Many types of Fuels for Space-Time Travels
Figure 1. A Spaceship refueling with liquid Hydrogen (LH2) in deep Space
Overview of different Fuel types for Space-Time Travel
You'll need different fuels for different things. LH2 is really too bulky for most air-breathing aircraft, but it's a waste to operate nuclear rockets on anything else, and spaceplanes almost require it for cooling and combustion speed (Figure 1). Methane is a much better launch vehicle fuel due to its density, which makes tanks far smaller and improves thrust density. And any decently developed industrial base will allow production of heavier hydrocarbons, for example by the Fischer-Tropsch process. And then there's various room-temperature chemical fuels and ion thruster propellants [1].
That’s good for planet Earth, especially when compared with rocket launches that rely on a popular alternative: Kerosene-based propellant. In the case of SpaceX, a single Falcon 9 flight emits about 336 tons of Carbon Dioxide—the equivalent of a car traveling around the World 70 times—according to John Cumbers, a former NASA synthetic biologist and CEO of SynBioBeta [2].
Advantages and Disadvantages of each Fuel Type
Whilst liquid fuels present disadvantages such as the potential for hazardous spills or leaks, one of the biggest issues discovered with such fuels is the relatively complex design, with an increased likelihood of things going wrong. If the liquid substance is cryogenic the fuel cannot be stored for long, and so the foundations for cryogenic storage facilities must be set up at the launch site. This is an area where Skyrora stands out from market competitors, with the propellants of our Skyrora XL vehicle designed to be stored for a longer launch window which is crucial for UK launches where weather conditions make go-for-launch difficult [3].
Pros: Thirty-percent better fuel economy than an equivalent gasoline vehicle, widely available, lower cost premium than for hybrid vehicles, engines deliver lots of torque for a given displacement, and any Diesel car can run on a blend of renewable Biodiesel fuel. With effort and investment, older diesel engines can be converted to run on pure waste vegetable oil (Figure 2).
Cons: Traditionally more engine noise and vibration. Additional emissions equipement drives up vehicle prices, which along with currently higher cost of Diesel fuel takes a big bite out of any savings. Most clean diesels require refills of Urea solution. Manufacturers won't warranty Biodiesel blends of more than five-percent of Biodiesel [4].
Figure 2. A Solar Sail in a Space-Time Travel
Current research and development in Alternative Fuel Sources for Space-Time Travel
Picking up fuel along the way — the Ramjet approach — will lose efficiency as the Space craft's speed increases relative to the planetary reference (Figure 3). This happens because the fuel must be accelerated to the spaceship's velocity before its energy can be extracted, and that will cut the fuel efficiency dramatically [5].
Whilst reusability of rockets benefits science, exploration and human spaceflight – one of the greatest drivers for stakeholders in the global launch segment is the scale and demand for in-orbit assets by industry and economy, fuelled in tandem by the plummeting costs and size of satellites (e.g. CubeSats), instrumentation, and even ride-sharing platform services [6].
Figure 3. A futuristic Warp Drive spaceship slicing through the Galaxy with neon blue lights
- Headed For Space. "Using Liquid Methane As Rocket Fuel – Advantages & Drawbacks" https://headedforspace.com/using-liquid-methane-as-rocket-fuel/
- Fortune.com. "Space travel is heating up—and so are rocket fuel emissions. These companies are developing cleaner alternatives to protect earth first." https://fortune.com/2022/12/05/space-travel-is-heating-up-and-so-are-rocket-fuel-emissions-these-companies-are-developing-cleaner-alternatives-to-protect-earth-first/
- Skyrora. "Rocket fuel: is it rocket science?." https://www.skyrora.com/rocket-fuel-is-it-rocket-science/
- Consumer Reports. "The Pros and Cons on Alternative Fuels." https://www.consumerreports.org/cro/2011/05/pros-and-cons-a-reality-check-on-alternative-fuels/index.htm
- Wikipedia. "Spacetravel under constant acceleration" https://en.wikipedia.org/wiki/Space_travel_under_constant_acceleration
- Spaceaustralia. "Renewable Rocket Fuels – Going Green and Into Space" https://spaceaustralia.com/feature/renewable-rocket-fuels-going-green-and-space