Chang'e-6 Moon soil contains rare rock from carbon-rich asteroid impact, hinting at how water reached the lunar surface

Key facts

• Scientists identified a rare rock fragment formed by a carbon-rich asteroid impact in lunar soil returned by China's Chang'e-6 mission from the Moon's far side.
• The fragment is a spinel-bearing troctolite-like rock containing olivine and plagioclase as main minerals, along with spinel, troilite, and traces of iron and nickel.
• Unusual chemical features include olivine with higher cobalt, nickel, chromium and phosphorus levels than typical Moon samples, a distinct oxygen signature, and high iridium content, suggesting a carbonaceous chondrite-like asteroid impact.
• The research, published in the journal Icarus under the title 'Delivery of carbonaceous materials to the Moon', offers clues about how water and other volatile materials reached the lunar surface via asteroid impacts.
• The fragment may have formed when material from a carbon-rich asteroid mixed with lunar norite, producing spinel-bearing troctolite through a route not previously identified.
• This is the first reported identification of material from beyond the Moon in Chang'e-6 samples.