New images revealed in a new report show that damage to the James Webb Telescope’s main mirror from a minor meteor strike in May was worse than previously thought.
Paper published on Tuesday Server Prepress Akademik arxiv.org He disclosed in detail about Webb’s performance while the telescope was operating that most micro-meteorite attacks on large Webb mirrors caused minor damage, but an attack in mid-May left the telescope with permanent damage.
“The impact of one small meteorite that occurred from 22-24 May 2022 UT exceeded previous staging predictions for damage caused by one small meteorite leading to further investigation and modeling by the JWST Project,” the report said.
Unlike the Hubble Space Telescope, which covers the main mirror that the telescope uses to collect light and focus light on scientific instruments in a cylindrical shell, Webb’s 6.5-meter split mirror is exposed to space. But looking at Webb’s orbit around Lagrange Point 2, or L2, a region of space about a million miles from Earth, scientists only estimate Webb encounters a small, potentially dangerous meteor once a month.
During the commissioning period from late January to June, during which the ground controller calibrated, aligned, and tested Webb’s mirrors and instruments, the main mirror was subjected to six precise meteor strikes.
Of these, five did minor damage, causing less than 1 nm of root wavefront mean square (RMS) error, which is a technical way of describing how much the Webb mirror distorts the starlight the mirror collects. Most of the distortion added by the five strokes beyond the mirror can be corrected, as the 18 hexagonal segments that make up the face can be individually and precisely adjusted.
But the sixth hit, hitting a mirror clip called C3, deals more damage that can be completely repaired. This micro-meteor strike increases the wavefront error of this sector from 56 nm to 178 nm after correction by modulating the section.
As each mirror clip is adjustable, damage to the C3 segment is compensated and does not affect the overall accuracy of the underlying Webb mirror, according to the report. The overall wavefront error of the entire mirror increases by about 9 nm due to the blow.
“It’s not yet clear whether the May 2022 Part C3 explosion was a rare event (i.e. an unfavorable initial strike from a small, high-kinetic meteor that statistically might only occur once every few years),” or whether it may be that the telescope is more susceptible to damage from micrometeorites than it is. previous launch modeling.”
The report further notes that the Webb project team is considering steps to mitigate future micrometeorite attacks, such as determining how long the telescope can be pointed in a known direction to expose the mirror to a greater likelihood of micrometeorite attack.
Maintaining the long-term health of the Webb Telescope is a top priority for NASA and astronomers everywhere.
After more than 20 years and $10 billion worth of development, the space telescope was launched aboard the Ariane 5 rocket on Christmas Day. The launch was more accurate than expected, provided enough motivation for Webb that he would use it to improve its trajectory after launch, and nearly doubled the observatory’s expected operational life—as long as the space rock didn’t damage its optics.
“Prior to launch, JWST is required to carry thrusters for a minimum of 10.5 years of mission,” the report said. “Now that JWST is in orbit around L2, it is clear that the remaining propellants will last more than 20 years of the mission’s life.”
–
