This week in Rocket History we once again have a carryover from last week, but this time of year seems to be very popular for launches, or at least it used to be.

On March 3, 1972, at 01:49 UTC, Pioneer 10 launched on top of an Atlas-Centaur SLV-3C with a Star 37E third stage, the first time this configuration had flown. After the third stage burnout, the spacecraft was traveling at 14.4 kilometers per second — at the time it was the fastest man-made object ever to leave the Earth/Moon system. It passed the Moon’s orbit after only 11 hours, and Mars’ orbit after just 12 weeks!

Pioneer 10 had a number of firsts. It was the first spacecraft to travel to the asteroid belt, the first to make a close observation of Jupiter, and the first to leave the solar system on June 13th, 1983. Until it was outpaced by Voyager 1 in 1998, it was the farthest man-made object from Earth.

Pioneer 10 was also key to making a number of significant scientific discoveries and observations, including:

• measuring the magnetic fields in interplanetary space
• the nature of Jupiter’s magnetic field
• composition of the solar wind

As Pioneer 10 was the first spacecraft to pass through the asteroid belt, scientists were not actually sure how dense the belt was. Smaller asteroids could not be detected from Earth, and there was a substantial fear that millimeters-wide particles were common and passing through the belt could end up being catastrophic for the spacecraft. Shortly after, it was discovered that while much smaller particles were three times more common in the asteroid belt than they were in the space near the Earth, fragments larger than one millimeter were not to be found and were probably extremely rare.

During the Jupiter encounter, the spacecraft malfunctioned due to the high radiation environment around the planet, but most systems recovered. Only some images of Io and Jupiter itself were lost. During the encounter, the spacecraft took high-resolution pictures of Jupiter.  The quality of the images it sent back was higher than anything that had been seen before of the gas giants, and the presentation of the images would later earn the Pioneer program an Emmy award!

After the Jovian encounter, Pioneer 10 went on to travel past the orbits of the rest of the outer planets, finally passing the farthest planet (which at the time was Neptune) on June 13, 1983. Its mission officially ended on March 31, 1997, but contact was maintained with the spacecraft to receive telemetry, which continued pouring in intermittently until the final signal was received on January 23, 2003.

It is currently estimated to be about 128 AU from the sun, traveling at approximately two AU a year or twelve kilometers per second.

More Information

The Pioneer Missions (NASA)

Pioneer 10 Departs Solar System (History)

PDF: Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016 (NASA)

Paper: On the Little‐Known Consequences of the 4 August 1972 Ultra‐Fast Coronal Mass Ejecta (Space Weather)

Update on Pioneer 10 (University of Iowa)

Termination of Pioneer 10’s Mission (University of Iowa)

Spacecraft escaping the Solar System (Heavens Above)