In September 2022, NASA’s Double Asteroid Redirection Test, or DART, made history when it crashed into an asteroid and demonstrated that a kinetic impact could redirect a space rock on a collision course with Earth.
The DART mission also sent groundbreaking images to Earth of the rubble-strewn surface of its target, Dimorphos, a small moon of the larger asteroid, Didymos. Not only have these images been used by scientists to imagine a landing procedure on Didymos, but they have also sparked a 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 to a European Space Agency declaration that the first challenge faced by astronauts aiming to navigate Dimorphos on foot would 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 might appear,” Murdoch said. “Rating 16.4 to 23 feet (5 to 7 meters) in diameter, the largest are typically the size of a house. Moving these boulders would likely require far more climbing and jumping than walking.”
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Despite being a considerable hurdle for potential future astronauts to overcome, these deceptively large rocks are more useful to planetary scientists who can use them to piece together Dimorphos’ origins.
The small moon’s large, rubble-strewn appearance suggests it formed when its larger parent Didymos spun fast enough to launch boulders from its surface into space. This theory is supported by the fact that Didymos appears to have a spinning top-like shape and appears to be free of loose boulders on its surface.
Another risk, if astronauts could walk on the surface of an asteroid, would be encountering a solid surface or sinking beneath its surface. When NASA OSIRIS-REx The mission visited asteroid Bennu in 2020, a video of its landing showed a leg of the lander hitting the ground too hard and nearly sinking. That’s because Bennu is a rubble-heaped asteroid so loosely packed that it resembles a child’s ball pit.
“A lot depends on whether its material is hard or soft, which would determine how high an astronaut could bounce or otherwise sink,” Observatoire de la Côte d’Azur research director Patrick Michel said in the statement. of ESA. “On the asteroid Bennu, visited by NASA’s OSIRIS-REx, you would clearly sink if you landed too hard.”
Another risk faced by a human astronaut aiming to walk on an asteroid would be the way they adhere to the asteroid’s surface. We don’t tend to worry too much about this on Earth as our planet’s gravity keeps us grounded. For a body with much less mass, gravity may not be enough to keep the astronauts from permanently losing balance. For example, the gravity of Dimorphos is less than a millionth that of Earth. Patrick said just 6cm per second of upward motion could be enough to send an astronaut into orbit around the asteroid they’re exploring.
“Jump too fast and you may never come down again because you may exceed your local escape velocity,” added Naomi. “Also, in the ultra-low-gravity environment, it would be easy to generate significant ground movement, potentially triggering a rock avalanche.”
This means that astronauts exploring an asteroid can use spikes or crampons similar to those used by mountain climbers to get attached to an asteroid. Alternatively, a thruster system could be used by astronauts to glide to the surface of the space rock similar to a scuba diver exploring the ocean floor. However, this method requires a lot of care.
“You should avoid contact with surface rocks while gliding, however, as they are likely sharp enough to snag your spacesuit, having never been smoothed by water or wind,” Naomi explained. “Added to the challenge, your weight would shift about 10-20% depending on where you are on the surface due to tidal forces from parent asteroid Didymos.”
Space exploration is probably disorienting enough, but astronauts will also have to deal with the dizzying effects of the constantly shifting sky above them. This could be especially important when exploring Didymos after it has been hit by DART.
“It is likely that Dimorphos was tidally locked before DART’s impact, but now it is probably rotating or ‘hovering’ – swinging – as it orbits Didymos,” said Patrick.
It could be a long time before astronomers visit Dimorphos or any other asteroid, but the DART follow-up mission, Hera, operated by the European Space Agency (ESA), will soon be visiting the moon. Scheduled to launch in October 2024, Hera will send two shoebox-sized CubeSats – Juventas and Milani – to land on Dimorphos for further observations of the moon.
When the CubeSats land, Juventas will use his gravimeter to ensure it can work no matter how it’s oriented, while Milani will use an accelerometer to record the force of its rebounds as it descends to the surface, better limiting the asteroid’s gravity. This data will be sent to Hera and may one day be useful to humans who aim to explore asteroids very carefully.
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Image Source : www.space.com