InSight may not be able to collect science data beyond this summer, thanks to long-term dust buildup on its solar panels.
InSight went into a protective safe mode on Jan. 7, temporarily shutting down its instruments after a huge dust storm prevented the solar-powered lander from soaking up enough sunlight. The spacecraft emerged from safe mode on Jan. 19, and things are now getting back to normal.
“Several weeks after the end of a dust storm on Mars, the solar panels of NASA’s InSight lander are producing almost as much power as they did before the storm,” NASA officials wrote in an update on Tuesday (Feb. 15).
Dust storms are measured by a factor called the optical depth, or tau, with a higher value meaning less sunlight reaching the ground. For this storm, Banerdt said the storm never got higher than about two. “It’s still pretty dusty, but not so dusty that it really threatened the spacecraft,” he said.
InSight could have handed dust storms with a tau of about four before the lack of sunlight available for power caused major concerns. By comparison, the Opportunity rover, whose mission ended after a dust storm in 2018, measured a tau of 10.8 before going offline.
InSight (“Interior Exploration using Seismic Investigations, Geodesy and Heat Transport”) touched down near the Martian equator in November 2018, on a mission to help scientists understand the planet’s interior structure and composition like never before. The lander has been doing this primarily by detecting and characterizing marsquakes.
The mission is still working on ways to clean the arrays, including procedures where the lander’s robotic arm scoops up dirt and drops it just upwind of the arrays, so that grains bounce off the array and jar loose accumulated dust through a process called saltation.
“It sounds like a crazy thing to do, but it actually works,” Banerdt said. The project has done it several times, and in each case it raised the output of the arrays by 1-3%.
Mission team members are also using InSight’s communications gear to precisely track the wobble of Mars’ axis of rotation, which yields information about the planet’s core. InSight carries a burrowing heat probe as well, but the little digger failed to get deep enough on Mars to return the desired heat-flow data.
InSight’s operations are funded through this year. Banerdt said that the mission has submitted a proposal as part of NASA’s ongoing senior review of planetary science missions for an extension in the event there’s a “cleaning event” that removes dust from the arrays and boosts the lander’s power. Such an event, though, is unlikely, he acknowledged. “We’re not betting our mortgage on it.”
The drop in power levels is due to the significant accumulation of debris on the craft’s solar panels from dust storms, which have blocked a great deal of sunlight required to energize the lander.
InSight’s primary mission lasted one Mars year, which is about 687 Earth days. The lander is currently operating during an extended mission, which is funded through the end of the year. InSight team members will try to get the lander through that finish line, though success is far from guaranteed.
That January dust storm specifically “expanded very rapidly” and did not provide “any early warning,” Banerdt said. Still, even though the storm was “pretty dusty,” but “not so dusty that it really threatened the spacecraft,” the mission is expected to end by December 2022.