Mars might be wetter than we thought.
A NASA research team studying the layered deposits of the Red Planet's south pole discovered what seem to be dozens of subsurface lakes, according to a recent study published in the journal Geophysical Research Letters.
This doesn't mean humans can survive easily on Mars, not least of which because many of the subsurface lakes are probably frozen. But it opens a door for future scientific missions to the Red Planet.
Dozens of water-ice deposits under Mars' pole
The volume of these Martian deposits was measured, and they contain layers that alternate from water ice to dust to frozen carbon dioxide, also known as dry ice. Notably, these layers are a physical record of the Red Planet's climatological history. For example, when the planet had a different global tilt than now, colder environments formed the frozen layers that scientists now investigate via surface-permeating radar. This latest study comes on the heels of an earlier, 2018 study that initially found water ice underneath Mars' south pole's surface. "We're not certain whether these signals are liquid water or not, but they appear to be much more widespread than what the original paper found," said a research scientist at NASA's Jet Propulsion Laboratory named Jeffry Plaut, in a statement from the agency.
The surface-penetrating radar was fired from the MARSIS instrument equipped on the European Space Agency's Mars Express orbiter, which bounced back to the probe in varying ways depending on the underlying material on Mars. Water is a very strong reflector of radar waves, which is how the probe identified the water ice below the south pole. We've known for a while that water ice is on the planet, but the totality of water ice present has remained unknown, with a colossal amount detected under the planet's north pole in 2019, and another hinting at an area of subsurface liquid water spanning six to 12 miles around the south pole.
NASA could investigate the geophysics of Mars' pole
However, the latest study pointed to dozens of bright reflection points throughout the pole, encompassing a much bigger region than scientists had thought. And incredibly, some of the water ice detected appears to be less than one mile beneath the surface of Mars. While this is an incredible find, the new water ice is likely frozen, since it lies in extremely cold areas that are roughly -81°F (-63°C). In a statement about the 2019 study that sought to know how liquid water could form near the planet's pole, Adhita Khuller of the new study said: "[I]t would take double the estimated Martian geothermal heat flow to keep this water liquid," according to a Gizmodo report. "One possible way to get this amount of heat is through volcanism. However, we haven't really seen any strong evidence for recent volcanism at the south pole, so it seems unlikely that volcanic activity would allow subsurface liquid water to be present throughout this region."
In other words, NASA (or another spaceworthy power) might need to send a rover to Mars' south pole to investigate local geophysics where liquid matter might reside. The agency had sent the two probes with the Mars Polar Lander in 1999 (dubbed Deep Space 2), but unfortunately, the instruments did not survive the long journey to the Red Planet. We've far to go before we can grasp the totality of Mars and come to know where, when, and why water ice and liquid water are there.