2. Ion Propulsion
Ion propulsion is currently the fastest form of space travel available and the most fuel efficient too. The technology basically discharges ion particles to move forward. Of course the science is a lot more complicated than that, using Xenon gas (which itself sounds all sci-fi like) and apertures and electrons etc. It was developed by NASA and has already been used several times, and not just by NASA. The first to use it was the Deep Space 1 probe which was launched back in 1998 which was to study an asteroid and a comet. The ion drive was shut down after three years, but the probe remains in active communication and can be reactivated if it is decided it is needed. The probe itself is in a continuous orbit of the sun (although probably not stable). It has also been used by the Japanese Space Agency and the European Space Agency on probes, and the ESA plans two more probes in the future. The drives are incredibly slow to start with for example, it takes three days to get up to about sixty miles per hour. But the drive increases the speed exponentially and builds continuously. Now in Star Trek you might have heard of warp drive or impulse drive but not an ion drive. Well firstly, the impulse engines are supposedly a type of ion drive and the Dominion use ion drives on their vessels (although probably not the same technology as they're both a lot quicker than that!). The technology was under development by NASA since the 1960s, and so it is likely that it was included in the series in order to make it seem authentic. In fact, ion drives are specifically mentioned in a pretty awful episode (possibly so bad it's good) episode of The Original Series Spock's Brain which aired later in 1968 than the first orbital test of an ion drive. John Brophy, the NASA Ion Propulsion System Manager for the Dawn space probe launched in 2007 referenced the episode as being the first one he remembers to have used an ion drive, although also notes that they are the propulsion for TIE Fighters in Star Wars too.