News FocusLunar and Planetary Science Conference

Icy-Hot Mercury's Water Pinned Down in the Dark

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Science  13 Apr 2012:
Vol. 336, Issue 6078, pp. 150
DOI: 10.1126/science.336.6078.150-a

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At the meeting, researchers heard that signs from the MESSENGER spacecraft orbiting Mercury strongly support the claim that the planet's polar regions harbor eons-old stores of water ice. To detect any possible water ice, MESSENGER carried the first neutron spectrometer to probe Mercury. Cosmic rays striking the planet's surface send neutrons flying into space. But the hydrogen of water ice could keep some neutrons from reaching MESSENGER. Planetary scientists reported that MESSENGER's neutron spectrometer had detected 1% fewer fast neutrons streaming from the north polar region than from the equator. Nearly pure water ice buried under a few tens of centimeters of insulating rocky soil could be responsible for the neutron decrease, the researchers said.