James Webb Space Telescope (JWST) has been struck by a small space rock. A micrometeoroid hit one of its main mirrors, but NASA doesn’t expect a significant effect on the observatory’s data.
JWST launched at the end of 2021 and reached its permanent orbit in January. Since then, the craft’s engineering team has been preparing the telescope’s instruments for science observations. The most delicate and finicky part of the observatory is its primary mirror, which is made up of 18 smaller, hexagonal mirrors coated in gold.
The solar system is full of micrometeoroids, most about the size of a grain of dust, so one hitting JWST isn’t unexpected. The mirrors were designed to withstand small impacts and were tested for this before the spacecraft launched. However, the one that hit the telescope in May was larger than anything the NASA researchers tested or simulated on the ground, and because it wasn’t part of a meteor shower, nobody predicted it. Had they known it was coming, the telescope’s operators would have been able to manoeuvre the craft to avert a direct impact.
“We have had four smaller measurable micrometeoroid strikes that were consistent with expectations, and this one more recently that is larger than our degradation predictions assumed,” said JWST team member Lee Feinberg at NASA’s Goddard Space Flight Centre in a statement.
While the impact’s effect on the telescope is detectable, it was found that future images won’t be degraded too badly. For now, JWST is still performing well above the level required for its planned science observations, including those of the early universe and the very first galaxies.
