Astronomers are starting to breathe again.
Two weeks ago, the most powerful space observatory ever built roared across the sky, carrying the hopes and dreams of a generation of astronomers in a tightly wrapped package of mirrors, wires, motors, cables, latches and thin plastic sheets on a pillar of smoke and fire.
On Saturday, the James Webb Space Telescope took a final crucial step around 10:30 a.m. by unfolding the last section of its golden hexagonal mirrors. Almost three hours later, engineers sent out commands to lock those mirrors in place, a step that amounted to its full deployment, according to NASA.
It was the most recent in a series of tricky maneuvers with what the space agency called 344 “single points of failure” while accelerating far into space. Now the telescope is almost ready for business, although more tense times are still in its future.
âI’m moved about it,â said Thomas Zurbuchen, NASA’s chief scientist, of all of the telescope’s mirrors finally snapping into place. âWhat an incredible milestone – we see this beautiful design in the sky now almost complete. “
The James Webb Space Telescope, named after a former NASA administrator who oversaw the formative years of the Apollo program, is 25 years old and $ 10 billion under construction. It is three times the size of the Hubble Space Telescope and is designed to look deeper into the past than its famous predecessor to study the first stars and galaxies to light up at the dawn of time.
The launch of an Ariane rocket on the morning of December 25 went without fail; So flawless that engineers said it saved enough maneuver fuel to extend the mission’s estimated lifespan by 10 years, possibly up to another 10 years, said Mike Menzel, mission systems engineer. at NASA Goddard. But the telescope must make a month-long trip to a place a million kilometers above sea level, well beyond the orbit of the moon, called L2, where the gravitational fields of the Earth and the sun mix together to create the conditions for a stable orbit around the sun.
With a primary mirror 21 feet in diameter, the Webb was too big to fit in a rocket. The mirror was therefore made up of segments, 18 gold-plated hexagons folded together, which had to fit into place once the telescope was in space.
Another challenge was that the telescope’s instruments had to be sensitive to infrared or âthermal radiation,â a form of electromagnetic radiation invisible to the human eye. Due to the expansion of the universe, the farthest and oldest galaxies fly away so fast that visible light from these galaxies shifts to longer infrared wavelengths. As a result, the Webb will see 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 the work.
After years of deployment testing on Earth, little surprises in space have emerged with Webb’s deployment, or the “knowing the telescope phase,” Bill Ochs, engineer at Goddard Space Flight Center and a project responsible for the telescope , told reporters on Monday.
Mission officials detected high temperatures on an on-board engine used only in the deployment process. Engineers therefore joined the telescope on Sunday to protect the device from the heat of the sun. Then Webb’s solar panels were readjusted when engineers noticed the telescope had lower power reserves than expected.
One of the riskiest moments came on Tuesday, with the successful deployment of a giant sunscreen, the size of a tennis court. It was designed to keep the telescope in the dark and cold enough that its own heat would not obscure the heat detected by distant stars. The screen is made of five layers of a plastic called Kapton, which is similar to Mylar and just as fragile, and which had occasionally torn during rehearsals of its deployment.
In fact, the course went perfectly this time.
âIt went incredibly well. I feel like we were all shocked that there was no drama, âsaid Hillary Stock, Sunshade Deployment Specialist at Northrop Grumman, the telescope’s main contractor.
Then on Wednesday, the telescope deployed its secondary mirror, which points to the 18 hexagons, reflecting what the telescope saw towards its sensors.
“We’re about 600,000 miles from Earth and we actually have a telescope,” Ochs said in the mission operations control room at the Space Telescope Science Institute in Baltimore.
As the telescope performed chore after chore, the astronomers who had waited for this telescope for 25 years began to relax.
âStrangely, I don’t feel so anxious anymore, my inherent optimism (hello optimism bias and anchor bias) is at its peak,â Priyamvada Natarajan, a Yale cosmologist, wrote in an email.
Three days later, the last mirrors locked in place and the Mission Control team erupted into applause and a flurry of high fives and punches.
“How does it feel to make history everyone?” Dr Zurbuchen asked those responsible for the mission in Baltimore once the lockdown is over. âYou just did. “
âNASA is a place where the impossible becomes possible,â said Bill Nelson, the former senator and astronaut who is now the administrator of NASA.
Garth Illingworth of the University of California, Santa Cruz said, âI can’t describe how amazing it is to have a full mirror. This is an amazing achievement for the JWST team.
Alan Dressler of Carnegie Observatories, who chaired a report that led to what would become the Webb Telescope, said that âwhat resonates right now is the extraordinary ability of our species to collaborate, to organize thousands of people to work with care, relentlessly, without selfishness. , and seemingly endless to greater human good.
Chanda Prescod Weinstein, astrophysicist at the University of New Hampshire, echoed her remarks: “It’s a reminder of how people can be successful when they work together.”
While the telescope is considered to be fully deployed, much remains to be done. There are still 49 of those “one-off failures,” according to Menzel. Problems with any of them could affect individual instruments in the mission or the entire spacecraft.
At the end of January, the telescope will be in its final orbit at L2. Astronomers will spend the next five months fine-tuning the mirrors to pool them and starting to test and calibrate their instruments.
Then the real science will begin. Astronomers have said the first image from the Webb Telescope will appear in June, but what no one will say.
Jane Rigby, project scientist for the mission at NASA Goddard, told a press conference on Saturday that the first images taken during the mirror alignments would be blurry and ugly. But once the mirrors are made to work together, she said the telescope images “would knock everyone’s socks off.”
“We are planning a series of ‘wow’ images to be released at the end of commissioning when we begin normal science operations designed to show what this telescope can do,” said Dr Rigby.
“I can’t wait to see the first light and then the first science,” wrote Michael Turner, a veteran cosmologist at the Kavli Foundation in Los Angeles, in an email. âIt will be even better for our COVID-riddled minds than Ted Lasso. “