U.S. astronaut, Buzz Aldrin, the second man to walk on the Moon, alluded to a monolith detected on Mars' moon Phobos. Speaking on a U.S. cable television channel he said: "We should visit the moons of Mars. There's a monolith there - a very unusual structure on this little potato shaped object that goes around Mars once every seven hours. 'When people find out about that they are going to say, "Who put that there? Who put that there?" Well the universe put it there, or if you choose God put it there." In 2007 the Canadian Space Agency funded a study for an unmanned mission to Phobos known as PRIME (Phobos Reconnaissance and International Mars Exploration).
Phobos is a vastly promising location for future exploration. The moon itself has long been an anomaly; its orbital characteristics suggest it may be hollow. More aggressive speculation suggests that Phobos may in fact be a derelict spacecraft of the "generation ark" variety described by science writers such as Isaac Asimov. Unexplained surface features such as the numerous converging grooves, together with the conspicuous monolith-like formations, pose the possibility that Phobos harbours uneroded structures deserving of close attention.