JWST Deployment Continues Smoothly, Completion Now Within Sight

The “29 Days on the Edge” of the deployment of the James Webb Space Telescope are merrily marching along as the sunshield’s last two layers successfully tightened today. Only minor hiccups have occurred since launch on December 25 and the end is in sight. Granted, critical steps remain and it is no time to become complacent, but the telescope’s unfolding is proceeding remarkably smoothly.

The JWST team at the Space Telescope Science Institute in Baltimore, MD excitedly announced at 11:59 am EST today that the fifth and final layer of the sunshield was fully tensioned. The first three were done yesterday; numbers four and five today.

Thomas Zurbuchen, head of NASA’s Science Mission Directorate, called sunshield deployment the “most challenging” of all the many steps in the process of unfolding the telescope from its stowed configuration. The 6.5-meter diameter telescope is too big to fit inside the Ariane 5 rocket that sent it into space, so now must be carefully unfurled step-by-step.

JWST is a joint project among NASA, the Canadian Space Agency, and the European Space Agency. Among other things, ESA provided the launch at no cost to NASA on Europe’s Ariane 5 launch vehicle.

NASA’s JWST Program Director, Greg Robinson, commented that “thousands of parts had to work with precision for this marvel of engineering to fully unfurl. The team has accomplished an audacious feat with the complexity of this deployment – one of the boldest undertakings yet for Webb.”

The sunshield deployment involved 139 of the 178 release mechanisms on the $10 billion space telescope, including 70 hinge assemblies, eight motors, 400 pulleys, and 90 cables.

Northrop Grumman is the prime contractor for the JWST spacecraft. The company’s sunshield manager, Jim Flynn, said this “milestone represents the pioneering spirit of thousands of engineers, scientists, and technicians who spent significant portions of their careers developing, designing, manufacturing, and testing this first-of-its-kind space technology.”

NASA provided live coverage of the release of these last two layers, offering a glimpse into mission control at STScI.

After all was said and done, NASA Goddard Space Flight Center’s JWST Project Manager Bill Ochs congratulated the team.

This is a really big moment. I just want to congratulate the entire team. We’ve still got a lot of work to do, but getting the sunshield out and deployed is really, really big. It constantly reinforces what I tell everybody that the JWST team is the best in NASA. … This is so unique what we do in this mission. We’re going to be bonded forever by what we’ve experienced not only through operations and with the mission ops team, but with all those who have worked on it for over 20 plus years. … Congratulations, everybody.

As Ochs said, the work is not done yet. Several critical steps remain including release of the secondary mirror and the two wings of the 18-segment primary mirror.

The gold-plated primary mirror collects infrared emissions from objects in the universe and relays them to the secondary mirror at the end of a tripod-like structure, which then sends them into the instruments in the center of the primary mirror.

The primary mirror had to be constructed in three parts to fit inside the rocket. Three of the segments on the left, and three on the right, are on wings that must be deployed as the last steps of the process.

NASA sunshield manager James Cooper told reporters today at a media briefing that the goal is to have all deployments completed by Monday.

The telescope still must travel the rest of the way to its final destination, the Sun-Earth Lagrange Point-2 (SEL).  Once there, it must cool down to the very cold temperatures needed for operations and the 18 mirror segments fine tuned so they collectively see a single sharp image instead of many fuzzy ones. NASA expects the first images usable for scientific analysis to be ready about 6 months after launch.

JWST’s design lifetime is 5 years, but many, if not most, NASA science missions far exceed their design lifetimes. JWST carries enough fuel for 10 years of scientific operations and could last longer because the Ariane 5 put it onto such a precise trajectory that less fuel than expected has been needed for mid-course corrections.

The sunshield could also be a lifetime-limiting factor depending on how often it is struck by micrometeorites. Northrop Grumman’s Flynn said during today’s briefing that, based on testing, micrometeorites will not shred the sunshield, but break into smaller fragments when they hit the first layer. They will penetrate into other layers and “degrade the performance of the sunshield over time,” but the expectation is it will last for at least twice the design lifetime, or 10 years.