
The Webb Space Telescope Will Rewrite Cosmic History. If It Works.
The James Webb Space Telescope has the potential to rewrite the history of the cosmos and reshape humanity’s position within it. But first, a lot of things have to work just right.
I think all of space science is really going to be holding its breath for this launch and deployment! Soooo many things that can go wrong.My only kvetch is with the title: “If it works.” Jinx, much?
On Monday, six motors on board the telescope began the process of fully extending the first of five layers of the sunshield. These tennis-court sized layers, each made of a polyimide film called Kapton, will shade the instrument and allow it to cool down to 50 Kelvin, which is -223 degrees Celsius and just 50 degrees above absolute zero. This cold environment is critical for Webb to observe infrared light and detect heat from very distant objects.
NASA's Webb project manager, Bill Ochs, said the first of these five layers should be completely deployed by the end of Monday. The goal is to extend the other four layers on Tuesday and Wednesday. After this time, the massive sunshield—the most complex aspect of an intricate deployment process—will be complete.
"I don't expect any drama," said Ochs of the next few days during a teleconference with reporters on Monday.
Following this sequence, NASA will be most of the way there. All told, from launch through commissioning, the Webb instrument must undergo 344 actions where a single-point failure could scuttle the telescope. Following sunshield deployment, Ochs said the Webb instrument will be through "70 to 75 percent" of these single-point failures.
The other major activities yet to be completed are the deployment of the secondary mirror support structure and the unfolding of the second of Webb's primary mirror wings. These activities could both be finished by this weekend and would effectively complete the deployment phase.
Although science operations will not begin until mid-2022, NASA engineers and thousands of scientists will then start to breathe a sigh of relief. It took 20 painstaking years to get Webb into space, and after fewer than 20 days, the telescope will either be fully deployed—or it won't.
The James Webb Space Telescope has finally arrived at its new home. After a Christmas launch and a month of unfolding and assembling itself in space, the new space observatory reached its final destination, a spot known as L2.
Guiding the telescope to L2 is “an incredible accomplishment by the entire team,” said Webb’s commissioning manager Keith Parrish in a January 24 news conference announcing the arrival. “The last 30 days, we call that ’30 days on the edge.’ We’re just so proud to be through that.” But the team’s work is not yet done. “We were just setting the table. We were just getting this beautiful spacecraft unfolded and ready to do science. So the best is yet to come,” he said.
The telescope can’t start doing science yet. “We’re a month in and the baby hasn’t even opened its eyes yet,” said Jane Rigby of NASA Goddard Space Flight Center in Greenbelt, Md. “Everything we’re doing is about getting the observatory ready to do transformative science. That’s why we’re here.”
There are still several months’ worth of tasks on Webb’s to-do list before the telescope is ready to peep at the earliest light in the universe or spy on exoplanets’ alien atmospheres (SN: 10/6/21).
“That doesn’t mean there’s anything wrong,” says astronomer Scott Friedman of the Space Telescope Science Institute in Baltimore, who is managing this next phase of Webb’s journey. “Everything could go perfectly, and it would still take six months” from launch for the telescope’s science instruments to be ready for action, he says.
Here’s what to expect next.
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At this point, the mirror is aligned to the telescope's primary instrument, the Near-Infrared Camera. The telescope, however, has four additional instruments, and the next few steps will see alignment with each of the remaining instruments so that the mirrors are positioned to perform well with all the hardware. In addition to NASA's ability to tweak the positioning, shape, and curvature of the segments, the secondary mirror and the instruments themselves can be shifted to ensure an alignment.
Final tweaking may take place after this process is complete, but after that, nothing will be left other than the ongoing calibration needed to keep everything aligned. According to NASA, the alignment process is expected to be complete by early May at the latest.
The mirror is now working with all five instruments, and limited only by physics.
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But we're not quite ready to start sciencing just yet. Each of Webb's instruments includes a variety of mechanical hardware, such as filters that block out specific wavelengths. This hardware has to be checked out to confirm it's functioning as planned, a process called instrument commissioning. That process is expected to take roughly two months, allowing science operations to start in mid-June.
In the meantime, NASA will also test the telescope's cooling systems and validate its testing/correction procedures to ensure that the primary mirror remains properly aligned.