Pioneer 10: Jupiter’s First Artificial Friend

Pioneer 10

Fifth from the Sun and by far the biggest planet of the solar system got its name from the king of ancient Roman gods and became Jupiter. This massive giant has a long history of surprising our scientists. Going back to 1610, when Galileo Galilei discovered its 4 moons, the way the people looked at the universe changed because those moons were beyond the Earth. But with the advancement of technology, Jupiter was able to show the earth his giant red spot, a storm wider than the earth, his ring system (not so bright as the infamous Saturn), and all its 67 moons. But scientists became thirsty for the inner world of Jupiter, and what he’s made of. This thirst couldn’t be quenched by just looking at the sky from the Earth. They wanted a very closer look so Pioneer 10 came to life as a result and was honored as the 1st artificial friend of Jupiter.

What is Pioneer 10?

Pioneer 10 is an American space probe (an artificial satellite that travels through space to collect information) and NASA’s first, mission to outer planets. Launched in 1972, Pioneer 10 then became the 1st of five artificial objects to achieve the escape velocity needed to leave the Solar System. This pioneer 10 was a stunning success. It was initially planned for a 21-month mission to fly near Jupiter, but it survived a whopping 30 years, garnering many firsts that may have been unmatched by any robotic spacecraft. Pioneer sent its last signal to Earth in January 2003 from a distance of 7.6 billion miles. And after that, this space probe has been sailing into deeper space, and now 50 years old it is somewhere at the edge of the solar system.

Pioneer 10’s Firsts

  • Pioneer 10 is the first spacecraft to carry a message from the earth to the outer solar system. The golden plaque in the spacecraft carried the message “brainchild of Carl Sagan”. It contains all the necessary data to talk with an alien. Strongly advised by Carl Sagan, the American Astronomer, the plaque features the nude figures of a human male and female along with several symbols which were designed to provide information about the origin of the spacecraft.
  • Pioneer 10 is the first spacecraft placed on a trajectory to escape the solar system into interstellar space.
  • It is also the 1st spacecraft to fly beyond Mars.
  • First spacecraft to fly through the main asteroid belt.
  • First spacecraft to fly past Jupiter.
  • Pioneer 10 was also able to cross the orbit of Neptune to become the first human-made object to go beyond Neptune.
  • The First spacecraft to use all-nuclear electrical power.
A detailed view of the message
Figure 2: A detailed view of the message

A Deeper Look at Pioneer 10 Mission

How it came to life?

In the 1960s, Gary Flandro, an American aerospace engineer of the NASA jet propulsion Laboratory, got the first idea of exploring the outer planets of the solar system which he named the Planetary Grand Tour. Therefore in 1964, NASA decided to experiment this by launching a pair of probes into the outer solar system. NASA Godard Spaceflight center set the 1st foot by creating the proposal for this twin space probe mission named Galactic Jupiter Probes which would pass through the asteroid belt and reach Jupiter as the name suggests.

The proposal came to life in 1969, the twins were named Pioneer F and Pioneer G which later got renamed Pioneer 10 and Pioneer 11. As the first step, NASA wanted these twins to explore the interplanetary medium past the orbit of Mars, study the asteroid belt, and explore Jupiter and its environment.

In 1970, NASA Ames Research Center was selected to manage the project and they wanted a “small, lightweight spacecraft which was magnetically clean, and which could perform an interplanetary mission”. Meeting the requirements, the Pioneer 10 bus (the main body and the structural component of a satellite or a spacecraft) is 36 centimeters (14 inches) deep with 76 centimeters (30 inches) long panels forming a hexagonal structure. The bus became the home for 8 out of 11 scientific equipment. This equipment compartment is laid with a honeycomb structure so that it can be safe from meteoroids. When launched the spacecraft had a mass of about 260 kilograms.

Design of Pioneer 10 and 11
Figure 3: Design of Pioneer 10 and 11
Pioneer 10 at its final stages of construction
Figure 4: Pioneer 10 at its final stages of construction

Launch and Its Journey Toward Jupiter

With the help of the Atlas-Centaur launch vehicle, Pioneer 10 left the Earth for its long journey on March 2nd, 1972 from the Space Launch complex 36A in Florida. It achieved a maximum escape velocity of 51,682 kilometers per hour faster than any previous human-made objects at that time. At the beginning of the voyage, direct sunlight caused some heating problems but it didn’t affect the mission.

 Launch of Pioneer 10
Figure 5: Launch of Pioneer 10

On July 15, 1972, the spacecraft entered the asteroid belt and emerged in 1973 after traveling about 435 million kilometers. The spacecraft had to face many asteroid hits yet it was able to measure the intensity of Zodiacal light in interplanetary space.

By December 1, 1973, Pioneer began sending better images of Jupiter to Earth. Pioneer’s closest approach to Jupiter was on December 4th, 1973 and it passed a series of Jupiter’s moon and blessed the earth with photos of Callisto, Ganymede and Europa (But not if Io because the photopolarimeter was affected by radiation). Up until December 31st, 1973, pioneer took about 500 photos of this giant with the highest resolution, clearly showing the landmarks such as the Great Red Spot.

Pioneer 10's photo of Jupiter which shows the Giant Red Spot and the shadow of the moon Io
Figure 6: Pioneer 10’s photo of Jupiter which shows the Giant Red Spot and the shadow of the moon Io
Pioneer 10 images of Jupiter and its 2 largest moons, Europa(left) and Ganymede(right) (Not according to a scale)
Figure 7: Pioneer 10 images of Jupiter and its 2 largest moons, Europa(left) and Ganymede(right) (Not according to a scale)

The Pioneer captured the first close-up photographs of Jupiter, recorded Jupiter’s severe radiation bands, identified the planet’s magnetic field, and discovered that Jupiter is primarily a liquid planet. It was also able to relay data on magnetic fields, energetic particle radiation, and dust populations in interplanetary space while in flight. It completed all targets but one due to incorrect commands that were disrupted by Jupiter’s strong radiation.

After achieving historical records, the Pioneer 10 rendezvous with Jupiter ended on January 2, 1974.

Images of Jupiter of ever-increasing size. These pictures were taken when the spacecraft sped away out of the Jovian system
Figure 8: Images of Jupiter of ever-increasing size. These pictures were taken when the spacecraft sped away out of the Jovian system

Pioneer 10 then went towards Saturn, the solar system’s very own ringed beauty, and crossed its orbit in February 1976, and was able to find out that the magnetic field of Jupiter is 800 million kilometers long, that is the distance between the two planets. Then, Pioneer crossed the orbit of Neptune on June 13, 1983, and again made a first – first human-made object to go beyond the furthest planet.

NASA was able to maintain routine contact with the spacecraft for over 2 decades until 1997 before it was terminated due to budgetary reasons but NASA received a signal from it on August 5th, 2000, and on January 23rd, 2003 it sent its last signal when it was 12.23 billion kilometers away from Earth. NASA knew that the RTG (Radioisotope Thermoelectric Generator) power source(a type of nuclear battery) was decayed and that it is hard for radio transmissions. Yet NASA’s final attempt to contact this history maker on March 4, 2006, failed.

Where is Pioneer 10 Now?

Now that its 50 years old pioneer 10 is heading toward the star Aldebaran in the Taurus constellation. And in about 2 million years, Pioneer 10 will arrive at the star.

Pioneer 10, despite now being a ghost craft still moving on its own carrying its very own history.


  1. In Depth | Pioneer 10 –. (n.d.). NASA Solar System Exploration.
  2. Pioneer 10: It’s been 50 years since NASA targeted Jupiter and beyond. (2022, March 2).
  3. Pioneer Plaque. (n.d.). NASA Solar System Exploration.
  4. Alaeva, L. (2022, April 21). Fifty years since the launch of the Pioneer 10 mission. Журнал the Universemagazine Space Tech.

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Article By Devanga De Silva, 2nd Year Undergraduate, Faculty of Science, University of Colombo

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