Crackling Planets - Static Electricity on the Moon and Mars

On the Moon, "Apollo astronauts never reported being zapped by electrostatic discharges," notes Calle. "However, future lunar missions using large excavation equipment to move lots of dry dirt and dust could produce electrostatic fields. Because there's no atmosphere on the Moon, the fields could grow quite strong. Eventually, discharges could occur in vacuum."

"On Mars," he continues, "discharges can happen at no more than a few hundred volts. It's likely that these will take the form of coronal glows rather than lightning bolts. As such, they may not be life threatening for the astronauts, but they could be harmful to electronic equipment."

So what's the solution to this problem?

Here on Earth, it's simple: we minimize static discharge by grounding electrical systems. Grounding them means literally connecting them to Earth - pounding copper rods deep into the ground. Ground rods work well in most places on Earth because several feet deep the soil is damp, and is thus a good conductor. The Earth itself provides a "sea of electrons," which neutralizes everything connected to it, explains Calle.

There's no moisture, though, in the soil of the Moon or Mars. Even the ice believed to permeate Martian soil wouldn't help, as "frozen water is not a terribly good conductor," says Landis. So ground rods would be ineffective in establishing a neutral "common ground" for a lunar or Martian colony.

Note the mars dust clinging to Sojourner's wheels. This is indirect evidence of electrostatic charging.

On Mars, the best ground might be, ironically, the air. A tiny radioactive source "such as that used in smoke detectors," could be attached to each spacesuit and to the habitat, suggests Landis. Low-energy alpha particles would fly off into the rarefied atmosphere, hitting molecules and ionizing them (removing electrons). Thus, the atmosphere right around the habitat or astronaut would become conductive, neutralizing any excess charge.

Achieving a common ground on the Moon would be trickier, where there's not even a rarefied atmosphere to help bleed off the charge. Instead, a common ground might be provided by burying a huge sheet of foil or mesh of fine wires, possibly made of aluminum (which is highly conductive and could be extracted from lunar soil), underneath the entire work area. Then all the habitat's walls and apparatus would be electrically connected to the aluminum.

Research is still preliminary. So ideas differ amongst the physicists who are seeking, well, some common ground ;)