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NASA discovers nearly one trillion tons of ice on Mercury

NASA has reportedly discovered a large cache of ice on the planet nearest to the sun, along with clues that may someday provide astronomers with the necessary data for determining how life got its start here on Earth.

In a hastily arranged news conference on Thursday, NASA officials announced the finding, saying new data from the MESSENGER spacecraft, which began orbiting Mercury in 2011, confirmed the presence of ice spots.

“The new data indicate the water ice in Mercury’s polar regions, if spread over an area the size of Washington DC, would be more than two miles (3.2 kilometers) thick,” said David Lawrence of John Hopkin’s Applied Physics Laboratory, who is part of the Messenger mission.

NASA scientists said the discovery is groundbreaking in the sense that the astronomy community was largely split over whether Mercury held any ice. Temperatures on the planet wary widely, swinging from 800 degrees Fahrenheit to -350 degrees Fahrenheit. Speaking Thursday, NASA scientists suspect large amounts of ice are located deep in craters scattered around the planet.

“In these planetary bodies, there are hidden places, as it were, that can have interesting things going on,” said Lawerence.

“It’s not something we expected to see, but then of course you realize it kind of makes sense because we see this in other places,” added planetary scientist David Paige, who is associated with the University of California, Los Angeles.

It remains unclear exactly how much ice is on the planet, although NASA says Mercury could hold ice reserves totaling upwards of one trillion tons.  Columbia University’s Sean Solomon, who serves as the principal scientist for Messenger, said there was enough ice there to encase Washington, D.C., in a frozen block two and a half miles deep. Meanwhile, Lawrence says current estimates have a large margin of error, but he estimates the total amount of ice to be well over 100 billion tons.

“If you add it all up, you have on the order of 100 billion to 1 trillion metric tons of ice,” said Lawrence. “The uncertainty on that number is just how deep it goes.”

The discovery raises a number of questions, including where the ice originated. NASA officials say the ice is more than likely the result of meteorite bombardments and planetary outgassing. Meteorites, especially in the past, potentially carried large amounts of water to Mercury’s surface. Outgassing of water from the planet’s interior could also provide a non-negligible flux of water to the surface, although this is speculative.

In addition, data obtained by MESSENGER identified icy spots that indicate ice may have melted, leaving a patch of dark material with a lower concentration of hydrogen. The researchers said this dark material could actually be the key to explaining how the water got there in the first place, although they declined to speculate further. Paige noted that the discover of organic compounds likely raises the odds of discovering organic compounds on other planets and moons within the solar systems.

“It could be that it’s not just a question of having planets in a habitable zone. Maybe you need all these other ices and organics out there in the outer solar system to seed the planet, to provide the raw the material,” said Paige.

It remains unclear when NASA plans to follow up on the finding. Speaking Thursday, NASA scientists downplayed any possibility that Mercury once hosted life. The team said they believe the organic compounds discovered on Mercury may, however, provide insight regarding how life began on Earth and how life may evolve on planets beyond the solar system. The U.S. space agency, which is currently engaged in its high-profile endeavor on Mars, does not have plans to launch additional missions to Mercury. That said, at least one MESSENGER team member held out hope of increased focus on the sun’s nearest neighbor.

Mercury is becoming the subject of new interest “where it wasn’t much of one before,” Solomon said.

The findings appear in a set of three papers published Thursday on the Web site of the journal Science.