I have always been a huge fan of science fiction. What really draws me to the genre is the fact that authors and movie-makers are not scared to “challenge our minds”, exploring ideas and concepts that might seem implausible, even ridiculous today. As Robert A. Heinlein puts it: “(Science fiction) is a realistic speculation about possible future events, based solidly on adequate knowledge of the real world.”
A popular saying is that “today’s science-fiction is tomorrow’s science fact”. The irony is that there is more truth to this statement than we would care admit. 30 years ago the ‘portable telephone’ and ‘information-highway’ were something of science-fiction. Today there are more cell-phones on the planet than people with the Internet being the number one source of information, communication and entertainment.
For this post, I am investigating some of the science fiction predictions for space travel – from the absurd to the “somewhat-plausible” to the “it-is-only-a-matter-of-time”.
Leaving Terra Firma
To get into space, you first need to overcome the effects of gravity – one of the fundamental forces of the universe that effects all matter at a macroscopic level.
Currently, the only technology available is rockets which is tremendously expensive – so much so that only governments, multi-national consortiums and the richest billionaires on earth are able to fund space projects. Rockets need to generate enough thrust to escape the pull of the earth’s gravity (g = 9.80665 m/s) and have to burn enormous amounts of expensive fuel in the process.
In his 2006 novel, Gradisil, Adam Roberts explores the idea of ordinary people being able to simply “fly” into orbit, setup habitats and live in space – which they call the “Uplands”. In order to do so, regular jet-planes are adapted to use the resistance of the earth’s magnetic field to produce lift. He called this effect, ‘magnetohydrodynamics’ where the plane’s wings becomes giant electro-magnets that cuts into the lines of force of the magnetosphere. The ascent is slow and similar to a seagull or eagle using the wind currents to systematically soar higher and higher.
Whether or not this technology is viable for future space travel is debatable. However, it provides an interesting alternative to current space programs’ investment in rocket technology. As one of the characters in the book explains (rather animatedly): “…because von Brown (the ex-Nazi scientist that eventually spear-headed the NASA space program – editor) was so influential, nobody explored other means of flying to space. When NASA planned to fly a hundred-kilo man into the orbit they could have taken the money they were going to spend on doing that and instead spent it on building a replica of the man in solid gold, that’s what the costs were.”
Another alternative for getting into orbit is the space elevator. The concept of space elevators were first proposed in 1895 by Konstantin Tsiolkovsky. Arthur C. Clarke introduced it to the wider science fiction audience in his 1979 novel, The Fountains of Paradise. Robert A. Heinlein (Friday, 1982) and David Gerrold (Jumping Off The Planet, 2000) also featured space elevators that reached into the sky like giant beanstalks.
The dynamics of such an elevator is not hard to grasp. A counter-weight needs to be placed into the earth’s orbit and connected to an anchor point on the surface with a strong cable or tether. The centrifugal force of the earth’s rotation will keep the counter-weight in place (think a bucket of water that you swing over your head without spilling any fluid).
Tsiolkovsky’s vision of the elevator was a bit more ‘anchored’ in his era’s understanding of physics and construction and consisted of a free-standing tower that reached the height of the geostationary orbit (like a giant Eiffel Tower). But today’s thinking is more towards using a very strong but light-weight cable that is capable of carrying its own weight as well as the additional payload that must be lifted. It needs to be about 35km long. The material has not been perfected yet, but scientist are currently working on carbon nanotube and diamond nanothread technologies.
The benefit of such a space elevator is that all the raw materials needed to construct spaceships can be exported from earth where it will be assembled in zero-gravity (by means of robots or humans).
In order to make it economically viable, such an elevator would probably consists of hundreds of cargo pods that move up and down together like a giant Ferris-wheel. It would obviously mean that a journey to the top could take many days as each pod needs to be unloaded at the top while an empty one is loaded at the bottom. But the money saved in relation to burning rocket fuel would be worth the while.
So let’s assume a new spaceship has been assembled outside the earth’s atmosphere or even on the moon. The next step is to launch it towards its destination – an action that also requires some sort of energy transfer.
In Kim Stanley Robinson’s 2015 novel Aurora, a star ship with the same name is launched by an electromagnetic “scissors” field. Two strong magnetic fields held the ship between them and when they were brought across each other, the ship was briefly projected at an accelerative force equal to 10 g’s. (Almost like squeezing a watermelon seed between the fingertips).
In addition to this, a powerful laser beam were concentrated on a capture plate at the stern of the ship’s spine for a period of 60 years, accelerating it to full speed.
But there are other objects in space like planets, moons and even suns whose energy could also be harnessed to propel spacecraft on long interstellar travels. The most famous example is Voyager I.
Voyager I was launched in 1977 and is the first human-made object to cross the heliopause (the boundary of the heliosphere) and enter interstellar space. On his journey to the edge of our solar system, Voyager had a little help from the gravitational fields of Jupiter and Saturn to sling-shot it towards its destination.
The mathematics behind such a manoeuvre is extremely difficult and commonly known as the “three body problem” – a reference to how the gravity of the sun and a planet will influence a third object’s trajectory. A brilliant 25-year-old mathematics graduate called Michael Minovitch solved this problem in 1961 (with the help of an IBM computer) and proved that an object that flew close to a planet could steal some of the planet’s orbital speed, and be accelerated away from the Sun.
Another problem is that the planets are not always in the correct position to execute the sling-shot. The Voyager missions were specifically planned to take advantage of the fact that Jupiter, Saturn, Uranus and Neptune would all be on the same side of the Solar System in the late 1970s. Such an opportunity would not present itself again in another 176 years!
In Aurora, Kim Stanley Robinson also used the inverse of the sling-shot effect to decrease the speed of his spaceship as it re-entered the solar system by using the planets’ gravitational fields for ‘aero-braking’. His ship also had a very intelligent computer on board that was able to make the required calculations during flight.
In Douglas Adam’s Hitchhiker’s Guide to the Galaxy series, he introduced us to the Bistromathic Drive which operates on a revolutionary way of understanding the behaviour of numbers. Just as Einstein observed that space and time was not absolute but depends on the observer’s movement in time, scientists discovered that numbers were not absolute, but depended on the observer’s movement in a restaurant.
The first non-absolute number is the number of people for whom the table is reserved. This will vary between the reservation, the actual amount of people showing up, the number of people joining the table during the evening and the number of people leaving the table when they see someone else turning up which they do not like.
The other non-absolute number is the arrival time – a number whose existence can only be defined as being anything other than itself. In other words the exact time when it is impossible that any other member of the party will arrive!
The novel further explains how these and other numbers are utilized in the drive so that the ship is capable of travelling two thirds across the galaxy in a matter of seconds.
Ion drives and more
Although the bistromatic drive will not be in production any time soon (or at all!) ion drives (or ion thrusters) are already a reality. The drive creates thrust by accelerating ions (charged particles) with electricity and has been used in the Deep Space 1 spacecraft that did a flyby of a nearby asteroid.
Although current ion drives does not provide blindingly fast acceleration (0-60 mph or 0-96 km/h in four days) the appeal to science fiction writers lay in the fact that the weight requirements for fuel are much lighter that traditional rockets. In theory it is also possible to ionize all elements known to man, so a spaceship could be build and fuelled on Mars, or Europa for example.
The concept of the ion drive has already been depicted as far back as 1910 by Donald W. Horner in his novel By Aeroplane to the Sun: Being the Adventures of a Daring Aviator and his Friends.
Another science fiction concept that is being taken seriously today is solar sails. Just as a normal ship use sails to harness the wind’s power, solar sails use the pressure of reflected solar radiation to propel the ship forward.
Jules Verne already mentioned the idea of light propelling spaceships in his 1865 novel From the Earth to the Moon although the science to explain this was not even available during that time. In 1951 an engineer named Carl Wiley wrote an article for Astounding Science Fiction (under a pseudonym Russel Saunders) called “Clipper Ships in Space”. This article influenced many science fiction writers, for example Pierre Boulle that mentioned these “sailcrafts” in his 1963 novel Planet of the Apes.
Finally, the most popular way of space travel used in science fiction today is of course the Hyperdrive, or faster-than-light (FTL) travel. Spaceships using this technology enters an alternative region in space, known as “hyper-space” by means of an energy field and exits at another location, thus performing travel that exceeds the speed of light.
Travelling via hyperspace, or “jumping” has been mentioned in short stories by Isaac Asimov (1940-1990), Arthur C. Clarke’s 1950 novel Technical Error, Star Trek, Star Wars as well as the Babylon 5 and Battlestar Galactica series.
Hyperspace might be a convenient way of bypassing Einstein’s Theory of Special Relativity stating that energy and mass are interchangeable, thus making speed of light travel impossible for material that weigh more than photons.
Space is big and even the closest star system to our own, Alpha Centauri, is 4.37 light years away.
With today’s technology the first humans that will reach Mars within the next two decades, have to endure a trip of 8.5 to 9 months just to get there. If we have any hope of reaching Alpha Centauri in one human’s lifetime, radical new ways of space travel must be invented.
And one science fiction writer’s dream today might just be the solution we were looking for all the time.