I fully agree with you. I have no idea what form of transportation will prove to be the most cost effective and robust: high flight rate with small payload; medium flight rate, medium payload; or infrequent launches of very massive rockets. Using propellant depots you don’t have to bet on the answer to this. The competitive launch market will determine the true answer. The depot will enable space utilization/exploration to win regardless of the answer.

It’s even more of a game changer than if that was another 600klb of satellites. Propellant is an easy first market for RLVs. Low-risk, simple interface, not as much mission-specific engineering, and it can be divided down into much smaller chunks if you want to do a small RLV. A 1klb to LEO RLV could easily get past the 50-100 flights a year worth of demand minimum feasibility point, while still only taking 1/6th of that market.

~Jon

This has got to be one of the major game changing opportunities in the whole concept of space access. In one swoop we triple the annual launch requirement from the current ~300 klb/year, to ~900 klb/year. This has the likely effect of encouraging mass competition and reduced launch costs not only for space exploration but commercial and national security needs as well.

I think Rob’s analysis is somewhat disingenuous because it implies that people are arguing for orbiting propellant depots because they would make sense with respect to the current space paradigm. Obviously they don’t and all his article does is set out the basic reasons why this is so.

Now, maybe there are some “enthusiasts” out there who are arguing this way but, from my experience, most present the case in a somewhat different manner: they recognise the constraints imposed by the current paradigm and try to figure out ways in which it could be changed. In my opinion, this is what NewSpace is all about.

Most see the cost of space access (i.e. launch costs) as being the greatest constraint, though many also site things like launcher availability and reliability as well as the demanding design and operational requirements they place upon payloads. Reusable launchers are considered the best way to reduce most of these constraints but current market demands are either too small or too conservative (e.g. comsats) to justify their development. So, this raises the question: what can be done to increase/evolve current markets and, more importantly, develop new ones?

Unfortunately, there is *no* easy answer to this question; no single solution that could change things, though some regard space tourism as one such a “killer app”. However, many consider the vast sums spent on government programmes as having the potential to tip the balance towards a new paradigm by fostering the development of new markets that encourage the development of new launch systems. Employing orbiting propellant depots within future human space exploration architectures would be one way of doing this because the majority of the “payload” launched into orbit would most likely be propellant (i.e. assuming no propulsion breakthroughs like gas-core fission or fusion engines). As such, it which would be amenable to launch by a wide range of systems and, more importantly, it could be utilised by other future government programmes and/or commercial ventures, once its utility has been demonstrated.

Concepts such as orbiting propellant depots therefore represent ways in which government resources (i.e. technology, credibility… cash!) can be used to foster a paradigm shift in the way we explore and, more importantly, exploit space for the benefit of all human kind. Nevertheless, many still consider the current paradigm as the best or only way to achieve this goal. Based upon his article, I assume Rob believe this too.

Dave

You’re excluding the middle. I have no reason to doubt that free markets will lower the cost — but it will happen slowly, by small percentages per decade rather than by multiples or orders of magnitude, because they’re starting in a zone of much higher real startup cost and much narrower market drivers than any previous new domain of transportation. That, rather than space per se, is what’s “inherently expensive.”

To use the well-worn comparisons with Columbus and the Wright brothers: by “much higher real startup cost” I mean that Columbus’ expedition happened in a world in which thousands of ships just like his, from hundreds of shipyards, were already routinely making money in European, Mediterranean and North Atlantic waters. The Wright brothers’ innovations were financed by the spare cash of a two-man bicycle shop. Neither situation is remotely like that we face in space.

By “narrower market drivers” I mean that within a few decades after Columbus — and with little technological advance in ships — gold was pouring in from the Americas, gold and slaves from West Africa, spices and other luxuries from the Indian Ocean and East Indies… with sugar and tobacco in the wings. I mean that within 15 years of Kitty Hawk, governments bought tens of thousands of aircraft during WWI. A couple of years after that, scheduled commercial point-to-point air transport was beginning — because large numbers of people had already long been traveling from London to Paris, Berlin to Vienna, etc., paying extra for speed, so air travel was a no-brainer extension. (Even then, it should be noted, direct and de facto government subsidy was important to the expansion of commercial air transport.)

Again, space is very different: unless you’re a believer in the wonders of He3, or in mass hypersonic transport just around the corner, the only near-term drivers are science, national prestige, and extreme tourism (which is a very different thing from point-to-point travel to run colonies, do business, or visit Aunt Agnes). Yes, I do believe in SSP, other space resources, and eventually flourishing colonies as long-term drivers — but it’s the relatively modest near-term drivers, and their relatively modest returns, that have to bootstrap us to where those become feasible.

Free markets are powerful and important, but they’re not magic.

Most significantly, people who cite “A Rocket a Day” for its tempting figure of $43K per V2 (or $13K marginal cost, both WWII $USD) rarely go on to acknowledge that even at a production run of 6,240, the $2B development cost works out to about $350K per V2.

For comparison, a Sherman tank cost $33K; a Mustang fighter $51K; a B-17 $140K.

To me, “we could get great economies of scale if our space access efforts followed the example of an increasingly desperate dictator with no more judgement about bang/buck than a bratwurst” has never been a terribly compelling argument.

Moving on, there’s also a huge body of evidence from the manufacture sector as a whole that increasing the life time production of a manufactured good results in a decline in the cost per unit of the good. I forget what the name of the rule of thumb is (I see it termed “learning curve” or “experience curve” in wikipedia for what that’s worth), but a doubling in the amount produced results in at least a 10% decline in price per unit.