A new study from Caltech suggests that the theory, developed by physicist Robert B. Leighton and planetary scientist Bruce C. Murray, may indeed be correct. Carbon dioxide makes up more than 95 percent of Mars’s atmosphere, which has a surface pressure of only 0.6 percent that of Earth. Direct sunlight on the CO2 ice deposited at the poles leads to its sublimation . Leighton and Murray predicted that, as exposure to sunlight shifts, atmospheric pressure could swing from just one-quarter that of today’s Martian atmosphere to twice that of today over cycles of tens of thousands of years.
Now, a new model by Peter Buhler of JPL, which Caltech manages for NASA, and colleagues from Caltech, JPL, and the University of Colorado, provides key evidence to support this. The layer-cake deposit contains as much CO2 as in the entire Martian atmosphere today.