ALH84001

In 1996, a team of NASA researchers made big news by announcing they had found evidence for life on Mars in a meteor that had come from Mars. The meteor had been the first found in 1984 in the Allen Hills of Antarctica, and had been labeled ALH84001.

The claim was controversial. Many scientists argued the tiny structures inside the rock the NASA team saw as fossils could have non-biological explanations. Supporters of the life theory often conceded that point, but argued the most likely explanation was life.

After a decade of intensive study of Mars by numerous spacecraft designed to pursue numerous approaches to data-gathering, the case for life on Mars-- either in the past or currently existing-- is far from clinched. However, an argument for a warmer, wetter Mars early in its history-- and perhaps fairly recently-- seems to be strengthening. That Mars, of course, would have been more conducive to life.

Using better tools and more knowledge than were available in 1996, a team at NASA's Johnson Space Center in Houston, which, it should be noted, included the key members of the 1996 team, has reexamined the meteor. The 2009 conclusion? The most likely explanation of the structures in the rock is Martian life.