No bug-eyed monsters: After hype, NASA finds carbon, chlorine on Mars

The soil sample where it was taken (left) and inside Curiosity's sample-halding machinery (right).

If you've been following the news from the Curiosity rover on Mars, you can be forgiven if you've had bad flashbacks to the Mars Phoenix lander. Back in 2008, rumors started circulating that Phoenix found evidence of life on the red planet, forcing NASA to hastily schedule a press conference in which they shot the rumors down. This time around, NASA has only itself to blame. About two weeks ago, one of its scientists told NPR the rover had made a discovery that would be "one for the history books." Naturally, he neglected to say what it was.

Speculation quickly focused on Curiosity's on-board chemistry lab, which has the ability to detect organic molecules. Although a variety of natural processes can lead to their formation, the presence of organic compounds could provide some indication of whether life was ever possible on Mars. When NASA announced a press conference on the latest Mars results, to be held at the American Geophysical Union meeting, it was careful to manage expectations. The organization noted, "Rumors of major new findings at this early stage are incorrect."

In fact, as scientist Ralf Gellert described it, the goal of the initial chemistry work was to find something completely un-special. This way, NASA could both get a picture of the average environment on the red planet and then confirm that its instruments weren't doing anything odd.