Which preposition to use with astronaut

at Occurrences 1%

I had calculated that while directing through the main bar a current of apergy sufficient to keep the Astronaut at a fixed elevation, I could easily spare for the eastward conductor sufficient force to create in the space of one hour the impulse required, but that in the course of that hour the gradually increasing apergic force would drive me 500 miles westward.

on Occurrences 1%

Taking leave, then, of the two friends who had thus far assisted me, I entered the Astronaut on the 1st August, about 4.30 P.M.

to Occurrences 1%

I had, of course, from the first been falling slightly behind the Earth in her orbital motion, and was no longer exactly in opposition; that is to say, a line drawn from the Astronaut to the Earth's centre was no longer a prolongation of that joining the centres of the Earth and Sun.

Which preposition to use with  astronaut