InSight Mission found little or no ice in the top 300 meters of the Martian subsurface near the equator.
NASA InSight lander has greatly contributed to our understanding of the red planet. The lander has helped us better understand what goes on inside Mars, beneath the surface. The lander has identified countless Marsquackes and even recorded the sound of Mars and the wind on the alien world. It has offered scientists a completely different perspective on studying Mars. And the lander continues to give.
According to a new analysis, inSight’s seismic data has revealed some surprises on the red planet.
A team of researchers from UC San Diego found that there is little or no ice in the top 300 meters of the subsurface beneath the landing site near the Martian equator.
There is a lot of porousness and weakness in Mars’ crust. There is a lack of cementation in the sediments.
“There’s no ice or not much ice filling the pore spaces,” explained geophysicist Vashan Wright of Scripps Institution of Oceanography at the University of California San Diego.
These findings don’t exclude the possibility that there are grains or balls of ice that are not cementing other minerals together. The question is, how likely is that type of ice to exist?
This second surprise contradicts a widely held belief regarding the fate of water on Mars. There is evidence that the red planet once contained oceans of water. A great deal of water was suspected to have become part of underground cement due to its mineral composition.
“If you put water in contact with rocks, you produce a brand-new set of minerals, like clay, so the water’s not a liquid. It’s part of the mineral structure,” said study co-author Michael Manga of the University of California Berkeley. “There is some cement, but the rocks are not full of cement.”
It is also possible for water to enter minerals that do not act as cement. According to Wright, the uncemented subsurface eliminates one way of preserving biological activity or traces of life. Rocks and sediments are protected from erosion by cement by their very nature.
There are no cemented sediments below InSight’s landing site near the equator, which suggests a water scarcity. If water existed at the Mars equator, conditions would be cold enough to freeze it. The average temperature at the equator is below freezing.
There has long been a suspicion among planetary scientists, including Manga, that the subsurface of Mars would be ice-filled. The suspicions they had have evaporated. At the Martian poles, however, there is still frozen ground ice and big ice sheets.
“As scientists, we’re now confronted with the most reliable data, the most accurate observations. And our models predicted that there should still be frozen ground at that latitude with aquifers underneath,” said Manga, professor and chair of Earth and planetary science at UC Berkeley.
The InSight spacecraft touched down on Elysium Planitia, a flat, smooth plain near the Martian equator, in 2018. The spacecraft was equipped with a seismometer for measuring vibrations caused by marsquakes and meteorites crashing.
In addition to images of Martian landforms and temperature data, scientists can tie this information to a vast body of knowledge about the planet’s surface. Based on the surface data, sedimentary rocks and lava flows might make up the subsurface. The team still had to take into account uncertainties about porosity and mineral composition in the subsurface.
It is possible to determine what type of material the marsquakes travel through from the seismic waves they produce. Seismic velocities are affected by cementing minerals, such as calcite, clay, kaolinite, and gypsum. For interpreting the velocities derived from the InSight data, Wright’s team applied rock physics computer modeling.
“We ran our models 10,000 times each to get the uncertainties incorporated into our answers,” said co-author Richard Kilburn, a graduate student working in the Scripps Tectonorockphysics Lab led by Wright.
In simulations, data best fit a subsurface dominated by uncemented material.
Subsurface exploration is important because if life exists on Mars, it would be located there. On the surface, there is no liquid water, and radiation would not harm subsurface life.
The Mars Life Explorer mission concept is NASA’s next priority after a sample-return mission. During the search, two meters of drilling will be completed in the Martian crust at high latitude in order to locate signs of life where ice, rock, and the atmosphere meet.
Mars Ice Mapper Mission, an international robotic mission to map Mars’ ice, is already in consideration to help NASA identify potential science goals for Mars’ first human missions.
Wright and three co-authors published their analysis in Geophysical Research Letters on August 9.
As of writing, InSight has captured 6,622 photographs of Mars, working for a total of 1318 Sols on Mars.
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