NASA Mars Curiosity Rover update: Mars may have once supported life, NASA says

(CNN) -- Dusty and desolate Mars once had conditions favorable for microbial life, NASA scientists announced Tuesday.

The conclusion was based on the Curiosity rover's analysis of a rock sample drawn from an ancient stream bed on the Red Planet.

The sample contained sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon -- "some of the key chemical ingredients for life," NASA said.

"We have characterized a very ancient, but strangely new 'gray Mars' where conditions once were favorable for life," said John Grotzinger, Mars Science Laboratory project scientist at the California Institute of Technology.