While JPL was working on robotic missions for NASA, other centers were launching astronaut-piloted missions to orbit Earth and the moon. JPL contributed to this effort by developing two robotic series of spacecraft that helped pave the way for the first humans to land on the moon. These lunar craft were the Rangers and the Surveyors.

The Rangers were a series of impact probes designed to fly to the moon and intentionally collide with it, returning images of the surface and the approaching impact. Despite the lab's spectacular success with the Mariners to Venus and Mars, JPL had enormous troubles with its Rangers, which were essentially identical to the early Mariners in design.

The Surveyors were "soft landers" intended to return information about the strength and composition of the lunar surface. They were the first vehicles to operate on the moon. They were also the first spacecraft built for JPL by a contractor -- in this case, Hughes Aircraft Company -- instead of by JPL engineers and technicians.

Surveyor 1 landed successfully on June 2, 1966, demonstrating that lunar dust would not simply swallow up a spacecraft, as some had feared. It also returned images and data about the strength of the surface. Five more successful Surveyors followed.

Surveyor 3, launched April 17, 1967, is probably the most famous of the spacecraft in the program. More than two years after the mission, the Apollo 12 astronauts landed their lunar module, Intrepid, near the defunct lander. They partly dismantled Surveyor 3, returning its television camera and other parts to Earth in November 1969. The camera is now at the National Air and Space Museum in Washington , D.C.