There’s the curious story of “Snoopy”, the (upper half, ascent stage) Lunar Module from the Apollo 10 mission.
Launched in a solar orbit on May 23, 1969, “Snoopy”, aka “LM-4”, has not been officially tracked but a Diane Neisus has computed its most likely orbit, that apparently takes it as far from Earth as 300 million km:
Apollo 10’s Lunar Module, called “LM 4” or “Snoopy”, is quite remarkable but nearly always forgotten against the much more glamourous Apollo 11 “Eagle”. Despite of that, “Snoopy” is quite fascinating in its own way:
(1) it is the only one of the real flown Apollo LM’s which still is somewhere out in space. All other LM’s burned up in earth’s atmosphere (Apollo 6, 9, 13) or were crashed into the moon, whether intended (Apollo 12, 14-17) or not (Apollo 11).
(2) LM 4 “Snoopy” up to now is the only spacecraft ever launched from moon orbit towards a sun orbit.
(3) “Snoopy” up to now is farthest out in space of all (former) manned spacecraft. In its heliocentric orbit it is as far as 2 AU from earth (during earth opposition)
(4) Apollo 10 and Apollo 12 share the record of the biggest number of real flight hardware objects left over by any of the Apollo missions (three major objects). Apollo 10’s are LM “Snoopy”, CM “Charlie Brown” and S-IVB 505. (As with most of the LM’s, the S-IVB’s of Apollo 13-17 were crashed into the moon; the S-IVB’s of Apollo 8-12 are the only ones sent to solar orbit. BTW, Apollo 12’s S-IVB came back in 2002 as object “J002E3”).
So, Snoopy really is a quite lonesome record-holder.
It is really fascinating to think there is a piece of late-1960’s Apollo hardware flying around the solar system, awaiting for the day when we’ll finally go out and return it home.