Lockheed Martin, the contractor working with NASA to take humans to Mars, introduced a reusable moon shuttle on Wednesday that it envisions as a prototype for a vehicle ferrying astronauts between the surface of the Red Planet and an orbiting space station.

The so-called lunar lander concept that the Bethesda, Md.-based company unveiled at the International Astronautical Congress in Bremen, Germany, could take a crew of four people and 2,000 pounds of cargo back and forth between the moon and the Lunar Gateway module, an orbiting outpost NASA aims to build in the 2020s. It wouldn’t need to refuel on the surface.