The Martian subsurface may be an excellent site to explore for potential modern life on the Red Planet, according to a new study, which comes as NASA’s Perseverance rover starts its quest for ancient life on Mars’s surface.
The research, which was published in the journal Astrobiology, examined the chemical makeup of boulders that were blasted from the surface of Mars and subsequently fell to Earth. According to the analysis, such rocks would provide the chemical energy required to support microbial communities that are similar to those that live in the darkest depths of the Earth if they were in regular touch with water.
These discoveries imply that a large portion of the subsurface of Mars may be livable since these meteorites may be indicative of large areas of the Martian crust.
“The big implication here for subsurface exploration science is that wherever you have groundwater on Mars, there’s a good chance that you have enough chemical energy to support subsurface microbial life,” said Jesse Tarnas, a postdoctoral researcher at NASA’s Jet Propulsion Laboratory who led the study while completing his Ph.D. at Brown University. “We don’t know whether life ever got started beneath the surface of Mars, but if it did, we think there would be ample energy there to sustain it right up to today.”
Recent years have seen the discovery of a massive biome that exists largely apart from the surface of Earth in the planet’s depths. These animals rely on the results of chemical processes that occur when rocks come into touch with water to thrive in the absence of sunshine.
One of such process is radiolysis, which takes place when water trapped in rock pores and crack spaces reacts with radioactive elements present in the rock. Water molecules are disassembled into their component constituents, hydrogen and oxygen, in the process.
The subsurface is one of the frontiers in Mars exploration. We’ve investigated the atmosphere, mapped the surface with different wavelengths of light, and landed on the surface in half-a-dozen places, and that work continues to tell us so much about the planet’s past. But if we want to think about the possibility of present-day life, the subsurface is absolutely going to be where the action is.
Professor Jack Mustard
The liberated hydrogen is dissolved in the remaining groundwater, while minerals like pyrite (fool’s gold) soak up free oxygen to form sulfate minerals. The oxygen preserved in the sulfates can be used by microbes to “burn” the dissolved hydrogen as fuel.
These “sulfate-reducing” microorganisms have been discovered living more than a mile deep, in water that hasn’t seen the light of day in more than a billion years, in sites like Canada’s Kidd Creek Mine.
Tarnas has been working with a team co-led by Brown University professor Jack Mustard and Professor Barbara Sherwood Lollar of the University of Toronto to better understand these underground systems, with an eye toward looking for similar habitats on Mars and elsewhere in the solar system.
The project, called Earth 4-D: Subsurface Science and Exploration, is supported by the Canadian Institute for Advances Research.
The goal of this new investigation was to determine whether Mars might harbor the components needed to support radiolysis-powered homes. They used information from the Curiosity Mars rover from NASA, information from other orbiting spacecraft, and compositional information from a collection of Martian meteorites that are indicative of various regions of the planet’s crust.
Radioactive elements including thorium, uranium, and potassium; sulfide minerals that might be turned to sulfate; and rock units with enough pore space to hold water were the ingredients the researchers were seeking for.
The research discovered that all the components needed to support habitats similar to those on Earth are present in sufficient quantities in a variety of Martian meteorites. This was especially true for regolith breccia meteorites, which were discovered to have the highest potential for life support because they were derived from crustal rocks older than 3.6 billion years.
Mars does not have a plate tectonics system like Earth does, which continuously recycles crustal rocks. Therefore, these historic landscapes have mostly not been altered.
The findings, according to the researchers, support the need for an exploration mission that seeks for indicators of modern life in the Martian subsurface. The researchers claim that there is grounds to think that groundwater exists on Mars today and that previous studies have discovered signs of an active groundwater system in the past.
For instance, a recent study suggested that the southern ice cap of the planet might be hiding a subterranean lake. According to a recent study, life-sustaining energy can be found wherever there is groundwater.
Tarnas and Mustard say that while there are certainly technical challenges involved in subsurface exploration, they aren’t as insurmountable as people may think. A drilling operation wouldn’t require “a Texas-sized oil rig,” Mustard said, and recent advances in small drill probes could soon put the Martian depths within reach.
“The subsurface is one of the frontiers in Mars exploration,” Mustard said. “We’ve investigated the atmosphere, mapped the surface with different wavelengths of light, and landed on the surface in half-a-dozen places, and that work continues to tell us so much about the planet’s past. But if we want to think about the possibility of present-day life, the subsurface is absolutely going to be where the action is.”
The research was supported by the Canadian Institute for Advanced Research.
