Although the impact was larger than what NASA expected, it does not appear to have caused significant damage to the mirror in question.
NASA’s expensive James Webb telescope has been hit by a micrometeorite. That is what the US agency says. This event is not entirely unexpected. “We knew from the start that Webb would have to endure the harsh space environment, including ultraviolet light and charged particles from the sun, cosmic rays and occasional impacts from micrometeorites,” said Paul Geithner, member of the James Webb team.
micrometeorite
The micrometeorite — probably no more than a particle of dust racing through space at an unimaginable speed — was on a collision course with one of the 18 mirrors (which are part of the primary mirror) that James Webb is equipped with. Fortunately, after an initial assessment, the damage seems to be not too bad. Despite a small, detectable defect, the telescope still works properly.
Unavoidable
NASA underlines that such micrometeorite impacts are inevitable. “We expected such events and took them into account when building the mirrors,” explains NASA. The mirrors of the telescope have been extensively tested using simulations. Still, the recent impact came as a surprise.
Bigger than expected
This is mainly due to the fact that the impact was larger than what NASA had modeled. “Since launch, we’ve been hit by four smaller measurable micrometeorites,” said NASA’s Lee Feinberg. “These were in line with what we expected. However, the most recent impact was bigger than our predictions. We will use this data to update our performance analysis over time. We will also develop operational approaches to ensure that we maximize Webb’s imaging performance for years to come.”
Amendment
James Webb has also been designed in such a way that the 18 segments of the main mirror can be adjusted individually. By changing the position of the affected mirror segment, technicians can cancel some of the deformation gained. At this point, the recently affected mirror has already been re-adjusted. There are still a few adjustments on the agenda to continue to refine the correction.
Maneuvers
To protect Webb from micrometeorites, protective maneuvers can also be performed. For example, the mirrors can be intentionally turned away when a known meteor shower passes by. However, the most recent impact was not the result of such a meteor shower and is currently considered an unavoidable, accidental event. However, engineers will now look for ways to reduce the effect of future impacts of similar dust particles.
No delay
Fortunately, the unfortunate event does not cause any delay. For example, the very first color photos of James Webb are still expected in mid-July. After this, Webb’s scientific observations will begin. Scientists have already requested time to use the telescope through a competitive process. And all sightings are carefully planned. For example, Webb kicks off by studying two special super-Earths, the lava-covered 55 Cancri e and the airless LHS 3844 b.
Fortunately, the dust particle does not throw a spanner in the works. Besides, we really don’t have to worry about the telescope’s performance. “James Webb’s performance continues to exceed expectations,” NASA said. “The observatory is fully capable of carrying out the science for which it was designed.”
Source material:
†Webb: Engineered to Endure Micrometeoroid Impacts ” – NASA
Image at the top of this article: Adriana Manrique Gutierrez, NASA Animator