NASA’s mighty new space telescope is hit by a larger-than-expected micrometeoroid

NASA’s powerful new space observatory, the James Webb Space Telescope, was bombarded by a larger-than-expected micrometeoroid in late May, causing detectable damage to one of the spacecraft’s 18 main mirror segments . The impact means the mission team will have to correct for the distortion created by the strike, but NASA says the telescope is “still operating at a level that exceeds all mission requirements”.

NASA’s James Webb Space Telescope, or JWST, is the agency’s incredibly powerful next-generation space telescope, designed to peer into the farthest reaches of the Universe and see stars and galaxies in time. are formed just after the Big Bang. It cost NASA nearly $10 billion to build and more than two decades to complete. But, on Christmas Day 2021, the telescope was finally launched into space, where it underwent an extremely complex deployment process before reaching its final destination about 1 million kilometers from Earth.

Since its launch, JWST has already been hit by at least four different micrometeoroids, according to a NASA blog post, but all of them were small and about the size NASA expected the observatory to have. A micrometeoroid is usually a small fragment of an asteroid, usually smaller than a grain of sand. The one that hit JWST in May, however, was larger than the agency had prepared for, though the agency didn’t specify its exact size. NASA admits the strike, which occurred between May 23 and May 25, caused a “marginally detectable effect in the data” and that engineers are continuing to analyze the effects of the impact.

NASA expected JWST to be hit by tiny space particles during its lifetime; Fast-moving grains of space rock are just one inescapable feature of the deep space environment. In fact, NASA designed the telescope’s gold-coated mirrors to withstand impacts from tiny space debris over time. The space agency also performed a combination of simulations and ground tests with sample mirrors to determine how best to strengthen the mirrors to withstand micrometeoroid impacts. However, NASA says the models they used for these simulations didn’t have such a large micrometeoroid, and that was “beyond what the team could have tested in the field.”

However, this is not a complete surprise. “We always knew Webb would have to contend with the space environment, which includes harsh ultraviolet light and charged particles from the Sun, cosmic rays from exotic sources in the galaxy, and occasional micrometeoroid strikes in our solar system,” Paul Geithner, technical deputy project manager at NASA’s Goddard Space Flight Center, said in a statement.

JWST’s main mirror being tested on Earth
Image: NASA

Engineers also have the ability to maneuver the JWST’s mirror and instruments away from rains of space debris, if NASA can see them coming. The problem, however, was that this micrometeoroid was not part of a shower, so NASA considers it an “inevitable chance event.” Still, the agency is training a team of engineers to find ways to avoid or potentially mitigate the effects of micrometeoroid impacts of this size. And since JWST is so sensitive, the telescope will also help NASA better understand how many micrometeoroids there are in the deep space environment.

Despite the strike, NASA remained optimistic in its article on JWST’s future. “Webb’s early-life performance is consistently well above expectations, and the observatory is fully capable of performing the science it was designed to do,” according to the blog. Engineers can also adjust the impacted mirror to help undo data distortion. The mission team has done this before and will continue to tinker with the mirror over time to get the best results. This is a process that will continue throughout the JWST’s expected five to ten years of life, as new observations are made and events unfold. At a time, NASA warns engineers won’t be able to completely undo the impact of the strike.

NASA engineers had to build JWST to be incredibly robust since the telescope is alone in space. Unlike its predecessor, the Hubble Space Telescope, which is currently orbiting Earth, JWST was not designed to be usable. This means that if something major breaks on the spacecraft, engineers will have to find a way to fix it from the ground. There is no capability at this time to send humans or a robotic spacecraft to give JWST a tune-up. This means that JWST will have to live with its slightly damaged mirror until the end of its mission, and NASA expects the spacecraft to be hit with even more debris over time.

In the meantime, the strike does not appear to have any impact on JWST’s schedule. In fact, news of this micrometeoroid comes just a month before a mission milestone. After spending the last few months finely calibrating JWST’s instruments and delicately aligning the spacecraft’s mirrors, the mission team is expected to unveil the first color images of JWST on July 12. NASA won’t say what the images will be, but they should be spectacular.

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