As Mars is approaching aphelion or the point at which it is the furthest away from the Sun, less sunlight reaches the spacecraft's dust-covered solar panels, lowering energy output. To overcome this, the NASA's InSight Mars lander ground staff has devised a novel method to raise the spacecraft's energy levels at a time when they have been declining.
The lander's robotic arm tossed sand toward one solar panel, allowing the wind to pick up part of the dust from the panel. As a result, each sol, or Martian day, gained around 30 watt-hours of energy, said the group.
Before InSight's two-year mission extension, the team had planned for this. The mission has been intended to function without scientific equipment for the next few months before restarting science operations later this year. InSight will reserve power for its heaters, computer, and other critical components during this time. The increased power should postpone the devices' shutdown by a few weeks, giving scientists more opportunity to collect extra scientific data.
Matt Golombek, a member of NASA's Jet Propulsion Laboratory's InSight science team in Southern California, speculated that it might be possible to hit the dust on the panels with sand grains that would "saltate," or jump off the solar panel surface and skip through the air in the wind. The larger grains in the wind may carry finer dust particles away.
To test the approach, on May 22, 2021, the 884th sol of the mission, at roughly noon Mars time – the windiest time of day – the scientists used the scoop on InSight's robotic arm to trickle sand adjacent to InSight's solar panels. It was simplest to put InSight's arm over the lander's deck, high enough for the winds to blow sand over the panels.
With winds gusting to 20 feet (6 meters) per second from the northwest, the trickle of sand corresponded with an instantaneous increase in the spacecraft's overall power. While there is no certainty that the spacecraft will have enough power, the recent cleaning will offer some useful buffer to InSight's power store for now.