On June 8, NASA discovered that its new powerful space observatory, the James Web Space Telescope, now has a small hole in one of its primary mirrors after being hit by a micrometeoroid larger than expected in deep space. The news came as a shock because the crash happened only five months after the telescope was used in space – but such strikes are simply an inevitable aspect of space travel, and more strikes are certainly on the way.
Despite the fact that its name implies, the space is not very empty. Within our solar system, tiny bits of space dust zoom through the regions between our planets at tremendous speeds that can reach tens of thousands of miles per hour. These micrometeoroids, no larger than grains of sand, are often small pieces of asteroids or comets that have separated and are now orbiting the Sun. And they are everywhere. A rough estimate of small meteoroids in the inner solar system puts their combined total mass at about 55 trillion tons (if they all merged into one rock, it would be about the size of a small island).
This means that if you send a spaceship into deep space, your hardware will surely be hit by one of these little pieces of space rock at some point. Knowing this, spacecraft engineers will construct their vehicles with certain protection to protect against micrometeoroids. It will often include something called a whipple shield, a special multi-layer barrier. If the micrometeoroid hits the shield, the particle will pass through the first layer and fragment even further, so the second layer will hit even smaller particles. Such protection is usually used around sensitive components of spacecraft for additional protection.
But with NASA’s James Web Space Telescope, or JVST, it’s harder. The gilded mirrors of the telescope must be exposed to the space environment in order to properly collect light from the distant Universe. And while these mirrors are made to withstand some shocks, they are more or less sitting ducks for larger micrometeoroid shocks, like the one that hit JVST in May. Although the micrometeoroid was still smaller than a grain of sand, it was larger than NASA expected – enough to damage one of the mirrors.
Spacecraft operators are modeling a population of micrometeoroids in space to better understand how often a spacecraft can be hit in any part of the solar system – and what particle sizes can strike their hardware. But even then, it is not a secure system. “It’s all likely,” said David Malaspina, an astrophysicist at the University of Colorado who focuses on cosmic dust strikes on spacecraft. The Verge. “You can just say, ‘I have this chance of being hit by a particle of this size.’ But whether you ever do it or not is a matter of chance. ”
Micrometeoroids have a wide range of origin stories. They can be the remnants of high-speed collisions in space, which shatter space rocks into tiny pieces. Asteroids and comets also bombard space particles and photons from the Sun over time, causing tiny fragments to break off. An asteroid can also get too close to a large planet such as Jupiter, where a strong gravitational force pulls parts of the rock. Or an object can get too close to the sun and get too hot, causing the rock to expand and fall apart. There are even interstellar micrometeoroids that are just passing through our solar system from more distant space settlements.
The speed of movement of these particles depends on which part of the universe they are in and the paths they travel around our star, on average about 45,000 miles per hour, or 20 kilometers per second. Whether it will crash into your spacecraft or not also depends on where your vehicle lives in space and how fast it moves. For example, NASA’s Parker solar probe is currently the closest object man has made to the Sun, and it travels at a maximum speed of more than 400,000 miles per hour. “It comes down to a 4-yard line, compared to land that’s in one extreme zone,” said Malaspina, who focused on studying the impact of micrometeoroids on the Parker Solar Probe. It also moves through the densest part of the region called the zodiac cloud, a thick disk of space particles that permeates our solar system. So Parker’s solar probe is sandblasted more often than JVST — and it strikes these particles at incredibly high speeds than a telescope would be hit.
Parker’s solar probe gives us a better understanding of micrometeoroids around the Sun, but we also understand the population around the Earth quite well. Whenever a micrometeoroid hits the upper atmosphere around our planet, it burns and creates meteoric smoke – tiny particles of smoke that can be measured. The amount of this smoke can tell us how much dust falls on the Earth over time. In addition, there were experiments on the International Space Station, where materials were placed on the outside of the orbital laboratory to see how often they were bombed.
While JVST lives approximately 1 million miles from Earth, it is still relatively close. Scientists also have an idea of what is there based on other missions sent into a similar orbit as JVST. And most things that get into a telescope aren’t that big of a thing. “Spacecraft are constantly hit by children,” says Malaspina. “By little, I mean parts of microns – much, much, much less than human hair. And mostly, spacecraft don’t even notice it. “In fact, JVST has been hit by small micrometeoroids four times before being hit by a larger micrometeoroid in May.
NASA did model the micrometeorological environment before the JVST launch, but in light of recent influence, the agency has convened a new team to refine its models and better predict what could happen to the telescope after future impacts. Current micrometeoroid modeling will try to predict things like how debris spreads through orbit if an asteroid or comet decays. This type of debris is more dynamic, says Malaspina, which makes it difficult to predict.
However, at the end of the day, anticipation will simply give you more knowledge about it when the spacecraft could be hit by large grains of dust. Such one-off influences are simply inevitable. JVST will continue to be destroyed over time, but that was a case that NASA was always ready for. “You just have to live with the probability that a particle of dust will hit you in the end, and you just do the best you can with engineering,” says Malaspina.
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