"X-Files," eat your heart out. Supporters of the theory that life on Earth was "seeded" by organisms from deep space got a boost recently, as analysis of the famous Martian meteorite ALH84001 indicated that it was transferred from Mars to Earth without being heated above 40 degrees Celsius. This relatively low temperature is not enough to sterilize bacteria or microorganisms. This means that Martian microorganisms, if present, could hitch a ride to Earth unscathed on similarly cool meteorites ejected from the Martian surface.
ALH84001 is well-known for providing the best evidence yet of extraterrestrial life. In 1996 microfossils of possible alien bacteria were discovered in the meteorite, yet scientists have argued about the conclusions ever since.
ALH84001 was formed in a magma chamber on Mars 4.5 billion years ago. After a minor planetary impact on Mars about 15 million years ago, it was launched into space, landing on Earth in Antarctica about 11,000 years ago.