Valhalla Helium-3 Cold Traps

Callisto's Valhalla basin is a vast multi-ring impact scar, and in the shadowed troughs between its rings the regolith never warms above about 80 kelvin. Over billions of years these cold traps have soaked up helium-3 implanted by the solar wind and Jupiter's magnetosphere, along with plenty of water ice.

Helium-3 prospector Paulo Teixeira mapped the traps from Valhalla Station using a scatter of Swarm Prospecting Beacons, which sniff outgassing volatiles and relay readings across a 300-kilometre mesh. Cryo Ice-Core Samplers then pulled sealed cores from the top 12 metres. The cores average 18 parts per billion helium-3 and 64 per cent water ice by mass, across trap deposits estimated at 900 million tonnes.

That grade sounds tiny, but helium-3 is the premium fusion fuel of the outer system, and the same processing plant can recover water for propellant. The area is open for staking: any member can plant Claimstake Survey Markers and register a block with the Claims Office. Members of the Jovian Helium-3 Consortium are already surveying neighbouring troughs.