The thermal stability of cold-trapped volatile compounds at the lunar poles

The Diviner Lunar Radiometer Experiment has made the first measurements of the radiometric temperatures of permanently shadowed regions at the lunar poles (Paige et al., AGU 2009). We have used the new constraints provided by the Diviner observations to identify the range of volatile species that can be cold-trapped at the lunar poles. Table 1 shows the representative annual minimum, maximum, and average temperatures of the Moon's cold traps. Table 2 shows our estimates of the temperatures at which selected volatile compounds can be cold-trapped on timescales of months, seasons, and billions of years. The results show that the coldest cold traps are capable of trapping a range of compounds more volatile than water over seasonal timescales and longer, whereas smaller cold traps are only cold enough to trap water. Regions outside of permanent shadow are cold enough to cold trap water during the lunar night, but not over longer timescales. Our results are consistent with the general concept of the migration of volatile species to the polar cold traps, but the composition, abundance and distribution of any cold-trapped species that may be present today remains highly uncertain. Table 1 Table 2