Planetary Evolution: a Photochemical Perspective
When
Where
Dr. Danica Adams
Earth and Planetary Sciences
Harvard University
The unique geologic preservation of much of Mars’ ancient surface provides a window into its earliest history, offering insights into the evolution of terrestrial planets. Extensive surface evidence suggests Mars once hosted large volumes of liquid water, implying a warmer climate sustained by a thicker atmosphere. Previous studies propose that CO2-dominated atmospheres enriched with H2 or CH4 could have driven warming, though such gases exhibit short atmospheric lifetimes. This talk will first present a novel explanation for long-lived warm climates lasting up to 40 million years: sustained hydrogen release through crustal hydration. The presentation will also examine why cool early CO2 atmospheres may have persisted for up to 10 million years before triggering a CO runaway state. Evidence of these redox transformations may remain preserved on the surface, and the discussion will address prior and future investigations to test this hypothesis, particularly through Mars Sample Return missions.
Like Mars, Venus may have undergone significant climate changes during its evolution. While modern Venus is a hot, arid world, the possibility of an early cool, habitable phase remains unresolved. This talk will examine when sulfuric acid hazes in Venus’ history could have cooled the planet enough to permit surface rainfall. This scenario may be testable with NASA’s upcoming Habitable Worlds Observatory (HWO), designed to observe exoplanets with Venus-like characteristics. Although HWO’s launch is years away, the talk emphasizes ongoing efforts to develop advanced modeling tools in preparation for interpreting its future data. By comparing models with existing exoplanet observations, the talk demonstrates that both microphysics and 3D physics are critical for accurate atmospheric interpretations. These analyses aim to refine our understanding of planetary evolution and advance insights into diverse planetary environments.
Host: Dr. Tyler Robinson