This artist’s conception shows the James Webb space telescope fully deployed in space. Credit: Adriana Manrique Gutiérrez, NASA animator
NASA’s James Webb Space Telescope crashed into one of its primary mirror segments between May 23 and 25.
Micrometeoroid shocks are an inevitable aspect of the operation of any spacecraft, which routinely withstands many impacts throughout long and productive scientific missions into space. Between May 23 and 25, NASA’s James Webb Space Telescope suffered an impact on one of its primary mirror segments.
After initial evaluations, the team found that the telescope was still operating at a level that exceeded all mission requirements despite a marginally detectable effect on the data. Exhaustive analysis and measurements are ongoing. Impacts will continue to occur throughout Webb’s life in space; events of this kind were anticipated in building and testing the mirror on the ground. After a successful launch, deployment, and alignment of the telescope, Webb’s early life performance is still well above expectations, and the observatory is fully capable of performing the science for which it was designed.
The Webb mirror was designed to withstand the bombardment of the micrometeoroid environment in its orbit around the L2 Sun-Earth of dust-sized particles flying at extreme speeds. While the telescope was being built, engineers used a mix of simulations and actual test impacts on mirror samples to get a clearer idea of how to fortify the observatory to operate in orbit. This more recent impact was greater than it was modeled and beyond what the team could have tested on the ground.
“We always knew that Webb would have to cope with the space environment, which includes harsh ultraviolet light and charged particles from the Sun, cosmic rays from exotic sources in the galaxy, and occasional micrometeoroid strikes within our solar system,” said Paul Geithner. technical assistant director of the project at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We have designed and built Webb with a range of performance (optical, thermal, electrical, mechanical) to ensure that it can carry out its ambitious scientific mission even after many years in space.” For example, due to the careful work of the launch site equipment, Webb’s optics were kept cleaner than needed while on the ground; its pristine cleanliness improves overall reflectivity and performance, thus improving overall sensitivity. This and other performance margins make Webb’s scientific capabilities robust to possible degradation over time.
In addition, Webb’s ability to detect and adjust mirror positions allows for a partial correction of the impact result. By adjusting the position of the affected segment, engineers can cancel out some of the distortion. This minimizes the effect of any impact, although not all degradation can be canceled in this way. Engineers have already made such a first adjustment for the recently affected C3 segment, and the planned additional adjustments of the mirror will continue to fine-tune this correction. These steps will be repeated as needed in response to future events as part of telescope monitoring and maintenance throughout the mission.
To protect Webb in orbit, flight crews may use protective maneuvers that intentionally move the optics away from known meteor showers before they occur. This latest move was not the result of a meteor shower and is now considered an inevitable casual event. As a result of this impact, a specialized team of engineers has been formed to look for ways to mitigate the effects of more micrometeoroid shocks on this scale. Over time, the team will collect invaluable data and work with micrometeoroid prediction experts at NASA’s Marshall Space Flight Center to better predict how performance may change, given that the telescope’s initial performance is better than ‘I expected. Webb’s large size and sensitivity make it a very sensitive micrometeorite detector; Over time, Webb will help improve knowledge of the solar system’s dust particle environment in L2, for this and future missions.
“With Webb’s mirrors on display in space, we expected the occasional impact of micrometeoroids to gracefully degrade the telescope’s performance over time,” said Lee Feinberg, Webb Optical Telescope’s element manager at NASA Goddard. “Since launch, we’ve had four times smaller measurable micrometeoroids that were consistent with expectations, and this one is more recent than our predictions of degradation were. We’ll use this flight data to update our performance analysis over time. and to develop operational approaches to ensure that we maximize Webb’s image performance to the best of our ability for many years to come. “
This recent impact did not lead to any changes in Webb’s program of operations, as the team continues to test the observational modes of scientific instruments and is preparing for the release of the first Webb images and the start of the scientific operations.