It may sound like finding a ski resort in the Amazon, but a team of scientists from the Planetary Science Institute claim to have found evidence that the super-hot planet Mercury has subterranean salt glaciers at its north polar region.
If there's one thing that Mercury is known for, it's that it's hot. Really hot. The closest planet to the Sun, during the day its surface temperature tops out at 800 °F (230 °C). It also has no atmosphere or magnetic field, and should be about as dry and lifeless as it's possible to be.
However, that may not be the case. There could be hidden glaciers at the north pole of Mercury that have been there for over a billion years, with evidence of their existence uncovered by later asteroid impacts.
According to the team, glaciers are more common in the solar system than once thought, citing the example of the nitrogen glaciers found on Pluto by NASA's New Horizons deep-space probe. The Mercurian ones would have been produced in Mercury's ancient past by water that seeped up from the planet's core while there was still volcanic activity. When the water reached the frozen subsurface polar region, it formed shallow seas that interacted with salt flows, forming buried glaciers, according to computer models based on data from NASA's MESSENGER orbiter.
The cold subsurface temperatures are a holdover from a time when the primordial Mercury still had an atmosphere, which shielded the poles from the Sun, allowing liquid water to form and for frozen regions to stabilize underground.
According to the team, these Volatile Rich Layers (VRLs) produced distinct geological structures in the form of sublimation pits. That is, pits left behind as the exposed salty ice flashed into gas as it was exposed to the vacuum of Mercury's surface by asteroid impacts. These were found inside craters, but not near the crater rims, supporting the idea that they were uncovered by impacts.
If this theory holds up, it will also have an effect on the search for life off Earth because such salty glaciers could harbor some form of microbial life. It would be too hostile for garden variety microbes, but it could be home to some of the extremophile life forms found on Earth in niche environments like the Atacama Desert, the Dead Sea, and in hot springs.
The research was published in The Planetary Science Journal.
Source: Planetary Science Institute
