To clean some dust from one of the solar panels, NASAThe InSight cartridge dripped sand over the panel. The wind-blown grains of sand then raised some dust on the panel, allowing the lander to gain about 30 watt-hours of energy on May 22, 2021, the 884th Martian day of the mission. Credit: NASA /JPL-Caltech
The spacecraft has successfully cleared some dust from its solar panels, helping to boost its energy and slow down when it will have to turn off its scientific instruments.
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Mars is approaching aphelion, its furthest point from the Sun. This means that less sunlight reaches the spacecraft’s dust-covered solar panels, reducing their energy power. The team had planned this before the two-year extension of the InSight mission. They designed the mission to operate without scientific tools for the next few months, before resuming scientific operations later this year. During this period, InSight will retain power for its heaters, computer and other key components.
The increase in power should delay the shutdown of the instruments by a few weeks, gaining valuable time to collect additional scientific data. The team will try to clear a little more dust from the same solar panel this Saturday, June 5, 2021.
Dust in the wind
The InSight team has been considering ways to try to clear dust from solar panels for almost a year. For example, they tried to pulsate solar panel placement engines (last used when InSight opened its solar panels after landing) to shake off the dust, but failed.
More recently, several members of the scientific team have begun to pursue the anti-intuitive technique of dripping sand near – but not directly on – the panels. Matt Golombeck, a member of the InSight research team at NASA’s Southern California Jet Propulsion Laboratory, said it may be possible to hit dust on sandstone panels that would “salt” or jump from solar energy panel surface and blow into the wind air. Then the larger grains can carry the smaller dust particles in the wind.
To test the technique, the team used a spoonful of InSight’s robotic arm to stream sand to InSight’s solar panels on May 22, 2021, the mission’s 884th salt, around noon on Mars, the windiest time of the day. . The easiest way was to place the InSight arm above the deck of the lander, high enough for the winds to blow sand over the panels. Of course, with winds blowing to the northwest with a maximum length of 6 meters per second, the jet of sand coincided with an instantaneous blow to the total power of the spacecraft.
“We weren’t sure it would work, but we’re happy it worked,” Golombek said.
While there is no guarantee that the spacecraft has all the power it needs, the recent cleanup will add a useful reserve to InSight’s power reserves.
Survival of Mars
The InSight panels outlived the two-year core mission they were designed for and now power the spacecraft through the two-year extension. Relying on solar power panels allows such missions to be as light as possible to launch and requires fewer moving parts – hence fewer potential points of failure – than other systems. Equipping the spacecraft with brushes or dust-cleaning fans would add weight and damage points. (Some members of the public suggest using the rotating blades of the Ingenuity Mars Helicopter to remove the InSight panels, but this is not an option either: The operation would be too risky and the helicopter is about 2145 miles or 3452 kilometers.)
However, as the Spirit and Opportunity Mars rovers have shown, gusts and vortices can clear solar panels over time. In the case of InSight, the spacecraft’s weather sensors detected many passing whirlwinds, but none cleared dust.
By August, when Mars is moving closer to the Sun in its orbit, InSight’s solar panels should be able to collect more energy, allowing the team to re-engage scientific tools. Depending on the power available, they can start by turning on some for short periods at key times of the day, as they did to save energy.
Whether the instruments are on or off, InSight operations will pause again around October 7, when Mars and Earth will be on opposite sides of the Sun. Known as the solar connection on Mars, this period occurs every two years. Because plasma since the Sun could interrupt radio signals sent to spacecraft at that time, all NASA’s Mars missions will become more passive, continuing to record data and send updates to Earth’s engineers, although no new commands will be sent to them. The moratorium on Mars commands will last several weeks until the end of October.