LESSON Realism in space

Discussion in 'BUILDING WORLDS' started by Lstorm, Mar 15, 2013.

  1. In science fiction settings, depicting space travel or space combat is very common. Unfortunately, even though it is such an oft-explored topic, space is often not represented correctly in fiction. While there is no problem with traditional, space opera style fights between fighter craft and big battleships, a lot of fun can be had with more accurate representations of space. It is also a problem that many authors who try to depict space realistically have no idea what they are talking about, and as such, their otherwise well-researched science fiction turns out to be laughable or mediocre at best.

    This workshop attempts to give an overview of what space is like and dispel the misconceptions that surround space travel and space combat. However, when reading this workshop, one must remember that space is still a new frontier which has not been completely explored yet. As such, some sections, especially the ones which address space combat, are just speculation, because space is still unknown to humanity and there have been no battles in space so far. Regardless of that, this workshop will attempt to provide a complete and realistic picture of space.

    This workshop is divided into Rules and Points. Rules are more of a general principle which has to be followed, while Pointes elaborate on an aspect of a Rule. If one wants to get a general idea of what space is like, they only have to read the Rules and can skip the Points. However, for a full understanding of the subject, reading all the Rules with all their Points is necessary. Now, without further ado, let us move on to the most important Rule.

    Rule #0: There is no good metaphor for space
    This is the one misconception most people fall prey to, namely, the misconception that they can base space travel and combat on something else. Unfortunately for them, space is nothing like humanity has encountered before, and as such, comparing it to something that all of mankind knows well is impossible. Only a few people have experienced what it is like to be in space, but even they have limited experience with it. Therefore, as soon as one starts making comparisons concerning space, they have already failed, for space is just as unique as water, air or ground. It can be likened to other concepts on a basic level, but ultimately, it is its own element which works according to its own rules.

    Rule #1: Space is huge
    The second most common misconception that seems to plague most science fiction authors is thinking that space is just like Earth and that one can get anywhere within a few weeks at most. However, the reality is that space is unimaginably huge. Just one light-second (the distance which light covers in one second) is roughly three hundred thousand kilometres, about seven times the length of Earth’s equator. To put such a distance into perspective, at the speed of sound, covering one light-second’s worth of distance would take about three hundred hours or approximately twelve days.

    • Point 1.1: Interplanetary distances
      Distances between planets are longer than one might think, and are usually expressed in Astronomical Units, which will be abbreviated as AU for the rest of this workshop. One AU equals to the average distance between the Earth and the Sun, which is about eight light-minutes, or eight times the distance which light covers in one minute. This is a distance which is hard to represent, but if one assumes that the Sun is a golf ball, then the Earth is about five metres (five and a half yards) away from it and is roughly the size of a half rice seed. Now consider that Venus, the planet which is the closest to Earth, would also be the size of a half rice seed in this representation and would be one and a half metres (one and a half yards) away from Earth.
    • Point 1.2: Interstellar distances
      The distances present between solar systems are simply huge, and are usually measured in light-years (the distance which light covers in one year) or parsecs (roughly three and a quarter light-years). Such distances cannot be represented properly, as Earth is only a speck of dust when compared to interstellar distances. Nevertheless, if one were to represent the whole Solar System with a golf ball, then one parsec would equal to roughly fifteen metres (sixteen and a half yards) and the closest star system would be about twenty metres (twenty two yards) away. Note that for this calculation, the Solar System was considered to have a diameter of fifty AUs.
    • Point 1.3: Visual range and sensors
      At the distances which were described previously, and even at a distance of a few light-seconds, visual input becomes nearly useless as objects will shrink to an insignificant size. Similarly, because of how huge space is, spacecraft would rarely get within visual range of each other, unless they wanted to meet up for some reason or they were headed along the exact same route. In such an environment, sensors and detectors are much more useful than large glass windows placed on a ship, which just beg to be attacked by an enemy. There are a lot of alternatives to detecting objects based on visual input, but that will not be covered in this section.
    • Point 1.4: Relationships between stellar bodies
      One thing most authors fail to consider with planets or even stars is that they move in relation to each other, something which must be compensated for. Even inside a single star system, planets move according to their orbit and will not stay in the same place, which means that a flight plan must be made before travelling between two stellar bodies. Just launching oneself in the general direction of a planet or a star is not going to work, and they will likely end up missing their target or having to drastically alter their course.
    • Point 1.5: Communication is not instantaneous
      Because of the large distances involved, whatever method of communication is used in space will ultimately take some time to reach its target. Even light-based and laser-based forms of conveying messages will only work without considerable time lag in an area of a few light-seconds, not to mention that light tends to scatter, possibly making the message incomprehensible. Radio wave based communications have the same effective radius. Therefore, communicating with a planet or another ship might have considerable lag on both ends of the communication, with long pauses on both ends.

    Rule #2: Space is three dimensional
    As people who walk on the ground, bound to a solid surface most of the time, humans tend not to consider the Z axis, or “up” and “down”. However, in space, thinking in three dimensions is a must if one wants to depict it accurately. Spacecraft can move in any and all directions of three-dimensional space, and as such, they can execute manoeuvres that seem unnatural to most people. They also may be in positions which seem awkward or just plain strange, not to mention that their design should reflect their ability to move in such a manner.

    • Point 2.1: Movement and orientation
      Spacecraft have the luxury of utilising three dimensions, which means that they can make full use of space. Unlike many vehicles, they are not limited to staying on a single plane and they can move in any direction their pilots steer them. Basically, spacecraft enjoy unlimited freedom in movement, except if they get too close to planets, so one should not limit themselves to thinking that they move on only one plane. Similarly, aboard a spacecraft, the only point of reference is the spaceship itself and the nearby stellar bodies. As a result, spacecraft can take up strange positions when seen from each other’s perspective. For example, one spaceship might see another flying “upside-down” from their point of view.
    • Point 2.2: Ship design
      While it is not easy to make predictions about how spacecraft will look like in the future, there are some things that should be kept in mind when designing spaceships. First of all, one must consider if said spaceship are capable of landing on planets, in which case they must be aerodynamic at least to some extent. With such ships, it is also important that they have a strong heat shield on their frame so they can withstand atmospheric entry and take-off. However, if that is not the case, then the possibilities are limitless, not to mention that aerodynamics can be thrown out of the window.

      As such, most spacecraft are likely to maximise their volume. This is especially true for cargo ships or passenger ships, which would be oriented towards carrying as many wares or people as possible. Aesthetic design is likely to be reserved for luxury cruisers or custom-made ships. In addition, only civilian ships would have windows as it would be considered a structural weakness on military craft. Speaking of military craft, spacecraft designed for combat must take into account that they can be attacked from any and all angles, so as such, they would have to have weapons placed all over their frames. It is also likely that combat ships would try to minimise their profile so they would be relatively harder to hit.

      Large thrusters should also be a staple of civilian ships, as if they are taken out, then a military ship becomes nothing more than a drifting coffin for its crew. Instead of a few large propulsion devices, it makes more sense to have smaller thrusters all over the frame, thus making the craft less vulnerable. Armour also must cover every part of a military ship evenly and may even be made in a way that it can be used to cover weapon ports or the thrusters themselves.
    • Point 2.3: Combat
      Depicting how two spacecraft would face off in space is not an easy task, especially considering the distances involved along with the large freedom of movement. The most basic problem of combat in space is the fact that due to the large distances, any weapon which is slower than the speed of light will be inevitably spotted before they impact if the distance between the two parties is large enough. Combine this with the fact that spaceships can move in three dimensions and it becomes evident that combat in space is more of a patience game than anything. Complicated calculations, strange manoeuvres, plenty of dodging and planning spread between hours of waiting for something to happen are likely to characterise space combat.

    Rule #3: Space is a vacuum
    One of the more perplexing misunderstandings about space is that it is often depicted as having friction, or something that automatically causes spacecraft to slow down when their engines are turned off. However, this is not the case as space is a near-perfect vacuum, meaning that there is very little friction. This is because space has very few particles in it, which need not to be in most cases. One has to throw the concept of friction out of their mind, along with the concept of air cooling, in order to get an idea of what space is really like.

    • Point 3.1: Frictionless movement
      Space is just so thin that friction may be ignored altogether for casual movement. That means that as long as a spacecraft does not collide with a stellar body or another spacecraft, it is going to keep moving. Of course, it may stop in a few million years, but a spaceship stopping dead in its tracks because its thrusters were taken out is an idea that has no foundation whatsoever. This also makes aerodynamics almost useless in space, as well as traditional methods of changing course, most of which rely on friction.
    • Point 3.2: Propulsion
      As a result of the previous point, any spacecraft must be fitted with small manoeuvring thrusters if they are to change their course in space. Otherwise, spaceships would be forced to travel along a straight line, which is not exactly ideal. Even this way, changing a path in space is not that easy, as the spaceship must first rotate itself towards the direction it wishes to go, then switch on its main thrusters. Even then, because of the frictionless nature of space, counter-thrusters must be used so that the spaceship does not overturn. It is important to note that in space, each movement must be compensated for by the thrusters eventually, or in other words, deceleration must follow acceleration.
    • Point 3.3: Fuel and time issues
      Because of the frictionless nature of space, the only limitation which spacecraft have is time. They can maintain a constant velocity for a very long time without spending any fuel or resources, so a spaceship may even be able to travel through the whole universe. Therefore, the only limitation fuel really imposes on spacecraft is average speed. As discussed in the previous section, acceleration must be followed by deceleration. Both of these processes require fuel, so fuel must be divided equally between the acceleration and deceleration portions, or the spaceship is likely to overshoot its target. A simple way of summarising this rule is that a spaceship does not use fuel to actually move, only to change its speed.
    • Point 3.4: Heat dissipation
      The fact that space is cold is a commonly held belief which happens to be true. Unfortunately, as it was mentioned before, space has very few molecules to actually convey its temperature with. This means that in space, overheating is a constant problem for spacecraft and one is more likely to die of suffocation than freezing if they go outside without a spacesuit. A side-effect of this is that spaceships look like a Christmas tree on infrared sensors, not to mention that they need some way to keep themselves cool. The easiest way to do this is to use radiators with large surface areas to interact with as many particles as possible, but there are also creative alternative solutions such as internal heat sinks.

    Rule #4: Achieving light-speed is impossible
    Accelerating to a considerable fraction of light-speed is no joke, nor is it an easy task as it requires an enormous amount of fuel and energy. Due to the effects of the theory of relativity, the closer one gets to light-speed, the more energy it takes to accelerate an object because of the relativistic effects. Achieving the speed of light is outright impossible with anything other than a photon and information cannot spread faster than the speed of light as a rule. Even at close-to-light speeds, several problems present themselves.

    • Point 4.1: Acceleration limits
      Whether one likes it or not, humans are fragile beings who cannot withstand infinite forces. High amounts of acceleration put an extreme amount of stress on the body and people need to be trained specifically so they can withstand large changes in acceleration. A spacecraft can only accelerate at a certain rate without smearing its crew across its internal components or causing permanent injuries to on-board personnel. A good rule of thumb is that the human body can withstand about ten to twelve Gs, or in other words, ten to twelve times the acceleration which gravity provides. Of course, this is by no means an absolute frame of reference and greater forces may be survived.
    • Point 4.2: Energy and shielding
      To put it simply, one would need an infinite amount of energy to accelerate any particle to light-speed, excluding photons. Even if that was not the case, accelerating to the speed of light requires enormous energy and fuel reserves. To give one an idea just how much energy would be needed for such a feat, an object with the weight of one gram would need more energy to be accelerated to the speed of light than what the electric grid of Earth produces. Another problem with relativistic speeds is that even though space might be considered a vacuum, it is not. At such large speeds, particles will start punching through the hull of the spaceship unless it is protected by very thick armour plates or an incredibly strong electromagnetic field. Spacecraft designed for relativistic speeds would have to be incredibly well-armoured at least on one front so they can survive these particles without becoming damaged, or they would have to have huge generators aboard for generating a repelling field.
    • Point 4.3: Mass and time dilation
      According to the theory of relativity, both mass and time dilate as one approaches the speed of light. Time speeds up for the person inside a vehicle travelling at relativistic velocities, while their mass increases, meaning that they will perceive the journey to be shorter than it really is and they will be heavier than when they started the journey. The closer one gets to the speed of light, the bigger these effects are, however, they only become significant at significant percentages of light-speed. As a result, acceleration gets progressively harder the closer one gets to the speed of light, as the same amount of force has to provide acceleration for a greater mass. The only positive point that can be said of relativistic effects is that they scale slowly.

    Summary and some pieces of advice
    Naturally, there is no need to uphold every single rule and point which is described in this workshop, and in fact, creativity with space travel and space combat is encouraged. One just has to remember that space is completely different from everything that is known to most people right now. There is no “correct” take on how to handle space, there are only realistic and less realistic takes. Both of them can be fun, well-thought out, innovative and consistent, not to mention that realistic and unrealistic takes can be blended together to create an interesting mixture.

    When it boils down to it, this workshop only exists to give ideas on what an aspect of space is really like. It is meant to be a guide for people who like everything in their works to be as realistic as possible. There is nothing wrong with creating one’s own rules for space as long as they remain consistent as even a correctly represented space battle can become boring if one cannot feel the tension. One should just read through these rules, sit back and think about what they want to include in their depiction of space. Only when they are absolutely sure of how they want to represent space should they truly begin building their interstellar empires and spaceships.

    One piece of advice is that one should be very careful when designing spacecraft, as spaceships which are too large present several problems if they are to be represented realistically. Another good thing to keep in mind is that the long travel times of realistic space travel are not a disadvantage to a world, in fact, they can be used to fledge out the world even more, to consider why several planets stay banded together even though they can barely maintain contact with each other. Similarly, long travel times make for excellent plot devices or can be the driving force of whole worlds.

    With that said, I hope that those who made it this far have fun with building their own version of space.