When the James Webb Space Telescope released five breathtaking images of the universe earlier this month, it marked the beginning of decades of precision engineering and astronomy. When these images were released last week, the build-up was so intense that NASA Administrator Bill Nelson likened the scene to a rally of cheer rather than a supposedly solid science gathering.
However, that pep may have dissipated since last week in light of the recent news that the telescope, despite its immense technological sophistication, has suffered irreparable damage due to a micrometeoroid.
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According to a report posted to the arXiv.org preprint database, a small rock collided with one of the telescope’s 18 gilded mirrors, causing extensive damage. In particular, mirror C3 has a bright white dent where gold should be at the micrometeoroid impact site. Although NASA describes the damage as “irreparable,” they added that it did not affect the telescope’s overall performance.
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“A micrometeoroid that hit segment C3 between May 22 and May 24, 2022 UT caused a significant irreversible change in the overall shape of this segment,” the report explains. “However, the effect was small at full telescope level because only a small fraction of the telescope area was affected.” The report explains that “two successive reconfiguration steps” resolved the issue.
Dr. Thomas Zurbuchen, assistant administrator at NASA’s Science Mission Directorate, predicted the agency’s ability to overcome this setback when it tweeted in June on early reports of micrometeoroid impacts on the telescope.
“Micrometeoroid impacts are an unavoidable aspect of working in space,” Zurbuchen wrote. “Recently Webb [telescope] received a blow to one segment of the main mirror. After initial evaluations, the team found that the telescope is still operating at a level that exceeds all mission requirements.”
A new arXiv.org report further explains that the tiny pebble that hit C3’s mirror was actually just one of 19 rocks that crashed into the James Webb Space Telescope between February and May 2022.
The James Webb Space Telescope is especially vulnerable to micrometer strikes because the telescope’s mirrors are open and exposed to the vacuum of space. The Hubble Space Telescope, in every sense the technological predecessor of Webb, had a cylindrical body that housed the observing technology. By contrast, the Webb Telescope is functionally a giant reflector open to space without a containment.
However, in addition to being smaller overall, another reason Hubble has been remarkably free from damage over the years is its location in space. Hubble conveniently orbits right above the Earth, close enough for spacecraft astronauts to come up and perform maintenance; whereas the Webb telescope is far away at a stable point in space where the sun and the Earth’s gravity balance each other perfectly, so that the telescope actually remains stationary relative to the Earth. However, due to the fact that few spacecraft have been sent to this point in space, known as L.2 Point, short for LaGrange Point – Astronomers have less knowledge of the risk of micrometeoroids in the region. On the contrary, low and medium Earth orbit, where Hubble lives, is saturated with manned spacecraft, and therefore its risks are well understood.
Space news website Space.com was pessimistic about the upbeat tone of NASA’s new report.
“Micrometeoroids are a well-known danger to space operations, and their impact is by no means new to scientists; The International Space Station and the Hubble Space Telescope are among the long-term programs that are still running despite accidental impacts on space rocks.” – Space.com wrote. “However, Webb’s orbit at Lagrange Point 2, about 1 million miles (1.5 million kilometers) from Earth, could change the risk profile significantly.”
Despite the failure of the C3 mirror, the James Webb Space Telescope is still an undeniable success. In one of its recently released images, the telescope determined the composition of the atmosphere of a distant planet called WASP-96b (which contained water). Other published images have shown a planetary nebula called the South Rim Nebula; five nearly neighboring galaxies, dubbed “Stefan’s Quintet”; the Carina Nebula, which to the whole world looks like a horsehair blanket thrown over a bright and colorful sky full of stars; and the softly named SMACS 0723, the clearest and most complete infrared image ever taken of the distant universe.
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