Art By: Don Davis Artist's concept of a catastrophic asteroid impact with the Earth Super-impacts (shown here) on the early Earth 3.5 billion years ago, may have wiped out life completely more than once. Medium impacts would have vaporized upper ocean layers destroying origin-of-life process. Some life may have survived at med-ocean ridges under thousands of feet of water. Revised history for the origin-of -life on Earth has been devoloped from new findings about the frequency and sizes of colossal impacts on our planet. The work was done by Bern Oberbeck and Dr. Kevin Azhnle. of NASA's Ames Research Center.