Mars rover announces discovery of water: When the Mars Phoenix Lander found water on Mars, NASA spread the word via Twitter. 'Are you ready to celebrate? Well, get ready: We have ICE!!!!! Yes, ICE, *WATER ICE* on Mars! w00t!!! Best day ever!!' tweeted the Phoenix Lander’s Twitter feed. Here, the Mars rover, Opportunity, casts a shadow in Nov. 2004.