Friday, May 30, 2014
Space Gas Station
If one is to look at some mission beyond Earth orbit, (Apollo or a Mars mission) normally, the procedure is to carry all the fuel required for the entire mission on a single launch vehicle. This is the equivalent to loading your car with all the fuel needed for a cross country trip. Such strategies greatly increase the cost of launch, especially when present prices are in the neighborhood of $10,000/lb. Certainly launches will become more economical in coming years as prices decrease, but there is still no reason to fill a vehicle with fuel when it could be filled with equipment or other supplies. True, the tanks will still exist, but the "Gas Station" would allow for smaller tanks on vehicles since journeys to fuel sources would be a bit shorter. Again, imagine a car going across country, but now with some gas stations along the way. Now you don't have to carry extra fuel or have such a large tank.
The primary issue with such a service, considering current launch technologies, is that the cost to lift the fuel for the "Gas Station" into orbit is identical to the cost of putting it up with the craft in the first place. For one-mission vehicles this is true. But what about satellites that need to maintain orbits, the ISS, an orbital taxi, or for the space shuttle to be boosted to a higher orbit, if it were still in service. In all of these cases the "Gas Station" makes a lot of sense. If a vehicle needs more fuel to continue a mission or to begin anew, then a location to refill is worth the price. Especially, when the other option is to organize a whole launch to refuel or build and launch an entirely new craft to replace the empty one.
For an example of a situation, where this would be usable today, imagine if a SpaceX Dragon capsule wanted to continue to Mars. Normally the capsule burns all of its fuel to reach orbit so that is its operational limit. If a "Gas Station" existed, the capsule could dock with it in orbit, fill up, and then fire its engines to break free of Earth gravity. This is, in fact, a maneuver that missions Like Mars One may need to consider but are only possible with a fuel station in place.
So the need for an orbital "Gas Station" certainly exists, even today. So what would it look like? If the Space Shuttle were still in operation one would assume that it could simply be one of the Shuttles' orange external tanks that was left in orbit and has since been refilled. But that is no longer an option. In the near future the creation of such a fuel depot would most likely require a series of launches with a Falcon Heavy hoisting filled tanks into orbit. These tanks could then either be combined into a single structure or spread throughout orbit to allow easier access to the fuel reserves.
In order to refuel craft, organizations would schedule dockings with the fuel stations through the operating company. Then they would fuel-up and pay based on the amount that they take. It would be identical to a normal Earth gas station.
In the beginning it would be necessary for the craft/organization in need of fuel to navigate to the fuel depot. But as the company operating the station grows it would be possible to implement mobile stations which go to where the fuel is needed or even to implement a team of drones to bring craft to it.
The technical challenges of such a project are significant. Rocket fuel is very hard to contain in large quantities for extended periods of time. Containing large quantities in orbit will be even more difficult. Then there is the problem of actually having the adapters needed to refuel the numerous variations of spacecraft. This will require the eventual creation on some type of standard across the industry.
Such an endeavor will require significant investment in early development and then the first launches. However, once the station is operational, the returns will come quickly, since the price of the fuel will be a markup of the the delivery cost to orbit. Such a station would likely only need to be emptied a few times to offset the cost of development and construction. One would have to determine the value, of the fuel, to organizations that want to give second chances to old craft, instead of launching new ones.
The expansion capabilities of such a fuel company would be unlimited. As the industry grows and space traffic increases multiple stations will need to operate in orbit and eventually around other planets. And as mining grows and water ice is brought back to Earth or the Moon the fuel stations can be filled with the refined hydrogen and oxygen. Thus reducing the price of the fuel.
These stations will become the waterholes of space. People will need and want to be near them. Because of this they could be the structures that space hotels and space docks are built off of in order to reduce the number of stops for human vehicles. Rental of such proximity space or connections will become lucrative for the company that owns the gas station.
Though the creation and implementation of an orbital fuel depot will be significant, it is a piece of infrastructure that will be so vital to the space industry that it will quickly pay itself off. It will be as important as the launch vehicles that carry the craft off of the Earth. While some billionaires are building space hotels and other the launch vehicles, it would not be a bad business decision to create a Space Gas Station.