A micrometeoroid that struck the Webb Telescope in late May caused permanent damage to the observatory, according to a report from the Space Telescope Science Institute.
The report, released last week by NASA and the European and Canadian space agencies, detailed the telescope's science performance through July 12, 2022, the day the telescope's first images were publicly released, and included a fascinating first look at the planet Jupiter as seen by Webb.
According to the analysis, the impact “exceeded pre-launch damage expectations for a single micrometeoroid.” The Webb Telescope team is now studying how to predict and mitigate future damage.
Micrometeoroids are pieces of rock that fly through space. When orbiting Earth, these rocks can reach speeds of up to 22,000 miles per hour and pose a regular hazard to astronauts, satellites , and spacecraft.
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In early June, a NASA announcement said a micrometeorite struck one of the Webb Telescope's hexagonal mirrors between May 23 and 25. The new report estimates the impact occurred between May 22 and May 24.
"We always knew that the Webb Telescope would have to overcome the space environment, which includes ultraviolet light and charged particles from the sun, cosmic rays from exotic sources in the galaxy, and occasional impacts from micrometeoroids within our solar system," said Paul Geithner, technical associate project manager at Goddard Space Flight Center , in a June release.
The Webb Telescope's mirrors were meticulously aligned to produce high-resolution images of very faint light sources in the distant universe. The recent report compared ground-based measurements of the optical quality of the mirror sections with the telescope's current quality. A significant error was found in section C3.
Because the C3 segment is only one of 18 hexagonal mirrors that make up the telescope's primary mirror, damage from micrometeoroids is relatively minor at the level of the entire telescope, the report said.
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Despite the damage, the team's initial assessment indicates that the Webb Telescope "should meet optical performance requirements for many years." Thanks to the telescope's precise launch, it is expected to be operational for 20 years and will spend its entire lifetime in L2, a point in space about a million miles from Earth.
The big unknown, the team said, is the rate at which the mirrors will degrade from micrometeoroids. In other words, how many more damaging space particles than expected will hit the $. At the time of the June announcement about the May impact event, the team had identified four micrometeoroid impacts that were in line with their expectations for such events, but the largest impact is a cause for concern. If the Webb Telescope is more susceptible to micrometeoroid impacts than scientists had expected, its mirrors will degrade sooner than expected.
It's possible that the team could shield Webb's optics from micrometeoroid impacts to protect its mirrors, but for that to happen, the impacts would have to be predicted. The Webb Telescope has been long overdue here on Earth, but for an observatory that launched and went live without a hitch, it was only a matter of time before space would throw a wrench into the Webb scientists' plans.
Source: gizmodo.com
