Water ice discovered on Mercury
6 Dec 2012 by Evoluted New Media
Water ice has been discovered on Mercury, despite it being the nearest planet to the Sun, often reaching a blistering 800 degrees Fahrenheit at its surface.
This discovery may seem surprising, but due to Mercury having almost no rotational tilt, its poles are virtually sunless. Researchers from NASA have also found organic material in several craters near Mercury’s North Pole that lie permanently in shadow.
“We thought the most exciting finding could be that this really was water ice,” said Maria Zuber, the E.A Griswold Professor of Geophysics in MIT’s Department of Earth, Atmospheric and Planetary Sciences, and a member of the research team. “But the identification of darker, insulating material that may indicate complex organics makes the story even more thrilling.”
Zuber and colleagues analysed observations taken by NASA's MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) mission, a probe that has been orbiting the planet and mapping its topography since April 2011. The results are published in Science.
The probe moves from pole to pole in an elliptical orbit of the planet. Last year, the researchers analysed the probe’s topographic observations to create a high-resolution map. The team found that the bright regions detected in radar lined up with permanently shadowed craters at the planet’s north pole (regions that despite the planet’s high temperature, never see the sun) indicating the possibility of water ice.
In the latest MESSENGER analysis, the team found that the probe’s reflectance measurements (taken with laser altimetry) matched up well with the previously mapped radar bright regions at the north poles. Two craters were particularly bright indicating reflective ice, but just south of the craters, others appeared dark with laser altimetry but bright in radar.
The data, together with a thermal model of Mercury indicated that the bright deposits corresponded to regions where water ice was stable at the surface. In the dark regions, the ice was stable within a metre of the surface. The dark insulating regions are consistent with complex organic molecules.
Additionally, MESSENGER’s neutron spectrometer detected more hydrogen than was expected at the planet’s north pole further confirming that Mercury is home to water ice.
MESSENEGER will continue to orbit Mercury, and Zuber expects future data will reveal information beyond the planet’s surface.
