Ice on Mercury

Ice on Mercury

Mercury Globe-MESSENGER mosaic centered at 0degN-0degE.jpg

Even though Mercury is the closest planet to the Sun and its surface reaches temperatures of roughly 430 degrees Celsius (800 degrees Fahrenheit), there is strong evidence that there is ice at Mercury’s poles.


Mercury’s Cold Craters

Compared to any other planet in our solar system, Mercury displays the largest range of surface temperatures. At its poles, Mercury has deep craters. These areas never feel the Sun’s heat and remain at temperatures below negative 220 degrees Celsius (-370 degrees Fahrenheit).

North pole of Mercury -- NASA.jpg


Hints of Possible Ice

The first clues that ice might be found at Mercury’s poles came in 1992 from the Arecibo Observatory in Puerto Rico (pictured below), which mapped the regions of high radar reflectivity. However, confirmation of ice had to wait until a spacecraft could study the planet closer.

Arecibo Observatory Aerial View.jpg


In 2011, NASA’s MESSENGER mission sent a spaceship into an orbit around Mercury. Onboard the craft, one instrument in particular, the Neutron Spectrometer, was critical in the discovery of ice. This instrument mapped neutrons that were emitted from elements on Mercury’s surface. Scientists analyzed the number and energy of these neutrons.

Fast, high-energy neutrons would suggest the presence of water. After analyzing the data, the neutron measurements suggested that water was present at the poles.


How did it get there?

The most likely explanation is that water-rich asteroids or comets seeded the planet with water. The water that fell into a crater would become “cold-trapped” and would remain for billions of years. Some scientists believe that is the same way water arrived here on Earth.


What’s the significance of this discovery?

Even though Mercury has water, scientists don’t expect atmosphereless Mercury to have life. Although, some have proposed that we could put life there.

Others have said that humanity could use the water as a resource for a future Mercury colony

“The water could also be an intriguing resource for people. Between the scorched equator and the frozen poles, temperatures on Mercury can be temperate, especially a few feet below the surface, where the soil insulates against the temperature swings between day and night — an ideal location to build a colony."

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