Ice in our Solar System. International Polar Year Web Presentation Gregory A. Neumann NASA Goddard Space Flight Center Greenbelt, MD 20771 Gregory.A.Neumann@nasa.gov. What are ices made of?. Solar system is 99% hydrogen, helium, carbon and oxygen, with >0.1% of neon, iron, and nitrogen
diffraction pattern from deuterated water at ~ 8 kbar
Fortes, A. D.
No surface ices exposed?
Volume backscattering in ice inverts circular polarization
J. K. Harmon, P. J. Perillat, and M. A. Slade, 2000.The case for the existence of polar ice on Mercury
Arecibo S-band radar map
Moon’s inclination to the Sun is only 1.5°, allowing permanently shadowed regions inside cratersIce on the Moon
Lunar Prospector Neutron Spectrometer looks for "slow" (or thermal) and "intermediate" (or epithermal) neutrons which result from collisions of normal "fast" neutrons with hydrogen atoms. The ice was thought to be spread over 10,000 to 50,000 square km and amount to 6 billion metric tons. A significant amount of hydrogen would indicate the existence of water - 4.6% over the north polar region and 3% over the south, at a depth of about 40 centimeters beneath dry regolith.
1) Fluxes of fast and epithermal neutrons from Lunar Prospector:
Evidence for water ice at the lunar poles, Feldman et al., Science, v. 281, p. 1496, 1998
No water (as OH-) was detected from the July 31, 1999 crash of Lunar Prospector into the Moon.Possible reasons: might have missed the target area; might have hit a rock; crash had too little energy to separate water from minerals; plume hidden from telescopes by crater walls; telescopes mispointed; or hydrogen simply may not be in the form of water ice.
The Clementine bistatic radar experiment, Nozette et al., Science, v. 274, p. 1495, 1996
MOLA Science Team