Last June, the Hayabusa2 spacecraft of the Japanese Space Agency (Jaxa) went into orbit around asteroid Ryugu. In December, Nasa’s Osiris-Rex craft began to orbit its asteroid, Bennu. Both spacecraft have been scouting the surfaces of their targets for places to try to touch and grab a sample to bring back to Earth. By the time you read this, the first Japanese attempt (slated for 22 February) may already have taken place.

The prize will be to get enough material from each asteroid that we can characterise the chemistry of these small bodies. Both targets have surface colours suggesting that they might be related to the dark “carbonaceous chondrite” meteorites, possible sources of the water and carbon that gave Earth the ingredients for life. But those colours, while suggestive, are not conclusive. We won’t know for sure until we have the pieces back in our labs.

It’s not easy to grab a sample; we really don’t know for sure how hard, or friable, the surface may be. The first Hayabusa mission (10 years ago) only got a few grains of rock from its target, asteroid Itokawa. Still, that was enough to match with ordinary chondrite meteorites.