Astronomers are starting to breathe again.
Two weeks ago, the most powerful space observatory ever roared into the sky, carrying the hopes and dreams of a generation of astronomers in a tightly packed package of mirrors, wires, motors, cables, latches and willow-like sheets of thin plastic on a pillar of smoke and fire.
On Saturday, around 10:30 a.m., the observatory, the James Webb Space Telescope, completed a final, crucial step by unfolding the last part of its gold, hexagonal mirrors. Nearly three hours later, engineers sent commands to lock those mirrors in place, a move that amounted to full deployment, according to NASA.
It was the most recent of a series of delicate maneuvers involving what the space agency called 344 “single points of failure” as they raced far out into space. Now the telescope is almost ready for operation, although more exciting moments lie ahead.
“I’m emotional about it,” NASA chief science officer Thomas Zurbuchen said of all the telescope’s mirrors finally clicking into place. “What an amazing milestone – we see that beautiful pattern up there in the sky now almost complete.”
Named after a former NASA administrator who oversaw the early years of the Apollo program, the James Webb Space Telescope is 25 years and $10 billion in the making. Three times the size of the Hubble Space Telescope, it is designed to look further into the past than its celebrated predecessor to study the first stars and galaxies to rise at the dawn of time.
The launch on an Ariane rocket on the morning of December 25 went smoothly; so flawless that the engineers said it saved enough fuel for maneuvering to significantly extend the mission’s estimated 10-year lifespan. But the telescope must make a month-long journey to a place a million miles higher, far beyond the moon’s orbit called L2, where Earth’s and the sun’s gravitational fields mix to create the conditions for a stable orbit around the moon. Sun.
With a primary mirror 21 feet wide, the Webb was too big to fit in a rocket, so the mirror was made in segments, 18 gold-plated hexagons that folded together, which were supposed to snap into position once the telescope was in space. .
Another challenge was that the telescope’s instruments had to be sensitive to infrared or “heat radiation,” a form of electromagnetic radiation invisible to the human eye. Due to the expansion of the universe, the farthest and earliest galaxies are flying away from us so fast that visible light from those galaxies shifts to the longer infrared wavelengths. As a result, the Webb will view the universe in colors that no human eye has ever seen.
But to detect infrared radiation from distant sources, the telescope must be very cold, only a few degrees above absolute zero, so that the telescope itself does not interfere with work.
After years of implementation tests on Earth, little surprises have surfaced in space during the implementation of the Webb, or the “scope phase,” Bill Ochs, an engineer at the Goddard Space Flight Center and a project manager for the telescope, told reporters on Monday.
Mission managers discovered high temperatures on an onboard engine that was only used during the deployment process, so engineers refocused the telescope Sunday to protect the device from the sun’s heat. Then the Webb’s solar panels were readjusted when engineers noticed the telescope had smaller power reserves than expected.
One of the most perilous moments came on Tuesday, with the successful unfolding of a giant sunshade the size of a tennis court. It was designed to keep the telescope in the dark and cold enough that its own heat wouldn’t obscure the warmth of distant stars. The screen is made of five layers of a plastic called Kapton, which is similar to Mylar and just as thin, and had occasionally torn during rehearsals of its deployment.
Actually, the unfolding went flawlessly this time.
“It went incredibly smoothly. I feel like we’re all a little shocked that there hasn’t been any drama,” said Hillary Stock, an awning installation specialist at Northrop Grumman, the telescope’s prime contractor.
On Thursday, the telescope unfolded its secondary mirror, which points to the 18 hexagons and reflected what the telescope saw back to its sensors.
“We’re about 600,000 miles from Earth and we actually have a telescope,” Mr. Ochs said Thursday in the mission operations control room of the Space Telescope Science Institute in Baltimore.
As the telescope completed one job after another, the astronomers who had waited 25 years for this telescope began to relax.
“Oddly enough, I don’t feel so anxious anymore, my inherent optimism (hello optimism bias & anchoring bias) is in full swing,” Priyamvada Natarajan, a Yale cosmologist, wrote in an email.
Two days later, the final mirrors locked in place and the Mission Control team erupted into applause and a wave of high fives and fist punches.
“How does it feel to make history for everyone?” dr. Zurbuchen asked the Baltimore mission managers after the lockdown was completed. “You just did it.”
“NASA is a place where the impossible becomes possible,” said Bill Nelson, the former senator and astronaut who is now a NASA administrator.
Garth Illingworth of the University of California, Santa Cruz, said, “I can’t describe how incredible it feels to have a full mirror. It’s an amazing achievement for the JWST team.”
“NASA and the US can still do great things,” Michael Turner, a veteran cosmologist with the Kavli Foundation in Los Angeles, wrote in an email. “I can’t wait for the first light and then the first science. It will be even better for our COVID-riddled minds than Ted Lasso.
While the telescope is considered to be fully deployed, much remains to be completed before astronomical observations are made. The primary mirror segments are not aligned enough to produce a coherent image, part of a process that will take about five months.
“But it’s certain that light can now in principle pass through JWST from objects in the universe and into Webb’s instruments – albeit at best as 18 very faint blobs, until it’s all tuned!” said Dr. Illingworth, an astronomer.
By the end of January, the telescope will be in its final orbit around L2. The astronomers will spend the next five months adjusting the mirrors to bring them into common focus and begin testing and calibrating their instruments.
Then the real science begins. Astronomers have said the first image from the Webb telescope will appear in June, but no one will say.
“I don’t know what the targets will be,” Antonella Nota, associate director of the European Space Agency, said during the NASA webcast on Saturday. “But I know one thing, they will be absolutely spectacular.”