ejecta

“They are able to show that ejecta from a crater the size of the Giordano Bruno … could survive for a long enough timescale in a co-orbital zone around Earth.”

If the researchers are right, and Tianwen-2 brings some of the asteroid back to Earth, it would be the first time scientists would be able to study a piece of lunar ejecta, Cheng says.

“If a piece of Moon ejecta is linked to a particular crater, that’s very exciting.”

It was long thought that high-speed collisions pulverized the comet ejecta, but now a 45-member team of researchers reports, in a paper published online in the journal Icarus this week, that heat is to blame.

Shimizu explains: "Due to the fact that volcanic ejecta deposited in the sea preserve well, they record a lot of information at the time of eruption. By using seismic reflection surveys optimized for this target and by identifying the collected sediments, we were able to obtain important information on the distribution, volume, and transport mechanisms of the ejecta."