The massive mirror of the Webb telescope hit by a micrometeoroid

One of the 18 golden segments of the James Webb Space Telescope’s giant mirror has been hit by a micrometeoroid, according to an update from NASA.

But while the space observatory said it happened in May, it is still on track to share its first high-resolution, color images of the telescope on July 12.

A micrometeoroid is a particle in space that is smaller than a grain of sand. The Earth’s atmosphere is regularly hit by millions of meteoroids and micrometeoroids, but most are vaporized when they hit the atmosphere, according to NASA.

The fully assembled James Webb Space Telescope with its sunshield and unitized vane structures that will fold around the telescope for launch. (NASA)

But spacecraft don’t have a bubble of protective atmosphere around them, so it’s almost impossible to avoid these impacts.

The Webb Telescope suffered such an impact between May 23 and 25, but “the telescope is still operating at a level that exceeds all mission requirements despite a marginally detectable effect in the data,” according to the Webb team.

The team continues to analyze and assess what happened and how it may affect the telescope’s performance. It’s also likely the first of many such experiences Webb will have during his time in space.

When the telescope and its massive mirror were built and tested on Earth, engineers made sure the mirror could survive the micrometeoroid environment the spacecraft would experience in its orbit about a million miles from Earth at some point. called L2, where the dust particles are accelerated. at extreme speeds.

Webb was put through his paces on Earth, and the team used both simulations and test impacts on sample mirrors to figure out what he would be up against.

May’s impact event was bigger than anything the team tested or could have modeled while Webb was still in the field.

“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,” said said Paul Geithner, technician. deputy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a statement.

“We designed and built Webb with a margin of performance – optical, thermal, electrical, mechanical – to ensure that it can accomplish its ambitious scientific mission even after many years in space.”

NASA has released an image captured by the Webb Telescope using its Mid-Infrared Instrument (MIRI). (NASA/ESA/CSA/STScI)

Fortunately, each hex mirror segment is fully adjustable, and the impacted segment has already been adjusted to alleviate some of the distortion. This is something engineers can continue to do in the future by monitoring Webb’s mirror for any signs of degradation in the space environment.

Webb’s flight team already moves the spacecraft’s mirror away from known events, like meteor showers, to protect the telescope’s optics. But this impact, which was not part of a meteor shower, was unplanned and “an unavoidable fortuitous event”, according to NASA.

“Because of this impact, a team of specialist engineers has been formed to research ways to mitigate the effects of new micrometeoroid hits of this magnitude,” according to a statement from the agency.

The Webb team will work closely with micrometeoroid prediction experts at NASA’s Marshall Space Flight Center in Huntsville, Alabama. and Webb will be able to help NASA scientists learn more about the solar system’s dusty environment at this point in orbit, which can help prepare for future missions.

“With the Webb mirrors exposed to space, we expected occasional micrometeoroid impacts to gracefully degrade the telescope’s performance over time,” said Lee Feinberg, Webb Optical Telescope Elements Manager at NASA. Goddard, in a press release.

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“Since launch we have had four smaller measurable micrometeoroid impacts which were in line with expectations and this one more recently which is larger than our assumed degradation predictions. We will use this flight data to update our analysis of performance over time and also developing operational approaches to ensure that we optimize Webb’s imaging performance for many years to come.”

Webb has already exceeded expectations since its launch in December, and the telescope is preparing for the start of science operations.

Webb will be able to peer into the interiors of exoplanet atmospheres and observe some of the earliest galaxies created after the universe began by viewing them through infrared light, which is invisible to the human eye.

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