A spaceship is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. All spaceship except single-stage-to-orbit vehicles cannot get into space on their own, and require a launch vehicle (carrier rocket).
On a sub-orbital spaceflight, a space vehicle enters space and then returns to the surface, without having gained sufficient energy or velocity to make a full orbit of the Earth. For orbital spaceflights, spaceship enter closed orbits around the Earth or around other celestial bodies. spaceship used for human spaceflight carry people on board as crew or passengers from start or on orbit (space stations) only, whereas those used for robotic space missions operate either autonomously or telerobotically. Robotic spaceship used to support scientific research are space probes. Robotic spaceship that remain in orbit around a planetary body are artificial satellites. To date, only a handful of interstellar probes, such as Pioneer 10 and 11, Voyager 1 and 2, and New Horizons, are on trajectories that leave the Solar System.
Orbital spaceship may be recoverable or not. Most are not. Recoverable spaceship may be subdivided by method of reentry to Earth into non-winged space capsules and winged spaceplanes. Recoverable spaceship may be reusable (can be launched again or several times, like the SpaceX Dragon and the Space Shuttle orbiters) or expendable (like the Soyuz). In recent years, we are seeing more space agencies tending towards reusable spaceship.
The trick to designing any machine, especially a spaceship, is knowing what its purpose and mission are… unfortunately science fiction provides us with few ships designed with those concepts in mind.
So today we’ll be looking at spaceship design from modern ships to those of the distant future, to some that might never exist outside of science fiction. We’ll also be deconstructing some sci-fi designs to see if they really make that much sense, and [a] examining some real-world design elements that are specific only to modern spaceship. Right now every spaceship is designed to be as light as possible, because every kilogram costs a lot of money to get into space.
Also, spaceship are most commonly lost in the launch phase, so if you want to assemble a bigger ship or station in orbit, you need a lot of launches, each of which might blow up on the pad or shortly after launch, and even for automated launches, that results in in missions exceeding budgets and introducing big delays. And so, in modern space exploration, if you can make a hammer that weighs half as much but costs a hundred times as much, you send that expensive hammer up instead of the cheaper and heavier one.
The major paradigms of modern spaceship design are extreme quality control, ultra-reliability, and the minimization of your mass, because failure is not an option. If a rare manufacturing defect in a half-penny resistor can disable a circuit that disables your $100 million probe, you’ll spend thousands of dollars making sure that half-penny resistor works right. This stands in contrast to the standards to which most mass produced items are held, where cost usually is a bigger concern than reliability or redundancy. You generally don’t pay 10 times as much for an appliance that will last twice as long or is half as likely to malfunction.
As a result, our perception and attitude towards modern terrestrial industry can warp our understanding of spaceship design. A good example is addressing the issue of radiation. Most spaceship rely on thin, but dense, shielding made usually of lead, gold foil or water, but other materials such as uranium can work as well. Thick shielding adds cost due to the weight, for fairly little added benefit. Another thing we have to consider is that not all of the ship needs to be shielded, only the areas which have vulnerable computer systems or lifeforms do, which saves on weight and cost.
We can also look to technological solutions to eliminate the cost and weight of shielding. For example, magnetic fields strengthened with ionized gases like xenon have been proposed for shielding against cosmic radiation, as they are able to deflect charged particles away from the crew. However these also come with trade offs - such a device consumes more power, so you have to have a bigger power source, which means more mass as well.
Of course, a more efficient power source can help solve that issue, and a total and cheap cure for cancer would minimize the need for shielding humans too. A different approach is to incorporate other components of your mass into your shielding. For example, water is a fantastic radiation shield - that’s one reason why we use it to shield radioactive material here on earth; you can design a spaceship’s storage for water and waste to double as your radiation shielding. Aerogels also offer a lightweight approach to shielding while having a minimal effect on mass, though the larger or faster the projectile, the thicker the layer of aerogel or the incorporation of a denser layer working in tandem.
Of course, if you’ve already well established yourself in space, and need to protect habitats’ long term inhabitants from radiation, you can always simply pile mass around your habitat. An established space industry can take advantage of low-gravity bodies like small moons or asteroids to save on launch costs, making thicker shielding practical. Some of our habitats and spaceship are likely to be built into existing small, rocky bodies as well, which will mean they come with their own free shielding. Perhaps the most important factor though, especially for spaceships, is the square-cube law.
If you make something bigger by simply expanding its geometry, the surface area will rise with the square of that increase while the volume rises with the cube of that value. Double a sphere’s radius, and it has four times the surface area, but eight times the volume. Make a cylinder ten times bigger along its long axis and radius, and it gets a hundred times the surface area and a thousand times the volume. If we want a space station that can hold a thousand times as much cargo or personnel, we make it ten times bigger, which also gives it a hundred times the surface area, and by default a thousand times the mass. But it’s not really necessary to make my shielding ten times as thick, we only need to extend it over one hundred times as much area, and now shielding accounts for a tenth the proportional mass that it did on the smaller version. And many other aspects of my ship also won’t need to scale up by 1000 either. So, I probably don’t need a thousand times as many spare parts for instance, even if I do need a thousand times as many components – which I probably wouldn’t anyways. You will always need two of any critical component or part, but that doesn’t necessarily mean you need two-thousand of them just because you have a thousand times as much space. For spaceships, bigger is often better. In other words, once you start making ships of a certain size, even if mass is still a big concern, radiation shielding really stops being an issue.
Even on interstellar ships plowing through the void at relativistic speeds, you really only need to increase your shielding on the nose of the craft. The easiest way to do this is to simply keep your spare fuel and water supply up front to soak up radiation. Hydrogen and water ice mostly won’t be harmed by it, and they will be stored in thick volumes, so you can design long and skinny ships with the front, thick shielding being proportionally smaller, reducing how much proportional mass you’re pushing around. So that’s our most likely layout for spaceships, they are skinny and long. This does not necessarily mean you build ships like long, ultra-thin wires, but you will generally want to optimize the shape of your spaceship by employing a minimum longitudinal cross-section.
A spear, needle, or arrow shape is preferred, not a blocky one. Generally it would be symmetric too, though they don’t necessarily need to be aerodynamic. There’s no air in space to cause drag; however, if you’re moving at highly relativistic speeds, the near-vacuum of the interstellar medium actually acts like a gas, though we’ll come back to that later. With that in mind you could easily introduce a lot of protrusions such as antennae, shielding, extra habitation pods, and so on, which destroys the image of a nice, sleek hull. Not every location or area on a ship needs the same level of protection, for example, you don’t particularly care if a random bit of space debris slams into an antenna, as such hardware is easily replaced or can even be manufactured on the ship. Indeed you might use less armor and shielding on spare water and fuel tanks to ensure any debris doesn’t fragment upon impact. That could cause a large exit wound, and which means your fuel or water will be lost to the void. If you can ensure debris only punches a small hole in those tanks, the leakage could be kept minimal during the tiny amount of time it would take to patch that small puncture, especially if you have a self-sealing material for the tanks. Indeed, perhaps such a self-sealing tank might leak an average of a few hundred kilograms to these minor punctures during the voyage.
However, if you were to use a more heavily armored tank, you’d have to attach many thousands of kilograms of additional armor, adding to your ship’s mass, and increasing your fuel bill. In this case, you’d want to go with the thinner tanks and just absorb the minor losses, because it’s an overall net gain. You are also very likely to have a lot of modular, reconfigurable, or retractable segments or pods on your ship. During the ship’s construction, you won’t be fighting air resistance or the drag of gravity, but once you embark on your journey, during your acceleration phases, you will effectively be back under gravity’s thumb. Of course the robustness of your ship design will need to consider the level of acceleration, and deceleration you intend to use. Short trips may accelerate harder for a brief time, whereas longer journeys may opt for a protracted, but lower and more efficient acceleration. Once the acceleration phase ends and you begin your coasting phase, which will be the majority of your trip, there’s no reason why you can’t begin to expand outward, adding segments and pods and extrusions of all types, but this must be measured against the fact that you will be increasing your ship’s cross section. If you wish to expand, you must decide how much radiation shielding and anti-collision armor you’ll give to each extrusion.
However, while you’re cruising, you even have the option to trail things behind your ship; maybe you detach your power generator and instead drag it behind you, apart from the ship, so whatever waste it produces can be ejected into space, instead of remaining part of your ship’s mass. You can reel the reactor back in when it’s time to fire your engines for your deceleration phase. There’s also the option to trail a radiator behind you, to help dissipate the excess heat all of your shipboard activities will generate. Indeed, interstellar craft might sport many thin radiating fins protruding from the hull. You could even add things to the front – radar, anti-collision lasers, or thin sails sent drifting in front of you to absorb collisions and minimize damage to the actual ship.
But then again, maybe not, because while losing an antenna or radiating fin or a few scraps of a thin fuel or water tank might not be a big deal, the fact is that the debris destroying your antennae is moving extremely fast, relative to your ship. Even small pebble- or sand grain-sized particles are essentially bombs at interplanetary speeds - and at interstellar speeds, those grains are atomic bombs. Any ships coming into an inhabited system might need to retract such flimsy protuberances. Should a radiating fin or antenna be knocked off your ship by interplanetary debris, at the speed you’ll be moving, even as you decelerate from interstellar speeds into the system, your lost equipment just became an entire nuclear arsenal’s worth of kinetic energy, rocketing towards your intended destination. Just imagine some space freighter decelerating into a densely inhabited system; it would be disastrous to essentially nuke the world you spent decades, or even centuries, to reach, with a loose or broken piece of hardware – so all of your protuberances and extrusions need to be pulled in to minimize your ship’s cross section again when you are in a system, in interplanetary areas. Unless of course you are an invading fleet, in which case all that potential debris becomes your target’s problem rather than yours.
Though speaking of space freighters, those are probably one of those things you’d only see in science fiction - specifically of the giant mega-freighters plowing through deep space variety. There’s plenty of room for freighters, but if we’re talking about moving large quantities of raw materials around, realistically, those huge container freighters really aren’t the best way to ship your resources. Instead, you’d attach a small ship to a large payload, essentially a slowboat, meekly cruising back towards the world or habitat or station that requires the materials, taking many years to arrive. A megaton of iron is just as valuable when it is on its way as it is the moment you acquire it. Let’s consider 3 likely cargos of raw materials one might haul around in the future. Ice, Gas, and metal ores. Let’s start with ice. Water in any form is rare in the inner system – outside of Earth, of course – but out past the asteroid belt, past the “frost line,” there are innumerable icy bodies, asteroids, comets, and ice-covered moons around the gas giants. This makes the concept of transporting large quantities of water very logical; if you’re building rotating habitats in the inner system, you’ll need that water to be shipped in. However, those icy bodies aren’t entirely pure water ice – they typically also contain chemicals such as frozen ammonia, methane, and so on – a little perk, resources that can be put to other uses. If your ship’s job is pushing ice out from Saturn’s Rings or the Kuiper Belt, that’s exactly what you would do: push it. You wouldn’t cut the icy body into pieces and haul them into a massive freighter, you’d simply attach your ship, which is probably rather small, to the icy body and use your engines to accelerate the body towards your destination.
However, you really aren’t just shoving the cargo – you don’t want to send a comet rocketing into the inner system on a ballistic trajectory. You will probably arrive at the ice with equipment that is basically a set of extra engines and a protective wrap. As you push the ice in-system, if it is unprotected, it will start to melt and outgas – which is what gives us those beautiful comet tails we all know. So you’ll want to wrap the ice in some sort of thermal protection – something that will keep the ice cold and frozen even as you approach the warmer inner system. You’ll want the wrap to maintain some pressure inside, so that any phase changes that do occur will be the ice melting into a liquid, instead of sublimating into a vapor. The wrap will also probably be reflective, especially to infrared radiation. While comets are beautiful to see, in this situation, we definitely want to avoid losing all that precious water. However, any sublimation and outgassing could make handy propellants to push that comet around, and an alternative to wrapping the comet. You could follow the comet closely and collect the gas and vapor so you don’t lose those resources to the vacuum. Once collected, you have many options for using these gasses: process the mix and separate all the molecules. Electrolyze the water to get the hydrogen to dump into your fusion drive or reactor. Or perhaps your ship has great mirrors or solar sails, which you can use to reflect and focus an energy beam at the comet to sublimate the ice into natural propellant. This superheated gas and vapor would push the comet in-system quite powerfully, and would get to its destination more quickly.
However, this method requires some decision making; how much of that material are you willing to lose in order to get the comet to its destination faster? You might of course do this entirely automated, but if you need on-site crew, they need a place to live, and you’re never going to be in a rush on ice, since the slower you go the higher your profit, minus the cost of salaries and equipment maintenance, which I’d imagine will be the dominant factors in deciding how slow you can push ice. They’re going to want to make a bit of a home out of that place, and of course might carve in ice tunnels or extract minerals to build more stuff – icy bodies typically have plenty of rock mixed in there too. This gets one thinking about ore freighters as well. Now you might opt to move a metal or carbon rich asteroid this same way. If that’s the case, given that many a freighter or colony ship might also be a mobile refinery and factory, they might not be moving raw materials but instead be making stuff out of them or refining as they go. I should also note that ship hulls and space habitat hulls are likely to be fairly generic, so you might start moving an asteroid and turning bits of it into a ship plating and end with a classic big space freighter full of a mix of ore, refined metal, and manufactured goods, all surrounded by cheap, standardized hull plating you could also sell at your destination.
One-use freighters in a sense, with a core ship for the crew and sophisticated components you couldn’t make en route. As to moving gas, the reality is that you probably would not, in favor of pressurizing and cooling it enough to be a liquid or solid. A great big balloon is going to leak on you, both from all the extra debris it might be punctured by from its larger size, and because any container has to be able to keep tiny gas molecules from slipping through, and that’s very hard to do with hydrogen for instance since its smaller than the atoms of the container material. So a gas freighter might end up looking a bit more like our classic image as it probably would be a ton of tanks filled with gas or liquid strapped to a ship. That crew doesn’t really need much room compared to the sizes involved, especially in terms of the habitat drum. This is all assuming you even need a crew but as we often mention on this show, the concept of a sophisticated ship computer able to replace a human crew doesn’t necessarily mean its ‘unmanned’. By and large you don’t need much brains for navigating space but many of the other tasks might start edging into an area where you need something animal-smart, and if it needs human-smart, you use a human. Or a person anyway, even if they might never have been born in the classic sense.
Artificial intelligence is a rather vague concept when you get to higher levels. Whether it’s an unmanned ship or a manned one, and for all the vagueness of that term in a futuristic sense, a ship is always going to have a computer on board. What else does it need? Well air and water and warmth if anything biological is in play, and a means to clean and recycle both. It’s tempting to assume spaceships will always have gardens or hydroponics onboard if people are on board, but plants aren’t the most mass-efficient way to scrub carbon dioxide out of the air. Short-run ships or those that need to accelerate fast like a warship probably wouldn’t bother. For everyone else, it offers at least a supplement of fresh food and something green to look at. Your crew needs to bring some home along though, and will always try to, within the limitations of the ship and mission. A ship that needs to be able to accelerate very fast and suddenly might have problems keeping a garden or hydroponics bay going so it doesn’t get smashed around by the sudden jerks or effective high-gravity, but I suspect that would simply results in lots of inventions to make it practical rather than abstaining from having them. When it comes to living quarters, ‘as close to home as possible’ will always apply, and where it can’t we either do our best, go without, or modify ourselves for it to not matter. That could be a minor thing like everyone wearing sunglasses and sunscreen because the ship or work environment in space was heavily flooded with UV light, or more likely the reverse, having sunrooms you could sit in that let you soak up the rays while the ship tended to be otherwise dim. Alternatively it could be big stuff like modifying a human to not need gravity, or handle gravity and acceleration better, or even uploading minds into computers or cyborgs to handle extreme conditions like acceleration or radiation.
Ships that spend a lot of time cruising or only undergo weak long accelerations like an ion drive , rather than fast burns like chemical rockets, are generally going to be able to have a much more regular layout of things like dining and food preparation and bathrooms and gardens. Alternatively, ships that do have to be ready for rapid burns need to have very specialized and specific places for eating, drinking, disposing of waste, and even sleeping. You might need to strap in. If the ship needs to be able to rapidly accelerate on short notice, you need padded walls or airbags in them, because a sudden 5-g burn might slam someone into the ceiling or wall of a corridor hard enough to shatter their bones. You might go the other way though and include padded suits instead, or pad objects that might not be secured. Pet collars on such a maneuverable spaceship, and I’m sure most with crews would have pets too, would likely feature air bags or balloons that could act as impromptu life support bubbles. Amusingly a coffee cup might have an accelerometer in it that triggered a lid and blew out a balloon, many tools might too. We often see boarding parties in science fiction fighting through corridors, but less so debris bouncing around or the combatants trying to blast or squirm through corridors that have blown out airbags down their length. On any such ship though, every bit of equipment is going to be secured when not in use and likely attached to tethers even when in use. A hammer or screwdriver kicked down a corridor by a rapid burn is a lethal object. Such ships wouldn’t have large rotating sections much either. We often picture stations or ships that provide gravity by rotation as being the whole thing rotating, but as we’ve noted in other episodes, usually the rotating section would be inside a larger superstructure, and on a ship, except a classic slowboat generation ark ship, that rotating drum is likely to be only a small part. They are a place for sleeping and relaxation or stationary work, like offices, kitchens, or workshops.
A ship doesn’t have to have only one drum though, it can have several of various sizes, even nested inside each other and providing different levels of gravity. Your issue there is that the smaller in diameter a drum is, the more times per minute it needs to rotate to produce the same gravity. Evidence suggests 2 RPM is beneath our threshold to feel nauseous but more RPMs are probably easy to acclimate to. That limits how small a drum can be, though it can be smaller if you don’t need full gravity and odds are some small workshop in a distant corner of a ship only needs enough gravity so stuff falls and things feel up and down, moon gravity might be enough. Propulsion is important for how a ship will be laid out inside, but of course it’s a big deal for overall ship configuration too. Indeed in the case of a ship attempting to achieve high delta-v, meaning a high cruise velocity, the so-called propulsion bus may have to represent the bulk of total mass: the “payload”, where you’d have crew quarters, cargo and life support, would look relatively small even if it’s in the thousands of tons, and it would be dwarfed by the engines, waste heat removal systems / radiators, and the fuel tanks, which may be the largest part of the ship, to obtain a high mass ratio. Let’s talk a little more about streamlining the outside of ships though. For the most part, as I mentioned earlier, ships don’t need be streamlined other than to cut down on overall mass and cross section, and might feature a lot of retractable equipment in exterior bays so you could store them under more cover when not in use and make it easier to get at them for repairs, be it antennas or radiators or sensors or big point-defense guns. We’ve got some special cases for streamlining though. Needless to say if you want your ship to be able to land on a planet or move into a gas giant it needs streamlining. Such ships have an excuse for more of the jet or plane look, as they have to deal with lift since they are going through air and gravity fields.
However space is not a true vacuum and at high enough speeds even in intergalactic space, as close to true vacuum as you can get outside a lab, it can act like air giving drag and friction, though not lift, or much anyway. If you’re flying above a galaxy at ultra-relativistic speeds you might get a tiny amount of lift you needed to account for. This does mean relativistic ships want to have a nose on them, so that if stuff hits, it deflects away, rather than just impacting against a flat wall. Of course at such speeds even a grain of sand is like a big bomb but it still helps to have that nose-cone, and I was apparently rather unintentionally ambiguous about that in our Interstellar Travel Challenges episode where we looked at the issues and options for ships moving at a decent percentage of light speed. I also mentioned there that you probably would never want to build a ship that ever went anywhere near light speed, but there are cases and setups where that would make sense. All the gas and dust lying around will be acting as drag, and even a ship with infinite fuel, either by some magic clarketech or by a pushing laser, will eventually reach a maximum speed where the ship drive or pushing laser equals out in thrust to the drag of the interstellar or intergalactic medium Even if you do reach highly relativistic speeds, you have a new problem, because even if you can clear out every speck of debris in front of you, that ambient radiation everywhere in the universe becomes a problem.
A really skinny ship with a magic stardrive can potentially get insanely fast, but would rely on technology we have not even an inkling of yet, and maybe ever. A pushing laser can be done though but introduces a new problem. A great big sail or mirror on the back also massively increases your ships cross section. The better you can focus that beam the smaller that cross section can be, but even if you can pull off a long relay of pushing stations so the beam is always tight, you still get an issue with light red shifting, and blue shifting. The faster you’re going, the more red-shifted the pushing beam will be, and thus the weaker it is and the less thrust it offers. On the flip side, all the ambient radiation you’re plowing through will be more blue shifted, and thus provide more thrust against you. Inside a galaxy this radiation drag is going to be way less than from all the gas and dust, even keeping in mind that there’s a lot more ambient radiation from all those stars.
Out in the intergalactic void though you still have to tackle Cosmic Background Microwave Radiation, which is evenly dispersed everywhere. Far, far in the distant future this will grow ever weaker, as it redshifts as the Universe expands, but right now it places a barrier at about a gamma of 133, according to calculations by Colin McInnes in his book “Solar Sailing”, where the red shifted pushing beam and the blue-shifted CMB radiation equalize out. Gamma by the way is the term for the Lorentz-factor in Special Relativity, we’ve discussed that more in other episodes but for a quick abridged version, this is how much time slows down for you relative to the outside universe or how much of your total energy is in kinetic motion rather than mass energy. A gamma of 133 would mean 133 seconds would pass on other people’s clocks for every second you experienced, or basically a bit over two minutes for each of your seconds. It also means you’d be moving at 99.9972% of light speed. In other words, if you were making the trip to the Andromeda Galaxy at this speed, 2.5 million light years away, you would personally experience only 19,000 years on the voyage. At that speed incidentally the light from any signal sent when you left would only arrive about a century before you on your 2.5 million year journey.
I doubt you could ever get to that speed, but it does mean that even if you do, your intergalactic crews still either need radical life extension or very-multi-generation-ships for the trips. Even frozen crews, as we mentioned in Sleeper Ships, need special measures to be taken to avoid being killed by buildup of radiation damage from the tiny amounts given off by the radioactive potassium isotopes in your bones and other isotopes in your body. Such ships can start slowing by just cutting off their pushing laser. Slowing down cost fuel and energy, so you want to get all the freebies you can, and at these speeds you’d start by slowing using ambient blue-shifted energy, then cosmic gas and dust, then hopefully by vanguard probes hitting stars ahead of you and building pushing lasers to slow you, using the technique we discussed in Exodus Fleet.
Magnetic sails can also help you with deceleration, their effectiveness increases with initial speed, and even today’s proposed designs could allow a braking rate of several milligees, though it may be less in intergalactic space due to its lesser density. The faster you’re going though, the more each mote of dust or photon you collide with reduces your speed, and here we see yet again how much ship design has to vary with things specific to purpose rather than technology available let alone any constant rules of ship design that apply across all levels of mission purpose, technology, and aesthetics. I’ll also note though before we close out that what we think of as a cool looking spaceship, or machine, often is altered by our exposure to it. When you get around to a rocket or a jet or a sportscar don’t look that particularly awesome until you know what they can do, and your mind tends to start altering what you think is cool to look at. Your default spaceship is likely to look a lot more boring and plain than what we see in scifi, but our descendants in the future might think those designs look pretty cool.