So, I’m in the process of editing the second book in my series, Tristan’s Choice.  People (my dad especially) have been commenting on an early draft about factual inaccuracies regarding some of might fight scenes, so of course I’ve been spending LOADS of time doing research to get it right.  This led me to researching fire, explosions, smoke, and guns in space.

The Unholy Trinity

We all know that an explosion can’t happen in space because space is, in fact, a vacuum.  Fire requires 3 elements:

• Oxygen
• Heat
• Fuel

There is no oxygen in space, so all those times in SciFi movies where we saw things blowing up in space, well, they weren’t entirely true, but maybe not as false as people would lead us to believe.

In the Firefly episode “Out of Gas,” a fire rushes through the ship and they vent it out the back.  I can’t say that the way the fire reacts once it leaves the ship is accurate (that would require complex mathematical calculations of the various physical forces including the contrast between the pressure loss of the ship on one side and the vacuum on the other), but since oxygen and fire are leaving the ship at the same time, I would expect that there would be visible flames outside the ship until it exhausted the oxygen or the oxygen dispersed into the vacuum sufficiently to drop below the threshold to maintain the fire.

Smoke in Space

The smoke from a fire reactions interestingly in vacuum or zero gravity.  Absent other forces, smoke disperses evenly in all directions, like dropping a dollop of food dye into a glass of water.  If this is a defunct ship/station with no life support systems left, it will simply flow out into the surrounding vacuum until it can no longer be identified as smoke.  If there are any other forces at work (e.g. HVAC system/life support, explosion), it will act a little differently, based largely on what forces are acting upon it.

Explosions will cause the smoke to move with the inertia of the explosion, while HVAC/life support systems will cause it to disperse faster.  In fact, it will make it extremely difficult to identify the source of the smoke, while could cost lives.

Guns in Space

This is actually a point that someone told me I did wrong, but I actually did correctly (even if I didn’t know it at the time).  Modern guns can operate in space.  Modern ammo uses a closed propulsion system.  There is no external fire/spark that would be hampered by the lack of oxygen.  While there is gun powder in the bullet and the gun powder creates a little mini explosion, it happens inside the sealed ammunition, so the “fire” won’t be extinguished until the bullet separates from the cartridge.  By that point, the damage is already done.  The bullet will fire in a straight trajectory without air resistance or gravity to hamper it.

Which also means that firing bullets in space could be quite dangerous if you miss your target.  There’s no telling what it would eventually hit because it would never slow down until it hit something.  No air = no resistance.