Pioneer 3
Encyclopedia
Pioneer 3 was a spin stabilized spacecraft launched at 05:45:12 UTC on 6 December 1958 by the U.S. Army Ballistic Missile Agency
in conjunction with the National Aeronautics and Space Administration. This spacecraft was intended as a lunar probe, but failed to go past the Moon
and into a heliocentric orbit
as planned, but did reach an altitude of 102,360 km before falling back to the Earth. The revised spacecraft objectives were to measure radiation in the outer Van Allen radiation belt
using two Geiger-Müller tube
s and to test the trigger mechanism for a lunar photographic experiment.
shell coated with a gold wash to make it electrically conducting and painted with white stripes to maintain the temperature between 10 and 50 degrees Celsius. At the tip of the cone was a small probe which combined with the cone itself to act as an antenna. At the base of the cone a ring of mercury batteries provided power. A photoelectric sensor protruded from the center of the ring. The sensor was designed with two photocells which would be triggered by the light of the Moon when the probe was within about 30,000 km of the Moon. At the center of the cone was a voltage supply tube and two Geiger-Müller tube
s. A transmitter with a mass of 0.5 kg delivered a phase-modulated signal of 0.1 W at a frequency of 960.05 MHz. The modulated carrier power was 0.08 W and the total effective radiated power 0.18 W. A despin mechanism
consisted of two 7 gram weights which could be spooled out to the end of two 150 cm wires when triggered by a hydraulic timer 10 hours after launch. The weights would slow the spacecraft spin from 400 rpm to 6 rpm and then weights and wires would be released.
The flight plan called for the Pioneer 3 probe to pass close to the Moon after 33.75 hours and then go into solar orbit. However, depletion of propellant caused the first stage engine to shut down 3.7 seconds early preventing the spacecraft from reaching escape velocity
. The injection angle was also about 71 degrees instead of the planned 68 degrees. The spacecraft reached an altitude of 102,360 km (109,740 km from the center of the Earth) before falling back to Earth. It re-entered Earth's atmosphere and burned up over Africa
on December 7 at approximately 19:51 UT (2:51 p.m. EST) at an estimated location of 16.4 N, 18.6 E. The probe returned telemetry
for about 25 hours of its 38 hour 6 minute journey. The other 13 hours were blackout periods due to the location of the two tracking stations. The returned information showed that the internal temperature remained at about 43 °C over most of the period.
While Pioneer 3 did not meet its primary mission objective of a lunar flyby, the data obtained was of particular value to James Van Allen
. The Pioneer 3 probe data in addition to the data from the previous Explorer 1 and Explorer 3
satellites led to the discovery of a distinct second radiation belt around the Earth
(e.g. characteristics). The trapped radiation starts at an altitude of several hundred miles from Earth (where the outer belt was first observed by Sputnik 2
and Sputnik 3
) and extends for several thousand miles into space. These Van Allen radiation belt
surrounding the Earth are named for Dr. James Van Allen
, in honor of his discovery.
Army Ballistic Missile Agency
The Army Ballistic Missile Agency was the agency formed to develop the US Army's first intermediate range ballistic missile. It was established at Redstone Arsenal on February 1, 1956 and commanded by Major General John B...
in conjunction with the National Aeronautics and Space Administration. This spacecraft was intended as a lunar probe, but failed to go past the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
and into a heliocentric orbit
Heliocentric orbit
A heliocentric orbit is an orbit around the Sun. All planets, comets, and asteroids in our Solar System are in such orbits, as are many artificial probes and pieces of debris. The moons of planets in the Solar System, by contrast, are not in heliocentric orbits as they orbit their respective planet...
as planned, but did reach an altitude of 102,360 km before falling back to the Earth. The revised spacecraft objectives were to measure radiation in the outer Van Allen radiation belt
Van Allen radiation belt
The Van Allen radiation belt is a torus of energetic charged particles around Earth, which is held in place by Earth's magnetic field. It is believed that most of the particles that form the belts come from solar wind, and other particles by cosmic rays. It is named after its discoverer, James...
using two Geiger-Müller tube
Geiger-Müller tube
A Geiger–Müller tube is the sensing element of a Geiger counter instrument that can detect a single particle of ionizing radiation, and typically produce an audible click for each. It was named for Hans Geiger who invented the device in 1908, and Walther Müller who collaborated with Geiger in...
s and to test the trigger mechanism for a lunar photographic experiment.
Spacecraft design
Pioneer 3 was a cone-shaped probe 58 cm high and 25 cm diameter at its base. The cone was composed of a thin fiberglassGlass-reinforced plastic
Fiberglass , is a fiber reinforced polymer made of a plastic matrix reinforced by fine fibers of glass. It is also known as GFK ....
shell coated with a gold wash to make it electrically conducting and painted with white stripes to maintain the temperature between 10 and 50 degrees Celsius. At the tip of the cone was a small probe which combined with the cone itself to act as an antenna. At the base of the cone a ring of mercury batteries provided power. A photoelectric sensor protruded from the center of the ring. The sensor was designed with two photocells which would be triggered by the light of the Moon when the probe was within about 30,000 km of the Moon. At the center of the cone was a voltage supply tube and two Geiger-Müller tube
Geiger-Müller tube
A Geiger–Müller tube is the sensing element of a Geiger counter instrument that can detect a single particle of ionizing radiation, and typically produce an audible click for each. It was named for Hans Geiger who invented the device in 1908, and Walther Müller who collaborated with Geiger in...
s. A transmitter with a mass of 0.5 kg delivered a phase-modulated signal of 0.1 W at a frequency of 960.05 MHz. The modulated carrier power was 0.08 W and the total effective radiated power 0.18 W. A despin mechanism
Yo-yo de-spin
frame|[[Payload Assist Module|PAM-D]] upper stage with the [[Phoenix |Phoenix]] spacecraft. The [[Star 48|Star 48-B]] engine is shown being spun, fired, yo-yo de-spun and jettisoned....
consisted of two 7 gram weights which could be spooled out to the end of two 150 cm wires when triggered by a hydraulic timer 10 hours after launch. The weights would slow the spacecraft spin from 400 rpm to 6 rpm and then weights and wires would be released.
Mission
Escape velocity
In physics, escape velocity is the speed at which the kinetic energy plus the gravitational potential energy of an object is zero gravitational potential energy is negative since gravity is an attractive force and the potential is defined to be zero at infinity...
. The injection angle was also about 71 degrees instead of the planned 68 degrees. The spacecraft reached an altitude of 102,360 km (109,740 km from the center of the Earth) before falling back to Earth. It re-entered Earth's atmosphere and burned up over Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
on December 7 at approximately 19:51 UT (2:51 p.m. EST) at an estimated location of 16.4 N, 18.6 E. The probe returned telemetry
Telemetry
Telemetry is a technology that allows measurements to be made at a distance, usually via radio wave transmission and reception of the information. The word is derived from Greek roots: tele = remote, and metron = measure...
for about 25 hours of its 38 hour 6 minute journey. The other 13 hours were blackout periods due to the location of the two tracking stations. The returned information showed that the internal temperature remained at about 43 °C over most of the period.
While Pioneer 3 did not meet its primary mission objective of a lunar flyby, the data obtained was of particular value to James Van Allen
James Van Allen
James Alfred Van Allen was an American space scientist at the University of Iowa.The Van Allen radiation belts were named after him, following the 1958 satellite missions in which Van Allen had argued that a Geiger counter should be used to detect charged particles.- Life and career :* September...
. The Pioneer 3 probe data in addition to the data from the previous Explorer 1 and Explorer 3
Explorer 3
Explorer 3 was an artificial satellite of the Earth, nearly identical to the first United States artificial satellite Explorer 1 in its design and mission...
satellites led to the discovery of a distinct second radiation belt around the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
(e.g. characteristics). The trapped radiation starts at an altitude of several hundred miles from Earth (where the outer belt was first observed by Sputnik 2
Sputnik 2
Sputnik 2 , or Prosteyshiy Sputnik 2 ), was the second spacecraft launched into Earth orbit, on November 3, 1957, and the first to carry a living animal, a dog named Laika. Sputnik 2 was a 4-meter high cone-shaped capsule with a base diameter of 2 meters...
and Sputnik 3
Sputnik 3
Sputnik 3 was a Soviet satellite launched on May 15, 1958 from Baikonur cosmodrome by a modified R-7/SS-6 ICBM. It was a research satellite to explore the upper atmosphere and the near space, and carried a large array of instruments for geophysical research....
) and extends for several thousand miles into space. These Van Allen radiation belt
Van Allen radiation belt
The Van Allen radiation belt is a torus of energetic charged particles around Earth, which is held in place by Earth's magnetic field. It is believed that most of the particles that form the belts come from solar wind, and other particles by cosmic rays. It is named after its discoverer, James...
surrounding the Earth are named for Dr. James Van Allen
James Van Allen
James Alfred Van Allen was an American space scientist at the University of Iowa.The Van Allen radiation belts were named after him, following the 1958 satellite missions in which Van Allen had argued that a Geiger counter should be used to detect charged particles.- Life and career :* September...
, in honor of his discovery.