TEarth may not have been the solar system’s only garden planet. For the first billion years or so, Mars was partially covered by water, as evidenced by dried-up ocean basins and riverbeds on its surface today. But three billion years ago, the planet lost its magnetic field, possibly due to a cooling of its core, which allowed the solar wind to strip away its atmosphere. This, it is thought, caused the water to evaporate into space.
But according to a new study in Proceedings of the National Academy of Sciencesit appears that the water could still be there, trapped in the pores of the volcanic rock 11.5 to 20 km below the Earth. If that much water were transported to the surface, it would cover the entirety of Mars, with an ocean about a kilometer deep surrounding the globe. Even underground, the presence of such large amounts of water could have significant implications for the possibility of life on Mars in the rock pores or mud.
“Water is necessary for life as we know it,” said Michael Manga, co-author of the study and professor of geophysics and planetary sciences at the University of California, Berkeley, in a statement. “I see no reason why (the underground reservoir) shouldn’t be a habitable environment. That’s certainly the case on Earth — deep, deep mines host life, the seafloor hosts life.”
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The new findings are the result of studies by the Mars spacecraft InSight, which landed on the Red Planet in 2018 and was in operation until 2022. InSight’s instruments included a seismometer that recorded marsquakes up to magnitude 5 – a moderate quake on the Richter scale. The tremors could have been caused by volcanic tremors, meteorite impacts or the contraction of the Earth’s crust, but more important than the source was the speed at which the energy was transmitted through the subsurface. Computer models of these measurements were consistent with the tremors passing through a water-soaked region 11.5 to 20 km deep.
“The available data are best explained by a water-saturated middle crust,” the authors write.
It’s not just the seismic data that suggests this conclusion. The amount of surface water trapped in Mars’ polar caps isn’t even close to explaining the amount that was once there, judging by the depth of rivers and ocean depressions. That means the water either sank or disappeared into space, and the new findings suggest the former was the case.
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“Understanding the Martian water cycle is critical to understanding how the climate, surface and interior evolve,” Vashan Wright, another co-author of the paper and an assistant professor of geophysics at the Scripps Institution of Oceanography at the University of California San Diego, said in a statement. “A useful starting point is identifying where and how much water is present.”
The presence of water could be of great importance to Mars’ biology and our understanding of its history, but we are no closer to one day being able to live off Earth. The deepest hole ever drilled on Earth is the super-deep Kola Borehole in northwestern Russia, which goes down about 12 km. That might be deep enough to touch the Red Planet’s waters, but no one is claiming it would be possible to transport the same kind of massive drilling equipment used to dig the Kola Hole to Mars.
“Drilling a 10-kilometer-deep hole on Mars would be difficult even for (Elon) Musk,” Manga told BBC News.
