Researchers first presented their proposal to NASA in 2017, revealing a boxy lander that would study both the surface and what’s below. The team didn’t need confirmation of the mission to get started — there have already been tests for its data antenna.

The moon is potentially the best candidate for life in the Solar System beyond Earth. Europa has a crust covered in water ice (there’s even evidence of sea salt). If there’s a corresponding water ocean underneath the surface, NASA might find evidence of life — even if it’s just the remnants of an earlier era. Clipper could also help determine the viability of human exploration of Europa, although any prospect of that is many years away.