Airships and Launch Systems
In the near future, it is highly likely that airships will be used for the first phases of an automated system for the transfer of materials to LEO. For its upper stages, the system will use small reusable rockets and sub-orbital payload transfer methods. This will create a pipeline into space that will be far cheaper than any alternative method that is likely to be developed for decades to come. Apart from the stratospheric airship described below - which requires some advances in the rapidly developing field of High Altitude Platforms (HAPs), all other components can be made cheaply with currently available technology.
There is a great deal of discussion, in many areas of space technology research, about reusable single stage to orbit (SSTO) launch systems and their inherent benefits. This tends to ignore the fact that a vehicle which launches from the ground and flies directly into orbit, is actually very poorly designed for each phase of its operation. Flying a mission to LEO and back, has at least six distinct stages just to get into orbit, and a similar number for the return trip to the ground.
Even if such a system can be made to work, it is an extremely inefficient way of doing each task, which equates directly with very high cost. Although such systems may be useful in contexts where convenience is a higher priority than cost, there is no realistic possibility that SSTO vehicles will be efficient enough to be the basis of a profitable space economy. Nor will ground launched fly-back boosters, even if they can be made to work, and even if their second stage can be made partly reusable, be anything other than a modest improvement over current ground launch rocket technology.
Alternatives to rocket propulsion, such as beam propulsion, rotovators, or ram accelerators, are either still too expensive or unachievable in the near term. We believe that advances in airship technology, in rocket design, and in all fields of electronics, computing and guidance - if they are correctly applied to build a multi-stage pipeline, where each component is optimised for the task it performs, allow for an improvement of several orders of magnitude over the current cost of launching to LEO.
A valid space economy will have to have the capacity to launch at least 1,000,000 tons per year to LEO. If investment and cash flow considerations limit the funding for initial operation of such a process to tens of billions of dollars per annum, then the cost per ton to LEO must be reckoned in tens of thousand of dollars per ton - not per kilo. We believe that a system which transfers payload through successive stages of airships and then through 4 stages of rocket propulsion can achieve launch costs of less then 10,000 dollars per ton, particularly for "dumb mass" cargoes in liquid form, which make up a very large percentage (about 75 percent) of total mass required for a working space economy.