Mars’ surface is inhospitable due to deadly cosmic rays and very large temperature swings. So, the subsurface is being considered for astronauts, and it may be where very simple life still exists on Mars. But how can we get there to study it?

Mars has many long, rounded, passageway caves; some are likely many miles long and more than a football field floor-to-ceiling. The main entrances are vertical “skylights” where the roof has caved in, leaving a circular hole. Driving a rover into such an entrance is impossible. Rotorcraft are now a clear alternative thanks to the success of Ingenuity, which flew on Mars in 2021-2022.

A Mars caving helicopter would have to fly back out daily to recharge and communicate with Earth. It would be too tricky to require landing in a dark cave to do the main science. Fortunately, many studies can be done while flying: temperature, humidity, making maps using lasers, sniffing for bacteria-like organisms, and using lasers to look for them. Instruments to do these either exist or are being developed by NASA. In this way, exploration of Mars deep underground is feasible NOW on a relatively low-budget mission.