How micrometeorite damaged the James Webb Space Telescope

In recent months, and especially in these days, the James Webb space telescope it has been under a media attention that is hardly seen in space. In fact, people have been involved who are usually not interested in these topics. Thanks to the first images released in mid-July and to those that were added later (despite being engineering) we now have a better idea of ​​what the performance of the JWST.

The difference in observing capacity with the Hubble Space Telescope is evident when focusing on objectives that benefit most not only from the technical and technological potential of the new telescope but also from observation in theinfrared. As we know we are only at the beginning of the adventure of JWST whereas the primary mission will have a duration of five years, the extended one of ten potentially renewable up to twenty years.

The James Webb Space Telescope and the Meteorite

Between 22 and 24 May the space telescope was hit by a micrometeorite. This damaged one of the primary mirror segments (specifically segment C3). While reducing overall performance, it enabled the James Webb space telescope in any case to have performances exceeding the expectations of scientists.


In the study for the commissioning of the JWST there is an analysis on how much the micrometeorite actually affected the space telescope. The document reads that the impact “It has exceeded pre-launch damage expectations for a single micrometeoroid, opening up to further investigation and modeling by the JWST Project. The Project is actively working on this issue to ensure a long and productive scientific mission with JWST.”.

The high frequency wavefront error was increased after impact with the micrometeoriteaccording to the findings. This type of event, although predicted, remains the one with the greatest margin of error in the predictive models studied. However, the current data, as written above, shows that there is still a good margin over standard performance.


As can be read in paragraph 4.7, in reality the impacts that would have caused problems would have been six (about one per month, as expected). These would have led to a deformation of the primary mirror of the James Webb space telescope which caused a modification of the wave front, which was then corrected, while the compromise of the spatial frequency is not correctable. The document adds that “Of the six micrometeorite impacts observed so far through wavefront detection, five have had negligible effects, contributing a combined total <1 nm to the overall wavefront error". The impact that damaged the C3 segment was significant and uncorrectable.

This is perhaps one of the biggest issues facing the space telescope it will face over the course of its operational life. In the study we read that “Mirrors and solar shading are expected to slowly degrade due to impacts from micrometeorites; detectors are expected to suffer slow cumulative damage from charged particles; solar shading and the multilayer insulation will degrade due to space agents “. Reaching 20 years of operational life will therefore not only be a question of the propellant to remain correctly in orbit around the L2 point, but something much more complex.

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