NASA’s Webb telescope has begun unfolding its audacious gold-plated mirror

Georgina Torbet - Jan 7, 2022, 3:22pm CST
NASA’s Webb telescope has begun unfolding its audacious gold-plated mirror

The launch of the world’s most powerful space telescope, the James Webb Space Telescope, was just the beginning of this space-based observatory. Having left Earth’s atmosphere and traveled over 250,000 miles away from our planet, it is now more than 70% of its way to its final orbit around the sun (via NASA).

NASA/Desiree Stover

The telescope has to do more than just travel, though. Many of the observatory’s components need to be large to help it take the most accurate readings possible, but there is only a limited amount of room inside a rocket. Once the telescope was released into space, it needed to unfurl itself into its final configuration.

The observatory recently hit a big milestone when it finished deploying its five-layer sunshield, which is the size of a tennis court and needed to be tensioned into place. Now, it is continuing to unfold with its secondary mirror and heat radiator in place, and it can take on its next big challenge: Unfolding its incredible hexagonal primary mirror.

Deploying the primary mirror

Mirror in deployment testing

NASA/Chris Gunn

On Friday, January 7, engineers began the process of unfolding the primary mirror. Consisting of 18 hexagonal, gold-plated segments, the mirror is one of the telescope’s most visually striking components. The primary mirror needs to be large as this is directly related to how much light the telescope can detect, which makes it more accurate (via NASA). James Webb’s mirror is 6.5 meters (21ft) across, which is the largest ever launched into space. Compared to the 2.4-meter (7.8ft) mirror used on James Webb’s predecessor, the Hubble Space Telescope, this big mirror will help the telescope to see out further into space.

Engineers couldn’t just build a 6.5-meter (21ft) mirror like Hubble’s, though, because it would be too large and too heavy to launch. Instead, they built the James Webb mirror in segments made from beryllium, which is both lightweight and strong. These segments fold in on themselves to fit into the rocket, and now it is time for them to unfold into their final configuration.

So far, according to NASA, the engineers have deployed one of the two primary mirror wings, which are side panels that hold the mirror in place. Deployment of the port side mirror wing began at 8:36 AM ET and was completed at 2:11 PM ET.

The next phase is the deployment of the starboard wing, which is planned for the weekend. Then the telescope should be fully deployed into its final form, ready to continue its journey to its orbit.


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