James Webb Space Telescope hit by large micrometeoroid
NASA’S next-generation space observatory has sustained its first noticeable micrometeoroid impact less than six months after launch. The James Webb Space Telescope launched in December 2021. It has spent the intervening months trekking out to its deep-space post and preparing for science observations, a complicated process that has gone remarkably smoothly. The space agency recently announced that the observatory has experienced its first few impacts from tiny pieces of space debris called micrometeoroids. But don’t panic: neither the observatory’s schedule nor its scientific legacy is expected to suffer.
“With Webb’s mirrors exposed to space, we expected that occasional micrometeoroid impacts would gracefully degrade telescope performance over time,” said Lee Feinberg, Webb optical telescope element manager at NASA’S Goddard Space Flight Center in Maryland. “Since launch, 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.”
All spacecraft are expected to experience and withstand micrometeoroid impacts, and Webb is no different. The observatory’s engineers even subjected mirror samples to real impacts to understand how such events might affect the mission’s science. However, the recent impact was larger than those that mission personnel had modelled or could test on the ground. Despite the impact coming so early in the observatory’s tenure, NASA officials are confident that Webb will still perform adequately.
Some micrometeoroid impacts can be predicted. For example, when the spacecraft is set to fly through known meteor showers, personnel can manoeuvre Webb’s optical systems into safety for these events. However, the recent impact was not part of such a meteor shower and was classified as an unavoidable chance event. After an impact occurs, engineers can individually adjust the 18 primary mirror segments on the observatory to keep the mirror as a whole finely tuned. As the Webb team continues to evaluate the impact, NASA is focused on better understanding both the particular event and the environment that the observatory will experience throughout its mission. The telescope is orbiting what scientists call the Earth-sun Lagrange point 2, located nearly a million miles away from Earth in the direction opposite the Sun.