Q: How do we know that the...
Q: How do we know that the meteorite containing evidence of ancient life on Mars actually came from that planet?
A: The meteorite is one of 12 similar rocks that researchers believe came from Mars. According to NASA, several of the 12 contain bubbles of gas that match gases in the Martian atmosphere measured during the Viking missions to Mars in the 1970s. Because this ratio of gases appears only on Mars and nowhere else in the solar system, researchers are confident that the rocks containing trapped gas came from Mars--and, by extension, so do the other rocks with similar mineralogical properties.
