There is no oxygen and no fire in space. If two spaceships collided, will they explode to balls of fire because of air and fuel inside them?
Actually, contrary to what you might expect after watching too many science fiction films, if two spaceships collided at moderate velocities (such as the velocities depicted in those films, no more than a few hundred mph) there would be no fireball whatsoever. The ships would suffer severe structural damage, there would be debris, pressurized compartments might rupture with the gas escaping from within, but no explosion, no fire. Even if fuel tanks were to rupture, the fuel would just rapidly expand and escape into space… there would be no or very little chemical reaction taking place.
On the other hand… in a more realistic scenario, if spaceships were to collide, it would happen at much higher velocities, quite possibly at typical orbital velocities, that is to say, several miles a second. This is of course not good news for moviemakers, as the entire event would be over within one frame of the film. Not very spectacular. But in this case, the tremendous kinetic energy of the impact would be sufficient to heat up, melt, even vaporize significant amounts of material. The result would be a flash and a fireball of sorts, hot plasma from the impact expanding and rapidly cooling. But this fireball will not be a fireball of combustion, just plasma that is superheated by the kinetic energy of the collision.
Credit: Viktor T. Toth