The Moon is dotted with pits that scientists think could lead to huge underground tunnels. But a space mission has never been sent to explore what could lie within.

“A view into the interior of a lunar cave would be true exploration – it would reveal unexpected scientific information,” says Francesco Sauro, cave scientist and planetary lava tube expert, as well as technical course director of ESA CAVES and PANGAEA.

ESA kick-started such a mission in 2019, when the Discovery element of ESA’s Basic Activities launched a public Open Space Innovation Platform (OSIP) call for ideas to detect, map and explore lunar caves. Five ideas were chosen to be studied in more detail through an ESA Discovery SysNova challenge, each addressing a different phase of a potential mission.

Most recently the two winning SysNova studies – RoboCrane and Daedalus – were united and expanded into one complete mission plan through ESA’s Concurrent Design Facility (CDF).

The mission would use a robotic crane (RoboCrane) to lower down a cave explorer (Daedalus) into a lunar pit. On its way down, Daedalus would explore and document the entrance to the cave, before mapping the closest part of the cave at the bottom.