Future Mars helicopter flights could make the air glow blue

With the great success of the Mars helicopter Ingenuity, we could be seeing plenty more aircraft exploring other planets in the future. And a recent study has highlighted a delightful possibility: That the blades of drones cutting through the thin atmosphere on Mars could cause the air around them to glow.

Similar to the effect of coronas here on Earth, this glow could be caused by blades generating small electric currents in the martian atmosphere. “The faint glow would be most visible during evening hours when the background sky is darker,” explained lead author of the study, William Farrell of NASA’s Goddard Space Flight Center, in a statement. “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 glow effect would be quirky and intriguing, but it isn’t a cause for concern over the well-being of future drones, according to the researchers. “The electric currents generated by the fast-rotating blades on drones are too small to be a threat to the craft or the Martian environment, but they offer an opportunity to do some additional science to improve our understanding of an accumulation of electric charge called ‘triboelectric charging’,” Farrell said.

Triboelectric charging is a type of static electricity, in which small electric charges build up when two materials rub together, creating a charge — like when you rub a balloon and put it close to your head and it attracts your hair. On Mars, a charge could build up on rotor blades as they cut through the atmosphere, exacerbated by the high levels of dust present on Mars. This charge builds up until the atmosphere starts to conduct electricity, dissipating the charge away from the craft.

This effect would be magnified by Mars’s thin atmosphere and could have enough of an impact to make the air around a craft glow a blue-purple color. But the researchers stress that this effect is only a prediction, and they would have to test the phenomenon using real flights on Mars to see if it would actually happen.

The research is published in the Planetary Science Journal.

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