Moon Miners' Manifesto

#99 October 1996

Launching Stuffs to Orbit

Peter Kokh

By "stuffs" we mean commodities any which we may wish to ship to orbit or space destinations beyond in relatively high volume and over a long period of time, on a regular basis - which, however, can be shipped in any quantity. A lot of small pay-loads do the trick as well as a few big ones. We are talking about materials or substances, not hardware of set and indivisible fully assembled size. Some examples are water, hydrogen, oxygen, nitrogen, methane, ammonia, (volatiles of which the Moon seems to have a paltry endowment) other gases and liquids, powders, compacted pellets, computer chips and other micro-assemblies etc. In other words we are talking "pipeline" items, not "truckload cargoes", items which at their destination can be placed in tank/bin/silo farms, etc.

That such "stuffs" can be sent to orbit and beyond in piecemeal fashion, does not in itself warrant a conclusion that that is the most efficient way to ship them. It only means that pipeline analogs ought to be considered on their own merits with any high system development costs weighed against the accelerated amortization expected from high volume, individual stuff category by category, or collectively en masse.

The pipeline concept of regular supply, can be satisfied in several ways. Assembly-line manufactured cheap small rockets launched often, is but one way. A high per unit time volume of traditional rockets, even if they are small, might add polluting exhaust gases to the atmosphere at a worrisome rate. The option would be to carry aloft only an orbit insertion/circularization engine to ignite well above the atmosphere. The initial boost to high altitude / high velocity suborbital trajectory would be made by an Earth-bound device such as a mag-lev mass driver or a gas gun.

Sandia National Laboratory in Albuquerque is one outfit investigating the possibility, and, of course, the military is very interested for the tactical applications it imagines.

A launch gun or launch track is only part of a working system, however, and promises to be a very capital-intensive, high upfront cost device. Further, it (either) could only accelerate projectiles and their hardy or hardened mini-payloads, at very high Gs (thousands!) into a forward position from which they could be, and would have to be, inserted into orbit by another part of the system.

The partnering part of the system could be a small onboard non-reused motor, or, in the case of commodities bound for geosynchronous orbit in a slot handy to an equatorially sited launch device, some kind of orbiting mass-catcher, anchored by the balance of its inertia and distance permanently overhead and downrange, ever poised to "catch" the steady stream, and somehow able to put the accumulated momentum from the catching process to good use in station-keeping. This can be arranged by putting the catcher at a slightly lower and normally faster altitude, with the steady momentum addition calculated to keep it at geosynchronous velocity all the same. I yield to the orbital mechanics experts.

Launch guns not on or very near to the equator would scatter their charges shot-gun style to a whole equator-stradling range of crisscrossing orbits, unless launch was restricted to just one narrow window a day. That would make poor economic sense, so the incentives to find a genuinely equatorial site should be "insistent".

Launch guns or tracks discharging at relatively high altitude above the thicker layers of atmosphere, would gain the further advantage duo of earning more altitude and velocity for the energy buck, while requiring less faring mass.

What about the pellet containers or capsules carrying the commodities? Three obvious possibilities are (1) Non-volatile self-contained solids might need no protective envelope, the minor ablation being deemed the cheaper option. (ice cubes as a container free way of shipping water would not seem very promising, however). (2) Empty the contents at destination and shipping the empty capsules or pellet projectiles back to Earth as cheap dunnage. And (3) make the container-farings of a material that is badly needed at the destination, in effect smuggling that material aloft as a stowaway co-shipment. Stainless steel, copper, brass, bronze, zinc, lead, platinum, gold, silver are just some of the choices. Effectively, this third method would produce maximum pipeline efficiency.

In the next article, we will talk about prime turf for such a pipelining facility. For this purpose, political, national, military and other usually primary considerations mean nothing. Location, location, location - as in real estate, for pipeline launch operations, location will be everything, the only thing.

Once assured volume of traffic warrants, for "stuffs" that can be pipelined, the Cheap Access to Space (CATS) answer(s) developed for large payloads and for personnel traffic may be an unsuitably expensive choice. However, until we have orbital or lunar facilities which will require relatively large reusable launch vehicles to bring up massive and bulky assemblies (habitat structure, energy production, material processing equipment - all in an earlier time frame), the demand for pipeline items will continue to be too low to justify the capital expense of a pipeline launcher. But it's never to early to do the research on the tree of engineering options on which the eventual designers and builders of such a system will rely. MMM

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