Cleaning solar modules with sand and wind, on Mars


From pv magazine Global

Insight is a robotic lander designed by the U.S. National Aeronautics and Space Administration and sent to Mars in 2018 to study the deep interior of The Red Planet. Since it started operating, at around 344 million kilometres from the Earth, the lander has accumulated dust on many of its parts, including the PV array that is crucial for repowering its batteries and keeping the machine functioning.

Although the panels are designed to provide enough power over a full Mars year even with significant dust accumulation, NASA is currently planning to hibernate the lander during the Martian winter and to shut down science instruments to keep its electronics warm.

Simultaneously, the agency has also begun to clean the panels of the array with a sort of handmade technique that is, somehow, producing interesting results. On May 22, which corresponds to the mission’s 884th Martian day, the lander’s robotic arm trickled sand near one solar panel, helping the wind to carry off some of the panel’s dust. The sand grains would strike dust on the panels by hopping off the solar panel surface and skipping through the air in the wind, with the larger grains being able to carry off the smaller dust particles in the wind.

“With winds blowing northwest at a maximum of 20 feet (6 meters) per second, the trickling of sand coincided with an instantaneous bump in the spacecraft’s overall power,” the agency explained. This operation was carried at noon, Mars time, which is the planet’s windiest time of day, and resulted in a gain of about 30 watt-hours of energy per ‘sol,’ or Martian day. “The power boost should delay the instruments being switched off by a few weeks, gaining precious time to collect additional science data,” NASA said in a statement, noting that a second attempt to clean the panels was also done on Saturday, June 5.

Despite the success of the operation, the agency said it is uncertain how much additional yield the cleaning will provide, although it gave additional helpful margin to Insight’s power reserves. At the end of the Earth summer, which corresponds to that of the Martian winter, the solar panels should be able to harvest more sunlight and turn the lander’s instruments back on.

A previous, unsuccessful attempt to remove dust from the modules was done almost a year earlier by pulsing the motor that opens and closes the solar array. The use of brushes or fans to clear off dust was excluded since the beginning, as these would have added weight and possible failure points.

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