James F. Kasting

The Pennsylvania State University

Primary Section: 15, Geology
Secondary Section: 16, Geophysics
Membership Type: Member (elected 2018)


James Kasting is a planetary scientist who is recognized for his work on planetary habitability and on the composition of Earth’s early atmosphere. He is perhaps best known for his work on habitable zones around stars, delineating the region in which a rocky planet can maintain liquid water on its surface. He was born in Schenectady, New York, but grew up in multiple locations, including Cincinnati, Ohio, Huntsville, Alabama, and Louisville, Kentucky. He was a school boy in Huntsville during the Apollo program when the Saturn 1b and Saturn V booster rockets were being designed and tested at Marshall Space Flight Center just outside of town. He majored in Chemistry and Physics as an undergraduate at Harvard University, then got his PhD in Atmospheric Sciences at University of Michigan. He was a postdoctoral fellow at the National Center for Atmospheric Research in Boulder, Colorado, then spent seven years at NASA Ames Research Center in California before joining the faculty at Penn State University in 1988. He co-chaired a design study for NASA’s Terrestrial Planet Finder—Coronagraph mission back in 2005-06 and remains interested in big, direct-imaging space telescopes that can search for habitable planets around other stars.

Research Interests

Dr. Kasting's current research is focused on understanding the rise of atmospheric oxygen on Earth by analyzing data on sulfur and oxygen isotopes in ancient sediments. Sulfur has four stable isotopes that can be fractionated in an anomalous, mass-independent manner by photochemical processes in an anoxic atmosphere. Modeling of this isotopic signature can shed light on the timing of when atmospheric O2 first rose to appreciable levels, around 2.4 b.y. ago, as well as on the nature of the atmosphere prior to that time, during Earth's Archean Eon. Similarly, oxygen has three stable isotopes, and these can be fractionated mass-independently in atmospheres containing appreciable O2. Modeling of these data can provide information on O2 concentrations during Earth's Proterozoic Eon, between 2.5 and 0.6 b.y. ago. Determining how and why atmospheric O2 rose on Earth is key to understanding its possible importance as a biosignature in the atmospheres of rocky exoplanets. This work is part of a larger effort by many astrobiologists to understand the origin and evolution of life on Earth along with its distribution in the universe.

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