Asteroid Didymos May Spin So Fast It Flings Rocks into Space

The asteroid Didymos witnessed its companion get slammed by NASA’s DART spacecraft, and Didymos itself may have interesting activity

By Meghan Bartels on March 29, 2023

An asteroid called Didymos recently had a close encounter with a spacecraft. Now it has divulged a dizzying secret: the half-mile-wide rock seems to be spinning so rapidly—completing a full rotation every two hours and 16 minutes—that its surface may be ejecting rubble, some carried out into space by solar wind.

Researchers made the discovery soon after NASA’s Double Asteroid Redirection Test (DART) spacecraft brought Didymos into the spotlight. Last September DART slammed into the asteroid’s moonlet Dimorphos nearly head-on, speeding up Didymos’s small companion asteroid enough to change its path and demonstrating that humans could protect Earth from a catastrophic asteroid impact if such a doomsday collision was predicted early enough.

The explosive visit also gave scientists an up-close peek at both asteroids, and DART will be followed by a thorough investigation of the binary asteroid system by the European Space Agency’s Hera mission. Beginning in late 2026, Hera will reconnoiter both Dimorphos and Didymos to take measurements of the rocks and show how DART changed the system.

The new study suggests Hera may also see a stream of rocks and dust flung off the equator of Didymos because of the asteroid’s fast spin, says Adriano Campo Bagatin, a planetary scientist at the University of Alicante in Spain and co-author of the research, which was published online in Icarus on March 11. The mechanism is just one way that scientists are realizing that asteroids can be active, dynamic places rather than quiescent lumps of rock. While it remains difficult to tell just how common such activity may be, the study is a reminder that asteroids across the solar system may be flinging their material out into the cosmos.

More:
https://www.scientificamerican.com/article/asteroid-didymos-may-spin-so-fast-it-flings-rocks-into-space/