.

“It wasn’t as easy as it sounds, but the ease that it looked like… it’s just a tribute to the people,” said Bill Ochs, mission project manager. “We went through what I think now is the exact amount of testing, the exact amount of engineering audits, the exact amount of design tweaks.”

Ahead of launch, mission managers said JWST would face 344 possible single points of failure. And because the telescope was intended to operate well beyond Earth’s orbit, there would be no opportunity to send a repair team to correct any flaws, as was the case with Hubble.

Although the riskiest part of the mission is over, some risks remain. The spacecraft will have to turn on its thrusters on January 23 to settle into its orbit around the L2 gravitational balance point and then establish a routine for years to come.

“There are 49 single point faults out of the original 344 that were not retired and will not retreat for the duration of the mission,” Menzel said. “These 49 are typical of all missions, things like jet tanks.”

The good news is that things have been surprisingly good so far. So smoothly, in fact, that the telescope has enough excess propellant to last much longer than the five to 10 years of operation originally expected.

“Generally speaking, it’s about 20 years of propellant,” Menzel said.

Update for 1:10 am PT on January 9: University of Washington astronomer Eric Agol, who plans to use JWST to study the potentially habitable exoplanetary system known as TRAPENIST-1said the following about the telescope’s deployment in an email:

“It is a testament to the careful planning that went into JWST engineering that, thus far, everything has gone smoothly. That does not mean that we astronomers can relax yet: there are still many things that must go right for the telescope to work as planned! But so many critical hurdles have been overcome that I feel much more optimistic that in six months we will have a working telescope. “

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