Scientist Smackdown: Are There Signs of Life in a Meteorite From Mars?

It's back. ALH 84001, the meteorite of Martian origin that NASA scientists claimed in 1996 contained evidence of life on Mars, has returned to the scene. This time, the team published a paper in the journal Geochimica et Cosmochimica Acta (the journal of the Geochemical and Meteoritic Society). And the scientists say they're more confident than ever that the meteorite shows signs of martian life. The NASA team of David McKay, Everett Gibson and Kathie Thomas-Keprta garnered widespread attention and even an announcement by President Bill Clinton when the 1996 paper came out. The NASA claim focused on nano-sized evidence: magnetite crystals embedded in the meteorite, which arrived here on Earth 13,000 years ago. Because some Earth bacteria secrete magnetite, McKay and his team argued that the mineral in the meteorite could be of biological origin, and the 'biomorphs" in this image (which is from the new study) could be ...