James Webb Space Telescope was hit by micrometeoroids five times since its launch

Between May 23 and 25, the James Webb Space Telescope (JWST) was hit by a micrometeoroid that has impacted one of its primary mirror segments, NASA said in a recent update on its website. The telescope continues to function at levels exceeding mission requirements.

A meteoroid is a fragment of an asteroid and can be either large or small. A micrometeoroid, though, is a microscopic fragment of a meteoroid and is smaller than a grain of sand. NASA estimates that millions of meteoroids and micrometeoroids strike the Earth's atmosphere every day but most burn up due to the friction.

Outer space, however, does not have any atmosphere, and spacecraft are at high risk from these particles. Even though their size might be small, micrometeoroids travel at extreme velocities and are one of the greatest factors space agencies take into account when building spacecraft, and the JWST was no exception. 

Built to withstand hits and much more

Engineers at NASA were well aware of the harsh environment at the L2 orbit that the JWST would occupy. From bearing cosmic rays originating from the distant depths of the galaxy to withstanding the impact of ultraviolet light and charged particles from the Sun, NASA's engineers have prepared the space telescope to remain strong in all scenarios.

"We designed and built Webb with performance margin – optical, thermal, electrical, mechanical – to ensure it can perform its ambitious science mission even after many years in space," said Paul Geithner, technical deputy project manager at NASA’s Goddard Space Flight Center in the update. 

To gain information on how to fortify the spacecraft against micrometeoroids, engineers used a mix of simulations as well as actual test impacts on mirror samples. Additionally, the space telescope's design allows the position of its mirrors to be adjusted to cancel out the distortion an impact may create. 

Webb Space Telescope's micrometeoroid hits

Lee Feinberg, the Webb optical telescope element manager at NASA, said that the space agency had observed four smaller but measurable micrometeoroid hits since the launch of the space telescope. The fifth one that occurred between May 23 and 25 was larger than NASA had predicted and caused an impact on the telescope's mirrors. 

Engineers have already performed adjustments to the C3 mirror that was impacted in the hit and have planned other adjustments to fine-tune corrections if needed in the future. The space agency has also formed a special team of engineers to look for ways to mitigate the effects of such future hits. 

The JWST's flight teams are also equipped to perform maneuvers such as turning away the telescope's optics to protect them from known meteor showers. Since the latest incident was not a part of a meteor shower, NASA has classified it as an unavoidable chance event. 

Although there is a marginal detectable effect on the data received from the telescope, after initial assessments, NASA is confident that the telescope is performing above its mission requirements. The incident is not expected to impact JWST's operation schedule, and efforts continue to get the space telescope ready for its science operations.