At the end of May, the Webb Space Telescope was attacked by space debris. A small pebble – a micrometeoroid – crashed into one of the hexagonal mirrors, causing irreparable damage to the device. It is relatively small and does not interfere with the operation of the telescope.
The event became known from the report of Space Telescope Science Institute, which was released last week. It describes Webb’s scientific performance until July 12, the day when the first pictures of the spacecraft got published. According to the report, the pebble hit the mirror between May 22 and 24. The collision “exceeded pre-launch damage expectations for a single micrometeoroid.”
Micrometeoroids are rock fragments flying through space. In the Earth’s orbit, they can develop a speed of up to 35,405 km/h, therefore constantly threaten astronauts and spacecraft.
Micrometeoroid impact damage was detected during inspection. Comparing ground-based measurements of the optical quality of the mirror segments with the telescope’s current quality, scientists found a significant error in the C3 segment. Since the C3 segment is only one of 18 Webb mirrors, the overall damage is relatively minor. According to the team’s initial assessment, Webb “should meet the optical performance requirements for many years.”
The Webb Telescope is expected to remain in orbit for 20 years. However, scientists do not know how many even more harmful than expected particles will hit the apparatus and how quickly they will be able to damage the mirrors. At the time of the report, four of the strikes were in line with forecasts, but one was cause for concern. If the telescope turns out to be more vulnerable to space debris, this could shorten its lifespan.