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The Aurora company has unveiled the new Interplanetary Airliner (usually simplified to space shuttle) offering both affordable and comfortable space travel to the middle and upper classes of the Hegemony. The Aurora shuttles would be capable of taking passengers from earth all the way to space and beyond.

What fuel could be used for a space shuttle to be able to go from a runway on earth into space? The fuel would have to be affordable as well as rather powerful.

Note:

Maximum distance for a flight would be from Earth to Luna or Earth to Eros.

In most cases flights dock with a space station and passengers board a ship more suited for long distance travel

Fuel that is plausible in the near future is alright

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    $\begingroup$ Beyond looking up the current fuels used by existing rockets I don't see any way to answer this. Note also this document : The tyranny of the rocket equation. which explains some fundamental problems for space flight fuel. $\endgroup$ – StephenG Mar 2 at 2:40
  • $\begingroup$ @StephenG I've always assumed maybe hydrogen could work $\endgroup$ – Celestial Dragon Emperor Mar 2 at 2:55
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    $\begingroup$ SIngle-stage-to-orbit: "A single-stage-to-orbit (or SSTO) vehicle reaches orbit from the surface of a body without jettisoning hardware, expending only propellants and fluids. The term usually, but not exclusively, refers to reusable vehicles. No Earth-launched SSTO launch vehicles have ever been constructed. To date, orbital launches have been performed either by multi-stage fully or partially expendable rockets, the Space Shuttle having both attributes." $\endgroup$ – AlexP Mar 2 at 3:40
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    $\begingroup$ this highly depends on several factors, such as how much of a scifi factor is permitted here. by this I are you looking at strictly realistic, already proven fuel methods. or do you mind us looking at imaginary yet plausible fuel sources such as nuclear fusion. also nobody knows how to fuel a ship if they dont know what kind of propulsion is being used. unless that is part of what youre asking. Please be a little bit more specific. please and thanks :) $\endgroup$ – Elias Rowan Albatross Mar 2 at 5:29
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    $\begingroup$ Although it might be a bit of hyperbole in naming an Interstellar craft travels between star systems, this is an interplanetary craft. I would see them for false advertising. $\endgroup$ – Sarriesfan Mar 2 at 11:49
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Any chemical fuel is cheap besides the spacecraft, the question is which one can give you the performance needed.

You are asking for quite a bit. A moon mission requires maybe 13km/s of deltaV. Using a specific impulse of 450s for Hydrolox engines, the best chemical fuel, you get a mass faction of 5%, for Eros this will dip even lower, to maybe 2-3%. This means your propellant weighs 20 times more than the rest of the craft

This is hard to achieve with the hydrogen tanks probably struggling to reach a mass ratio of 1/20, since H2 has notoriously low density.

So either you use a multistage rocket, or switch to some nonchemical drive system, or possibly several drive systems. The 900s ISP of NERVA, a nuclear thermal engine gives you a a mass faction of 22%, much more workable. You'll still have to deal with hydrogen as remass, and you have a nuclear reactor to play with.

If you go to a system like laser launch, you don't require any propellant at all to get to orbit, and can perform the rest of the mission with whatever chemfuel strikes your fancy.

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The British Skylon is well suited for that job. https://en.m.wikipedia.org/wiki/Skylon_(spacecraft) Its engine is combined-cycle, which means it can work as an air-breathing jet when in the atmosphere, and a rocket-powered in space. This reduces the oxygen needed on-board.

The space-plane's single-stage concept is an earth-to-orbit shuttle. All by itself, it does not seem to be sufficient to earth-to-deep_space ferrying. However, it is possible to extend the range with fueling stations in orbit.

Bringing fuel into orbit is yet prohibitively expensive. However, water on the moon may provide us with hydrogen and oxygen for rockets. Lifting the water into orbit is feasible due to the moon's weaker gravity. Electrolysis via solar energy will convert water into fuel. https://en.m.wikipedia.org/wiki/Lunar_water

In the nearer future, Helium-3 for fusion drive may be exploited. Helium is ejected via solar wind and is embedded in the lunar rocks. There are plans to mine it as well. https://en.m.wikipedia.org/wiki/Helium-3

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  • $\begingroup$ +1 gives me an excuse to have fancy refueling stations and tourists traps slightly beyond earth orbit. Seeing as getting the fuel from the moon or other rocks isn't that much of an issue $\endgroup$ – Celestial Dragon Emperor Mar 2 at 19:31
  • $\begingroup$ We should let die the ridiculous myth that lunar He3 is exploitable despite its ridiculously low density per ton of regolith, or the fact that we haven't even started to design a working He3 reactor, or the fact that it isn't as aneutronic as is said. If you really want a clean nuclear fusion reactor, go a step further and use proton-boron. $\endgroup$ – Eth Mar 4 at 15:15
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closed cycle gas core nuclear rockets are the go. In this system, you have uranium hexafluoride encased within a diamond/quartz shell, which undergoes fission reaction. This reaction heats up the gas, and it proceeds to glow brightly in the UV range--around 40000 degrees K.

The hydrogen fuel is seeded with oxygen gas and metal salts, which absorbes the UV radiation strongly, which heats up to almost 30000 degrees K, and the envelope for the gaseous fuel is kept from melting by a constant stream of hydrogen gas flowing between the layers of the envelope.

The gas expands away at velocities around 22000 kilometres per second, or an ISP of 2200s, with a mass ratio of e or a convenient 1:2.71, this is enough to launch from earth to LEO twice without refueling at all, while not even needs an atmosphere!

hydrogen gas with a pinch of uranium hexafluoride. That is what fuel you would be using!

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  • $\begingroup$ Of course you somehow have to keep the elemental, 30000 K fluoride from vaporizing everything and anything in its path, demolishing your engine. Also, do not use Hydrogen as buffer gas. Use something heavy and inert, Xenon or Krypton. Hydrogen has insanely high heat transfer rate, which is not counterproductive for an insulation layer. $\endgroup$ – Whitecold Mar 3 at 20:29
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Nuclear pulse propulsion would work. Using 1960s technology, it should be possible for a spacecraft using a nuclear pulse engine to carry approximately 6,000 tons to the moon and back on one tank of fuel, IIRC.

Of course, the downside is that you're using nuclear bombs as your primary propellant (subkiloton yields inside the atmosphere, larger outside it), by dropping them out of the back of the rocket and setting them off so that the blast wave hits a 20m armor plate on the back of your rocket, which is then connected to the rest of your rocket with giant hydraulic shock absorbers. Fallout can be minimized by using a launch platform constructed of an iron plate coated with a thin layer of graphite dust, or by using another form of propulsion to gain a few hundred meters of altitude before activating the nuclear pulse engine, so that the nuclear fireballs aren't touching the ground.

This was unfortunately prevented from occurring in our timeline by the Nuclear Test Ban Treaty banning the civilian use of nuclear explosives, but that might not be a factor in your world.

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