Mars Insight snapped a selfie of its dust-coated solar panels in early 2018.
NASA / JPL-Caltech

Mars Insight researchers have caught a lucky break — for a change. The lander’s Seismic Experiment for Interior Structure (SEIS) instrument witnessed a magnitude-5.0 marsquake on May 4, 2022. Though not large by Earth standards, the temblor was the largest recorded on another planet.

The event occurred just three days before power levels on the lander dropped due to accumulation of Martian dust on its solar panels, and the lander entered a preemptive safe mode.

Marsquake spectrum
A spectrogram of the May 4th marsquake.
NASA / JPL-Caltech / ETH Zurich

The finding breaks the previous record for largest marsquake, a 4.2-magnitude quake that Insight detected on August 25, 2021. To date, Insight has detected more than 1,313 marsquakes since it touched down on the Red Planet in November 2018. The quakes give researchers a way to look into the Martian interior, enabling them to measure the thickness of the crust and the size and structure of the planet’s mantle and core.

“Since we set our seismometer down in December 2018, we’ve been waiting for ‘the big one,'” says Bruce Banerdt (NASA Jet Propulsion Laboratory) in a recent press release. “This quake is sure to provide a view into the planet like no other. Scientists will be analyzing this data to learn new things about Mars for years to come.”

Studying marsquakes has allowed researchers to pin down the diameter of the planet’s core — 1,830 km (1,137 miles), to within 50 km — as well as the thickness of the crust, which extends as deep as 37 km (to within 10 km).

Diagram showing marsquake source
Quakes on Mars can come from the crust or the mantle, and they may bounce off the core.
NASA / JPL-Caltech

Scientists think that the prime sources of marsquakes are faults and impacts. While the exact source of the recent “big” quake is unknown, other 4th-magnitude quakes have been tied to the Cerberus Fossae, a region of parallel fissures.

Marsquake seismogram
A seismogram recording of the May 4th marsquake.
NASA / JPL-Caltech

Studying the interior composition of Mars is crucial in understanding how it compares to other terrestrial worlds, and more specifically how it contrasts with Earth and the Moon, for which we have quake data. Ideally, researchers would like to put seismic landers on Mercury and even Venus as well, as alluded to in the recent Planetary Decadal Survey.

Viking 1, NASA’s first successful landing on Mars, also had a seismometer package onboard, but strong winds made measurements impossible. NASA’s Dragonfly helicopter headed to Titan in 2027 will also feature a seismometer.

Other Aspects of Insight

Launched on an Atlas V rocket from Vandenberg Air Force (now Space Force) Base in California on May 5, 2018, the Insight lander touched down at Elysium Planitia on November 26, 2018. The mission also included another first: a pair of CubeSats (MarCO-A and MarCO-B), which flew along with Insight and imaged Mars during flyby. Insight’s seismometer was built by the French space agency (CNES).

SEIS
Insight’s mechanical arm sets SEIS down on the Martian surface.
NASA/JPL-Caltech

Designed as the first dedicated geophysical research station on the planet, Mars Insight had its share of problems to overcome. The biggest was the deployment of the Heat Flow and Physical Properties Package (HP3). HP3 included a percussive drill to probe the Martian interior, but it never managed to reach its target depth for useful observations. Ironically, it was the tough consistency of the crusty soil at the site that thwarted drilling attempts — an unexpected snag, as the hoped-for sandy soil was one of the reasons researchers selected Elysium Planitia in the first place.

SEIS
Deployment of the wind and thermal shield over the SEIS detector.
NASA/JPL-Caltech

Winter Is Coming

Insight’s primary mission took two years (equivalent to one year on Mars) and is complete. Now, although approved for an extended mission through the end of 2022, Mars Insight is battling a familiar problem for solar-powered Mars missions: The lander’s panels have been getting increasingly dusty, and the mission just entered safe mode on May 7th as its power levels dropped. The amount of sunlight is also decreasing as the site enters Martian winter.

Power levels
Power levels (and the appearance of Insight’s solar panels) shortly after landing versus early 2022.
NASA / JPL-Caltech

Engineers lengthened Insight’s life using an innovative method to help clear Insight’s solar panels: using dirt to clean dirt. Controllers employed the lander’s scoop arm to sprinkle regolith across the panels. The larger dirt particles picked up finer dust as the wind blew them off the panels, ultimately making the panels cleaner. The team proved the effectiveness of this technique on May 22, 2021.

InSight Arm
Insight scooped up dirt to clean off its solar panels.
NASA / JPL-Caltech

“Insight has transformed our understanding of the interiors of rocky planets and set the stage for future missions,” says Lori Glaze (NASA’s Planetary Science Division) in a recent press release. “We can apply what we’ve learned about Mars’s inner structure to Earth, the Moon, Venus, and even rocky planets in other solar systems.”

Sunset
A blue Martian sunset for Insight.
NASA/JPL-Caltech

Hopefully, the mission that has provided us with so much “insight” into the Martian interior will wake up once again and phone home.


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