James F. Kasting

Biosketch

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 Ph.D. 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

James Kasting's research group is interested in the long-term evolution of atmosphere and climate on Earth, as well as on our nearby planetary companions, Venus and Mars. They have argued that the so-called "faint young Sun" problem on Earth can be solved by higher atmospheric CO2 concentrations in the distant past that would have created a stronger greenhouse effect. Atmospheric CO2 and planetary surface temperature are entwined in a negative feedback loop within the carbonate-silicate cycle that helps keep the climate stable over long time scales. This same feedback should operate on Earth-like exoplanets, implying that the habitable zone around Sun-like stars, where liquid water could be present on a planet?s surface, is relatively wide. Kasting's group is also interested in the rise of atmospheric O2 on Earth and in the question of whether O2 might be a reliable biosignature on exoplanets. Ultimately, they hope that researchers will test their theories of planetary habitability and look for evidence of life by building large, direct-imaging space telescopes that can observe planets around nearby stars and obtain spectra of their atmospheres.