Pioneer 2

Pioneer 2
	The lunar orbiter Pioneer 2.
Mission type	Lunar orbiter
Operator	NASA
Mission duration	42 minutes, 10 seconds; Failed to orbit
Apogee	1,550 km (960 mi)
Spacecraft properties
Manufacturer	Space Technology Laboratories
Launch mass	39.2 kg (86 lb)
Start of mission
Launch date	8 November 1958, 07:30:21 GMT
Rocket	Thor DM 18-Able I
Launch site	Cape Canaveral, LC-17A
End of mission
Decay date	8 November 1958, 08:12:31 GMT
Instruments
	Ionization Chamber
	Magnetometer
	Temperature Sensors
	Micrometeoroid Sensor
	Proportional Counter Telescope
	Television System
	Pioneer program ← Pioneer 1 Pioneer 3 →

Pioneer 2 (also known as Able 3)^[3] was the last of the three project Able space probes designed to probe lunar and cislunar space. The launch took place at 07:30:21 GMT on 8 November 1958. After Pioneer 1 had failed due to guidance system deficiencies, the guidance system was modified with a Doppler command system to ensure more accurate commands and minimize trajectory errors. Once again, the first and second stage portion of the flight was uneventful,^[4] but the third stage of the launch vehicle failed to ignite, making it impossible for Pioneer 2 to achieve orbital velocity. An attempt to fire the vernier engines on the probe was unsuccessful and the spacecraft attained a maximum altitude of 1,550 km (960 mi) before reentering Earth's atmosphere at 28.7° N, 1.9° E over NW Africa.

A small amount of data was obtained during the short flight, including evidence that the equatorial region around Earth has higher flux and higher energy radiation than previously considered and that the micrometeorite density is higher around Earth than in space. The reason for the third stage failure was unclear, but it was suspected that the firing command from the second stage, which contained the guidance package for the entire launch vehicle, was never received, possibly due to damage to electrical lines during staging.

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