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In September 2022, NASA’s Double Asteroid Redirection Test, or DART, made history when it collided with an asteroid and proved that a kinetic impact could redirect a space rock on a collision course with Earth.
The DART mission also sent back groundbreaking images of the debris-strewn surface of its target, Dimorphos, a moonlet of the larger asteroid Didymos. These images have not only been used by scientists to envision a landing procedure on Didymos, but have sparked legitimate interest in what it would be like to set foot on the asteroid or similar space rock.
In a video explaining what it would be like to explore an asteroid, planetary scientist Naomi Murdoch explained in a European Space Agency rack that the first challenge for astronauts looking to navigate Dimorphos on foot will be the boulders scattered across the surface of this 170-meter-wide body.
“The boulders covering the surface of Dimorphos are much larger than they appear,” Murdoch said. “At about 16.4 to 23 feet (5 to 7 meters) in diameter, the largest are typical house size. Moving over these boulders would probably involve a lot more climbing and jumping than walking,”
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Despite being a significant obstacle for would-be future astronauts to overcome, these deceptively large rocks are more useful to planetary scientists who can use them to uncover Dimorphos’ origins.
The moonlet’s large debris-strewn appearance suggests it formed when its larger parent Didymos spun fast enough to launch boulders off its surface into space. This theory is supported by the fact that Didymos appears to have a spinning top-like shape and there do not seem to be any loose boulders on the surface.
Another risk, if astronauts could walk on the surface of an asteroid, would encounter a solid surface or sink below the surface. When NASAs OSIRIS REx mission visited the asteroid Bennu in 2020, video of the landing showed that one leg of the lander landed too hard and nearly sank. This is because Bennu is an asteroid packed so loosely that it resembles a children’s ball pit.
“A lot depends on whether the material is hard or soft, which would determine how high an astronaut can bounce or else sink,” said Patrick Michel, research director at the Observatoire de la Côte d’Azur, in the ESA statement. “On the asteroid Bennu, visited by NASA’s OSIRIS-REx, you would clearly sink if you landed too hard.”
Another risk for a human astronaut who wants to walk on an asteroid is how they adhere to the asteroid’s surface. On Earth, we don’t worry too much about this, because our planet’s gravity keeps our feet on the ground. For a body with much less mass, gravity may not be enough to keep astronauts from permanently losing their balance. Dimorphos’ gravity, for example, is less than a millionth of Earth’s. Patrick said an upward movement of just 6 cm per second could be enough to send an astronaut into orbit around the asteroid they are investigating.
“Jump too fast and you may never come down again because you could exceed the local escape velocity,” Naomi added. “In addition, in the ultra-low gravity environment, it would be easy to generate significant ground motion, potentially triggering a rock avalanche.”
That means astronauts exploring an asteroid can use spikes or crampons similar to those used by mountaineers to stay attached to an asteroid. Alternatively, a thruster system could be used by astronauts to glide over the surface of the space rock in a manner similar to a diver exploring the ocean floor. However, this method requires a lot of care.
“However, you would want to avoid contact with surface rocks while gliding, as they are probably sharp enough to snag on your space suit, as they have never been smoothed out by water or wind,” Naomi explained. “Adding to the challenge, your weight would shift by about 10 to 20% depending on where you are on the surface due to the tidal forces of the Didymos parent asteroid.”
Space exploration is probably disorienting enough, but astronauts will also have to deal with the dizzying effects of the ever-changing sky above them. This can be especially important when exploring Didymos after it’s been hit by DART.
“It is likely that Dimorphos was tidal before DART’s impact, but is now probably rotating or ‘librating’ – wobbling – as it orbits Didymos,” Patrick said.
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It may be a long time before astronomers visit Dimorphos or any other asteroid, but the DART follow-on mission, Hera, operated by the European Space Agency (ESA), will visit the moonlet soon. Scheduled to launch in October 2024, Hera will send two shoebox-sized CubeSats — Juventas and Milani — to Dimorphos to make further observations of the moonlet.
When the CubeSats hit the ground, Juventas will use his gravimeter to ensure he can operate no matter how he is oriented, while Milani will use an accelerometer to record the force of his bounces as he surfaces, allowing the gravity of the CubeSats is better limited. asteroid. This data is sent back to Hera and may one day be useful to people who want to examine asteroids very carefully.
