Webb Space Telescope deploys its sun shield

NASA’S revolutionary James Webb Space Telescope has transformed itself into what looks like a giant kite, successfully deploying a tennis-courtsize sun shield designed to keep it operating at extremely cold temperatures. This was the most nerve-racking phase of the $10 billion mission so far, one flagged repeatedly by officials who had reviewed plans for the telescope and wondered if such a novel design could reliably work.

The telescope launched Christmas morning from French Guiana atop an Ariane 5 rocket. The telescope, including the sun shield and all other hardware, was folded up inside the cone of the rocket. It has since had to unfurl itself while hurtling through space. Engineers tested the sun shield on the ground but could not duplicate the conditions of space.

The effort to unfurl and then tighten the fivelayer, 70-foot-wide sun shield — which NASA describes as providing protection against solar radiation equal to SPF 1 million — took several days, with commands sent from the Operations Center at the Space Telescope Science Institute in Baltimore.

The deployment concluded midday Tuesday with the “tensioning” of the fifth and final layer, a process involving mechanical release devices that account for more than half of the 344 potential single-point failures on this complex mission.

“It’s a unique design, never been tried before, never been built before, never been successfully deployed in orbit,” John Durning, the deputy project manager for the Webb mission, told The Washington Post early Tuesday.

The mission has had a couple of hiccups.

At one point, NASA project managers put deployments on pause to analyze readings from the solar array that were somewhat different from what they had expected and made technical adjustments. Durning said it’s important to avoid overtaxing the team, which is working 12-hour shifts that sometimes have to be extended.

All the major deployments to date — including that of the solar arrays needed to power the observatory — have gone splendidly, Durning said.

“I am thrilled,” he said. “I’ve been on the job 15 years. To see it unfurl in space, it’s awe-inspiring.”