Podcast Episode 18 – Travel in Space


Episode 18: Learn About Travel in Space

Listen as host Randy Ellefson talks about travel in space. This includes the different types of engines, what to include inside a ship, and why we have a lot of freedom to decide how long it really takes to get anywhere.

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In This Episode You’ll Learn:
  • The different engine types we can use, how they differ, and consequences of each
  • How the distance between locations impacts travel in space in ways unique to space
  • What we must consider about the external structure of our ships
  • What to include on the inside of ships and pitfalls to watch out for

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Episode 18 Transcript

Hello and welcome to The Art of World Building Podcast, episode number eighteen. Today’s topic is travel in space. This includes the different types of engines, what to include inside a ship, and why we have a lot of freedom to decide how long it really takes to get anywhere This material and more is discussed in chapter 5 of Creating Places, volume 2 in The Art of World Building book series.

Do you want practical advice on how to build better worlds faster and have more fun doing it? The Art of World Building book series, website, blog, and podcast will make your worlds beat the competition. This is your host, Randy Ellefson, and I have 30 years of world building advice, tips, and tricks to share. Follow along now at artofworldbuilding.com.

Engine Types

It’s fair to say that most of us have no experience traveling in space. The result is a need to do research on what this is really like. We can also rely on TV shows that we’ve seen, whether those are fictional in nature – and movies – or we can rely on TV shows that are more informational. Now, as it turns out, I work at NASA, but I am not a rocket scientist. But I do have access to people who are rocket scientists and I have run some of what I’m going to tell you by them to get their buy-off on this.

The first thing we want to talk about is propulsion because there are different kinds of engines that are used in space or in an atmosphere. Some of these are real and some are fictional. One thing I’ve noticed that’s interesting is that if an engine type is real, authors don’t typically spend the time explaining how it works, but if it’s fictional, we do.

However, we don’t really need to do that if we don’t want to. I suspect one reason this happens is that authors have as little interest as the average person in explaining how an actual technology works, but when we’ve made up something interesting, we’re trying to attract the attention of the audience as well and say, “Hey, wouldn’t it be cool if this thing existed and it could do this? Here are some ideas on how that might work.” And it’s all speculative. Some science fiction makes a lot of mention of this, like in Star Trek, but others don’t make any mention of it at all. So, you have a choice here. If you don’t want to write a bunch of techno babble that you typically hear in Star Trek, then don’t.

Air-breathing Engines

So, the first kind of engine we’ll talk about are the air-breathing ones. These are obviously designed for when there is an atmosphere. In other words, this is not in space where, obviously, there is no atmosphere. So, in an episode about travel in space, why am I talking about this? Well, because your ships might still have such engines. Now, with real technology, I don’t explain in this podcast any more than in a story of mine how it actually works for the reasons I just mentioned. So, I’m not going to cover all the different types of air-breathing engines. We just need to decide if our spaceship has these.

Why would they? Well, arguably, space engines are designed for space. Therefore, they may have attributes that don’t make them work quite as well in an atmosphere. Therefore, our ship may be able to alternate between these. When I watch certain science fiction shows and movies, I sometimes hear the pilot say something like, “Switching to so-and-so power,” as they are changing from one type of maneuvering to another. Sometimes that means when they’re going from space to an atmosphere or the opposite. This is a detail we can add to our ship to make it more believable.

Now, if we like the idea that we have ships that don’t need this, we can still do that because, in any science fiction setting, just as today, we have different technology. Some of it is old and some of it is newer. So, we could have our characters on a ship that is old and, therefore, they have to do this kind of switching back and forth between air-breathing engines and space engines. We can have a character remark that he’s making this change and say that this spaceship is a bit of a clunker because they still have to do this, and he prefers the one he doesn’t have to make this kind of switch. Obviously, this is just subtle detail and not something critical to the plot, but such little details can make things more believable.

Besides, why have all of your ships be the same? This and other issues with their vessel could be the reason why they’re on the lookout to acquire something better, which is certainly something that would add to your plot. They might want to steal something or buy something and not have the funds to do so, or someone might have stolen their ship and now the best they can do is afford this clunker. This issue of having to switch back and forth between engine types could be one of the things that this adds. Another issue with multiple types of engines is that they’re probably going to have different fuel sources and, therefore, they could run out of fuel for one type of engine but not the other.

Space Engines

Let’s talk about space engines. Space engines are divided into two categories: Those that allow faster-than-light speeds (or FTL) and those that do not, which are known as slower-than-light (or STL). Only the slower-than-light ones are real. Everything else is fictional. For slower-than-light engines, the propulsion is at least a little bit similar to atmospheric engines in that something is being ejected, usually from the rear of the vessel. This is, of course, what propels the ship forward. This is one reason why these types of engines could be used in atmospheric conditions instead of something that is specifically designed for atmospheric conditions.

Some STL engines could propel the ship fast enough that this can cause time dilation. This is when two observers experience a difference in how much time has passed. We sometimes see this in science fiction where the captain tells the pilot to travel at a certain speed but not to go beyond a certain threshold because that’s going to cause this time dilation. They may say, “Go up to speed eight, but no faster.” Sometimes the captain will explain why, but really the pilot’s going to understand already. So, sometimes, that kind of exposition is only being said for the sake of the audience.

One solution to that sort of scenario is to have an ignorant character standing there and ask the question, “Captain, if we’re in such a hurry, why don’t we go up to speed nine or ten when the ship can do that?” And have the captain explain why. We’re so used to that kind of thing that we accept it, but if you stop and think about it, it’s not that believable because anyone who lives in a society that has space travel is going to understand time dilation.

Here on Earth we do have space travel, but so few of us do that that most of us are only dimly aware of this. The only reason we’ve heard of it at all is from watching science fiction. But using the Star Trek example, in that sort of future where there is so much space travel going on, people are going to know this. We may need another solution, such as instead of the ignorant character, have someone else say, “Not in the mood for any time dilation today, Captain?” or something to that effect.

Let’s take a look at some fictional faster-than-light drives, all of which are public domain, which means we can use these ideas.

Jump Drive

One of them is called “jump drive.” As the name implies, the ship can simply jump from one place to another one like it’s being teleported there. As you can imagine, this is pretty convenient. What if you had a personal version of this right now and you could simply jump from home to work and back? While this is pretty cool, the problem that this creates for us as storytellers is that it pretty much eliminates all drama, tensions and problems that come with having to travel from one place to another. We’re not going to run into enemy ships that are going to bother us unless we run into them when we arrive. We’re not going to run across a distressed ship that needs help. In space, we don’t really deal with monsters typically, but there’s this issue of when you’re traveling, stuff happens. Well, that’s not going to happen in this scenario.

In that sense, there could be a lack of tension and, therefore, a lack of drama. And that’s not necessarily a good thing. If you have this sort of drive, I would suggest using it sparingly in your setting so that this is something rare. It’s also a little too easy for characters to get out of trouble with this if they’re doing something and then enemy ships show up, they can simply jump right out of there. They’re not going to have to fight unless the jump drive is malfunctioning or something. As you might expect, since there is no actual travel, a ship that has a jump drive is not going to experience time dilation when they use it.


Another type of drive is the hyperdrive, which is a drive that moves a ship into hyperspace. This is a fictional, separate dimension that is adjacent to normal space. Storytellers often use this idea that a ship that’s in hyperspace has difficulty or it’s not even possible to interact with a ship that’s in normal space. One reason we do this is that hyperspace has some advantages and, therefore, we should also give it some disadvantages. The greatest advantage is the speed with which it allows a ship to travel great distances. This type of drive also experiences no time dilation when people return to normal space.

Warp Drive

That brings us to the last space engine, and that is warp drive. This is probably associated with Star Trek for many of us, but this is a public domain idea. There’s this idea that there are different levels of warp, such as warp five being slower than warp six. The instantaneous travel, like jump drive, is not possible with warp. There is also no time dilation, but one of the issues here is that the ship is remaining in normal space. One thing that I don’t see mentioned typically is that there are plenty of objects with which a ship can collide. Despite the word “space,” there is a lot of stuff out there. It’s just that it is fairly well spaced out.

My big point here is that a ship is not going to be traveling this fast unless it has some sort of shield to protect itself from that kind of debris. So, a believable detail we can add is that there’s been some sort of battle and, as a result, the ship’s shields are down and someone says, “Hey, we need to get out of here at warp drive,” and someone else says, “Well, no. We can’t do that because we could hit something.” Having to leave that scene of the battle at a slower speed could also pose problems for them.

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Distance Issues

Now we’re going to look at distance. One of the realities of space is that any two locations are not going to be a fixed distance from each other. Everything is orbiting something. Moons orbit planets, planets orbit suns, and even the sun orbits the galaxy. All of that this means is that the distance between two places is always changing. In a previous episode about land travel, I talked about writing the words “not drawn to scale” on our map. Well, if we’ve created a map of a star system, we don’t even need to do that because it’s not going to be relevant. There’s also the caveat that no one can show up and tell us that our fictional star system has things that are a different distance from each other than they really are. One impact of all of this is that two objects, like two planets, might be on the same side of the sun, or on opposite sides, or somewhere in between.

As you can imagine, this could significantly change the amount of time it takes to travel from one to the other. In some science fiction, authors make no mention of this, but in other stories, they do. The way we would typically want to do this is to basically say that the characters need to get from where they are now to another place, but maybe they don’t have enough fuel to make the journey, given how far away that other location is at the moment. Maybe they have to wait a week or a month to do this. Or they could leave right now, but one of the issues is that it’s going to take a month to get there when they need to get there in only two weeks, maybe because there is an event taking place on that location in two weeks. Someone could remark, “It’s too bad that this didn’t happen several months ago when the planets were closer.”

This is also the sort of situation where if someone had a jump drive, it would be very advantageous because it wouldn’t really matter. On the other hand, if they don’t have it, then maybe they have to use hyperspace. Maybe they need to use slower-than-light travel, but they need to go beyond that threshold that’s going to avoid time dilation. They’re going to go so fast that they will cause time dilation and there’s just no choice. They’ve got to do it. Mentioning this sort of detail or putting it into your storyline is one way to make things more believable. One good thing about all of this is that it gives us flexibility to inject this sort of problem into our story.

At times, we might want to make it suddenly very easy for the characters. Like two planets or locations happen to be relatively close and they’re happy about that. Other times, we may want to make it more difficult. Try not to imagine that everything just works out magically and that there is no problem, ever.

Also bear in mind that when a ship is traveling to meet a planet, for example, it’s not traveling to where that planet is now, but where that planet is going to be. Naturally, this sort of thing involves computers figuring out some of this math for us, but what if the computers are down? Can we have a character who is pretty good at this sort of thing doing it manually? They can at least start their journey based on the manual calculation. Then, if someone gets the computer working, they can input the fixes later. This is another way to be more believable.

One of the problems we could face is trying to figure out should we first create engines that can travel a certain speed and, therefore, cover a certain distance in a certain amount of time, and then base our story around that, or should we create our story idea first and then figure out what kind of engines we want to make available? That includes coming up with engines that don’t quite do everything that our characters need. This is also one way to force them into a situation where they have a ship that doesn’t do the job, but if they had a different ship, well, then that would take care of the problem, such as a ship that has jump drive. I would say that we should invent a propulsion system first and then alter how far away locations in our story are based on the needs.

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External Ship Structure

One question we may face as world builders is what is the internal structure of our spacecraft? In a visual medium like television and film, we’re also going to worry about the external view because we’re going to have depictions of this on-screen. Now, most likely, if we are working in that sort of medium, we are going to have somebody who has designed that spacecraft for us, but for all I know you are the sort of person who depicts that spacecraft.

When it comes to the exterior of a ship, there is a tendency to draw something that is aerodynamic looking, even if it’s designed to be in space. One notable exception to that is the Borg Cube from Star Trek. When it comes to these more aerodynamic ships, one of the reasons we do this is that this ship may have to operate within an atmosphere. Now, we may decide that the ship is never, under any circumstances, going to operate within an atmosphere, and therefore we can get away with something that is not aerodynamic. Otherwise, if we think there’s any possibility it can enter an atmosphere and operate there, then we should make it aerodynamic. Any character who sees such a non-aerodynamic vessel is going to automatically assume it can’t operate in an atmosphere.

But just because something is aerodynamic looking doesn’t mean that it is designed for atmospheres. So, why would it still look that way? Well, just because we expect it. There is still the matter of slower-than-light propulsion ejecting matter, which is sometimes on the sides, but it could also, most likely, be on the rear. And then there’s the reality of needing to look forward through a window, for example, at the space that you are traveling through. Both of these lend themselves to that similar ship shape.

However, when it comes to that window, we could dispense with the actual window and use a series of view screens instead. There are other issues like this that we can consider, but basically it doesn’t have to be that way. It just can be. If we present it that way, the audience is never going to shrug and say, “Why in the world does it look like that?” We basically accept that without even thinking about it.

We may also want to consider where the ship can be loaded. On Earth, when you’re getting on a cruise ship or anything else on the water, the cargo typically goes on the bottom, regardless of whether it’s loaded from the back or the side. The reason for this is that we don’t want to make the ship top-heavy so that it doesn’t topple over. In space, we obviously don’t have to worry about that. Unless there is artificial gravity, the cargo is not going to weigh anything. That kind of brings up another point. Why don’t we ever see a cargo hold on a science fiction vessel where everything is basically floating? It’s always shown as it is pulled down. It’s just sitting there. The obvious answer for this is that it’s easier for the film crew to film it that way rather than using special effects to show everything floating all the time. But it seems plausible that you would not want artificial gravity in the cargo hold.

Of course, this is going to depend on how the ship is generating that artificial gravity. If it’s one of the more believable rotating vessels, then obviously everything has gravity and there’s only so much you can do about that. However, on that note, if you do have a rotating vessel, there’s going to be more gravity on the farthest reaches of that vessel than towards the center where there’s still going to be almost none. Once again, this is something that is sometimes overlooked. It’s a nice detail we can add for believability. Most of the living space would obviously be on the farthest reaches of that so it has the maximum gravity that they’ve intended for people to have. But there might be maintenance things that are happening towards the center of that vessel where those people have to float.

Now, if we don’t have to worry about that cargo having a weight to it, we could assume, “Hey, it can be loaded anywhere.” Well, what if people have done that and they’ve loaded all the cargo on, say, the left side of the ship, and then this space-faring vessel enters an atmosphere? Suddenly, it’s going to have gravity and all that weight is going to be on one side. The next thing you know, our ship is lopsided and it might crash. Naturally, this is one scenario where maybe they do have artificial gravity in the cargo hold all the time so that they don’t have to worry about this. But it could also be a situation where as they are preparing to enter an atmosphere, they have to go and turn on more artificial gravity there, or something to that effect. Maybe they also have to move the cargo around prior to this. If the cargo was loaded in space, maybe they didn’t worry about this, but if the cargo was loaded on the ground where there is gravity, then they would have worried about this. But then, maybe once they’re into space, they rearrange things.

There are some other considerations like where the weapons are located and where the engines really are, but we can basically make up a lot of that. The big thing we need to worry about there is that we don’t want guns that can accidentally shoot into the ship. By the same token, we obviously don’t want engines that are going to burn up part of the ship. What this really means is that the slower-than-light engines that are ejecting matter to cause propulsion are probably going to be on the sides or in the back, but really the faster-than-light engines with these fictional ways of getting around, we can pretty much put that anywhere. We might have a ship design where the slower-than-light engines are on a typical location that we would see on an atmospheric engine, but the faster-than-light ones, we could just decide to put that wherever we want. We could put that further inside the ship so that it is more protected from enemy fire.


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Internal Ship Structure

Let’s talk about the internal structure of our ship. If our ship is really small, so much so that only two people can fit inside it, for example, then the internal structure doesn’t really matter because it’s probably a single room. But if we’re talking about something like the Enterprise from Star Trek, then the structure of the ship does matter. One reason is that characters need to move between locations, like the bridge, the cargo, the engine room, and their quarters. We may have active scenes such as aliens breaching the ship at a certain place in the hull, and it might be five minutes for our characters to get there at a full run, but they need to get there in two minutes because, otherwise, the aliens are going to destroy something.

To some extent, we could just make up scenarios like that, but if we’re going to use the ship repeatedly, we may want to have a sense of this so we can be consistent. We don’t want it to take five minutes to make that trip in one story and then two minutes in another and then ten minutes in a different one. Having planned out our ship to some degree helps us think of scenarios like this to start with. We can organize our vessel to avoid one problem, but we’re probably going to set up another one. So, no ship is foolproof and any scenario could come up where it just causes a problem.

There are certain realities that are going to exist on a ship, such as the living quarters being somewhere near the dining areas. Now, that said, if you’ve ever been on a cruise ship, they do have the main dining area, but they have all sorts of smaller restaurants spread throughout the vessel. Such a scenario will also be true on a large spacecraft. Similarly, there will also be things like lounges in different locations so people can relax regardless of where they are.

Things like propulsion and cargo are typically located towards the rear of a vessel. More importantly, they are farther away from the living quarters because most people don’t want to be near that, partly because that area tends to be a little bit on the dirty side. If you’re creating a passenger ship, this is something to keep in mind. The cheaper rooms are going to be in such an area, or at least near that area.

If we do plan out our ship, I would suggest not going overly detailed unless it’s really going to matter to your story. For example, you may want to say that engineering is on deck six towards the rear of the vessel, and it’s on the port side, for example. You can just leave it at that. You don’t have to say that adjacent to that is some other area. You can basically decide a certain deck and one side of the ship has a certain number of things, and not actually figure out exactly what is right across from each other or next to each other until it matters in your story. Being a little more generic and general about the location of these things gives us some flexibility if we need to change things later.

As for what we’re going to include in our ship, we obviously need a bridge, which is the command center where all the decisions are being made and where a lot of the senior officers are during the important scenes. We’re obviously also going to need to living quarters. Now, one thing that we may want to do there is have the officers have better quarters than the regular crew. Whether our ship is a passenger vessel or not, it’s going to have a certain amount of entertainment. It’s just that the number and type of those are going to vary. Even on a military ship, we’re still going to have shops because people need to buy supplies. On a passenger ship, many of those shops are going to be concentrated in a mall-like area.

Any vessel could also have a jail, which is also called the brig. A military vessel is almost certainly going to have something like this, but even the passenger ones may have one. We may also want to plan out where the escape pods are if these are going to be used in our story. These are typically going to be mostly near the living quarters, but some of them are also going to be spaced throughout the ship so that those who are working the ship and controlling it when it needs to be evacuated still have somewhere to get to relatively quickly rather than having to go all the way back to their living quarters.


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Where to Start

Finally, let’s talk about where to start with space travel. The first decision we should really make when planning a vessel is to decide where it’s going to operate: only in space or both in space and in atmospheric conditions? Another early decision: Is this a cargo ship, a passenger ship or a war vessel? In some cases, it could’ve started this life out as one thing and have been converted into another. We should also decide whether the purpose of our ship is local travel near the planet where it originated from or is it intended to go in between solar systems or even stars? This will determine what sort of engines are needed. If the local solar system is relatively peaceful, then it may also determine how many weapons it has. We should also figure out what kind of events we want to take place on this ship and what kind of vulnerabilities it might have which can be exploited by the way we layout the ship.

These are just suggestions. You can do things in whatever order you decide. One of the general recommendations I always make is if you have an idea for something, just work on that first. The best point of origin is an idea.


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