Combustion-based Thrust Drive (CTD)
One of the oldest propulsion systems to be used in outer space, a combustion-based thrust system involves the burning of liquid propellant (fuel, in other words. Older variants of this system use gasoline, newer ones use a combination of gasoline, liquid oxygen and liquid nitrogen). The burning propellant is expelled at extreme speed from engine, producing thrust. The CTD is essentially rocket technology. Top speeds in deep space may reach up to 55,000 kilometers/hour, significantly faster than Ion-based drives. However, the CTD requires a far more demanding source of fuel than Ion Drives do, and as such, is suitable only for use with starfighter-sized craft - anything larger would use far too much fuel to be even remotely cost-efficient. The exhaust from combustion drives has also shown to have a corrosive effect on the ozone layer of planets, meaning that it is best used in outer space only.
The primary propulsion system aboard any spacecraft larger than 30 meters, the Ion drive functions by expelling a stream of electrically charged molecules from the thruster - resulting in a blue beam of light emitting from the drive of the starcraft. Though they cannot achieve speeds nearly as high as that of combustion-based systems, ion drives are nevertheless the primary form of propulsion for nearly all spacecraft. They are exponentially more economical than CTDs, and they can directly tap into the ship's fusion reactor, meaning that they do not require an external source of renewable fuel like CTDs do.
In physics and nuclear chemistry, nuclear fusion is the process by which multiple nuclei join together to form a heavier nucleus - it is the same process by which stars release the energy that warms the planets in their orbit. It is accompanied by the release or absorption of energy depending on the masses of the nuclei involved. Fusion power refers to power generated by nuclear fusion reactions. In this kind of reaction, two light atomic nuclei fuse together to form a heavier nucleus and release energy. Until the development fusion power, space travel was simply not feasible - it required far too much energy to be achieved by any other means. Fusion power, a derivative branch of nuclear science, is the sole most abundant source of energy known to mankind. Though they are expensive, all starcraft larger than fighters are equipped with a fusion reactor, of necessity. Fusion reactors are much safer than earlier fission reactors and combustion-based power systems, for damage to a fusion reactor does not cause any sort of violent explosion, but rather simply extinguishes the reaction taking place within. This makes them ideal for use on warships, which are often put into dangerous conditions.
FTL, or faster-than-light drives are various forms of accelerators or drives that enable a space craft to move faster than light speed, thus covering vast distances in a short time. Three types of drives exist:
The Hyperdrive is not directly a propulsion system, but is rather an accelerator that propels an already moving starcraft to exponentially faster speeds (thousand times the speed of light). When thus accelerated, travel between adjacent planets in the same solar system can be reduced to as little as a few minutes. Travel between adjacent solar systems requires anywhere between a few hours and a day, making the creation of small interstellar governments rather easy. While any vessel can include a hyperdrive, the hyperdrive is limited to a range of roughly 1 light year every 6 hours.
Hyper Drives are most common among species that are either new to the galactic scene or technologically backwards, and are quickly replaced by Jump Drives when possible.
A jump drive allows a starship to be instantaneously teleported between two points. A jump drive enables a spacecraft to go from one point in space to another point, which may be several light years away, in a single instant.
A jump drive enables a space craft to execute a jump from anywhere in normal space and move directly to any other location. The jump drive is, however, subject to limitations such as distance from strong gravity wells. Also, the total distance per jump is limited and multiple jumps may be needed to reach the final destination. Jump drives require significant power and require time to "re-energize" the jump drive after a jump, thereby limiting the frequency at which jumps can be executed.
A Jump Drive has an average jump range of 10 light years.
The Jump Drive is the most common FTL drive.
A Gate Drive is similar to a Jump Drive, but where the Jump Drive is limited by distance and distance from strong gravity wells, the Gate Drive is not. Gate Drives are known to only very few species, and the technology is considered unattainable by most species.
Qutan Gate Drives are known as Fer'ren Gates, but function exactly like a regular Gate Drive.
A Gate Drive has an average jump range of 500 light years.