China sets out to sample an unusual near-Earth asteroid

Following its successes retrieving lunar samples from both the near and far sides of the Moon, China is planning an encore, sending a probe to snatch material from a near-Earth asteroid. The target of the Tianwen-2 mission, which is expected to launch by the end of the month, is a chunk of rock named 469219 Kamo'oalewa. It is one of just seven asteroids that fall into a little-understood class known as quasi-satellites of Earth--and it could also be the first known asteroid comprised of lunar material. That hypothesis could be confirmed by laboratory studies of fragments collected by Tianwen-2, which are due to be returned to Earth about 2.5 years after launch. "This is an ambitious mission to explore a fascinating object," says astrophysicist Amy Mainzer of the University of California, Los Angeles.