The end is nigh for NASA's marsquake hunter.
"The spacecraft’s power generation continues to decline as windblown dust on its solar panels thickens, so the team has taken steps to continue as long as possible with what power remains," NASA officials wrote in an update (opens in new tab) on Tuesday (Nov. 1). "The end is expected to come in the next few weeks."
InSight touched down in November 2018, on a mission to help scientists map Mars' interior in unprecedented detail. The lander has succeeded in that goal, detecting more than 1,300 illuminating marsquakes.
"Observing how the seismic waves from those quakes change as they travel through the planet offers an invaluable glimpse into Mars' interior but also provides a better understanding of how all rocky worlds, including Earth and its moon, form," NASA officials wrote in the update. (InSight was supposed to supplement its marsquake data with measurements from a burrowing heat probe, but the latter instrument did not manage to get deep enough underground to do its work.)
InSight has far outlasted its primary mission lifetime of two Earth years. But the clock is ticking, thanks to the dust that regularly rains down on its solar arrays. The dust buildup got so bad this summer that the mission team had to turn off all of InSight's other instruments to keep its seismometer suite running.
"We were down to less than 20% of the original generating capacity," InSight principal investigator Bruce Banerdt, of NASA's Jet Propulsion Laboratory in Southern California, said in Tuesday's update. "That means we can’t afford to run the instruments around the clock."
Things got worse after a recent dust storm dumped even more grains on the already ruddy InSight. The mission team turned the lander's seismometer off to save power during the storm. It's back on now, but the power will likely run out in a few weeks.
The tightknit InSight team of about 30 people are busy readying for end of mission, including archiving collected data for future science studies and packing up a twin engineering model called "ForeSight," which had been used (in part) to troubleshoot the problems with the burrowing heat probe. (Those efforts did not succeed.)
"We'll be packing it up with loving care," Banerdt said of ForeSight, which will be placed in storage, potentially for future missions to use. "It's been a great tool, a great companion for us this whole mission."
There is no rescue plan for InSight, which launched without solar panel-cleaning measures due to weight and power concerns. Sometimes Mars missions get lucky with a gust of wind blowing away dust, but it's unlikely that enough wind will come along to prolong InSight's life significantly at this point, NASA officials emphasized.
The agency will not declare the mission over until InSight misses two check-ins with the spacecraft orbiting the Red Planet that relay its information back to Earth, such as NASA's Mars Reconnaissance Orbiter. Even after that, NASA's Deep Space Network of radio dishes will continue listening in case the lander phones home.
The team's focus in the coming weeks will be squeezing as much science as possible out of Insight, just like they have for the past few months.
"We'll keep making science measurements as long as we can," Banerdt said. "We're at Mars' mercy. Weather on Mars is not rain and snow. Weather on Mars is dust and wind."
Elizabeth Howell is the co-author of "Why Am I Taller (opens in new tab)?" (ECW Press, 2022; with Canadian astronaut Dave Williams), a book about space medicine. Follow her on Twitter @howellspace (opens in new tab). Follow us on Twitter @Spacedotcom (opens in new tab) or Facebook (opens in new tab).