But beyond helping us pinpoint the best spots to search for life, these caves could bring us one step closer to a permanent presence on the Moon and safe exploration at Mars – the ultimate goal of the Artemis program.

“We don’t think there’s life to find on the Moon now, but some day the life on the Moon might be us,” said Jennifer Blank, the principal investigator for the BRAILLE project at NASA Ames. “And if I were going to the Moon, I’d want to go to a lava tube.”

On Earth, these caves are home to complex ecosystems, all supported by microbes that “eat” rocks – converting rock material into energy for life. The scientists of the BRAILLE project believe such life could exist – or have once existed – in the caves of Mars as well.

“Orbital satellite data suggests that there are a lot of these lava tubes on Mars,” said Blank. “If there is life there, those tubes are a good place to look. And if there was life in Mars’ ancient past, that’s where it’s most likely to be preserved.”

Roving Through Caves

The BRAILLE team’s first descent occurred at Valentine Cave, one of over 750 at Lava Beds National Monument in northeastern California, close to the state’s northern border. Smooth walls around 15 feet high and walkways up to 70 feet wide make it a practical place to drive a rover, and its well preserved lava flow features are similar to what we expect to find inside a Martian lava cave.

With proper lighting, the cave’s layers of microbial material and mineral deposits can create a dazzling array of colors. But NASA’s cave rover, CaveR, is equipped to do more than sightsee; it’s outfitted with a host of scientific cameras and imaging tools. These instruments take in small amounts of light reflected off of the cave wall’s surface, allowing scientists to identify chemical components that reveal the telltale signs of life. The rover also uses a laser scanner to map the subterranean caves.

BRAILLE’s three-week deployment involved sample collection from nine different caves, tackling scientific questions ranging from geochemistry to DNA sequencing.

One of the most significant of their many results is a working theory the team calls the “Micro-Mineral Continuum,” describing how past and present microbial life appears in the caves.

Between two endpoints on this spectrum – from the walls being visibly bare rock to coated with colored films of microscopic life – are a range of different features, textures and secondary minerals created by the interactions of those microbes with the basaltic rock and water that drips down into the caves.

By studying the continuum further in future returns to Lava Beds and understanding the interplay between geology and biology in these caves, scientists will be able to know what they’re looking at when we one day send rovers to Martian caves.