Sci-Fi Blunders: Space Science

In a far off time in a distant sector of the galaxy, we watch a spaceship explode from the bridge of our starship. The ship is at that moment rocked with sound and motion from the fury of the explosion. Great billowing pillows of flame erupts in a uniform ball complete with sparks a traces of dark smoke.

Great picture, ain't it? Too bad it's all wrong.

Explosions are interesting things. They are the extremely rapid expansion of material into a less dense volume. On Earth, most of our explosions are pyrotechnical, that is from burning or combustions. In space, you can have a couple other types of explosion: kinetic impact, hull ruptures, collisions with anti-matter. You name it.

Now, the first problem is the fire: From the Fire in Space entry, we can see that you are not likely to ever see flames from anything in the vacuum of space. Glowing embers or sparks, maybe, but not great wads of flame. Even if there were flames, the speed of expansion is so rapid that the flames would last a split second before being dispersed.

The second problem is even more exasperating. You can't hear sound in space. Space is a relative vacuum so there's no matter for the sound to travel through (Remember that sound is a mechanical wave passing through stuff like air or water). To make things even worse, the ship is a dozen or more kilometers away. Even if there were sound, there is no way it's going to reach your ship or rock at the speed of light. Sound travels much, much slower than light—roughly 331 meters per second. You would see the ship explode than a few seconds or hours later you would hear it explode, assuming you could hear anything in a vacuum.

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One of the coolest special effects sequences in history is the shots of the X-Wing fighters in Star Wars banking and diving on the Death Star. Not to be outdone, we see Cylon Raiders in Battlestar Galactica flip on their wing and dive into a planet's atmosphere from the vacuum of space.

But despite how cool these shots look, it still doesn't change the fact they are wrong. If you look closely, you will notice the X-Wing fighter maneuvers like a WW II airplane. The Cylon Raiders beautiful wing tip and dive is almost exactly like a similar maneuver performed by today's jet fighter pilots. But you can't do these maneuvers in space without wasting a lot of fuel. Fighter planes get their maneuverability from the air they are flying through. Turning requires loosing momentum in one direction and gaining it in another. Space ships have no problem adding momentum, but they do have a problem losing it because they operate in the vacuum of space.

An aircraft uses the air to provide lift and maneuvering thrust. When the pilot turns the tail rudder, air is deflected at an angle to the plane's flightpath causing the plane to turn. If the pilot banks, air resistance takes the plane's forward momentum while the plane's engine gives it forward thrust in a new direction. A spaceship has no atmosphere to use flight control surfaces. Each point of maneuverability must be replaced by a thruster to brake and push the spaceship into a new direction. Trying even the most basic aircraft moves in a spaceship will probably result in you tumbling out of control but still moving in the same direction.

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