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Pioneer 10

Pioneer 10Pioneer 10. © based on NASA images

Pioneer 10, originally called Pioneer F, has the distinction of being the first spacecraft to have overcome the escape velocity from the solar system. The space craft was launched 40 years ago in the year 1972, on March 2, from Cape Canaveral in Florida.

Cape Canaveral
Cape Canaveral. © NASA

In addition, it has the credit of being the first spacecraft to fly by Jupiter and get many close-up images, first craft to cross the asteroid belt, and the first spacecraft to make it to the outer solar system.

Pioneer 10 was launched using a three-stage Atlas-Centaur launch vehicle. It was launched to travel directly to the planet Jupiter without parking in the earth’s orbit. The spacecraft sent back a number of images of Jupiter that it had taken while flying past the giant planet. However, communication with the spacecraft was lost in the year 2003, when it was at a distance of about 12 billion kilometers away from earth.

Pioneer 10 mission

The construction and launch of Pioneer 10 was part of the Planetary Grand Tour that was conceived to exploit a rare planetary alignment that would occur in the outer solar system. This was as early as in 1964. After much reasoning and research into exploring the planets of the outer solar system, it was decided that the space probes Pioneer 10 and Pioneer 11 would be launched in specific favorable periods in 1972 and 1973 when the cost of the propellant required would be less.

Jupiter. © NASA

NASA approved the mission in the year 1969 to launch Pioneer F and Pioneer G. However, these two spacecrafts were later renamed as Pioneer 10 and Pioneer 11. These two space probes were part of a series of unmanned missions to the space called the Pioneer Program. These missions were to be launched between the years 1958 and 1978. Among the objectives of the mission was to get the spacecraft to explore going across the asteroid belt to explore Jupiter’s environment. Close to 150 scientific instruments were carried by the spacecraft to make numerous observations about the radiation that surrounded Jupiter, study the nature of the charged particles and make observations about the meteoroids and asteroids, etc.

The NASA Ames Research Center which managed the project contracted TRW to build Pioneer 10 and Pioneer 11 in the year 1970. The spacecraft was to be launched on a date between the 17th February and 29th March to enable the space craft to reach Jupiter in November 1974. This date was, however, revised to December 1973 for fear of overlap of communications.

Asteroid BeltAsteroid Belt. © NASA images

The trajectory of Pioneer 10 was designed such that the craft could gather maximum amount of information about the radiation around Jupiter, even if it meant destruction of some of the systems in the spacecraft.

Design of the spacecraft

The main compartment of the spacecraft is about 36 cm deep with the top and bottom having hexagonal shape. The side panels are about 76 cm long. The main compartment houses the propellant in a spherical tank and also holds 8 of the 11 scientific instruments. An insulated layer of aluminized kapton and mylar layers is used for heat control. The components inside the compartment generate close to a hundred watts. The spacecraft weighed about 260 kg at launch.

Pioneer 10
Pioneer 10. © NASA

About 36 kg of the hydrazine propellant was held in a spherical tank at the time of launch. The fuel was supplied to three pairs of hydrazine thrusters. Each pair was used for a different purpose. Whereas one pair helped to maintain the spin rate, the second pair controlled the altitude and the third was helpful in maintaining the forward thrust.

The power required for Pioneer 10′s operations were obtained from four radioisotope thermoelectric generators. The fuel was plutonium-238 placed inside a capsule and shielded from the heat. The power generators were placed at a safe distance from instruments in the space probe. At launch, the generators provided a power of 155 watts, which reduced to 140 watts when it reached Jupiter. In spite of the half life of plutonium-238 being 87.7 years, the power output has decreased more than expected. In 2005, the total power output was just 65 watts. This reduction has been attributed to the quality of the thermocouple joints that has deteriorated.

The high gain antenna is a parabolic aluminum dish which is 9 feet in diameter. This antenna remains oriented towards earth for communication purposes. The data was transmitted using the S-band frequencies.


Pioneer 10 carries various scientific instruments for making scientific observations. Some of them are listed below:

- Charged particle instrument for detecting cosmic rays.

- The quadrispherical plasma analyzer to detect solar wind particles that originate from the sun.

- The cosmic ray telescope for collecting data about the energy range of the cosmic ray particles as well as their composition.

- The helium vector magnetometer to make a study of the magnetic field interaction of the solar wind with Jupiter. It was also useful in mapping the interplanetary magnetic field.

- The meteoroid detectors to record the impact of the small meteoroids striking the space probe.

- An UV photometer to determine the quantities of helium and hydrogen, both in space and on planet Jupiter.

In addition to the instruments, Pioneer 10 also carries an aluminum plaque anodized with gold with information about our planet in case the space probe is intercepted by intelligent forms of life in space. The plaque has figures of a nude man and woman in addition to several other symbols that give information as to where the space probe has originated from.

Aluminum plaque anodized with goldAluminum plaque anodized with gold. © NASA images


Pioneer 10 was the first ever spacecraft to go beyond the orbit of Mars. It also crossed the asteroid belt and flew very close to Jupiter. Before and after flying past the planet of Jupiter, Pioneer 10 collected data about the radiation of energy particles and magnetic radiation of Jupiter and dust populations in the zodiacal cloud. It transmitted to the earth hundreds of photographs of the planet Jupiter and its moons. Pioneer 10 also measured and sent back measurements of the Jovian atmosphere. Based on the data that was sent back by the space probe, scientists identified plasma in the magnetic field of Jupiter. It also discovered that Jupiter’s huge magnetic tail is about 800 million km long and covered all the distance between Jupiter and Saturn.

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