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Why there aren’t cameras to capture the unfolding of James Webb Space Telescope

With the final deployment of the James Webb Space Telescope today, you might be disappointed to learn there won’t be any photos or videos of the telescope unfolding.

When the Perseverance rover landed on Mars last year, the public was treated to stunning images of the rover being lowered from its descent stage onto the planet’s surface. There was even a video of the landing, showing this remarkable event from multiple angles captured by cameras placed all over the rover’s landing system.

So how come there aren’t similar cameras showing the unfolding of the James Webb Space Telescope?

In a recent blog post, NASA revealed that they did consider putting cameras on the telescope to cover its deployment. These cameras could also have been useful for diagnosing any problems which occurred during the telescope’s deployment or operations. However, when the proposal was examined in-depth, the team found that it was not going to work.

“Adding cameras to watch an unprecedently complicated deployment of such a precious spacecraft as Webb sounds like a no-brainer, but in Webb’s case, there’s much more to it than meets the eye,” said Paul Geithner, deputy project manager-technical for the Webb telescope at NASA’s Goddard Space Flight Center, in the post. “It’s not as straightforward as adding a doorbell cam or even a rocket cam.”

There are two big challenges to having cameras on Webb. The first is that, because the telescope unfolds in an elaborate process, there wouldn’t be one single location where a camera could observe all of the deployment processes. There would have to be multiple cameras, and the wiring for these would have to run across the telescope, potentially causing problems.

The other big issue is one of light from the sun. Webb is designed to reflect sunlight away from its sun-facing side, so it doesn’t get too hot, but that means that this side is very shiny which would cause constant glare for cameras. On the cold side of the telescope, there wouldn’t be enough light for cameras to see anything, and these cameras would have to work at very low temperatures.

In the end, the engineers decided that Webb’s other sensors would be more useful than cameras to get a picture of the condition of the telescope.

“Webb’s built-in sense of ‘touch’ (for example, switches and various mechanical, electrical, and temperature sensors) provides much more useful information than mere surveillance cameras can,” said Geithner.

“We instrumented Webb like we do many other one-of-a-kind spacecraft, to provide all the specific information necessary to inform engineers on Earth about the observatory’s health and status during all activities.”

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