Pioneer 10 is Launched

U.S. #1556 pictures Pioneer 10 passing by Jupiter.

On March 2, 1972, Pioneer 10, the first spacecraft to leave our Solar System, was launched from Cape Canaveral, Florida.

The planning for Pioneer 10 first began in the 1960s, when Aerospace engineer Gary Flandro suggested a “Planetary Grand Tour.” The tour would take advantage of a rare alignment of the outer planets of our solar system. NASA developed a proposal for a pair of “Galactic Jupiter Probes” to pass through the asteroid belt and provide the first close-up pictures of Jupiter.

The proposal was approved in February 1969, and the two spacecraft, which later came to be known as Pioneer 10 and Pioneer 11, were built. They would become the first of several probes to explore the outer solar system. Over 150 scientific experiments were suggested for these missions. These included imaging Jupiter and moons, taking infrared and ultraviolet images, determining the makeup of charged particles, and measurement of the planetary atmosphere.

U.S. #3189i – Pioneer 10 stamp from the Celebrate the Century pane.

The first of the probes, Pioneer 10, was launched successfully on March 2, 1972, aboard an Atlas-Centaur launch vehicle. Pioneer 10 was the fastest man-made object at that time, passing the Moon only 11 hours later. Within 10 days all the scientific instruments aboard the probe were active and ready to report back data.

Along the journey to Jupiter, Pioneer 10 became the first probe to detect interplanetary helium atoms. And on July 15, 1972, it was the first spacecraft to enter the asteroid belt between Mars and Jupiter. During the eight months Pioneer 10 traveled through the belt, it found that most of the particles within it were smaller than a millimeter.

Pioneer 10 began approaching Jupiter on November 6, 1973. Early tests showed the planet’s magnetic field was inverted compared the Earth’s. On November 26, NASA scientists received the first close-range photos of Jupiter. Image quality improved in the coming days and by December 2, photos of Jupiter were shared with the public in real-time. This later earned the Pioneer program an Emmy award for its presentation to the media. During this time, over 500 images of Jupiter were sent back to Earth. As Pioneer 10 passed behind Jupiter, communication ceased, but infrared scanners showed that the planet radiated more heat than it received from the Sun.

Item #M5470 – First Day Covers honoring Pioneer 10 and Mariner 10.
Item #M5470 – First Day Covers honoring Pioneer 10 and Mariner 10.

After passing Jupiter, Pioneer 10 crossed Saturn’s orbit in 1976 and Uranus’ in 1979. After crossing Neptune in June 1983, Pioneer 10 became the first man-made object to go beyond the major planets of our solar system. The mission officially ended on March 31, 1997, when the probe reached a distance of 6.2 billion miles from the Sun, though it was still able to transmit data back to Earth. The probe’s signal grew weaker the farther it traveled, and the last discernible transmission was received on April 27, 2002. NASA continued to receive very weak signals for several months, with the last arriving on January 23, 2003.

Scientists estimate that Pioneer 10 is over 8 billion miles from Earth today. At the suggestion of Carl Sagan, both Pioneer 10 and 11 carry a gold-anodized aluminum plaque in case they are ever found by life forms from another planet. It includes male and female figures and symbols telling the origin of the probe.  Click here to learn more about the plaque.

Click the images to add this history to your collection.

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  1. very interesting information. People that love stamps also, in my opinion, love to study history…..I’m one of them. At university I took many history courses as merely electives so that I could graduate with a degree in pre-medical. I have been collecting stamps since 1955…..springboard off of my mother’s collection. I wish that I had more money to buy the older stamps that I am still missing from my collection. This Day in History idea is great.

  2. I stood in my back yard with parents and neighbors pointing to the passing of Sputnik almost 60 years ago. It was a curious feeling as we were not sure what this meant except that Russia had beaten us to this point and that can’t be good. In the following years with manned flights, which we knew the name of every astronaut to leave a launching pad, we knew the objective of each mission and that the ultimate goal was to go lunar. As time went on past that goal interest seemed to wane due to less familiarity with the goals and people. Pioneer, because of it’s lengthy goal, did little to change, until the years passed and close encounters occurred noting progress and achievement. Considering a 30 year itinerary that left the solar system, a phenomenal accomplishment for all involved.

  3. As a child of the “Space-Age” I always took great interest in any of the new pictures (new at the time) from these probes. I started my collection with all the space related stamps and covers before expanding my interest.

  4. I was fortunate enough to have been one of the beach spectators the night Pioneer 10 launched. I was on a temporary assignment to Florida and having not really having anything else to do I joined the crowd along the beach the night of March 1st. Well a glitch occurred and the mission was delayed 24 hours and I had to decide did I want to try again the following night. I did try and I’m glad I did. The blast off was spectacular, as the cliche goes, it turnrd the night into day, all along the beach. All through the years I would hear of Pioneer 10 latest exploits and would remember that night, remembering when America could do things.

  5. That disk included Chuck Berry’s version of “Jonny Be Good”.
    Great article: was swept up in the science fervor of the 60’s.Education in sciences boomed as we tried to ” beat” the Russions.

  6. I hope the disk also contains music and spoken human language in various musical types, indicating the variety of cultures and languages that exist in our planet. I believe it does! America’s space program is secretly tide to the German technology that was brought to The United States, following the last months of WWII. “Paper Clip 700”.

  7. To try and comprehend the vastness of space – 11 Billion miles is less than 0.2% of a light year. The nearest star to our solar system is about 4.2 light years away. It would take Pioneer 10 approximately 112,000 years to reach that star – and that is just one star of the 100’s of Billions in our Milky Way galaxy. We are very, very, very tiny!!

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