The Martian “rover-veteran” of NASA Opportunity recently successfully “experienced” the shortest days of the Martian year, while the solar panels of the rover remained almost dust-free. However, in the future, in 2018, the rover may be expected by powerful dust storms, say members of the scientific team of the mission.
Rovers Spirit and Opportunity landed on the surface of Mars in January 2004 with a mission that was to continue for as little as 90 sols (Martian days), equivalent in duration to the three terrestrial months. Currently, communication with the Spirit rover is lost, but Opportunity continues to work successfully on the surface of the Red Planet, transferring to the Earth important scientific information.
The Opportunity rover is highly dependent on solar energy and in the event of a lack of illumination its activity drops significantly. Therefore, the Martian winter, when the Sun in the sky of the southern hemisphere of the planet where the rover is, rises and sits closer to the north, members of the scientific team of the mission try to periodically place the rover on the slopes facing north to the solar panels. Currently, the rover explores the so-called Valley of Perseverance, located on the inner slope of the Endurance crater with a diameter of 22 kilometers, and the Opportunity rover command, when the rover descends the crater, periodically makes stops on the north-facing sites for charging batteries. The rover team calls these sites “water lilies”, drawing an analogy with frogs jumping from one lily to the other and moving thus on the surface of the reservoir.
Not every Martian winter Opportunity rover was in such favorable conditions for recharging energy. For example, in 2011-2012. He spent 19 weeks in the same place, because he did not have enough energy to go to another nearest site, which has a favorable charging of solar panels tilt.
Also, the amount of dust in the Martian atmosphere and directly on the solar panels of the rover affects the security of the rover. The wind can sweep the dust off the solar panels, but at the same time, strong winds lift dust into the air and reduce the illumination of the panels. The next powerful dust storm is expected on Mars in 2018, scientists believe.