The Aries Ib is a fictional spacecraft seen in the film 2001: A Space Odyssey. It is a ball-shaped lunar lander built for providing regular passenger commuting between Earth's orbit and the Moon, just as the Orion III spaceplane (both operated by Pan Am) provided for travel between the Earth and Space Station V. It is nuclear powered, the high performance of its engines allowing it to make a fast transfer to the moon (at about one day, compared to three days which were necessary for Apollo). It also carries a retractable landing gear.
Read more about this topic: List Of Spacecraft From The Space Odyssey Series