2002 Annual Science Report
University of California, Los Angeles Reporting | JUL 2001 – JUN 2002
Celestial Influences on Planetary Environments
Two dramatically different terrestrial impact records were investigated by Frank T. Kyte and his numerous collaborators. Early Archean impact-produced spherule beds, thicker than those at the K-T boundary, contain signature chromium isotope ratios indicative of an extraterrestrial source (Kyte et al., submitted). These global-scale event beds provide direct evidence for the longevity of the late, heavy bombardment of the Earth-Moon system. At the other end of the geological timescale, Kyte and collaborators recovered significant quantities of unmelted meteoritic material from the Eltanin impact into the Southern Ocean (Kyte, 2002). Fragments of the impactor were found in seafloor cores on a Polarstern expedition.
Mathematician Ferenc Varadi and his colleagues have been using fast workstations to study the behavior of the solar system over the past 250 million years (Varadi et al., 2002). An unexpected feature revealed by these many months-long calculations was that the inner planets experienced some kind of dynamical transition about 65 million years ago (Varadi et al., 2001). The coincidence in time of this transition with the K-T impact that extinguished the dinosaurs suggested a possible causal relationship: Perhaps more asteroids were thrown into Earth-crossing orbits by this chaotic change in solar system dynamics? This possibility is now being investigated by adding suites of asteroids to the solar system models.
PROJECT MEMBERS:Bruce Runnegar
RELATED OBJECTIVES:Objective 5.0
Describe the sequences of causes and effects associated with the development of Earth's early biosphere and the global environment.
Define climatological and geological effects upon the limits of habitable zones around the Sun and other stars to help define the frequency of habitable planets in the universe.
Model the future habitability of Earth by examining the interactions between the biosphere and the chemistry and radiation balance of the atmosphere.