PLANETARY SCIENCE:
The Changing Picture of Volatiles and Climate on Mars
Bruce M. Jakosky, Robert M. Haberle, Raymond E. Arvidson
Many questions still remain unanswered about the climate history and possible past biological activity on Mars. In their Perspective, Jakosky et al. discuss recent results from space probes and other studies that are changing scientists' views of martian climate. Observations of holes in the frozen carbon dioxide layer suggest that underlying water ice is being exposed on seasonal cycles, and models indicate that frost deposition may not be driven entirely by local energy balance. Axial obliquity--the tilt of Mars' rotational axis that gives rise to planetary seasons--may also be having a bigger effect than previously thought. And geological mapping shows features that may be glacial in origin, implying a wet past. Despite the large uncertainties, such studies will be important in understanding whether biological activity was part of Mars' history.
B.M. Jakosky is at the Laboratory for Atmospheric and Space Physics and Department of Geological Sciences, University of Colorado, Boulder, CO 80309, USA. R.M. Haberle is at the NASA/Ames Research Center, Moffett Field, CA 94035, USA. R. E. Arvidson is in the Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130, USA. E-mail: bruce.jakosky{at}lasp.colorado.edu
