Electrical charges on Phobos could compromise future missions

A new study shows that solar wind creates potentially dangerous electrical charges across Mars' moon Phobos.
By Ed Mason | Oct 24, 2017
Researchers at NASA have discovered that solar wind -- the the stream of electrically charged particles that the sun blows out into space -- creates a complex electrical environment on the Martian moon Phobos.

This study is important because NASA plans to one day send astronauts to the distant satellite. In fact, Phobos is a potential destination for the first base around Mars. However, powerful solar eruptions could affect any astronauts or scientific equipment on the moon.

Phobos orbits incredibly close to Mars, and, since it has no atmosphere and no magnetosphere, it moves directly through streams of solar wind. That then causes the moon to absorb electrically charged particles on its dayside, which leaves a void on its nightside. Such phenomena create an unbalance, which causes negatively charged electrons to fill the void and statically charge the moon's nightside.

"We found that excess charge builds up in these regions during all solar wind conditions, but the charging effect was especially severe in the wake of solar eruptions like coronal mass ejections, which are dense, fast gusts of solar wind," said Farrell, according to Space.com.

In the study, scientists modeled the flow of the solar wind around Phobos. That revealed the buildup of static charge on the nightside can reach 10,000 volts in some materials, including the Teflon suits worn by astronauts during lunar missions.As a result, astronauts and rovers moving across Phobos could build up large electrical charges. Then, when they touch a conductive surface they could release that energy in a giant burst.

NASA currently hopes astronauts will explore Mars by traveling to Phobos and then remotely operating robots on the Martian surface. That will help reduce the considerable time delay faced by Earth-based operators. However, the natural phenomenon around the satellite could pose some problems.

 

Astronomers hope to further study the electrical fields in order to a find way to negate or avoid them during any future missions.

"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 lead author William Farrell, an astronomer at NASA's Goddard Space Flight Center, in a statement. "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."

The new findings are outlined in the journal Advances in Space Research.

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