Pioneer Jupiter 40th anniversary
December 4, 2013

NASA Remembers Pioneer’s Exploration Of Jupiter 40 Years Ago Today

Lee Rannals for - Your Universe Online

Forty years ago, man’s perspective of what blanketed the night sky grew even more dense as Pioneer 10 made its closest approach to Jupiter. On December 4, 1973, NASA’s Pioneer 10 spacecraft sent back images of Jupiter as it passed by, showing images of the darkest and brightest sides of the planet.

“The most dramatic moment was after closest approach and after the spacecraft was hidden behind Jupiter. Here, images gradually build up into a very distorted crescent-shaped Jupiter,” NASA said.

Pioneer 10 became the first spacecraft to get close enough to Jupiter to send back revelations about the properties and phenomena of the Solar System’s largest planet.

The trajectory of the spacecraft took it along the magnetic equator of Jupiter, where the ion radiation is concentrated. Peak flux for this electron radiation is 10,000 times stronger than the maximum radiation around Earth. This radiation caused false commands to be generated, most of which were corrected by contingency commands. However, an image of Jupiter’s moon Io and a few close ups of the planet were lost.

During Pioneer’s pass, the spacecraft succeeded in obtaining a few images of the moons Ganymede and Europa. The image of Ganymede showed low albedo features in the center and near the south pole, while the north pole appeared brighter.

Pioneer came within about 81,000 miles of the outer atmosphere of Jupiter during its approach, helping the spacecraft obtain some close-up images of the Great Red Spot and the terminator. Communication ceased as the spacecraft passed behind the gigantic planet.

“This historic event marked humans' first approach to Jupiter and opened the way for exploration of the outer solar system - for Voyager to tour the outer planets, for Ulysses to break out of the ecliptic, for Galileo to investigate Jupiter and its satellites, and for Cassini to go to Saturn and probe Titan,” NASA explained.

Pioneer 10 not only imaged the planet and its moons, but it also took measurements of Jupiter’s magnetosphere, radiation belts, magnetic field, atmosphere and interior. NASA said the measurements of the radiation environment near Jupiter were crucial in designing the Voyager and Galileo spacecraft.