An asteroid called Didymos recently had a close encounter with a spacecraft. The 0.5 mile (0.5 mile) wide rock appears to rotate very rapidly, appearing to rotate once every 2 hours and 16 minutes, suggesting that its surface may be shedding debris. Some of it may have been carried into space by the solar wind.
The researchers made the discovery shortly after NASA’s Double Asteroid Redirection Test (DART) spacecraft spotlighted Didymos. Last September, DART slammed into the asteroid moon Dimorphus almost head-on, speeding up Didymos’s smaller companion asteroid enough to change its course, and if such a apocalyptic collision was predicted early enough. , demonstrated that humanity could protect the Earth from a catastrophic asteroid impact.
The explosive visit will allow scientists to see both asteroids up close, and DART will be followed by an in-depth survey of the binary asteroid system by the European Space Agency’s Hera mission. Starting in late 2026, Hera will be scouting both her Dimorphos and Didymos to take rock measurements, showing how DART has altered the system.
Adriano Campo Bagatin, a planetary scientist at the University of Alicante in Spain and a co-author of the study, said the new study could also see a stream of rocks and dust ejected from Didymos’ equator by Hera due to the asteroid’s fast rotation. suggests that there ispublished online at Icarus This mechanism is just one way scientists are realizing that asteroids can be active, dynamic places rather than static rock masses. While it remains difficult to determine exactly how common such activity is, the study is a reminder that asteroids throughout the solar system may be ejecting their material into space. I will give it to you.
The study also supports long-standing theories about how the DART target Dimorphus formed, says Yun Zhang, a planetary scientist at the University of Maryland. “How the system was formed in the first place is like a puzzle for scientists,” she says.
One theory is that Didymos formed alone and rotated so quickly that it could not be held together, eventually tossing the material that coalesced and formed Dimorphus. researchers want to understand whether Didymos has this ability to eject mass from its surface,” Zhang said.
At present, this work is theoretical and based almost entirely on remote observations collected prior to DART’s impact. From Earth, Didymos can only be seen as a bright spot, so scientists can’t gather direct data on materials that could be ejected from the asteroid.
Dante Lauretta, a planetary scientist at the University of Arizona, said of the new research he wasn’t involved in, “It’s a good place to start, and that’s all we can do.
Team members collected all the data on Didymus’ shape, size, mass and composition. The DART mission helped researchers determine the size of the asteroid, but many of these are based on past observations from Earth. Based on years of observation since the asteroid was discovered in 1996, the team also knew of Didymos’ rapid rotation speed. This indicates that the asteroid is likely shaped like a coma. Inflate.
The researchers input this information into a computer model that would cause Didymos to spin fast enough to cause material near the equator to accelerate outward with a force greater than counteracting the asteroid’s gravity, causing the material to lift off the surface. made it clear that
From there, matter has four potential destinations. It could escape into space, be trapped in orbit around Didymos, return to the surface of the asteroid, or land on Dimorphus. Campo Bagatin and his colleagues calculated that more than 97% of his lifted material should return to Didymus’ surface within about four hours. The team’s simulations showed that of the remaining floating bits, most of the larger debris—in this case particles at least a few centimeters in diameter—would eventually land on Demorphos.
This isn’t the first asteroid to be banished for throwing its own guts into space. Lauretta is leading another NASA asteroid mission, his OSIRIS-REx, which will deliver fragments of the space rock Bennu to Earth this September. Shortly after the spacecraft arrived at Bennu in December 2018, he and his colleagues were shocked to discover that the asteroid was spewing pebbles into space.
Identifying active asteroids is a reminder of just how dramatic our cosmic neighborhood is, he says. “The idea that the solar system is a static environment is really wrong,” says Lauretta. “It’s a very dynamic place. Things are changing. Things are colliding with each other. Processes that have been going on for 4.5 billion years are still happening.”
Still, especially in the case of Didymos, scientists will have to wait for Hera’s mission, scheduled for October 2024, to understand just how much the asteroid’s surface is changing. Campo Bagatin said the spacecraft should be able to directly observe this possible debris using two black-and-white asteroid framing his cameras. You should also notice color differences in recently lost material on the asteroid’s surface, notes Zhang.
“Unfortunately, it’s hard to say what’s really around Didymos until Hera’s mission gets there,” Campo Bagatín says.
