A new analysis of seismic data from NASA’s Mars InSight Planetary Mission has revealed some startling facts.
First surprise: there is little or no snow in the top 300 meters from the surface below the landing site near the Martian equator.
“We found that the crust of Mars is weak and porous. The sediment is not well cemented.
And there’s no ice or too much ice to fill the pore space,” said Vasan Wright, a geophysicist at the Scripps Institution of Oceanography at the University of California San Diego.
Wright and three co-authors published their analysis August 9 in the journal Geophysical Research Letters.
Their paper was titled “A Minimal Cemented Shallow Crust Beneath InSight.”
“This finding does not rule out that there may be ice grains or small ice balls that do not hold other minerals together,” Wright said. “The question is, how likely is ice to exist in this form?”
Second surprise: This goes against the core idea of what happens to water on Mars. The Red Planet may have harbored seas of water early in its history.
Many experts suspect that most of the water becomes part of the minerals that make up underground cement.
“If you put water in contact with a rock, you create a new set of minerals. Like soil, water is not liquid.
It’s part of the mineral composition,” said co-author Michael Manga of the University of California. Berkeley. “There is some cement, but the stone is not filled with cement.”
“Water can also get into minerals that do not act as cement. But an unincorporated subsurface layer removes a way to preserve the record of life or biological activity,” Wright said.
Cement essentially holds rock and sediment together, protecting them from damaging erosion.
The lack of cemented sediment indicates a water deficit 300 m below the InSight landing site near the equator.
Below average freezing temperatures at Mars’ equator mean that if there was water, the conditions would be cold enough for the water to freeze.
Subsurface water on Mars defies expectations: Physics links seismic data to rock and sediment properties.
Many planetary scientists, including Manga, have long suspected that the subsurface of Mars would be filled with ice.
His doubts were cleared. However, large ice sheets and frozen frozen ice have remained at the poles of Mars.
The InSight spacecraft landed on Elysium Planitia, a flat, smooth plain near the Martian equator in 2018.
Its instruments include a seismometer that measures vibrations caused by earthquakes and impacted meteorites.
Scientists can link this information to a vast amount of knowledge about the surface.
Contains images of the Martian landscape and temperature data. Surface data suggest that the subsurface may consist of sedimentary rock and lava flows.
However, the team had to take into account uncertainties about subsurface properties such as porosity and mineral content.
The seismic waves from Mars earthquakes provide clues about the nature of the material they pass through.
Possible cementing minerals such as calcite, clay, kaolinite and gypsum. All these affect the seismic velocity.
Wright’s team at Scripps Oceanography applied computer modeling of rock physics to interpret the velocities derived from this InSight data.
“We ran each model 10,000 times to incorporate uncertainty into our answers,” said co-author Richard Kilburn, a graduate student working in the Wright-led Scripps Tectonorocphysics Lab.
The simulation showing the subsurface consisting mostly of non-cemented material is best suited to the data.
Scientists want to probe beneath the surface of Mars. Because if there was life on Mars, it would be there.
There is no liquid water on the surface, and life below the surface would be protected from radiation.
Following the sample return mission, NASA’s priority for the next decade is the conception of the Mars Life Explorer mission.
The goal is to drill two meters into the Martian crust at high latitudes in search of life where ice, rock and the atmosphere come together.