The Rivers of Mars: Searching for the Cosmic Origins of Life

In July 1996, a NASA team led by David McKay and Everett Gibson announced the discovery of fossilized traces of microbial life in ALH84001, a meteorite from Mars recovered from the Antarctic. Skeptics insist that the life-like chemical traces found in the meteorite could have been formed by non-biological processes; but most scientists on both sides of the debate agree that the organic compounds, life-derived or not, did originate on Mars.-- How did the meteorite arrive on earth? How was its age determined?-- What makes the scientists so sure it came from Mars?-- What might the findings tell us about life on our own world?