The James Webb Space Telescope has enabled astronomers to see the interiors of vast, distant galaxies, but coincidentally, smaller objects nearby are also being studied.
These are micrometeorites, little mysteries running through the land. solar system At lightning speed. It’s too small for scientists to directly observe in deep space, but it shouldn’t be ignored. james webb space telescope (JWST or Webb) can be proved. Since JWST’s Christmas 2021 launch, engineers have detected more than 20 of her micrometeorite impacts into the telescope. Only one significantly damaged the observatory. The mission is adjusting its operations to reduce the frequency of micrometeoroid collisions, but even so, the impact itself is perhaps the least anticipated data from a powerful new observatory.
Margaret Campbell-Brown, a meteor physicist at the University of Western Ontario in Canada, told Space.com: “Of course, we grieve for them when their mirrors hit the meteor.”
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The JWST team was temporarily concerned that scientists had underestimated the threat posed by these tiny particles in May 2022. Impact of relatively large meteorites In the observatory’s huge golden mirror, even before normal scientific observations began.
But by the time the observatory celebrated its one-year anniversary from its Christmas 2021 launch, the team’s confidence had returned. The scientists decided that the micrometeoroids of concern were large enough that he did not expect to encounter such an object more than once a year. Engineers determined that the particles reached a particularly vulnerable spot.
Lee Feinberg, optical telescope element manager for JWST at NASA’s Goddard Space Flight Center in Maryland, told Space.com about the impact. “At the moment, it’s really a very small thing.”
However, with JWST now targeting perhaps 20 years of operation, the team decided to play it safe. Adaptation of observation strategies Limits the amount of time the telescope is vulnerable to the most energetic impacts. “He hopes these pictures of the Carina Nebula will look just as beautiful 20 years from now,” Feinberg said.
And that means understanding micrometeoroids.
unusual observatory
JWST is in a unique situation. A $10 billion observatory sits on what scientists call the Earth and the Sun Lagrangian point 2 (L2) and about 1 million miles (1.5 million kilometers) away from Earth in the direction opposite the Sun. L2 is one of the pockets of the solar system where gravitational tags are balanced, making it a relatively cheap outpost in terms of fuel. Sun.
However, the scientists sent only a few spacecraft to L2, none of which had the JWST vulnerability. The telescope’s giant mirrors are exposed to space, and engineers monitor their smoothness to help scientists make sense of the data.Compare its design to something like an observatory Hubble Space TelescopeIt is covered with a tube that absorbs shock without noticeable scratches.
“We can actually monitor this at a level of detail no one has been able to do before,” said Feinberg.
Concerns abounded in May, but the engineers working on the JWST knew from the beginning that micrometeorites would hit the observatory. His Bill Cooke, director of his NASA Meteor Environment Office at the Marshall Space Flight Center in Alabama, told Space.com: “ISS [the International Space Station], Chandra, Hubble — Name the rides that have been there for years, but they were all hits. Most of the hits are not critical to mission operations, but they do hit. ”
Early in the JWST design process, mission personnel simulated the impact of micrometeoroids on mirrors, but Feinberg said engineers had no way to accelerate the tiny particles to the speeds they would reach in the solar system. , pointed out that the experiment is impossible. It really mimics the force of impact. Scientists also used models of the time to figure out how many hits the observatory would undergo during his projected five-year lifespan.
“That’s kind of how we dealt with it from a JWST development standpoint,” says Feinberg. “And, to be honest, I didn’t really think much about micrometeoroids or our mirrors until I actually went to space.”
discovery of meteorites
But while Feinberg and countless colleagues were making JWST a reality, meteor scientists were also busy improving their understanding of the universe around us.
Scientists have determined that only about 10% of micrometeoroids are related to the meteors we know best. Perseus again LeoThe remaining 90% of micrometeoroids are what scientists call sporadic, moving solitarily and moving rapidly through the solar system in random orbits, which can make them more difficult to understand.
Althea Moorhead, NASA Marshall meteor scientist, told Space.com:
(Feinberg said the JWST team believes the effects the observatory is detecting are sporadic.
Scientists also know what kind of objects micrometeorites come from: from about 90% Comet 10% from asteroid, are either rare active asteroids or debris from collisions between rocks in space. And the origin of micrometeoroids shapes their impact. “Of course, it makes a big difference if the spacecraft hits solid rock, as opposed to a fluffy mass of tiny particles,” Campbell-Brown said. one, and the other one is like being shot.”
Micrometeoroids are too small to be seen with any telescope, making them difficult to study, so scientists combined three main approaches.
First, scientists can study nearby meteor bodies thanks to their interaction with Earth’s atmosphereAs each meteoroid moves through the atmosphere, its edges heat up and erode, leaving behind what scientists call an ionization trail. This can be detected by specially tuned radar systems.
“The small particles themselves are too small to be seen on radar,” Campbell-Brown said of meteors. “All of these electrons in the atmosphere have carrier-sized scattering cross sections, so we can get very good signals from these very small particles.”
And these traces provide scientists with a wealth of data. The observatory used by Campbell-Brown, the Canadian Meteor Trajectory Radar in Ontario, captures the trails of thousands of meteors each day, which is enough information to calculate the orbits of each object. We get the orbits of thousands of meteors every day, and it really helps us understand where these tiny particles are coming from,” Campbell-Brown said.
Second, scientists can see data from two important missions. NASA He Created Three Lofts pegasus spacecraft In the 1960’s and 70’s. Each equipped with huge wings designed to catch meteorites, soaring to altitudes reached by Apollo astronauts.Following Pegasus in the 1980s Long-term exposure facilityAfter remaining in orbit for about six years, the Space Shuttle program returned to Earth, allowing scientists to study meteor impact scars first-hand.
The spacecraft’s data is limited, as there are only four objects that have never left Earth’s orbit, but it is still useful. “Most of our data is looking at meteors, but it’s nice to have other forms of detection that can help clear up some of the ambiguities,” said Moorhead.
help from computer
But the last technique is modeling, because basically that’s all scientists get in the way of observations.
Scientists can use computers to simulate the smallest debris in the solar system, both its formation and path. They can smash asteroids to pieces, create artificial comets, watch them drip material through their neighborhoods, and test how. JupiterThe enormous gravitational pull of , can shape the path of the meteor.
Modern models are powerful enough to include which direction the particles are coming from. “Our model has advanced to the point where it can show which direction is the riskiest to look in, whereas the older model was less clear. This is particularly important information for the JWST. Because impacts from are more energetic and cause more damage.
Still, understanding what’s going on around JWST can be a tricky task. Because both direct sources come from the Earth’s immediate vicinity, he has no guarantee that the two regions are identical when it comes to micrometeorites.
“The problem we have is that the only meteors that are commonly observed are near the Earth, because either we see them in the Earth’s atmosphere or they affect satellites in some way,” he said. Orien Egal, Canadian planetarium Rio Tinto Arkan, who works on modeling meteor showers, told Space.com.
“You can never say, ‘I’m pretty sure this is happening in L2,'” she added. We’re looking at theoretical and numerical models and using them as a basis to predict what might happen elsewhere in the solar system.”
And so far, JWST’s experience suggests that scientists have made good progress in estimating the environment at L2. Still, observatory personnel have fine-tuned the approach, limiting the amount of time the telescope’s mirrors are facing forward.
As scientists consider the JWST legacy in the years to come, no one expects micrometeorites to receive top billing. It may not even be the last observatory with a mirror of It’s worth knowing what’s going on there.
Email Meghan Bartels at [email protected] or follow her on Twitter @.Mega Bantels. follow us @ on Twitterspace dot com and Facebook.
