In the mid 90's I was communicating with the folks over at the mission design and astrodynamics at JPL.my question was where the present locations of the upper stages of the pioneer 10 and 11 and voyager 1 and 2 are.it is pretty settled that the centaurs are in solar orbit or reentered earths atmosphere.
The solid star motors locations however was not known for sure. AIAA astrodynamics papers for the early part of these 4 missions however do state the initial injection aimpoints for these spacecraft and hence there star motors.pioneer 11 had a wide dispersion ellipes and was aimed somewhat forward of Jupiter in its orbit.this had to be corrected in pioneer 11's TCM-1 so I am not sure what orbit the star motor is in.MY guess? it would be in a Ulysses like orbit.pioneer 10 and voyager 1 and 2 had excellent initial injection aimpoints.all three where in that solar system escape trajectory that exists to about 20 30 Jupiter radii out on Jupiter trailing orbit.
Therefore there are 7 objects escaping the solar system.one point of consideration is that as the spacecraft separated from the star motors the motors dropped tethered wieghts to slow them and thus engage in an avoidance manuver.but this would not have been enough to slow them from a escape trajectory.
I have been trying to lobby the folks over at south west research to place a memento of humanity on the Pluto missions upper stages as a interstellar message in a bottle but so far with out much luck
help me convince them fellow forum members please