Launched in April 2001, the Mars Odyssey spacecraft was sent by the US National Aeronautics and Space Administration (NASA) to look for evidence of water on Mars. A little over a year later, NASA announced that water had been detected there in the form of ice, suggesting the possibility of microbial life on the Red Planet. The Phoenix lander confirmed the presence of water in 2008. The presence of what element led NASA researchers to conclude that there was indeed water on Mars? Discuss
Source: The Free Dictionary