Surprise, Surprise: Subsurface Water On Mars Defies Expectations

Physics relates the characteristics of rocks and sediments to seismic data.

New seismic data analysis from NASA's Mars InSight mission has revealed a few significant surprises.

The first surprise is that there is little to no ice in the upper 300 meters (1000 feet) of the subsurface under the landing location near the Martian equator.

"We discover that Mars' crust is permeable and fragile. The sediments lack enough cementation. According to geophysicist Vashan Wright of the Scripps Institution of Oceanography at the University of California San Diego, there is either no ice there or not much ice present in the pore spaces. On August 9, 2022, Geophysical Research Letters released a study by Wright and three other writers.

The existence of ice grains or tiny ice balls that are not binding other minerals together is not ruled out by these observations, according to Wright. "How probable is it that ice will exist in that form?"

The second surprise defies a prevalent hypothesis of what transpired to Mars' water. It is thought that the early past of the red planet may have included seas of water. Many researchers hypothesized that a significant portion of that water ended up in the minerals that go into making subsurface cement.

"If water is exposed to rocks, it creates a new set of minerals, such as clay, and ceases to be a liquid. According to research co-author Michael Manga of the University of California Berkeley, it is a component of the mineral structure. Though the rocks are not completely covered in cement, there is some of it.

Minerals that do not serve as cement may also absorb water. However, Wright noted that the uncemented subsoil eliminates one method of keeping a record of life or biological activity. By virtue of their very nature, cements keep rocks and sediments together, preventing them from being eroded away destructively.

In the 300 meters (1000 feet) under InSight's landing site near the equator, there may not be enough water to support the presence of cemented sediments. The typical temperature in the equator of Mars is below freezing, therefore if water existed there, the temperature would be low enough for it to freeze.

Manga and other planetary scientists have long had the suspicion that the Martian subsurface might be covered with ice. Their misgivings have vanished. At the Martian poles, large ice sheets and frozen ground ice still exist.

"As scientists, we now have access to the greatest information and observations. And according to our predictions, the aquifers beneath the frozen earth should still exist at that latitude, said Manga, professor and head of Earth and planetary science at UC Berkeley.

A flat, clean plain near the Martian equator called Elysium Planitia is where the InSight spacecraft made its 2018 landing. A seismometer that gauges earthquake and meteorite shocks was one of its devices.

This information may be linked to a vast body of surface-related data, such as temperature and photographs of Martian landforms. The surface data suggested that lava flows and sedimentary rock may make up the subsurface. The team still had to take into consideration unknowns about subsurface characteristics like porosity and mineral richness.

A marsquake's seismic waves can provide information about the materials they travel through. Seismic velocities are impacted by potential cementing minerals as calcite, kaolinite, clay, and gypsum. The velocities acquired from the InSight data were interpreted using computer modeling of rock mechanics by Wright's team at Scripps Oceanography.

To account for errors in our conclusions, we ran our models 10,000 times each, according to co-author Richard Kilburn, a graduate student at Wright's Scripps Tectonorockphysics Lab. The findings are best suited by simulations that depict a subsurface made primarily of uncemented materials.

In order to find out if there is life on Mars, scientists want to go beneath the surface. Since there is no liquid water on the surface, radiation protection would apply to life below ground. The Mars Life Explorer mission idea will be a NASA priority for the following ten years after a sample-return mission. Drilling two meters (six feet) into the Martian crust at high latitude is the plan in order to look for life where ice, rock, and the atmosphere converge.

The planned multinational robotic Mars Ice Mapper Mission is already being taken into consideration by NASA to assist in identifying potential scientific objectives for the first human trips to Mars. Young scientists are prepared to participate in such expeditions with the aid of Scripps Oceanography.

Jhardel Dasent, another graduate student in the lab Wright directs, stated, "I've heard the Earth may become inhospitable my entire time growing up. I've reached the age when I can help create the knowledge about another planet that might lead us there.