Science fiction is a core part of being a geek. Being a hard-core Star Wars fan, or a die hard Star Trek fan, you would know very well that most interplanetary Sci Fi stories come with their own armada of awe-inspiring spacecraft. These spaceships or spacecraft are built by legendary ship builders using legendary techniques and are more often feats of an engineering marvel than not.
And one of the most interesting things about these spacecraft is mostly what they run on. Have you ever wondered how the Infinite Improbability Drive on the Heart of Gold works? Or perhaps the Class 0.5 Hyperdrive on the Millennium Falcon has been of more interest to you? Even if the answer is no, it is undeniable that these crafts would be – literally and figuratively – a shell of themselves without their ‘drives’ (which is what are going to call their major operational mechanisms from here on). Despite, and perhaps, because of the wide variety of options from all of the science-fiction, these drives can be majorly classified into several broad types.
Ion Drive Engines
Perhaps the most realistic option in science-fiction, ion-drive engines offer the direct advantage of reducing the amount of fuel needed for the same thrust, thus offering greater fuel efficiency. But how does it work?
Briefly speaking, ions are charged particles of any element. And since they carry a charge, their velocity can be manipulated with electricity. Putting a magnetic field in place gives an ion-drive the ability to accelerate ions to enormous velocities. These ions are then released to provide thrust to the craft. To explain the energy generated, think of it like this – when an ion passes through an electrostatic or electromagnetic grid engine, the potential difference of the electric field involved is converted to the ion’s kinetic energy. While the acceleration is very low due to the low mass involved in the thrust, this acceleration can be maintained for far longer than what is possible with chemical engines, making it an ideal choice for a fictional spacefaring civilisation.
Interesting fact: Ion drive engines are real – to some extent. A number of deep space missions – current and planned – are using ion engines for propulsion.
In terms of popularity, the Star Wars universe has seen a large number of these drives. In fact, the popular TIE fighters expand to Twin Ion Engine fighters. Although, when it comes to speed, ion engines should not be the first choice due to the low acceleration that they can provide. In fact, popular franchise Battlestar Galactica often incorrectly refers to ion-drive powered ships achieving light speed, which is nowhere near possible.
Dark Matter engines
Dark matter has largely been an unexplainable mystery, be it for scientists in real life or fictional worlds. It has been used as the source or explanation for everything from super-powerful guns, a city full of metahumans, and super-powerful ships that can achieve unexplainable feats.
One of the most recurrent and popular cases is Futurama, where dark matter forms the primary fuel for starships. In the series, the only known source of dark matter is the excretion of Nibblonians, a species that existed even before the Big Bang (an interesting origin, nonetheless). In the series, the dark matter is ‘burned’ in large furnaces, channelling it through an afterburner which gives the ship enough speed to cover the entire universe in a matter of days. But how is ‘faster than light’ (FTL) speed explained? The dark matter moves the universe around the ship, instead of the ship itself! Another notable example of a dark matter drive is from Space Pirate Captain Harlock, a manga-inspired story where dark matter engines grant the ship Arcadia the ability to travel at a massively FTL speed (and immense destruction abilities).
Interestingly, this idea isn’t as unheard of in reality as one would expect. An NYU physicist Jia Liu had proposed a spaceship design that would scoop up dark matter particles at the front. According to the theory that dark matter is made up of neutralinos, the particles would annihilate each other and provide sufficient energy, if directed correctly, to reach light speed in a matter of days. Of course, this involves a ton of assumptions, as does any other theory that proposes dark matter as an energy source since we barely understand its true nature.
Solar powered propulsion
Solar power in space is real and is used in a number of orbital spacecraft and satellites. But to use solar power as a source of propulsion is far fetched, even for science fiction. The area of solar cells required combined with the size of the batteries needed to store the solar power are enough to render it unfeasible as a sole source of power in our own solar system. A higher density of stars, however, does make this a possibility. A more popular form of star-based power in science fiction is harnessed by using solar sails.
Since James Clarke Maxwell discovered that light exerts a certain amount of pressure on objects it falls upon, the idea of solar sails propelling spacecraft has captured the imagination of many creative minds. Initially appearing in Jules Verne’s 1865 novel From the Earth to the Moon, the idea got a strong boost in popularity with Arthur C. Clarke’s Sunjammer almost a hundred years later. In fact, NASA’s first solar sail mission to deep space has been dubbed “Sunjammer” in Clarke’s honour.
Other notable examples include the Bajoran lightship from Star Trek: Deep Space Nine and Count Dooku’s solar sailer from Star Wars Episode II: Attack of the Clones. And just like the others, even this idea has found a real counterpart ever since the beginning of the space race.
Lightsail 2, the successor to the Planetary Society’s Lightsail-1 (formerly Lightsail-A), is set to be launched aboard the first operational SpaceX Falcon Heavy in 2018 to test the viability of solar sails as a propulsion mechanism for CubeSats. Additionally, in 2010, IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) was launched as the first spacecraft to use solar sails as a primary propulsion system. And there are even more projects planned in coming years.
And then there are these
While most spacecrafts in science-fiction try to base their propulsion mechanism in current scientific advancements, there are some that have redefined what a propulsion mechanism can do and used entirely out of the galaxy thinking to travel across space like never before.
If you’re a true geek, it’s highly likely that you are familiar with Hitchhiker’s Guide to the Galaxy. The iconic Heart of Gold spacecraft in the series uses an Infinite Improbability Drive to travel at, well, infinite speed (what else could it be, right?). According to the book, the drive works on a combination of a Finite Improbability Generator and a cup of tea with a little bit of Brownian motion thrown in. This allows the drive, and the ship it powers, to travel through every conceivable point in every conceivable universe simultaneously every time it is used, making it the fastest ship possible in science fiction. It also allows for some very interesting variations and storylines, which you should definitely check out if you haven’t already.
Any geek worth his money knows about Doctor Who and TARDIS. The space-time transcending police box that the Time Lord travels in is actually a Type 40 time and space machine from Gallifrey, his home planet. The ship, if we may call it so, derives its powers from multiple sources. One of the primary ones is the Eye of Harmony, which is the nucleus of a black hole created by early Time Lords – essentially, a singularity. This allows the ship to travel through the time vortex without actually travelling through space, although the TARDIS is shown to fly on several occasions as well.
At this point, it wouldn’t be entirely wrong to compare the volume of space-based science fiction out there with space itself. Hence, it might have been fairly impossible on our part to cover every possible type of popular spacecraft-propelling drives and engines in sci-fi. Although, if you think we missed out a particularly significant one, do let us know at firstname.lastname@example.org. And just in case you’re building one of your own, we call dibs on the test-drive!