They just announced on NASA TV that they found ice on Mercury's pole.
Listen live:
http://blogs.discovery.com/inscider/...#mkcpgn=fbsci1
Press Conference on MESSENGER results from Mercury
NASA will host a news conference at 2 p.m. EST on Thursday, November 29, to reveal new observations of Mercury's polar regions from the MESSENGER spacecraft. The briefing will be carried live on NASA TV.
The information below, although historically accurate, has not been substantially updated since circa 2005, we will be updating the page to include the new results from the MESSENGER mission.
Mercury would seem to be one of the least likely places in the solar system to find ice. The closest planet to the Sun has temperatures which can reach over 700 K. The local day on the surface of Mercury is 176 earth-days, so the surface is slowly rotating under a relentless assault from the Sun. Nonetheless, Earth-based radar imaging of Mercury has revealed areas of high radar reflectivity near the north and south poles, which could be indicative of the presence of ice in these regions (1-3). There appear to be dozens of these areas with generally circular shapes. Presumably, the ice is located within permanently shadowed craters near the poles, where it may be cold enough for ice to exist over long periods of time. The discovery of ice on the Earth's moon can only serve to strengthen the arguments for ice on Mercury.
How was the evidence for ice found?
Investigations of Mercury were done from Earth using the Arecibo radio telescope, the Goldstone antenna, and the Very Large Array (VLA). The Goldstone/VLA study (1) used the NASA Deep Space Network 70-m Goldstone dish antenna to transmit 8.51 GHz, 460 kW, right circularly polarized radar waves towards Mercury. The reflections were received by the National Radio Astronomy Observatories 26 VLA antennas. Calibration and processing of the radar returns showed radar-bright (high radar reflectivity) with depolarized signatures at the north pole. The Arecibo observations (2,3) were made by transmitting an S-band (2.4 GHz), 420-kW, circularly polarized coded radar wave at Mercury. The wave reflects off Mercury back to Earth. The wave is both transmitted and received by the Arecibo radio telescope. Filtering and processing the return signal gives a radar reflectivity map of Mercury's surface with a resolution of approximately 15 km. About 20 anomalously reflective and highly depolarized features were observed at the north and south poles.