Characterization of JWST science performance from commissioning

"...This document characterizes the actual science performance of the James Webb Space Telescope (JWST), as known on 12 July 2022. Following six months of commissioning to prepare JWST for science operations, the observatory is now fully capable of achieving the discoveries for which it was built. A key part of commissioning activities was characterizing the on-orbit performance of the observatory. Here we summarize how the performance of the spacecraft, telescope, science instruments, and ground system differ from pre-launch expectations. Almost across the board, the science performance of JWST is better than expected. In most cases, JWST will go deeper faster than expected..."

[PDF]: https://arxiv.org/ftp/arxiv/papers/2207/2207.05632.pdf

Interesting under "Fault management"

"... JWST has experienced seven safe mode entries (six safe haven and one inertial point mode) since launch. The majority of these safe mode entries were a result of on-orbit learning of the nuances of the control system behavior and system level interactions. All of the safe mode entries’ underlying causes are understood and several updates to the fault management and control system set items have been loaded to flight software to prevent the issues from recurring..."

and under "Micrometeoroids"

"...During commissioning, wavefront sensing recorded six localized surface deformations on the primary mirror that are attributed to impact by micrometeoroids. These occurred at a rate (roughly one per month) consistent with pre-launch expectations. Each micrometeoroid caused degradation in the wavefront of the impacted mirror segment, as measured during regular wavefront sensing. Some of the resulting wavefront degradation is correctable through regular wavefront control; some of it comprises high spatial frequency terms that cannot be corrected. There should also be a small effect on the telescope throughput, which is not yet measurable. Of the six micrometeoroid strikes detected thus far through wavefront sensing, five had negligible effects, contributing a combined total of < 1 nm to the overall wavefront error..."

"...By contrast, the micrometeoroid which hit segment C3 in the period 22—24 May 2022 UT caused significant uncorrectable change in the overall figure of that segment. However, the effect was small at the full telescope level because only a small portion of the telescope area was affected. After two subsequent realignment steps, the telescope was aligned to a minimum of 59 nm rms, which is about 5-10 nm rms above the previous best wavefront error rms values. It should be noted that the drifts and stability levels of the telescope mean that science observations will typically see telescope contribution between 60 nm rms (minimum) and 80 nm rms (where WF control will typically be performed)..."