Easy does it there TWFM!
The hostility/annoyance is strong with you, in that last sentence!
Joking aside, I'm actually glad to see that Snickeldorf is showing an interest in space exploration, and I would certainly STRONGLY ENCOURAGE everyone who shows an interest in science/space, thinks about, and then asks hypothetical questions like this.
But ya, if I am not mistaken I think Snickeldorf is asking this:
If a loan astronaut aboard a space launch vehicle, SUDDENLY has to abandon the vehicle in mid launch for some reason, how would NASA handle the space craft from that point forward?
Here are a few thoughts I had about that:
1) Would NASA simply allow the launch-vehicle's flight computers, to continue with the launch portion of the mission, and guide it to a low-Earth parking orbit?
2) If so, that's actually not a bad idea! That would give the space-ship's computers a chance to re-orient themselves, run diagnostics, and receive re-entry plans/guidance from NASA.
3) If however, the ship's computers have somehow failed, or could not handle a re-entry plot, transmitted by NASA, then a "rescue" mission might become necessary to rescue the lone vehicle.
Such a rescue mission would have to involve docking with the ship, so that another astronaut could climb onboard, and see if he/she could safely return to the ship to Earth.
4) Or... another option, of course, would be to somehow guide the launch-vehicle back to Earth, IMMEDIATELY, from the moment it was abandoned by the astronaut.
But launches are HIGHLY chaotic/crazy events. That thing is travelling towards an upward trajectory at INSANE speeds, that could actually tear the ship apart, if it started to try to turn around, and land in those conditions.
So I would assume letting it go to a nice gentle parking orbit (so that everyone can take their time, and slowly plan for re-entry) might actually be the best bet in a scenario like that?
I'd be interested to read what others think about that?