NASA’s Mars Reconnaissance Orbiter (MRO) recently caught a glimpse of the agency’s retired InSight lander, documenting the accumulation of dust on the spacecraft’s solar panels. In the new image (taken Oct. 23 by MRO’s High-Resolution Imaging Science Experiment (HiRISE) camera) InSight’s solar panels have acquired the same reddish-brown hue as the rest of the planet.

After touching down in November 2018, the lander was the first to detect the Red Planet’s “marsquakes” revealing details of the crust, mantle and core in the process. Over the four years that the spacecraft collected science, engineers at NASA’s Jet Propulsion Laboratory (JPL), which led the mission, used images from InSight’s cameras and MRO’s HiRISE to estimate how much dust was settling on the stationary lander’s solar panels, since dust affected its ability to generate power.

NASA retired InSight in December 2022 after the lander ran out of power and stopped communicating with Earth during its extended mission. But engineers continued listening for radio signals from the lander in case wind cleared enough dust from the spacecraft’s solar panels for its batteries to recharge. Having detected no changes over the past two years, NASA will stop listening for InSight at the end of this year.
Scientists requested the recent HiRISE image as a farewell to InSight, as well as to monitor how its landing site has changed over time.

“Even though we’re no longer hearing from InSight, it’s still teaching us about Mars,” said science team member Ingrid Daubar of Brown University in Providence, Rhode Island. “By monitoring how much dust collects on the surface – and how much gets vacuumed away by wind and dust devils – we learn more about the wind, dust cycle and other processes that shape the planet.”

Dust Devils and Craters

Dust is a driving force across Mars, shaping both the atmosphere and landscape. Studying it helps scientists understand the planet and engineers prepare for future missions (solar-powered and otherwise) since dust can get into sensitive mechanical parts.

When InSight was still active, scientists matched MRO images of dust devil tracks winding across the landscape with data from the lander’s wind sensors, finding these whirling weather phenomena subside in the winter and pick up again in the summer.

The imagery also helped with the study of meteoroid impacts on the Martian surface. The more craters a region has the older the surface there is. (This isn’t the case with Earth’s surface, which is constantly recycled as tectonic plates slide over one another.) The marks around these craters fade with time. Understanding how fast dust covers them helps to ascertain a crater’s age.

Another way to estimate how quickly craters fade has been by studying the ring of blast marks left by InSight’s retrorocket thrusters during landing. Much more prominent in 2018, those dark marks are now returning to the red-brown color of the surrounding terrain.

HiRISE has captured many other spacecraft images, including those of NASA’s Perseverance and Curiosity rovers, which are still exploring Mars, as well as inactive missions, like the Spirit and Opportunity rovers and the Phoenix lander. 

“It feels a little bittersweet to look at InSight now. It was a successful mission that produced lots of great science. Of course, it would have been nice if it kept going forever, but we knew that wouldn’t happen,” Daubar said.