Landing on Mars' Moons May Electrocute Astronauts
When it comes to exploring Mars, its two moons seem to offer a safe and practical vantage point. Instead of landing on the red planet directly, astronauts have long hoped to instead land on Phobos and Deimos, where they might control machines that rove the Martian surface and collect samples for further research.
That strategy might be out of orbit for now, though-new research suggests that the lack of an atmosphere on Phobos and Deimos means both moons are electrically charged.
Because they have no atmosphere the moons are exposed to solar winds- electrically-charged gas that comes from the surface of the sun at about one million miles per hour. These winds hitting the surface of Phobos and Deimos means that the moons become giant conductors of electricity, holding charges of up to 10,000 volts.
"We found that astronauts or rovers could accumulate significant electric charges when traversing the night side of Phobos—the side facing Mars during the Martian day," said William Farrell of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "While we don't expect these charges to be large enough to injure an astronaut, they are potentially large enough to affect sensitive equipment, so we would need to design spacesuits and equipment that minimizes any charging hazard."
When that solar wind strikes the side of Phobos that exists in daytime, the surface absorbs plasma, creating a void on the opposite nighttime side that the plasma flow cannot enter. Nonetheless, the ion and electron rich wind creates a strong electric field.
"The study shows that this plasma void behind Phobos may create a situation where astronauts and rovers build up significant electric charges," adds NASA. "For example, if astronauts were to walk across the night-side surface, friction could transfer charge from the dust and rock on the surface to their spacesuits. This dust and rock is a very poor conductor of electricity, so the charge can't flow back easily into the surface — and charge starts to build up on the spacesuits."
This would be just fine on the daytime side of the Phobos, as the solar wind and ultraviolet radiation remove the excess charge. On the nighttime side, however, the ion and electrons are so dense and low in the plasma void that they can't weaken the charge. Hence the 10,000 volts in materials like Teflon, which the suits used in the Apollo missions are made from. It would only take an astronaut touching something conductive, like a piece of equipment, to release this charge. Think of the static shock you get when walking over a carpet barefoot and then touching a metal doorknob.