NASA’s James Webb Space Telescope is about to transform into its final form

NASA’s incredibly powerful James Webb Space Telescope has been in space for three days now, but perhaps the riskiest part of its journey to deep space is just getting underway. Soon, the telescope will initiate an intricately choreographed mechanical dance as it slowly contorts its shape and unfurls, in order to reach its final form for observing the distant cosmos.

It’s a type of reverse space origami that’s never been performed before, but it’s absolutely necessary for the James Webb Space Telescope, or JWST, to fulfill its mission. The telescope was simply too massive to launch on any operational rocket while fully extended. So when it catapulted into space on top of a European Ariane 5 rocket on Christmas Day, it made the nail-biting trip folded in on itself like the world’s most expensive Swiss Army knife.

Now over the course of the next two weeks, JWST will twist and reshape — deploying one beam here, a mirror there — until it is completely configured for peering into the deepest parts of the Universe. “We sometimes call Webb the ‘Transformer Telescope,’” Amy Lo, the JWST alignments engineer at the telescope’s primary contractor Northrop Grumman, tells The Verge. It’s a daunting process with hundreds of moving parts that engineers have tested over and over again on the ground, as it has to be nothing short of flawless. But there are many points along the way where the failure of one small release mechanism or pulley could jeopardize the future of the entire JWST mission. While mission controllers on the ground have a few troubleshooting techniques they can employ if something gets stuck, ultimately the JWST spacecraft must do every deployment on its own to near perfection.

JWST completely folded up on top of the Ariane 5 rocket before launch.
Image: NASA / Chris Gunn

JWST is heading to a final destination roughly 1 million miles from Earth, and there are no operational rockets or spaceships that can safely bring astronauts to such a distance to give the telescope a tuneup. And even if humans could reach it, JWST just isn’t designed to be serviceable. So if the telescope breaks in a fundamental way, that’s it for a mission that is running NASA a total of $9.7 billion.

It may all sound like needless complexity for a mission of this magnitude, but there never was an easy path for JWST, according to NASA. “I actually strongly believe it’s not possible to make it simpler within the constraints that we have,” Thomas Zurbuchen, the associate administrator for the science mission directorate at NASA, tells The Verge. “This is what it is.”

Designers of JWST knew from the beginning that their creation would have to unfold while in space. In 1996, when scientists first proposed making a telescope like this, NASA’s administrator at the time, Dan Goldin, challenged engineers to create the spacecraft with a primary mirror that was up to eight meters wide. Ultimately, designers settled on a mirror that was 6.5 meters, or 21 feet across, but that decree determined JWST’s folded fate.

That’s because the largest rockets currently flying aren’t wide enough to carry a mirror of that size. Whenever you launch something into space, the spacecraft has to fit inside a rocket’s payload fairing — the bulbous structure that sits on top of the rocket throughout the first part of flight. The fairing is critical, as it shrouds the spacecraft during launch, protecting the payload from the atmosphere until reaching space. However, the fairing’s width is a major limiting factor for a spacecraft’s design, since the vehicle must fit inside. It’s a problem that those in the space industry often refer to as the “tyranny of the fairing.”

JWST’s primary mirror folded vs fully deployed
NASA/Chris Gunn

The Ariane 5 rocket has one of the widest payload fairings currently on the market, spanning 5.4 meters, or nearly 18 feet wide. But that’s still too small to house JWST’s mirror fully extended. So from the start, JWST mission designers built the mirror in segments, with two flaps on either side that could swivel inward and outward. It was a major design challenge, as the segments need to come together to behave like a single, flat mirror in order to gather light from the distant cosmos. “Unfurling a primary mirror has never been done before on orbit in space,” says Lo.

JWST will deploy its mirror flaps around 12 to 13 days after launch. But before that happens, the observatory has an even more complex deployment that it must get through, one that will take up to six…

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