Ranger 3 was a space exploration mission conducted by NASA to study the Moon. The Ranger 3 robotic spacecraft was launched January 26, 1962 as part of the Ranger program. Due to a series of malfunctions, the spacecraft missed the Moon by and entered a heliocentric orbit.
The Ranger 3 space probe was designed to transmit pictures of the lunar surface 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.
Spacecraft design
Ranger 3 was the first of the Block II Ranger designs. The basic vehicle was 3.1 m high and consisted of a lunar capsule covered with a balsa wood impact-limiter, 635 mm in diameter (25 inches), a mono-propellant mid-course motor, a retrorocket with a thrust of 5080 pounds force (22.6 kN), 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 an 11.5 kg 1 kW·h 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 omnidirectional antenna. White paint, gold and chrome plating, and a silvered plastic sheet encasing the retrorocket furnished thermal control.
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 images. Ranger 3 missed the Moon by approximately 36,800 km on January 28 and entered a heliocentric orbit. Some useful engineering data were obtained from the flight.
Even worse, equipment at a Florida tracking station malfunctioned and picked up Ranger 3's orbital parameters 5 minutes late. Meanwhile, the Agena restarted and sent the probe out of Earth orbit, but another error in its guidance program resulted in yet another trajectory error. As a consequence, the spacecraft reached the Moon 14 hours early and on January 28 missed striking the Moon by 36,793 kilometers (22,862 miles).
The trajectory errors made impact with the Moon impossible, but Ranger 3 could still have been used for deep-space studies. So the flight controllers issued commands to unfurl the camera boom, and on January 28 an amended computer program was uploaded. However, midway through the upload, the probe's signal strength began to weaken and the onboard computer system failed completely. Without a functioning computer, the spacecraft was not able keep its high-gain antenna aimed at the Earth, which impeded communication with controllers on the ground.
Mission failure, propellant exhaustion, and cancellation
The TV camera did transmit images, but since the antenna was now pointed away from Earth, the received images were extremely weak and noisy. It was possible to see the reference crosses on the camera lens, illuminated by reflected sunlight from the probe's chassis, but the Moon was not visible.
With the computer dead, Ranger 3 became completely unresponsive to any ground commands and the Earth and Sun sensors were rendered useless. The gyroscopes continued to maneuver the probe and ground controllers momentarily reacquired a lock on the antenna, but without stable attitude control, they could not hold it steady. As they were unaware of the computer failure, they continued sending commands to Ranger 3 in vain. Sporadic tracking of the probe continued until January 31 when the attitude control thrusters exhausted their propellant supply, at which point the mission was officially terminated.