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Two materials, sapphire and synthetic quartz, have been found for use in Ge detector mounting assemblies. These materials combine desirable mechanical, thermal, and electrical properties with the radioactive cleanliness required to detect minimal amounts of K, Th, and U.

UREY, a proposed NASA Mars Scout mission will, for the first time, measure the absolute age of an identified igneous rock formation on Mars. By extension to relatively older and younger rock formations dated by remote sensing, these results will enable a new and better understanding of Martian geologic history. Thus, Mars will join the Earth and the Moon as the third body in the Solar System for which absolute dating has been accomplished.This revolutionary science mission can be accomplished within the Mars Scout programmatic boundaries because of both extensive heritage and innovative technology.The heritage includes the interplanetary carrier stage, the Mars direct-entry system, the Mars lander, and the Mars rover that had been planned for the Mars 2001 mission before it was cancelled. Urey innovations include two ongoing technology developments that can support a revolutionary science approach. First, miniaturizing of instruments to measure K and 40Ar has proceeded sufficiently to allow in situ dating. Second, the ultrasonic drill, which has been under development at Jet Propulsion Laboratory for several years, can be carried on an existing small rover with design and operational heritage from the Mars Pathfinder mission. The rover's mobility is important because it can carry the drill from the landing site to a remote bedrock location where it can acquire a pristine sample by drilling into that bedrock. The rover will return the sample to the lander for analysis. These in situ analyses will produce new data about Mars chronology, geology, petrology, and chemistry that will significantly change our understanding of the history of the red planet.