Saturday, October 01, 2011


My wife and I recently went to see the film Moneyball. I'm not a huge fan of baseball, but I had heard about the concept that the Oakland A's used to build a very good team on a shoestring budget. It was a very good film. I say that not because it sparked a latent interest in baseball, but because it got me to thinking about a few other things. To wit: what, precisely, will the United States do with its manned spaceflight program now that the Shuttles are going off to various museums and exhibits around the country?

I know, last time we talked about this, I promised a peek into a scenario where they might actually have reached the Shuttle's original advertised sortie rate of one flight per week. I got to thinking about it, though, and that requires a detour into Crazytown that I'm not quite ready for yet. I'll get around to that sooner rather than later, just not today.

So, we're stuck with the basic question of what to do next. And then, on the way home from the theater, it struck me. The problem all along is that we've been trying to field a New York Yankees program on an Oakland Athletics budget. And that's worked out about as well as anyone ought to expect it to. The main problem is that, ever since 1968, the long-range plans have all assumed massive budget increases that just won't happen.

It's time for a new paradigm. Taking a cue from Moneyball, I'm going to identify a couple of over-valued and under-valued "players" whose status needs to be re-evaluated. In no particular order:

(1) Heavy Lift: The question has to be asked -- do we really need a dedicated heavy lift booster? Do we need to re-create a Saturn V class rocket? I used to think so, but I've changed my mind. Dedicated heavy lift rockets are problematic at best from an economic point of view. They only make sense if you have a lot of heavy payloads going up on a fairly consistent schedule. If you only use them once or twice a year, the unit cost becomes hideous. You build and use at most ten or twenty in a decade, which means that you have to spread the cost of the factory and tooling over at most ten or twenty flights. This alone massively inflates the cost of a project that uses heavy lift. Which, in turn, makes the up-front "sticker shock" so harsh that the project never climbs up out of the planning stage. The Constellation program is only the most recent example of this. So, in our new paradigm, screw heavy lift. We're going to figure out a way to get by without it. And, with a few key enabling technologies, we can do just that.

(2) Closed-Loop Life Support: Part of the rationale for heavy lift is that interplanetary manned spacecraft need to be huge. If you have to carry all of your consumables (food, air, water) as cargo, you have to have about 30 kilograms of supplies for each crew, each day. That's just about a ton per crew per month. A minimum-energy trajectory to Mars takes nine months, and it can take as long as a year for the return launch window to open. So, at thirty months duration, we're talking 30 tons of food, water, and oxygen for each crew member. That's 120 tons for a crew of four. The largest part of that figure is water. If you can figure out how to recycle the water, you can cut that figure down drastically. Freeze-dried food and oxygen come to a little more than 1 kilogram per day. You would need a week or two of reserve water supply, but you could cut 120 tons down to less than ten. Savings like this cascade through the entire system.

(3) High-Efficiency Propulsion: Another part of the rationale for heavy lift is the fact that interplanetary spacecraft need so much fuel, not just for Earth escape, but for returning to Earth later on. Obviously, if you have more fuel-efficient engines, you don't have to haul as much fuel along with you. Taken together, these last two items make the spacecraft design much lighter. And since weight lifted into orbit is a big part of your cost, this makes the program as a whole more affordable.

(4) In-Space Refueling: That's all well and good, of course, but if you still have to lift the fully-fueled spacecraft into orbit all at once, you still need a heavy lift booster. That's where our last enabling technology comes in. If you develop the techniques for transferring fuel in orbit, you don't have to lift the whole thing all at once. You can lift the crew cabin first, then the fuel tanks, then the engines, then the fuel. And, once the ship returns from its first flight, it can be refurbished, refueled, and used again.

(5) Reusable Launch Vehicles: That's all nice, but we still have the problem of being able to get into low Earth orbit economically. Re-use is fairly important, if you want to get costs down. Operational simplicity is also important, of course, but you really want to be able to use expensively-machined components like engines more than once before dunking them into the ocean. Fortunately, we've run into a spot of luck on this score:

It's not completely reusable. But, if it works, enough components can be reused to bring operating costs down substantially. Also, the Falcon 9 core is the key ingredient for:

(Honest, I don't work for these guys. I just like their work.)

Bearing all of this in mind, where do I think we should go from here? Mainly, I think it's not really NASA's job to build a new rocket. Rockets, we've got. Good ones. What we need is for them to work on (2) through (4) above. If you've been paying attention, this is the "flexible path" option outlined in last year's Augustine Committee report. These goals ought to be achievable on a fairly modest budget. With those three things in hand, they can leverage private industry's work, and carry off an awesome program of exploration for a very reasonable price. And isn't that what we're paying them for?

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