Mud particles within the Martian environment can generate static electrical energy, however are usually not sufficient to hazard the rovers

Lightning is one of the most powerful forces in nature. Up to 1 billion volts of electricity can flow into a strike in less than a second. Such a large build-up of energy can even be produced by a relatively simple cause – two particles rubbing against each other. A team at the University of Oregon has now investigated whether these simple interactions can cause lightning in a place they haven’t seen before – Mars.

The simple answer to this question is: yes, during dust storms or other events that involve a lot of dust flying around, there will be a “lightning bolt” on Mars, but not nearly as large as the storms observed on Earth. The Martian atmosphere is too thin to hold the voltages required to produce the dramatic lightning strikes common on Earth.

UT video about the lack of atmosphere on Mars.

However, there will still be much smaller electrical discharge events. They can even be visible at close range at certain wavelengths, as dust storms can give off a faint glow if they are not exposed to direct sunlight. This glow will mainly come in the form of radio waves that are invisible to the human eye.

Many researchers have previously tried to model the electrical activity of the Martian atmosphere. The UO team took a different route, taking into account many variables that confused previous efforts. They used a simple glass cylinder with dust particles in it. However, they made it their goal to take into account two different considerations that other experiments failed to take into account.

The yellow and white cloud in the lower center of this image is a Martian “dust tower” – a concentrated cloud of dust that can be thrown dozens of miles above the surface. The blue and white feathers are clouds of water vapor. This image was captured by NASA’s Mars Reconnaissance Orbiter on November 30, 2010. Photo credit: NASA / JPL-Caltech / MSSS

First, they charged the cylinder itself electrically so that it repels the dust used in the experiment. The cylinder itself was relatively small – four inches in diameter and eight inches in length. In the past, researchers had allowed dust to come into contact with the glass cylinder, which was unlike any material on Mars itself. There were concerns that the ability to contact non-Martian materials would affect the study’s results.

Another challenge to previous experiments was using rocks similar enough to what was found on Mars. Joshua Méndez Harper, a research engineer and author of the paper, had relatively easy access to the type of volcanic rock, similar to that found on Mars, when he worked in the UO’s volcanology department.

Graphic of the test setup for the isolation of the Martian material.
Photo credit: Méndez Harper et al.

The combination of only Martian analog material in the cylinder as well as the isolation of adjacent non-Martian material means that this is the closest possible way to truly model the environment on Mars electrically.

The core of why the Martian atmosphere would not support the great lightning strikes on Earth is the lack of atmosphere. The electric fields that the sparse Martian atmosphere can withstand are around twenty thousand volts per meter, compared to three million volts per meter in the much denser Earth’s atmosphere.

In this image of the Earth from the International Space Station, air glow (along with a lightning sprite) is visible. Photo credit: NASA

Since lightning is a disturbance of the atmosphere itself, the higher the electric field to which it is exposed, the more spectacular the lightning is. At the levels the Martian atmosphere is exposed to, only small electrostatic discharges are likely to be supported, similar to those you would experience if you rub your socks on a carpet and touch a metal doorknob in winter.

This is actually good news for the current residents of Mars – rovers like perseverance and curiosity can withstand the small electrical discharges that the Martian atmosphere allows. For larger discharges, the guiding frame of the rovers could act like a lightning rod, with less than ideal consequences for the rovers themselves.

UT video about Martian dust storms.

The lack of a lightning bolt could also affect longer-term settlement, although the possible effects are still unclear. In addition, lightning plays a role in the formation of organic compounds. It is not yet clear whether the denser Martian atmosphere of the past was able to support the high-energy bolts required to produce these organic compounds.

For now, we can say that Endurance and the other rovers on the surface will most likely not be the focus of a visible thunderstorm. But look carefully with the right gear and you may be able to see a faint glow surrounding them.

Learn more:
UO – Mars rover safe from lightning strikes, new UO research results
NSF – Mars rover safe from lightning strikes, research results
UT – lightning detected on Mars
Icarus – Detection of spark discharges in a moving Martian dust simulant isolated from foreign surfaces

Mission statement:
Curiosity Rover Selfie.
Photo credit: NASA / JPL-Caltech / MSSS

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