161 Washington, April 8 Do you know that a NASA spacecraft launched 20 years ago is still working at the Red Planet? For two decades, the longest-lived spacecraft at the Red Planet, 2001 Mars Odyssey, has helped locate water ice, assess landing sites, and study the planet's mysterious moons, NASA said. Launched 20 years ago on April 7, the orbiter, which takes its name from Arthur C. Clarke's classic sci-fi novel "2001: A Space Odyssey", was sent to map the composition of the Martian surface, providing a window to the past so scientists could piece together how the planet evolved. But it has done far more than that, uncovering troves of water ice, serving as a crucial communications link for other spacecraft, and helping to pave the way not just for safer landings but also future astronauts.