getty Scientists report that the damage caused to the James Webb Space Telescope (JWST) during a micrometeoroid in late May 2022 may be worse than first thought. In a new paper published in the wake of Webb’s incredible first images last week, a team of scientists described the space telescope’s performance during its startup phase. They reported problems that “cannot be fixed” as well as a “small effect on the performance of the telescope, which is not yet measurable.” Writing about the projected lifetime of the Webb telescope, the report said: “At present, the biggest source of uncertainty is the long-term effects of micrometeoroids that slowly degrade the primary mirror.” As I mentioned earlier, Webb’s 6.5m primary mirror comprises 18 beryllium-gold segments. One of them, called C3, was struck by small dust particles between May 23 and 25, 2022. Since launch, Webb has been hit by five other, smaller micrometeoroids. A small strike per month is about what engineers predicted before launch. “After initial evaluations, the team found that the telescope is still performing at a level that exceeds all mission requirements,” Thomas Zurbuchen, Associate Administrator in NASA’s Science Mission Directorate, said in a tweet after the C3 hit. However, the new report suggests that the damage to the C3 segment could be more severe than first thought. “Of the six micrometeoroid impacts detected so far through wavefront detection, five had negligible effects,” the report states. Wavefront detection refers to the aberrations detected in the Webb optics. “In contrast, the micrometeoroid that hit segment C3 on 22-24 May 2022 UT caused a significant non-corrective change in the overall shape of this segment.” Additionally, the report said this event “exceeded pre-launch damage expectations for a single micrometeoroid, sparking further research and modeling by the JWST project.” Illustration of the James Webb Space Telescope. NASA GSFC/CIL/Adriana Manrique Gutierrez Although it may have enough propellant to last 20 years—a decade longer than previously expected—the engineers who designed Webb know that its mirrors and solar shield will inevitably be slowly degraded by micrometeoroid impacts. It is also expected that Webb’s probes will gradually be damaged by charged particles, while the solar shield and innovative five-layer insulation will be degraded by space weather. Since its mirror is exposed to space, it is difficult for Webb to avoid micrometeoroid impacts. “Inevitably, any spacecraft will encounter micrometeoroids,” says the report, which describes “six identified surface deformations on the primary mirror attributed to impact by micrometeoroids.” Was the “C3 crash” an accident? “It is not yet clear whether the May 2022 impact on the C3 segment was a rare event or whether the telescope may be more susceptible to micrometeoroid damage than pre-launch modeling predicted.” the report said. It is hoped that it was just a once-in-a-year event, but the team will now investigate the micrometeoroid population in Webb’s area, how the impacts affect the beryllium-gold mirrors and how it mitigates further impacts. One possible solution could be to minimize the time spent looking in the direction of the orbital motion, which has statistically higher rates and energies of micrometeoroids, he said. A $10 billion infrared-looking space telescope, Webb launched on Christmas Day 2021 and has been orbiting the L2 point about one million miles/1.6 million kilometers from Earth since February. I wish you clear skies and open eyes.
