 Ranger 2 | |||||||||||||||||||
| Mission type | Technology | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Operator | NASA | ||||||||||||||||||
| Harvard designation | 1961 Alpha Theta 1 | ||||||||||||||||||
| COSPAR ID | 1961-032A | ||||||||||||||||||
| SATCATno. | 206 | ||||||||||||||||||
| Mission duration | 2 days | ||||||||||||||||||
| Spacecraft properties | |||||||||||||||||||
| Manufacturer | Jet Propulsion Laboratory | ||||||||||||||||||
| Launch mass | 304 kilograms (670 lb) | ||||||||||||||||||
| Power | 150 W | ||||||||||||||||||
| Start of mission | |||||||||||||||||||
| Launch date | 18 November 1961, 08:09:00 (1961-11-18UTC08:09Z) UTC | ||||||||||||||||||
| Rocket | Atlas LV-3 Agena-B | ||||||||||||||||||
| Launch site | Cape CanaveralLC-12 | ||||||||||||||||||
| End of mission | |||||||||||||||||||
| Decay date | 20 November 1961 (1961-11-21) | ||||||||||||||||||
| Orbital parameters | |||||||||||||||||||
| Reference system | Geocentric | ||||||||||||||||||
| Regime | Low Earth (High Earth planned) | ||||||||||||||||||
| Semi-major axis | 6,574.2 kilometres (4,085.0 mi) | ||||||||||||||||||
| Perigee altitude | 150 kilometres (93 mi) | ||||||||||||||||||
| Apogee altitude | 242 kilometres (150 mi) | ||||||||||||||||||
| Inclination | 33.3 degrees | ||||||||||||||||||
| Period | ~89 minutes | ||||||||||||||||||
| |||||||||||||||||||
Ranger 2 was a flight test of the Ranger spacecraft system of theNASARanger program designed for future lunar andinterplanetary missions. Ranger 2 was designed to test various systems for futureexploration and to conduct scientific observations ofcosmic rays,magnetic fields,radiation, dust particles, and a possiblehydrogen gas "tail" trailing the Earth.[1]
Ranger 2 was of the Ranger Block 1 design and was almost identical toRanger 1. The spacecraft consisted of ahexagonal base 1.5 metres (4 ft 11 in) across, upon which was mounted a cone-shaped 4-meter-high (13-foot) tower of aluminum struts and braces. Twosolar panel wings measuring 5.2 metres (17 ft) from tip to tip extended from the base. A high-gain directionaldish 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 aLyman-alpha telescope, arubidium-vapormagnetometer,electrostatic analyzers, medium-energy-rangeparticle detectors, twotriple coincidence telescopes, a cosmic-ray integratingionization chamber,cosmic dust detectors, andscintillation counters.[1]
Thecommunications system included the high-gainantenna 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 8680solar cells on the two panels, a 53.5 kilograms (118 lb)silver-zinc battery, and smaller batteries on some of the experiments. Attitude control was provided by asolid state timing controller,Sun andEarth sensors,gyroscopes, andpitch and rolljets. The temperature was controlled passively by gold plating, white paint, and polishedaluminum surfaces.[1]
Shortly afterRanger 1's unsuccessful mission,Atlas 117D andAgena 6002 were rolled out toLC-12 for the next attempt. Once again, getting the booster and spacecraft ready for flight proved a frustrating experience. On October 24,NASA received the news from theWest Coast of the United States that a hydraulics failure had preventedDiscoverer 33 from reaching orbit the previous day, which necessitated taking Agena 6002 down from the stack and giving it a thorough checkout. The stage was found to have the same problem asDiscoverer 33's Agena, necessitating repair work. It took until mid-November before everything was finally ready. Liftoff took place at 3:12 AM EST on November 18. An improper autopilot signal resulted in Atlas BECO taking place 0.4 seconds early. Thus the sustainer phase of flight was initiated with below nominal velocity, but the vehicle reached orbit successfully since the guidance computer was programmed to not issue the SECO command until the proper velocity was achieved. A similar event occurred on the launch of SAMOS 4 a few days later and was caused by the switch malfunctioning from its location on the side of the extremely cold LOX tank. The switch was moved to the fuel tank on subsequent Atlas-Agena vehicles.[2]
An inoperative roll gyro caused loss of Agena roll control from the moment of staging. The first burn was performed successfully but the control gas was exhausted trying to keep the vehicle stable so when it came time for restart, the engine shut down after only one second of operation due to ingestion of control gas. Unlike withRanger 1, the Agena had not operated long enough to achieve any significant ISP and so the probe was left in an evenlower orbit. Tracking antennas could not lock onto the probe or send it any commands, nor could the attitude control system stabilize it.Telemetry and instrument data were still received for a few hours, but eventually the orbit decayed too low and after only one day and 19 orbits, Ranger 2 reentered theatmosphere and burned up. As a result of the failure, Agena vehicles would get a version of the Atlas's Spin Motor Rotation Detection System to ensure proper gyroscope operation at launch.[3][1]
