Number 283 (Story #1), August 27, 1996 by Phillip F. Schewe and Ben Stein POSSIBLE EVIDENCE FOR LIFE ON MARS has been reported by a team of scientists studying an ancient rock found in Antarctica in 1984. Minerals in the rock suggest that it came from Mars, where it was probably ejected by a giant meteor impact event some millions of years ago. The rock itself, referred to as ALH84001, was formed billions of years earlier, at a time when Mars was warmer, wetter, and presumably more hospitable to life. What does the rock tell us? Team leader, NASA scientist David McKay, says that several strands of evidence, none of which is conclusive by itself, together point toward the existence of ancient life forms on Mars. Microscopic inspection of the rock shows, for example, the presence of organic molecules called polycyclic aromatic hydrocarbons, which can come from the breakdown of biological or non-biological sources. Also present in the sample were minerals sometimes (but not always) associated with bacteria, namely carbonate granules, magnetite, and pyrrhotite. Finally, sample images show 100-nm-sized ovoid shapes which, McKay suggests, might be the fossilized creatures themselves. Various outside scientists have been impressed by the data but skeptical of a biological interpretation; they argue that non-biological causes could account for all of the new findings. Meanwhile, government officials, including President Clinton and NASA administrator Daniel Goldin, have expressed great interest in this research, and proposals for new Mars-oriented projects will doubtless receive great attention. (David S. McKay et al., Science, 16 August 1996.)