Illustration: M. Weiss/UCSC

Astrobiology studies the limits of planetary habitability, informing us about our own biosphere and Earth’s fragility and uniqueness. Our closest planetary neighbors appear lifeless. In its low-pressure, low surface-gravity environment, Mars has been unable to hold onto surface liquid water while our while own sister planet, Venus, is hot enough to melt lead on its surface. As we work to understand the limits of planetary habitability, we will learn about the sustainability of life here on planet Earth. Astrobiology Initiative members from the Earth and Planetary Science (EPS) department at UCSC perform active research to characterize the interiors, surfaces, and atmospheres of Solar System planets, including Earth.

Francis Nimmo studies the surface and interiors of planets and their satellites. He has been involved in many NASA missions such as Cassini to Saturn, New Horizons to Pluto, and the planned Europa Clipper to Jupiter’s icy moon. His work has revolutionized our understanding of the internal structure and evolution of icy bodies in the outer Solar System. He led the study that provided evidence for the subsurface ocean on Pluto and investigated the subsurface processes that cause vigorous plumes at the south pole of Saturn’s icy moon Enceladus. These icy bodies are geologically active, and their subsurface oceans are one of the most likely places in the solar system for extraterrestrial life.

Many icy moons possess liquid water oceans beneath the surface. Some moons, like Enceladus (left panel), have ice shells with plumes from subsurface oceans jetting into space; others, like hazy Titan (center) or Pluto (right) have thicker ice shells. See more Illustration: Danielle Jolette

Using computer models, Xi Zhang’s group simulates the chemistry and flow patterns in planetary atmospheres to understand their evolution. His work on hydrocarbon chemistry and organic hazes in the atmospheres of Pluto and Saturn’s moon Titan directly relates to prebiotic conditions on early Earth. His studies of cloud formation on Venus and dust storms on Mars help us understand how water is transported and even lost to space. Through these studies we learn how planets like Venus and Mars evolve into the apparently unihabitable worlds we stay today.  

Myriam Tellus leads a group analyzing meteorites—the ancient fossils from our early Solar System—to constrain the timescales and conditions of formation of the building blocks of planetary bodies. Utilizing a variety of geochemical tools, her group focuses on several important questions such as how did planet Earth acquire its ocean via water delivery from space. By heating primitive meteorites in the laboratory, Tellus’ group recently simulated the formation and composition of secondary atmospheres outgassed from the interiors of terrestrial planets. 

Earth is our most well-studied planet. UCSC faculty use complex models to describe the coupling between Earth’s interior, atmosphere, climate, and biosphere. As space data is collected from other solar system bodies, we can test the fidelity of our predictions and improve upon our models. The
 long-term goal is to apply these models to objects beyond the solar system to indentify the most likely abodes of life given the plethora of exoplanets identified in the solar neighborhood. 


Read about our research in Astrophysics.