It is inevitable for a space telescope to be hit by a micrometeoroid, but the expensive Webb Space Telescope was still in the test shooting stage a while ago, and it has been hit by a high-energy micrometeoroid in a statistically rare area. After several months of discussion, in order to avoid the impact of Webb Telescope’s follow-up observation schedule, NASA decided to help the telescope “turn the direction” and avoid looking directly at the direction of high-energy micrometeoroids to protect the position of the particularly sensitive primary mirror.
The $10 billion James Webb Space Telescope (JWST) can be knocked out by a few tiny, high-velocity micrometeoroids. According to NASA statistics, the Webb telescope has suffered 14 micrometeoroid impacts so far, with an average of 1 or 2 measurable impact events occurring every month.
According to the report of the US Space Telescope Science Institute (STScI), at the end of May this year, the Webb telescope was hit by an unusually large micrometeoroid, which caused obvious damage to some areas of the primary mirror C3 (see the sudden light spot in the right picture below). The overall optical performance is still twice the standard. Simply put, it has not affected the telescope’s working ability, but it is hard to guarantee that it will survive every time in the future.
▲ The Webb telescope was hit by an unusually large micrometeoroid in May this year, causing significant damage to one of the primary mirrors. (Source: STScI)
The Webb telescope team is more concerned about the hidden impact and hit crisis of the event, or simply bad luck of the telescope, because this impact is quite rare regardless of the energy of the micrometeoroid (with 2 times the relative velocity and 4 times the kinetic energy) or the location of the impact Statistical events.
In order to ensure that the telescope can continue to operate in the best condition, NASA has divided the “micrometeoroid avoidance zone (MAZ)” and decided to flip the telescope to reduce the observation time of the main mirror pointing to the MAZ area. Of course, flipping does not mean that the telescope will never be able to observe the MAZ sky, but it will be safer to observe at different positions on the orbit and at other times.
Except for some scheduled targets with tight schedules (such as solar system objects that would have to wait for a long time if missed), the primary mirror will still face the MAZ area to observe celestial objects. Overall, flipping the primary mirror has more long-term advantages.
(First image source: webbtelescope.org)
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