For the past six months, Scott Friedman and a team of approximately 160 scientists and engineers have been working on one of the most daunting to-do lists in all of science. Almost every day, they left everything at 1:30 p.m. ET to meet and find out how close they got to their goal: to get NASA’s James Webb Space Telescope, the most powerful space observatory in the story, be fully operational.
During each meeting, they reviewed all the work they had done over the past 24 hours with the observatory, which is currently zooming through deep space about a million miles from Earth. Sometimes their tests and measurements had gone well the day before, and they were moving forward with the next task. Other times, there would be hiccups.
“We would also have our programmer there and say,‘ Okay, this one didn’t work, so it needs to be reprogrammed. Let’s put it on schedule as soon as we can so we can continue, ‘”he tells The Verge Friedman, the scientist in charge of the James Webb Space Telescope at the Space Telescope Science Institute, or STScI. “And that was a tricky business.”
“It was a complicated business”
It would always be a monumental task to launch the James Webb Space Telescope, or JWST. Equipped with the largest mirror we have ever sent into space, the observatory is ready to fundamentally transform astronomy as we know it by capturing the light of stars and galaxies that formed while the Universe was in the his childhood. But before JWST could begin collecting all these baby images of the cosmos, NASA and STScI, which oversees the telescope’s operations and science, had to know that all of JWST’s state-of-the-art instruments and hardware could work in tandem to get the job done.
Now, the commissioner team is finishing its work, having successfully completed all its tasks just a few weeks after its summer deadline. For a telescope that is already a decade behind, the equipment was remarkably punctual, all things considered. Thanks to his efforts, JWST is about to begin its first year of epic observations of science. This period of astronomy transformation will begin with the publication of the first full-color images taken by the observatory on July 12. NASA has not yet said exactly what the images will be, but we do know that they will include a detailed view of the atmosphere of a planet outside our Solar System and the “deepest image of our Universe ever taken,” according to to NASA administrator Bill Nelson.
“What I’ve seen only excites me,” Pam Melroy, NASA’s deputy administrator, said during a press conference before the image was released, “as a scientist, as an engineer, and as a human being.”
Aligned correctly
JWST has been on an odyssey. The observatory, which has taken about two and a half decades and nearly $ 10 billion to build, first had to survive the intensity of its launch on Christmas Day last year. Then, once it arrived in space, it underwent a complex and complex deployment process to achieve the proper configuration to observe the cosmos. (JWST was too big to throw himself in his final form, so he had to throw himself folded over himself like a well-packed Swiss Army knife.)
The development was a two-week-long nervous process that included hundreds of moving parts and more than 300 events known as single-point failures – procedures that had to work or could jeopardize the entire mission. But miraculously, or perhaps thanks to years of engineering and testing, the deployment went exactly as planned, with the mission team working until New Year’s Eve to deploy some of the most hardware. crucial of JWST.
JWST launching into space from French Guiana to South America on an Ariane 5 rocket. Photo by Bill Ingalls / NASA via Getty Images
But almost as soon as development was over, the team of engineers began to focus on the JWST mirror. The observatory’s iconic gold-plated mirror, which spans more than 21 feet in diameter, is actually made up of 18 hexagonal mirror segments that must be aligned so precisely that they work as if they were a single mirror. And they weren’t very prepared to do that. To begin with, engineers first had to remove each of the segments of the devices known as “snubbers”: equipment that kept the mirrors in a comfortable position for space travel. “We launched them in a safe position for launch, but it doesn’t necessarily allow you to move the mirrors back and forth to align them,” said Lee Feinberg, the elements manager for JWST’s optical telescope at NASA. and The Verge.
This process lasted a little over a week, with each segment moving half an inch from its launch positions. Still, that was just the beginning. “That wasn’t even an alignment,” Feinberg says. “That was getting to the point where we could start, really.” The team then had to wait for JWST’s main infrared camera, NIRCam, to cool down enough to be able to start using the instrument to collect images. Once NIRCam was nice and cool, they used the mirrors to take their first photo with JWST, pointing all the segments of the mirror towards a single bright star. The result: 18 different versions of this same star.
“That was getting to the point where we could start, really.”
This was what the team expected; all segments pointed in marginally different directions. Thus began the meticulous process of moving each segment of the mirror a little so that these 18 pieces would eventually behave as one. To adjust the position of a mirror, the team had to move the actuator to the back of the segment, slowly adjusting it in a tiny amount. The alignment team would use JWST’s instruments and take photos of their progress, sending these images to Earth. A number of algorithms would analyze the work and determine how to make further adjustments. Then the whole process would happen again. Step and repeat.
The mirror is segmented into JWST before launch. Photo of Northrop Grumman
Things were going by a snail’s pace, as each movement had to be done sequentially. And the team had to be very careful when moving each segment, checking the exact position of each piece when they had been made so that the mirrors would not collapse unintentionally. But finally, after three months of tedious work, JWST’s mirrors focused hard.
“When the mirrors started to align, they were shifted from one to the other in millimeters,” Feinberg says. “And when we finished, they were aligned to the nanometers, so a million improvement in alignment.”
Calibration
While the mirror alignment was underway, the rest of the startup team focused on JWST’s four main instruments. In addition to NIRCam, there are NIRSpec, MIRI and FGS / NIRISS. All four contain spectrographs, which break light into a spectrum that scientists can analyze for more information about distant objects. Three of them also have cameras (NIRSpec is the odd one). Just as the strings of a guitar must be tuned correctly before using them, so must the very complex instruments of JWST. The job of the start-up team was to calibrate each of the instruments to make sure they were ready and working properly when the first year of observatory science began.
JWST instruments were first started and checked when the mirrors were still aligned, as the equipment needed the camera and other instruments to help adjust the mirror segments. However, the most solid calibration work could not really begin until the mirrors were fully aligned, which took about four months.
“Each spacecraft has a very unique personality when put into orbit.”
Now, for the past two months, the team has been putting the instruments into practice, going through a long list of time-consuming measures. “Sometimes they were fast, but sometimes it was 12 hours of observation with a lot of associated observations,” Friedman says.
Some of this work involved simply using the instruments to observe standard stars, measuring their light and positions in the sky. The team then crossed out what they measured with what they know about these stars based on decades of past research to find the corrections that needed to be made. All cameras, even JWST’s NIRCam, have some distortion built into their images. According to Friedman, by measuring these distortions, teams can correct them in the future.
Some of the calibrations involved demonstrating the skill of JWST. The observatory can only have four main instruments, but each instrument has different modes of operation that offer different capabilities, and the start-up team had to test and verify each mode. The observatory as a whole also has different modes of operation that have had to be calibrated. For example, JWST will need to be able to track relatively fast moving objects such as asteroids and moons from the outer planets of our Solar System, so the launch team practiced this capability by fixing in test asteroids, using “guide” stars as references to the sky to make the asteroid appear still. It’s all a complicated job that hadn’t been tested in space before. “It’s one thing to write it down on a piece of paper and try everything you can on the ground, but it’s not the same as flying it,” Friedman says. “We have to prove these things.”
“None of these million things went wrong. They all went well.”
For the most part, Friedman says the whole calibration and commissioning process went very well, but …