NASA reports that the James Webb Space Telescope (JWST) was hit by a micrometeroid last month. The tweet from NASAWebb stated:
In late May, Webb sustained a dust-sized micrometeroid impact to a primary mirror segment. Not to worry: Webb is still performing at a level that exceeds all mission requirements.
A second story explained how NASA tested the JWST for just such instances, though the final sentence was a little more worrisome:
Webb’s mirror was engineered to withstand bombardment from the micrometeoroid environment at its orbit around Sun-Earth L2 of dust-sized particles flying at extreme velocities. While the telescope was being built, engineers used a mixture of simulations and actual test impacts on mirror samples to get a clearer idea of how to fortify the observatory for operation in orbit. This most recent impact was larger than was modeled, and beyond what the team could have tested on the ground.
And this sentence is also worrisome:
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.
The $10 billion space telescope, which is still working to become operational, is not expected to share images until mid-July. Unlike the Hubble Space Telescope, NASA cannot send astronauts out to the JWST to make periodic repairs. The JWST currently sits in the L2 Lagrange point about 1 million miles away. All NASA can do now is try to compensate for the damage as best it can.