Secret Space Programs
Project Able
..
Pioneer-1 with the vernier rockets ignited. The Falcon engine is on the other side
of the probe and the camera eye is visible on the waist.

President Eisenhower approved the first american lunar program, partly derived from JPL's Project Red Socks, on March 27, 1958.

The plan envisaged five ARPA (Advanced Research Project Agency) coordinated missions: three managed by USAF (United States Air Force) and two managed by the US Army.

In 1958, it must be remembered, almost all of the space programs were managed by the military: NASA (National Aeronautic and Space Administration) was formed only on October 1 of that year on the structure of the far more modest NACA (National Advisory Commitee for Aeronautics).

The plan resulted too ambitious from the start: the Americans had no experience of interplanetary navigation, and their launchers left much to be desired. In spite of this, the USAF was planning of putting a satellite around the Moon right from the first attempt!

The USAF probe was built inside two squat glass fiber cones joined at their base by a cylinder and topped by a separable cluster of eight small vernier rockets and by a solid propellant, 13.3 kN thrust rocket based on the Falcon air to air missile. The Falcon rocket was to be used to slow the probe until it entered lunar orbit.
The spacecraft had a height of 45 cm, a diameter of 72.5 cm and weighted 38 kg.

The scientific instruments weighted 18 kg and included: a simple camera in which an oscillating mirror scanned the Moon sending its image to an infrared lead sulfide photodiod, a radiation counter, a simple search coil magnetometer and a microphone to register the impact of micrometeorites.

The small probe was covered by a series of removable black and white stripes to control its temperature and was sterilized by exposing it to ultraviolet rays.

The launcher was to be a Thor-Able, made by joining a medium range Thor missile the second (Able) stage of the ill-fated Vanguard rocket and a solid propellant third stage. The launcher could send 39 kg to the Moon.
The flight plan required that, 60 hours after lift-off, the Falcon retrorocket was ignited and the probe inserted in any erratic orbit around the moon (sic !). The batteries were designed to last for two weeks.

The fourth Thor-Able was mated to pad 17A of Cape Canaveral in the summer and the first lunar shot in history was made four minutes late at 12.18 GMT on August 17, 1958 before a small number of journalists.
Only 77 seconds into the flight, the Thor's turbopump seized and the missile exploded. The telemetry of the probe was received for 123 seconds more, to its impact with the Ocean.

The probe did not receive a name and is indicated as Pioneer-0 or Able-1. The launch attracted much interest and was the first aired on TV by NBC. As there was still no live feed at the time, the launch was shot on a film which was then flown to the West Coast, taped and finally aired.

Before the launch of the second probe, the whole program was transferred to NASA, with the USAF and the ARmy acting as simple consultants. It was NASA who gave the probes the name Pioneer, series which eventually counted eighteen planetary probes up to the end of the Seventies and notably Pioneer-10, the first probe to fly-by Jupiter and to leave the Solar System.

The new agency decided not to waste any time the first NASA launch, on October 11, 1958, just ten days after its foundation, was that of a lunar probe: Pioneer-1 (or Able-2): the second USAF orbiter whose launcher, just two days before lift of, was missed by a few tens of meters by the debris of another missile which blew up in flight.
The flight of Pioneer-1 went very well up to burn off of the third stage, when it was noticed that the second stage had burned off too early, maybe because its accelerometers were wrongly programmed. In any case, the space probe was not only not fast enough to reach the Moon, even after starting the tiny vernier rockets but not fast enough to enter Earth orbit, so that it would soon fall back to Earth on a parabolic trajectory. The only hope of at least partially saving the mission was in the Falcon motor, whose ignition would have enabled to establish a very high Earth orbit (130.000 x 30.000 km) or even performing a fly-by of the Moon, if the probe could be turned 180 degrees. Alas, there was no way of turning the probe, but any attempt to start the engine, four from Hawaii tracking station, four from Florida, were unsuccessful: the temperature of the on board batteries was lower than 2 degrees Celsius and they could not provide the required electricity.

Pioneer-1 flew up to 113.854 km from Earth, less than a third of the distance of the Moon and fell back, disintegrating in the atmosphere after a 43 hours, 17 seconds flight. The mission was a failure, but the probe transmitted interesting data on the Van Allen belts, measuring their extension, on micrometeorites. registering only 0.0052 impacts per second per square meter of sensor. Using the small vehicle as a repeater, the antennae of Jordell Bank, England and Milestone Hill, Massachusetts, were briefly linked, demonstrating the transoceanic communications that are now a thing of every day (NOTE: this story is not confirmed by the detailed account on Jordell Bank space tracking activites by Sven Grahn). Pioneer-1 was also the first space launch to be aired live on TV.

The second NASA lunar probe was launched one day late on November 8, 1958. Pioneer-2, or Able-3, was very similar to the preceding probes, but it had some important modifications: the NOTS (Naval Ordnance Test Station) infrared camera was replaced by a lighter, visible camera built by STL (Space Technology Laboratories) that offered also a better resolution. Its place was moved from the waist to the lower cone. A cosmic ray counter was added and the batteries were replaced altogether, after they failed on Pioneer-1. For this probe another transoceanic communication attempt was scheduled. The launcher received some modifications to the staging system and a new system of integrating accelerometers to shut off the engines at the exact desired speed. All these precautions were useless because the third, solid, stage did not ignite at all. Pioneer-2 burned over Africa after a 45 minutes parabolic flight during which it reached 1.600 km into space.

Bibliography

  • Baker, H.: "Aw, Hell, Television is Here"; Air & Space, December 2000/January 2001, pp. 22-23
  • LePage, A.; The Great Moon Race: In the Beginning...; EJASA, Vol. 3 No. 10, May 1992
  • Powell, J. W.: Thor-Able and Atlas-Able; JBIS, vol. 37, pp. 219-225
  • Stuhlinger, E.; Mesmer, G.; Space Science and Engineering; New York, McGraw-Hill
  • Wilson, A.: The Eagle has Wings; London, British Interplanetary Society
  • First U.S. Lunar Probe Fails After Promising Launch, Aviation Week, August 25, 1958, pp. 20-23
  • Army Plans Two Moon Shots Next Month, Aviation Week, November 17, 1958, pp. 28-30 
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