Data from a U.S. spacecraft launched in 2004 to study Mercury confirmed there’s ice on the hot and airless planet’s north pole, a finding that may point to the origin of water on Earth and elsewhere, scientists said.
The ice detected by the National Aeronautics and Space Administration’s Messenger spacecraft was found on parts of Mercury that remain permanently in the shade on its north pole, according to three papers published online ahead of print in the journal Science. The atmosphere-less planet’s conditions are probably too extreme for life, said Greg Neumann, an author of two of the papers.
The water was likely deposited there by comets or icy asteroids, though that isn’t certain, said Neumann, a geophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Observing how the deposits form may be important for understanding how other planets acquire water, Neumann said.
“We’d like to know how these deposits actually form,” Neumann said. “These processes aren’t easily simulated in the lab. There are parallels with how water is found on other planets, and this may be how water was found on earth.”
Interstellar ice balls seem the most obvious culprits, though they aren’t the only way water could have arrived. Water is easily formed, consisting of hydrogen and oxygen. Hydrogen is ejected from the Sun in solar winds, and can interact with oxygen already on Mercury’s surface. Or perhaps the water erupts from the inside of the planet, Neumann said.
Dark material, probably organic deposits, covers the ice elsewhere, the scientists report.
Mercury is an extreme planet, with surface temperatures that can reach over 700 degrees Kelvin, or about 800 degrees Fahrenheit. This, in combination with the planet’s lack of atmosphere, means water exposed to sunlight would rapidly turn into gas and escape into space, according to NASA. However, the ice is located in permanently shadowed craters near the poles, where the temperatures never rise over 102 degrees Kelvin, or about -276 degrees Fahrenheit.
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