Moon Miners' Manifesto

#97 July 1996

Launching People to Orbit

Peter Kokh

I remember Tom Rogers' audience gripping pep talk at the banquet at the 1988 International Space Development Conference in Denver. He foresaw a day when people - workers, tourists, and settlers -would be the principal item shipped to space. Indeed, people are the one thing it makes sense to ship to space rather than produce there from on site resources. It will be this traffic that opens space. And until this traffic begins in earnest, probably with tourists, space will largely be a venue for a token scouting elite, and for Earthbound armchair voyeur wannabes - like us.

If this proves true, Cheap Access to Space ("CATS") solutions developed for large hardware items like space station modules and communica-tions satellites may very well not prove optimal for the coming traffic in live-and-wanting-to-stay-that-way bodies. The Space Shuttle was early-on likened to an all-purpose "pick-up truck" for space. That doesn't make it qualify as a good bus or highway coach, much less a good family car. The shuttle and its paper study replacements are in fact crewed cargo ships, cargo ships that can take along a small hardy and hardened crew.

While hardware payloads may come in a set range of sizes, occasional oversized loads being low traffic items, the optimum size for a people shuttle will change as the sustained demand and volume of traffic grows. The 29 passenger DC-3 once did just fine. But today, it is often more economical to fly planes that carry several hundreds at once. The point is that a CATS solution not amenable to "scaling up" may be an unhappy choice as a people carrier, even if it does deliver airline style operation and fast turnaround time.

Shuttle time to orbital destinations is short, shorter even than the average domestic airlines hop - not counting the time you may have to sit on the pad prior to taking off! Given the expected shortness of surface to orbit flights, a high "packing" density in the cabin may be tolerable. Demand for a "window seat" may well be higher than that aboard airliners, given that the scenery will be much less prosaic. That "see one cloud, see them all; see one farmer's field, see them all" attitude will not be common, even for seasoned shuttle travelers. This demand, if carriers choose to meet it, may place constraints on cabin design, and may make some SSTO configurations much more popular than others. Right now, in the early stages of CATS R&D, such considerations are at the bottom of the list. But in time, that list will be turned end for end.

Competing SSTO configurations may favor competing ground-based infrastructure (spaceport launch and land facilities). In the early days of space tourism, low traffic volume will bring with it few choices of gateways. If you want to go, you will not complain about flying to a distant departure field. But as traffic grows, at first chartered but eventually scheduled, it will be economical to offer more gateways, departure points convenient to more population centers or perhaps at more major airline connection hubs. If that is the case, SSTO configurations that are the less versatile and place higher and more expensive to meet constraints on spaceport infrastructure will lose out in competition (all else being equal) to those that can take off from nearly anywhere and land nearly anywhere.

The general public will want lower accelera-tions than seasoned crews can tolerate. This will be another major design consideration not currently given much weight. Compromises are inevitable, however. It could be for example, that the only way to bring the ticket price down to a mass-use threshold may be the use of an Earth-bound first stage such as a mag-lev sled at a high altitude, and preferably low latitude (near equatorial) "aero-spaceport" and there will be few of these if indeed more than one. Such a development will move orbit-bound traffic in patterns opposite to the decentralized paradigm suggested above. The use of piloted piggyback fly-back boosters would also tend to limit gateway choices.

When it comes to moving regular people traffic between Earth and Lunar orbits, and between lunar orbit and the lunar surface, still other vehicle configurations may prove to be the most economical. Thus, even though the McDonnell Douglas Delta Clipper family configuration is inherently more versatile when it comes to landing site, not even requiring an atmosphere, that doesn't mean that just because it can land and take of from the Moon (or anywhere else) that it is the most economical confi-guration in that specialized environment.

Certainly for Earth-Moon ferry traffic, where we are concerned with flight times of many hours to a few days, cubic foot allowance per person will have to be much more generous, with diversions galore.

And when it comes to Mars, the usual "space. shuttle" pattern will be set on its ear. Instead of a surface-based vehicle that can get to orbit and then return, we will need, at first at least, an orbit-based vehicle that can land anywhere (look, ma, no run-ways) and get back to orbit. Who can say, (let's agree to have fun here) perhaps for that purpose a saucer-shaped vehicle may do better than a winged one. After all, it is the orbit-based "surface shuttle" paradigm that UFO lore invokes.

So while we are supporting CATS, let's be aware that the early answers may not prove to be the best answers - we need to explore all the options if we want not just to open space to more hardware, but also to more - quantum leaps more - people. MMM

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