Sixty-five million years ago dinosaurs ruled the warm Cretaceous Earth. Without warning, this world was swept away forever by the impact of an asteroid about 15 km in diameter, leaving a huge scar now called the Chicxulub crater in Yucatan, Mexico. This catastrophe set the stage for the ascendance of our own biological group, the mammals. Although the fact of this impact is now established beyond doubt, the precise means by which an impact could wipe out such a large fraction of the Earth\'s inhabitants is not fully understood.
An expected 90 day robotic odyssey on Mars has stretched into a two year scientific marathon. Dr. Grant, a geologist with the Center for Earth and Planetary Studies, helped pick the landing sites and works on day-to-day operations of the Spirit and Opportunity Rovers. Youll see the latest photos, learn what Martian mysteries have been uncovered and find out how scientists plan to push the limits of future robots in space. Dr. John A. Grant, III joined the Smithsonian in the fall of 2000 as a Geologist at the Center for Earth and Planetary Studies at the National Air and Space Museum.
Using results from models of the atmosphere/ocean/sediment carbon cycle, the impacts of fossil-fuel CO2 release will be examined including the effect on climate many thousands of years into the future, rather than for just a few centuries as commonly claimed. Prof. Archer will explain how aspects of the Earth system, such as the growth or melting of the great ice sheets, the thawing of permafrost, and the release of methane from the methane hydrate deposits in the deep ocean, take thousands of years to respond to a change in climate.