Asked by: Mike Libman, Brentwood
Drones come in various guises, the simplest being those propelled by electric-powered rotors. And in principle at least, there’s no reason why a modified one shouldn’t be able to whiz around the Red Planet – though the practicalities are pretty challenging.
Like a helicopter, an Earth-bound drone is kept aloft by directing air downward, the resulting thrust counteracting the force of gravity. The good news is that the surface gravity on Mars is barely one-third that of the Earth, so the rotors don’t have to work so hard to combat its effect. The bad news is that the Martian atmosphere is far more tenuous than that of Earth, with a density 60 times lower. So for a given weight of drone, the rotors must be much more effective at generating the downward thrust. That means increasing the size of the rotors, their number, their spin-rate – or some combination. Doubling the number of rotors and their length might do the trick, but the result would be pretty unwieldy.
Then there’s the problem of powering the thing: the Red Planet gets less than half the level of solar energy we do. It’s all possible, and NASA is looking into it – but perhaps a mini airship design would be more practical.
Robert is a science writer and visiting professor of science at Aston University.