On June 8, NASA revealed that its powerful new space observatory, the James Webb Space Telescope, now has a small dome in one of its primary mirrors after it was bombarded by larger-than-expected microscopic meteors in deep space. The news was a bit shocking, as the impact occurred just five months after the space telescope was launched – but such impacts are simply an inevitable aspect of space travel, and more attacks are sure to come.

Contrary to its name, the space is not completely empty. In our solar system, tiny particles of cosmic dust travel through the regions between our planets at tremendous speeds that can reach tens of thousands of miles per hour. These tiny meteorites, no larger than a grain of sand, are often tiny pieces of asteroids or comets that have crashed and are now orbiting the sun. Everywhere. A rough estimate of small meteorites in the inner solar system Its total mass is estimated at 55 trillion tons (If they were all joined together into one rock, it would be the size of a small island.)

This means that if you send a spacecraft into deep space, your instruments are sure to bump into one of these little bits of space rock at some point. Knowing this, spacecraft engineers will build their vehicles with some safeguards to protect against the impacts of micro-meteorites. They often have something called the Whipple Shield, which is a special, multi-layered barrier. If a small meteor hits the target, the particle will pass through the first layer and continue to collapse, hitting the second layer with smaller particles. This cover is usually placed around the sensitive parts of the spacecraft to provide additional protection.

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But in the case of NASA’s James Webb Space Telescope (JWST), the matter is more complicated. Gold-coated telescopic mirrors must be exposed to the cosmic environment in order to properly collect light from the distant universe. And while these mirrors are designed to withstand some hits, they look a bit like a sitting duck for larger micrometeorite strikes, like the one that hit JWST in May. Although the exact meteor was still smaller than a grain of sand, it was larger than NASA had expected — enough to damage one of the mirrors.

Spacecraft operators are modeling the assemblies of microscopic meteorites in space to better understand how often a spacecraft can collide with any part of the Solar System — and what size particles can collide with its instrumentation. But until then, it’s not a foolproof system. “It’s all possible,” says David Malaspina, a University of Colorado astrophysicist who focuses on the effects of space dust on spacecraft. edge. “You can just say, ‘I have a chance of hitting a particle that big. “But whether you do it or not, it happens by chance.”

Examples of different types of Whipple shielding
Photo: NASA

Micrometeorites have many origins. These could be the remnants of high-speed collisions in space that smash space rocks into tiny pieces. Over time, asteroids and comets are also bombarded by cosmic particles and photons from the Sun, causing tiny scraps. An asteroid could also come close to a planet the size of Jupiter, where a strong gravitational pull extends over chunks of rock. Or the object may get too close to the sun and get too hot, causing the rocks to expand and break into pieces. There are even microscopic interstellar meteorites passing through our solar system from distant cosmic neighborhoods.

The speed at which these particles travel depends on the region of space they are in and the path they take around our star, on average about 45,000 miles per hour, or 20 kilometers per second. The probability of it hitting your spaceship also depends on where your spaceship lives in space and how fast it is moving. For example, NASA’s Parker Solar Probe is currently the closest man-made object to the sun, traveling at a top speed of more than 400,000 miles per hour. “It’s about 4 yards out, compared to Earth at one end region,” says Malaspina, who has focused on studying the effects of micrometeorites on the Parker Solar Probe. It also travels through the densest part of the region known as the constellation cloud, the thick disk of cosmic particles that permeates our solar system. So the Parker Solar Probe is under more sand attack than the JWST – and collides with these particles at incredibly high speeds from the telescope.

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Parker Solar Probe allows us to better understand micrometeorites around the sun, But we also have a good understanding of the population on Earth. When a small meteor hits the upper atmosphere around our planet, it burns up and creates meteor smoke – tiny, measurable smoke particles. The amount of this smoke can tell us how much dust is hitting the Earth over time. In addition, experiments were conducted on the International Space Station with materials installed on the outside of an orbiting laboratory to see how often they were bombed.


Art display of NASA’s Parker Solar Probe
Photo: NASA

Although JWST lives about a million miles from Earth, it is still relatively close. Scientists also have an idea of ​​what’s out there based on other missions that have been sent into an orbit similar to that of JWST. Most things that end up in a telescope are not that important. “A spacecraft hits young children all the time,” Malaspina says. “I mean fractions of a micron — much smaller than a human hair. Most of the time, the spacecraft doesn’t even notice it.” In fact, JWST had already been hit by four small meteors before it hit a larger micrometeorite in May.

NASA designed the micrometeorite’s environment prior to the JWST launch, but in light of the recent impact, the agency has formed a new team to improve its models and better predict what might happen to the telescope after future impacts. Modeling of current micrometeorites will attempt to predict things like the spread of debris into orbit in the event that an asteroid or comet crashes. According to Malaspina, this type of wreck is more dynamic, which makes it more difficult to predict.

However, at the end of the day, prediction will give you more knowledge about it when A spaceship can hit a large area of ​​dust. These one-time effects are simply inevitable. The JWST eruption will continue over time, but NASA has always prepared for it. “You just have to live with the possibility that you will eventually bump into some dust-sized particles and do your best at engineering,” Malaspina says.