Common Misconceptions About Space Travel

This section has been stolen even more directly from this website. However, it's necessary for this to be posted. Forgive me for my copyright infringement. More will be added as they appear.

1. Space isn't an ocean. This isn't true--spacecraft, unlike sea-going vessels, don't have to deal with friction. They also travel in three dimensions, rather than two, and their decks will not be laid out as though they were a ship. This changes other aspects of design also; there absolutely would not be a "bridge" placed at the "top" of the ship, or even a defined "top" and "bottom" for that matter.
   
2. Space exists in three dimensions. A spacecraft has no limits on how far up or down it will go, and can travel to infinity in any given direction. Not that you'd want, to, but what this means is that you must think three-dimensionally. There is another aspect of space of interest--there is no defined up or down. These are subjective in space.
   
3. There is no sound in space, and nobody can hear you scream. Due to the fact that there is no air in space, or any other medium to carry sound for that matter, battles will be silent. You will, of course, hear sounds from your ship--your weapons firing, crew working, your engines--but you cannot listen in on another ship.
   
4. There is no friction in space. If you burn engines, you accelerate; if you are moving, then, at one kilometre per second, and you stop burning engines, you will coast forever at one kilometre per second until you do something to change this (or you hit something, as unlikely as that is).
   
5. It makes no sense to speak of a rocket's range. Going from the above, a rocket can coast infinitely. The real measure of performance is delta-v, a linguistic shorthand derived from equations that means "change in velocity". What this means is that the "gas" you have left is measured in delta-v. If you've three hundred kilometres per second of delta-v for a mission, your hypothetical ship can accelerate to one hundred fifty kilometres per second, coast for however long it needs to, then slow to a stop. Please keep in mind that you really ought to have lots more delta-v than this, or even what the mission requires, due to emergencies, course corrections, or, in the case of a military spacecraft, the unpredictability of the mission itself.
   
6. There is no practical way to avoid detection by the enemy in space. On Earth, an aeroplane can be practically invisible to radar; this is also possible in space. However, thermal signatures of ships can be detected at great distances--CH-powered engines, enabling you to cross the system in about six months, could be detected from the next star. Even a shuttle could be spotted throughout the whole solar system, and a maneuver thruster could be spotted at one astronomical unit (the distance between Earth and her Sun). This is because the cosmic background temperature is three Kelvins--exhaust is much hotter. Not even a coasting ship can remain undetected, as human beings live at about two hundred eighty Kelvins. You'd stick out like a neon sign.
   
7. Fuel and reaction mass are different. Chemical rockets burn and eject the same substance, but a nuclear rocket has nuclear fuel to provide energy and ejects hydrogen (sometimes something else) out the back to push the spacecraft along. You will, in a nuclear rocket, never run out of fuel (not quite, but your ship will be long retired by then). Reaction mass is another matter.
   
8. Rockets will have wings. Before you stare at me--I don't mean wings for flying. You'll need heat radiators, which are discussed in the Starship Design topic, which really could look like wings if you did it right. This might be a good way to add some artistic license to your spacecraft.
   
9. A human being won't pop when exposed to vacuum. For those of you who watch movies, 2001 got it right. A human being exposed to vacuum would stay alive for about ninety seconds, and would remain conscious for about ten seconds. If you are re-pressurized within about ninety seconds, you will probably live, though with temporary blindness and other problems. These will disappear quite quickly. This, of course, assumes you don't hold your breath--if you do, your lungs will rupture and you are a total goner.
   
10. Spacecraft are not boats. On any normal boat, the decks are laid out horizontally from bow to stern, but on a rocket, the decks will be stacked on top of each other like a skyscraper, with the engine at the "bottom". This is because the direction of "down" when the engine is firing will be the direction the exhaust is going--if you accelerate at 9.84 m/s^2 (acceleration due to Earth's gravity or 1G), your crew will feel as though they are being pulled backwards at 9.84 m/s^2 or 1G. The only exceptions to this rule are for shuttles, which genuinely are part aircraft and will probably be laid out this way, or with artificial gravity constructions--but we'll get to that later.
    
11. Spacecraft do not always fly in the direction the nose is pointing. After you've accelerated, you can use manoeuvring jets to fly 'sideways' through space if you want. This can be very useful--to bring weapons to bear, for example...
    
12. Spacecraft will not have windows except in very particular circumstances. They represent a huge structural weakness, especially in combat, and will likely not provide much of a view at any rate--sure, astronomy is interesting, but if you really want to see the stars, there'd be other sensors that can provide you with that experience. Besides that, if you look directly at the Sun, you won't see anything for the rest of your life. This goes doubly for combat featuring nuclear weapons and high-powered lasers.