The web telescope hit by the micrometeoroid, but gets no major damage

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NASA’s $ 10 billion James Webb Space Telescope has had a tough encounter with an extraterrestrial danger: It was whirled by a micrometeoroid.

The micrometeoroid attack does not appear to have significantly obscured Web’s view, or made it unable to perform revolutionary observations of the universe, including capturing light emitted more than 13 billion years ago, near the dawn of time. The telescope, which was launched from French Guiana at Christmas, is still being calibrated and has apparently performed brilliantly.

But the direct hit on a mirror surprised NASA and is still being analyzed. Details of the micrometeoroid attack were revealed by NASA in a blog post dedicated to Webb.

“Between May 23 and 25, NASA’s James Webb Space Telescope struck one of its primary mirror segments,” the NASA Webb blog states. “After initial assessments, the team found that the telescope still performs at a level that exceeds all assignment requirements despite a marginally detectable effect in the data.”

The 18 segments of the mirror can be adjusted individually in response to meteoroid impacts such as this, NASA said.

“By adjusting the position of the affected segment, engineers can cancel some of the distortion … although not all deterioration can be canceled in this way,” the NASA blog states. “Engineers have already made an initial such adjustment for the recently affected segment … and further planned mirror adjustments will continue to fine-tune this correction.”

The exact size of the micrometeoroid is not known. It could not have been larger than a grain of sand, said Heidi Hammel, a planetary astronomer who has long been involved in the telescope and will use it to study our solar system. Even something so small can cause damage due to the enormous speed at which the telescope orbits the sun and periodically slams into a random particle.

This was a known danger, because even though it is lonely out in space, it is not as empty as it seems.

“There is no loss of science at all from this incident.… This telescope is out there in space – we knew there would be little impact on it. We were just surprised that one hit so fast,” Hammel said.

She said researchers had expected such an impact every five years or so on average.

This extraordinarily complex observatory, announced as the long-awaited successor to the still functional Hubble Space Telescope, orbits the sun in a position that holds it approximately 1 million miles from Earth. It’s too far away for astronauts to visit, and it’s not made for fixing or replacing instruments.

Webb has been going through a “commissioning phase” for several months as the instruments have been calibrated and the 18 gold-plated, hexagonal mirrors are aligned to function as a single solid mirror approximately 21 feet in diameter.

So far, NASA has reported nothing but success.

“Astronomers are dizzy at how well things are going (but also nervous about not pondering, yes we can also be superstitious) and anxious to start doing science!” said astrophysicist Michael Turner at the University of Chicago in an email.

The telescope, which was folded at launch last year, blossomed over the course of many days as the scattered sunshade opened and the mirrors were deployed. The telescope traveled for 29 days to reach its outpost, an orbital position known as L2 where other telescopes have operated safely and offered scientists data on the frequency of micrometeoroids.

“While the telescope was being built, engineers used a mix of simulations and actual test effects on mirror samples to get a clearer idea of ​​how to fortify the observatory for in-orbit operation. This last impact was greater than it was modeled, and beyond what the team could have tested. on the ground, it says on the NASA Web blog.

Webb is different from most telescopes: it is wide open, with the mirrors exposed instead of hidden in a tube. The telescope is designed to observe the universe at infrared wavelengths that are outside the detection range of Hubble.

This requires mirrors and instruments that are extremely cold, which is why the mirrors face away from the earth and the sun at all times. NASA has announced that the “first light” images will be released on July 12, but has not said what they will show.

However, it has already produced an image of a star, used to focus the mirrors. In the background of that image are many galaxies whose light was sent billions of years ago, and it has thrilled astronomers who expect Webb to look deeper into space (and into the past) than Hubble, which was launched in 1990. .

Webb has several goals, including studying the earliest light in the universe, which is emitted a few hundred million years after the big bang. It will also look at the evolution of galaxies, and study objects in our own solar system, including small, icy bodies that orbit the sun far beyond the orbit of Neptune.