Ranger 1

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Ranger 1 was a spacecraft in the Ranger program of unmanned space missions. Its primary mission was to test the performance of those functions and parts necessary for carrying out subsequent lunar and planetary missions; a secondary objective was to study the nature of particles and fields in interplanetary space. The spacecraft was only partially successful, due to failure of a rocket late in the mission.


Spacecraft design

The spacecraft was of the Ranger Block 1 design and consisted of a hexagonal base 1.5 m across upon which was mounted a cone-shaped 4 m high tower of aluminum struts and braces. Two solar panel wings measuring 5.2 m from tip to tip extended from the base. A high-gain directional dish antenna was attached to the bottom of the base. Spacecraft experiments and other equipment were mounted on the base and tower. Instruments aboard the spacecraft included a Lyman-alpha telescope, a rubidium-vapor magnetometer, electrostatic analyzers, medium-energy range particle detectors, two triple coincidence telescopes, a cosmic-ray integrating ionization chamber, cosmic dust detectors, and solar X-ray scintillation counters.

The communications system included the high gain antenna and an omni-directional medium gain antenna and two transmitters, one at 960.1 MHz with 0.25 W power output and the other at 960.05 MHz with 3 W power output. Power was to be furnished by 8680 solar cells on the two panels, a 57 kg silver-zinc battery, and smaller batteries on some of the experiments. Attitude control was provided by a solid-state timing controller, Sun and Earth sensors, and pitch and roll jets. The temperature was controlled passively by gold plating, white paint, and polished aluminum surfaces.



The Ranger 1 spacecraft was designed to go into an Earth parking orbit and then move into a 60,000 by 1,100,000 km Earth orbit. The purpose was to test systems and strategies for future lunar missions.

Delay of the launch


  • Delay of the 1st countdown
    • July 26: Trajectory information required by the Range Safety Officer was delayed.
    • July 27: A guidance system malfunction in the Atlas booster.
    • July 28: Engineers found that the guidance program to be fed into the Cape computer contained an error.
  • 1st countdown. July 29.
    • 83 minutes before launch: Power interruptions occurred, requiring momentary holds to permit all stations to check and recover.
    • 28 minutes before launch: Commercial electrical power failed. Inadequate allowance had been made for changes in cable sag caused by variations in temperature on the new power poles recently installed at Cape Canaveral Air Force Station.
  • 2nd countdown. July 30. Engineers discovered a leak in Ranger's attitude control gas system.
  • 3rd countdown. July 31. A valve malfunctioned in the liquid-oxygen tank on the Atlas booster.
  • 4th countdown. August 1. Ground controllers turned on a spacecraft command applying high voltage to the scientific experiments for calibration purposes. Immediately all stations reported a major spacecraft failure. An electrical malfunction had triggered multiple commands from the central clock timer, and Ranger 1 "turned on" as it had been programmed to do in orbit. The explosive squibs fired, solar panels extended inside the shroud, and all the experiments commenced to operate. Project engineers disengaged Ranger 1 from the Agena and hastily returned it to Hangar AE. Meantime the launch was rescheduled for August 22, the next available opportunity. Subsequent tests and investigations determined the activating mechanism to have been a voltage discharge to the spacecraft frame; although engineers suspected one or two of the scientific instruments, they could not determine the precise source of the discharge with certainty. In the days that followed they replaced and requalified the damaged parts, and modified the circuitry to prevent a recurrence of this kind of failure.

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