Launch Date November 26, 1959 | 07:26 UT
Launch Site Cape Canaveral, Florida, USA | Launch Complex 14
Destination Earth's Moon
Type Orbiter
Status Unsuccessful
Nation United States
Alternate Names Atlas Able 4, Able IVB, Pioneer-X


Orbit the Moon, take photographs and study the interplanetary environment with a variety of sensors. This was the first U.S. mission to use a two-stage Atlas rocket that allowed heavier payloads to be hurled into space.


None. Forty-five seconds after liftoff, the spacecraft's nose fairing broke away and the rocket tumbled and exploded. Contact was lost 104 seconds after launch.

In Depth

This mission used the first of four spacecraft designed by Space Technology Laboratories for a lunar assault in 1959 and 1960; two of them had originally been slated for Venus orbit (in June 1959), but mission planners had redirected their missions after the success of the Soviet Luna 3 mission.

All the scientific experiments and internal instrumentation were powered by nickel-cadmium batteries charged from 1,100 solar cells on 4 paddles. Each probe also carried an internal hydrazine monopropellant motor for lunar orbit insertion at a range of 5,000 miles (8,000 km) from the Moon. Ideal lunar orbital parameters were planned as 4,000 x 3,000 (6,400 x 4,800 kilometers) The missions also inaugurated the first use of the Atlas-with-an-upper-stage combination, affording increased payload weight.

During this first launch, the nose fairing began to break away just 45 seconds after liftoff. Aerodynamic forces then caused the third stage and payload to break away and explode. The ground lost contact with the tumbling booster at T+104 seconds. Investigation showed that the 3-m fiberglass shroud failed because there had been no measures to compensate for pressure differentials as the rocket gained altitude.


Launch Vehicle: Atlas-Able (no. 1 / Atlas D no. 20)

Spacecraft Mass: 373 pounds (169 kilograms)

Spacecraft Instruments

  1. high-energy radiation counter
  2. ionization chamber
  3. Geiger-Mueller tube
  4. low-energy radiation counter
  5. two magnetometers
  6. photo-scanning device
  7. micrometeoroid detector
  8. aspect indicator
  9. radio receiver to detect natural radio waves
  10. transponder to measure electron densities

Additional Resources

National Space Science Data Center Master Catalog: Pioneer P-3

Far Travelers: The Exploring Machines

Selected References

Siddiqi, Asif A. Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, NASA, 2002.

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