Facing another launch delay, work resumes on James Webb Space Telescope

Northrop Grumman engineers monitor a test of the mechanism that will be used to slightly separate the James Webb Space Telescope’s mirrors and instruments from the heat generated by the spacecraft’s electronics and propulsion systems after the observatory reaches orbit. Image: Northrop Grumman

After weeks of downtime in the wake of the coronavirus, engineers have resumed near-normal work readying the James Webb Space Telescope for launch. Most recently, the deployable tower assembly, a telescoping structure will be used to separate JWST’s mirrors and instruments from hotter sections of the spacecraft, was extended in a key test at Northrop Grumman’s California manufacturing facility.

NASA managers are assessing the impact of the COVID-19 work stoppage on JWST’s eventual launch date. NASA science chief Thomas Zurbuchen said earlier this week that launch, which had been targeted for next March, will be delayed to later in the year.

“We will not launch in March, absolutely will not launch in March,” he told the Space Studies Board of the National Academies of Sciences, Engineering and Medicine. “That is not in the cards right now. It’s not because they did anything wrong. It’s just not going to be in the cards, and it’s not a fault, or mismanagement of some type.”

He said senior managers plan to meet next month to establish a revised timeline.

“I’m very optimistic of this thing getting off the launch pad in ’21,” he said, but added “there still is a lot of mountain to climb.”

The deployable tower assembly, or DTA, is a critical component that will enable the telescope to operate at the ultra-low temperatures required for its planned infrared observations of the early universe.

Resembling a large black pipe, the DTA is made out of graphite-epoxy composite material, stretching 3 metres (10 feet) when full extended. To fit inside the Ariane 5’s 5.4-metre (17.8-foot) nose fairing, the James Webb however, the DTA will extend, separating the telescope’s mirrors and instruments from the spacecraft bus housing its electronics and propulsion systems.

By opening a gap between the two sections, the DTA will help JWST’s active and passive cooling systems to down to their operating temperature of around 50 degrees above absolute zero.

“The deployable tower assembly worked beautifully during the test,” said Alphonso Stewart, lead engineer of the observatory’s deployment systems. “It performed exactly as predicted. This was the first time that this part of Webb was tested in its flight-like configuration to the highest level of fidelity we possibly could.”