Pioneer 11

Key facts

Mission & specifications

Mission

Pioneer 11 was the first spacecraft to fly past Saturn, and a scout that blazed the trail for the Voyagers. Launched on 6 April 1973, a year after its sister Pioneer 10, it crossed the asteroid belt and reached Jupiter in December 1974, skimming far closer to the cloud tops — about 43,000 kilometres — than any craft before it. It used Jupiter's enormous gravity to fling itself clear across the Solar System toward Saturn, a daring trajectory that doubled as a test of the slingshot the Voyagers would later use. On 1 September 1979 Pioneer 11 became the first probe ever to reach Saturn, passing about 21,000 kilometres above its clouds. It discovered a previously unknown ring and a small moon, measured Saturn's magnetic field, and — crucially — confirmed that a spacecraft could cross the ring plane safely, scouting the route Voyager would soon follow. Like Pioneer 10, it carried the engraved gold plaque designed as a message to any extraterrestrial finders. After its planetary encounters Pioneer 11 sped on toward the edge of the Solar System; its last coherent signal was received in September 1995. It now drifts silently toward the constellation Aquila.

1. 1973Launch toward Jupiter and SaturnLaunch

   An Atlas-Centaur sends the second Pioneer on a path across the Solar System.

2. 1974Jupiter flybyFlyby

   Skims closer to Jupiter than any craft before it and uses its gravity to swing toward Saturn.

3. 1979First flyby of SaturnFlyby

   The first spacecraft ever to reach Saturn; finds a new ring and a small moon.

4. 1979Scouting the way for VoyagerMilestone

   Confirms a spacecraft can cross Saturn's ring plane safely, clearing the Voyagers' route.

5. 1995Last contactMission end

   The final coherent signal fades; Pioneer 11 drifts on toward the constellation Aquila.

Images

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