|Harvard designation||1961 Alpha Theta 1|
|Mission duration||2 days|
|Manufacturer||Jet Propulsion Laboratory|
|Launch mass||304 kilograms (670 lb)|
|Start of mission|
|Launch date||18 November 1961, 08:09:00UTC|
|Rocket||Atlas LV-3 Agena-B|
|Launch site||Cape Canaveral LC-12|
|End of mission|
|Decay date||20 November 1961|
(High Earth planned)
|Semi-major axis||6,574.2 kilometres (4,085.0 mi)|
|Perigee||150 kilometres (93 mi)|
|Apogee||242 kilometres (150 mi)|
Ranger 2 was a flight test of the Ranger spacecraft system of the NASA Ranger program designed for future lunar and interplanetary missions. Ranger 2 was designed to test various systems for future exploration and to conduct scientific observations of cosmic rays, magnetic fields, radiation, dust particles, and a possible hydrogen gas "tail" trailing the Earth.
Ranger 2 was of the Ranger Block 1 design and was almost identical to Ranger 1. The spacecraft consisted of a hexagonal base 1.5 m across, upon which was mounted a cone-shaped 4-meter-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 scintillation counters.
The communications system included the high-gain antenna and an omnidirectional medium-gain antenna and two transmitters at approximately 960 MHz, one with 0.25 W power output and the other with 3 W power output. Power was to be furnished by 8680 solar cells on the two panels, a 53.5 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, gyroscopes, and pitch and roll jets. The temperature was controlled passively by gold plating, white paint, and polished aluminum surfaces.
The spacecraft was launched into a low Earth parking orbit, but an inoperative roll gyro prevented Agena restart. The spacecraft could not be put into its planned deep space trajectory, resulting in Ranger 2 being stranded in low Earth orbit upon separation from the Agena stage. The orbit decayed, and the spacecraft reentered Earth's atmosphere on 20 November 1961.
- "National Space Science Data Center - Ranger 2". National Air and Space Administration. Retrieved 19 June 2012.
- Space Flight Operations Memorandum - Ranger 2 (Post-flight Mission Analysis)
- Lunar impact: A history of Project Ranger (PDF) 1977