James Webb Space Telescope Completes Deep-Freeze Testing

James Webb Space Telescope Completes Deep-Freeze Testing

NASA’s long-running James Webb Space Telescope project is nearing completion, but it needs a lot of testing before the agency sends it up into space where any undetected issues could prove disastrous. Several months ago, the completed telescope optical hardware was loaded into a vacuum chamber and cooled to extremely low temperatures. After removing Webb from the deep freeze, NASA now reports that all systems are go.

About $10 billion has been spent building the James Webb Space Telescope, but the construction phase was finished way back in late 2016. Since then, NASA has been conducting tests on the hardware to ensure it will operate correctly once in space. It would obviously like to avoid a repeat of Hubble’s launch, which required a Space Shuttle mission to correct its blurry vision in the early 90s. However, Webb will be much farther away than Hubble at the Earth-Sun L2 Lagrangian point.

Webb will be subjected to frigid temperatures at the L2 Lagrangian point, so the deep freeze test is a necessary step before launch. Engineers loaded the telescope into Chamber A at Johnson Space Center, which was depressurized and cooled to almost absolute zero (20-40 Kelvin). First on the agenda, NASA tested to make sure the 18 individual mirror segments would move and operate as a single unit in a cold vacuum — they worked perfectly. Next, the guidance system underwent testing. The team simulated the light of a distant star and told the telescope to track it. Webb’s sensors were able to spot the false star and follow it as it moved.

This phase of testing ended in late 2017 as the telescope was removed from the vacuum chamber, but the results give NASA confidence all the optical systems will work correctly in space. However, there’s still more testing to do. While construction of the Webb is complete, the hardware isn’t all integrated yet. The telescope’s next stop is Northrop Grumman’s facilities in Los Angeles. That’s where the optical component will join the main spacecraft body.

A render of Webb’s final configuration.
A render of Webb’s final configuration.

Engineers will go over the systems to ensure the sunshield deploys properly. Over 180 components need to work perfectly for the sunshield to deploy, and that’s essential to the mission. The shield protects Webb from the heat of the sun, allowing it to take more accurate mid-infrared readings. Scientists will also test that the hardware can survive the vibration associated with launch.

The James Webb Space Telescope will eventually make its way to French Guiana for launch aboard an ESA Ariane 5 rocket. That should happen in Spring 2019 if there are no delays.

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