The discovery of the mineral jarosite in rocks analyzed by the
Mars Rover, Opportunity, on the Martian surface had special
meaning for a team of Syracuse University scientists who study
the mineral here on Earth. Jarosite can only form in the
presence of water. Its presence on Mars means that water had to
exist at some point in the past. The trick is in figuring out if
jarosite can be used as a proxy for determining when, and under
what conditions, water was present on the planet. The SU
scientists have done just that. In a recent study published in
the October 15 (v. 310) issue of Earth and Planetary Science
Letters, Suzanne Baldwin, professor of Earth Sciences in SU’s
College of Arts and Sciences; and Joseph Kula, research
associate and corresponding author for the study, established
the “diffusion parameters” for argon in jarosite. In simpler
terms, they discovered a way to use the noble gas argon, which
accumulates in jarosite over time, to determine the age of the
mineral and the surface conditions under