The problem of static
Mars has been in the news quite a lot lately, especially with the success of the recent Sojourner landing and “Mars hoax“. Well, the red planet is back in the news again due to an issue that most people — unless you’re in the electronics sector — much on earth: static electricity. On Mars, though, it’s a much bigger problem for two reasons. Firstly, the potential to create an electrical charge is much greater on Mars, than it is on Earth.
When certain pairs of unlike materials, such as wool and hard shoe-sole leather, rub together, one material gives up some of its electrons to the other material. The separation of charge can create a strong electric field.
Here on Earth, the air around us and the clothes we wear usually have enough humidity to be decent electrical conductors, so any charges separated by walking or rubbing have a ready path to ground. Electrons bleed off into the ground instead of accumulating on your body.
NASA will have to overcome this obstacle in order to establish Mars and lunar bases. But the problem isn’t as simple as it might seem at first glance. Here on Earth, the moisture in the air and the ground makes absorbing the excess electrons that build up quite easy. But on Mars (and the moon), there is almost no moisture. An astronaut touching, for instance, the door to a lunar or Mars base could fry the sensitive electrical circuitry in his suit. Apollo astronauts didn’t have this problem, probably because they were not active enough to create the static charges necessarily to create an electrical shock. But astronauts on Mars, using heavy equipment, might.
On Earth, the best ground is, well, the ground. But on Mars, it might well be the martian atmosphere itself, with a little help:
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.
Solving the same problem on the moon, though, might be a little bit different:
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.
As always, more research and testing needs to be done. Regardless, frying space suits is a sure way to get oneself stranded on terra firma far away from home.
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