Mass: 305 to 367 kilograms (675 to 809 pounds)
Configuration: Cone-shaped structure mounted on six-sided base, flanked
by pair of solar panels. Dimensions about 3 to 4 meters (10 to 13 feet) high, 1.5 meter
(5 feet) in diameter, spanning about 4.6 to 5.2 meters (15 to 17 feet) across solar panels
Science instruments: Varied; early Rangers emphasized study of radiation environment
in space, while later Rangers featured television cameras
The Ranger project of the 1960s was the first U.S. effort to launch probes directly
toward the Moon. The spacecraft were designed to relay pictures and other data as they
approached the Moon and finally crash-landed into its surface. A variety of difficulties
plagued the first several attempted missions in this series, but the later Rangers were
finally a complete success.
Ranger 1 was launched from Cape Canaveral, Florida, on August 23, 1961, followed by the
launch of Ranger 2 on November 18 of that year. In both cases, the Agena B rocket engine
failed to restart and both spacecraft reentered Earth's atmosphere a short time later.
Ranger 3 was launched January 26, 1962, but an inaccuracy put it off course and it
missed the Moon. Ranger 4 had a perfect launch on April 23 of that year, but the spacecraft
was completely disabled. The project team tracked the seismometer capsule to impact just
out of sight on the far side of the Moon, validating the spacecraft's communications and
navigation system. Ranger 5 missed the Moon following its launch on October 18, 1962, and
was disabled. Ranger 6 was launched January 30, 1964, and had a flawless flight culminating
in impact as planned on the Moon; its television system, however, was disabled by an in-flight
accident and could take no pictures.
The next three Rangers, with a redesigned television, were completely successful. Ranger
7 was launched July 28, 1964, and sent more than 4,300 pictures on its way down to target
in a lunar plain, soon named Mare Cognitum, south of the crater Copernicus.
Following launch on February 17, 1965, Ranger 8 successfully completed its mission with
a planned crash-landing in Mare Tranquillitatis, where the Apollo 11 astronauts would land
4-1/2 years later. Ranger 8 garnered more than 7,300 images.
Ranger 9 was launched March 21, 1965, and impacted the Moon in the 90-kilometer-diameter
(75-mile) crater Alphonsus, sending back more than 5,800 images.