NASA engineers successfully test deployment of second James Webb Space Telescope mirror

NASA engineers successfully test deployment of second James Webb Space Telescope mirror
Image courtesy of NASA.

Engineers at the US National Aeronautics and Space Administration (NASA) have successfully tested the system that will deploy the secondary mirror of the James Webb Space Telescope (JWST), the agency said on 6 August.

The James Webb Space Telescope is a large, space-based observatory, optimized for infrared wavelengths, which will complement and extend the discoveries of the Hubble Space Telescope. It is expected to launch in 2021.

NASA intends for the telescope to cover longer wavelengths of light than Hubble and to have greatly improved sensitivity. The longer wavelengths should let it “look further back in time to see the first galaxies that formed in the early universe, and to peer inside dust clouds where stars and planetary systems are forming today”.

Before it can do any of these things, the telescope must “perform an extremely choreographed series of deployments, extensions and movements” to “bring the observatory to life” shortly after launch. In its fully deployed form, the telescope is too big to fit in any rocket available so it has been “engineered to intricately fold in on itself to achieve a much smaller size during transport”.

Technicians and engineers recently tested commanding the JWST to deploy the support structure that holds its secondary mirror in place. NASA sees this as is a critical milestone in preparing the observatory for its journey to orbit.

“The proper deployment and positioning of [the JWST’s] secondary mirror is what makes this a telescope – without it, Webb would not be able to perform the revolutionary science we expect it to achieve,” Lee Feinberg, optical telescope element manager for the JWST at NASA’s Goddard Space Flight Centre in Maryland, said in a statement that included a time-lapse video of the test.

“This successful deployment test is another significant step towards completing the final observatory,” he added.

It also demonstrated that the electronic connection between the spacecraft and the telescope is working properly, and is capable of delivering commands throughout the observatory as designed.

The secondary mirror is one of the most important pieces of equipment on the telescope, and is essential to the success of the mission. When deployed, this mirror will sit out in front of the JWST’s hexagonal primary mirrors, which form an iconic honeycomb-like shape.

This smaller circular mirror serves an important role in collecting light from the telescope’s 18 primary mirrors into a focused beam. That beam is then sent down into the tertiary and fine steering mirrors, and finally to its four powerful scientific instruments.

The project’s next significant milestone will be the mating of the two halves of the telescope, which are being built separately. The construction of the telescope has been marred by delays and cost overruns that have pushed the launch date from 2018 to 2021.

The JWST is named after James E. Webb, NASA’s second administrator. Webb is best known for leading Apollo, a series of lunar exploration programs that landed the first humans on the Moon. He also initiated a vigorous space science program that was responsible for over 75 launches during his tenure, including America’s first interplanetary explorers.

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