AIUI you could:
set a Cygnus spacecraft afire - a bit archaic.
set a Cygnus spacecraft on fire
set fire to a Cygnus spacecraft.
However, if they have "set a fire inside a Cygnus spacecraft" that seems to mean either that they have taken a fire and moved it into the spacecraft, or that they have put the ingredients for a fire in place - ready to be lit later. Disclaimer: other verbs describing the starting of fires are available).
Did an AI write this phrase?