Ranger 3 was designed to transmit pictures of the lunar surface to Earth stations during a period of 10 minutes of flight prior to impacting on the
Moon, to rough-land a seismometer capsule on the Moon, to collect gamma-ray data in flight, to study radar reflectivity of the lunar
surface, and to continue testing of the Ranger program for development of
lunar and interplanetary spacecraft. Due to a series of malfunctions the
spacecraft missed the Moon.
Spacecraft and Subsystems
Ranger 3 was the first of the so-called Block II Ranger designs. The basic vehicle was 3.1 m high and consisted of a lunar capsule covered
with a balsawood impact-limiter, 65 cm in diameter, a mono-propellant
mid-course motor, a 5080-pound thrust retrorocket, and a gold- and
chrome-plated hexagonal base 1.5 m in diameter. A large high-gain dish
antenna was attached to the base. Two wing-like solar panels (5.2 m
across) were attached to the base and deployed early in the flight. Power
was generated by 8680 solar cells contained in the solar panels which
charged a 11.5 kg 1000 W-hour capacity AgZn launching and backup battery.
Spacecraft control was provided by a solid-state computer and sequencer
and an earth-controlled command system. Attitude control was provided by
Sun and Earth sensors, gyroscopes, and pitch and roll jets. The telemetry
system aboard the spacecraft consisted of two 960 MHz transmitters, one at
3 W power output and the other at 50 mW power output, the high-gain antenna,
and an omni-directional antenna. White paint, gold and chrome plating, and
a silvered plastic sheet encasing the retrorocket furnished thermal control.
The experimental apparatus included: (1) a vidicon television camera, which employed a scan mechanism that yielded one complete frame in 10 s; (2) a gamma-ray spectrometer mounted on a 1.8 m boom;
(3) a radar altimeter; and (4) a seismometer to be rough-landed on the lunar
surface. The seismometer was encased in the lunar capsule along with an amplifier,
a 50-milliwatt transmitter, voltage control, a turnstile antenna, and 6
silver-cadmium batteries capable of operating the lunar capsule transmitter for
30 days, all designed to land on the Moon at 130 to
160 km/hr (80 -100 mph). The radar altimeter would be used for reflectivity
studies, but was also designed to initiate capsule separation and ignite the
The mission was designed to boosted towards the Moon by an Atlas/Agena, undergo one mid-course correction, and impact the lunar surface. At the appropriate altitude the capsule was to separate and the retrorockets ignite to cushion the landing. A malfunction in the booster guidance system resulted in excessive spacecraft speed. Reversed command signals
caused the spacecraft to pitch in the wrong direction and the TM antenna to
lose earth acquisition, and mid-course correction was not possible. Finally
a spurious signal during the terminal maneuver prevented transmission of
useful TV pictures. Ranger 3 missed the Moon by approximately 36,800 km on
28 January and is now in a heliocentric orbit. Some useful engineering data
were obtained from the flight.
Total research, development, launch, and support costs for
the Ranger series of spacecraft (Rangers 1 through 9) was
approximately $170 million.