NASA says goodbye to the Mars rover Opportunity after 15 years of exploration, officially declaring it dead after being unable to contact it since last June, after a massive dust storm on the Red Plant darkened the sky for months, blocking sunlight from reaching the rover's solar panels. NASA tried one final time to make contact Tuesday night, and sent a last wake-up song from the emotional team members. Opportunity landed on Mars in 2004 with a twin rover, Spirit. They were only supposed to last for 90 days, but Spirit lasted for seven years, and Opportunity kept on until now. Among the scientific information Opportunity discover, the biggest finding was evidence that ancient Mars had water flowing on its surface that might have been capable of sustaining microbial life.