The Japanese satellite Kaguya has been gone a long time — it crashed into the surface of the moon in June 2009. But the data it collected nearly a decade ago is still revealing incredible lunar secrets, and the Japanese space agency JAXA confirmed Wednesday the existence of an enormous cave in the moon. It’s the perfect place for a moon base.

Kaguya first spotted a giant vertical opening in the moon’s Marius Hills region back in 2009, but it’s only now that analysis of the radar data has revealed just how big this cave is. It’s more than 150 feet wide and deep and is more than 30 miles long. That’s a ton of space for a potential lunar base.

The big advantage of building a base inside such a cave is the natural protection that it would provide from cosmic radiation. The moon has next to no atmosphere, meaning any longtime inhabitants would be exposed to cosmic rays that we don’t have to worry about here on Earth, where we are naturally shielded.

Could the first moon base be built in there? JAXA

While we certainly could come up with a way to protect ourselves — and we’re going to have to, if we want long-term habitation of worlds like the moon or Mars — the cave could do the job for us.

There are other advantages, according to JAXA. The cave interior would also shield astronauts from meteorite impacts — again, more of a concern on the moon than on Earth because of the lack of atmosphere — and it would also have a more stable temperature.

It’s thought that this cave and others like it are lava tubes, created by volcanic blasts some 3.5 billion years ago. The team’s full findings are presented in the latest issue of Geophysical Research Letters.