The Webb telescope, named after a former NASA administrator, left Earth in a thundering launch from a rain-forest-ringed spaceport. The mood in town in the days before launch was cheery optimism, with an undercurrent of low-grade panic. When I asked the engineers and scientists there about the launch, they would make a bit of a nervous face before returning to a confident expression. The launch wasn’t the scary bit; Webb was riding on one of the most reliable rockets in the industry. The deployment sequence was another story. When I asked them about that, their face would turn into a perfect imitation of the grimace emoji. Astronauts managed to build the International Space Station in orbit, yes, and to repair the Hubble Space Telescope when it needed fixing. But they wouldn’t be able to help Webb after it launched. The mission is a very complicated series of “this has to work” moments. If something had jammed during deployment and couldn’t get unstuck, the next Hubble would have become a new piece of space junk.
The first “this has to work” moment came just a half hour after Webb launched. The observatory released its solar panel, stretching it like an insect arching a wing toward the sun. Now the observatory could power itself and could move on with ever more complex steps on the checklist that has consumed the scientists until today.
From there, the deployment sequence reminded me of The Great British Bake Off, a cosmic version of the Showstopper Challenge. Like the bakers, engineers had presented the world with a picture of what their beautiful space telescope would look like in the end, and now they had to make it happen. Astronomers around the world, eager to use Webb’s data in their research, braced themselves for some kind of catastrophe to topple the effort. They ran into a couple of issues but managed to adjust; when some motors became a little overbaked by the sun, for example, engineers shifted the observatory slightly away to reduce the heat. Some employees tested positive for the coronavirus and isolated themselves at home, where they continued working remotely.
The release of Webb’s diamond-shaped sun shield, the cover that will protect the observatory’s mirrors and instruments from our star’s glare, was undoubtedly the most stressful part. The five-tiered shield is the size of a tennis court, and each layer is made of material as thin as a human hair. Engineers had warned, in the days before launch, that this sun shield, floppy and unpredictable, could snag and potentially doom the whole mission. But earlier this week, each layer snapped into its final position, just as engineers had imagined. “We’ve nailed it,” Alphonso Stewart, Webb’s deployment systems lead, told reporters after it happened. And then this morning, engineers completed the last big “has to work” moment, moving the telescope’s mirrors into their final honeycomb shape.
Perhaps few are more surprised at this outcome than some of the people who work on the mission itself. [Continue reading…]