This simulation shows the paths followed by the Pioneer 10 and Pioneer 11 spacecraft.
Pioneer 10 was launched on 2nd March 1972 and then flew past the planet Jupiter on 3rd December 1973.
Pioneer 11 was launched on 5th April 1973 and then flew past the planet Jupiter on 2nd December 1974, and the planet Saturn on 1st September 1979.
The starting date for the simulation is 1st May 1973 - well over a year after the launch of Pioneer 10 and a few days after the launch of Pioneer 11. If you run the simulation forward, you can watch Pioneer 10's encounter with Jupiter, followed by Pioneer 11's encounters with Jupiter and Saturn. You can see how the paths (orbits) followed by the two spacecraft are changed by the encounters, and in particular, how Pioneer 11 used the gravity assist from Jupiter to set it on course for the encounter with Saturn several years later. Note that both spacecraft ended up on hyperbolic orbits - leaving the solar system, never to return.
Since different computers run at different speeds, you may need to edit the evolution time step to get the simulation to run at an acceptable rate.
You can find out more about Pioneer 10 and Pioneer 11 from the following websites:
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