Ranger 2

Organization:	NASA
Major Contractors:	Jet Propulsion Laboratory
Mission Type:	Lunar Science
Satellite of:	Earth
Launch:	November 18, 1961 at 08:09:00 UTC
Launch Vehicle:	Atlas-Agena B
Decay:	November 20, 1961
Mission Duration:	2 days
Mass:	304 kg
NSSDC ID:	1961-032A
Webpage:	NASA NSSDC Master Catalog (http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1961-032A)
Orbital elements
Semimajor Axis:	6,574.2 km
Eccentricity:	.?
Inclination:	33.3°
Orbital Period:	~89 minutes
Apogee:	242 km
Perigee:	150 km
Orbits:	32
Instruments
Lyman-Alpha Telescope  :	scan earth to study hydrogen constituent of exosphere
Magnetometer :	Measure magnetic field in interplanetary space

Ranger 2 was a flight test of the Ranger spacecraft system of the 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.

Spacecraft design

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 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 scintillation counters.

The communications system included the high gain antenna and an omni-directional 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.

Mission

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 November 20, 1961.

External link

• Lunar impact: A history of Project Ranger (PDF) 1977 (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19780007206_1978007206.pdf)