Mars is a dusty place, and new simulations find that tiny helicopters flying in the Martian atmosphere may build up a charge on their propellers and casing. And according to research lead William Ferrell: The faint glow would be most visible during evening hours when the background sky is darker. NASA’s experimental Ingenuity helicopter does not fly during this time, but future drones could be cleared for evening flight and look for this glow.

The physics behind this is very similar to the phenomena of rubbing a balloon on your hair or on a pet and then using the balloon to either get your hair to stand on end or stick the balloon to a wall. Friction between two very different kinds of surfaces can allow electrons to jump from one object to another.

And this brings us to my favorite word in physics: that difference between surfaces is referred to as their triboelectric value. Cats have a large positive value, and balloons are more on the negative side of the series. Similar can be said of helicopter blades versus Martian dust.

Here on Earth, when ships at sea enter storms, a charge can build up on masts. Same with airplanes in storms. We also see friction when the ash in volcanic plumes builds up a charge. In all instances, this glow, referred to as St. Elmo’s Fire, often precedes lightning. On Mars, that isn’t a concern, so I for one look forward to a future of tiny glowing helicopters flitting through the Martian twilight.

More Information

NASA Goddard press release

“Will the Mars Helicopter Induce Local Martian Atmospheric Breakdown?,” W. M. Farrell, J. L. McLain, J. R. Marshall, and A. Wang, 2021 March 10, The Planetary Science Journal