July 17th, 2005

Brad @ Burning Man

The Spaceship You Have (conclusion)

OK, put yourself in the place of the guys at NASA in 1973, who had to decide how to deal with Congress to get any money they could during a nationwide economic meltdown, and then decide what to do with that money. Given that the Appropriations Committees were having a hard enough time funding essential government services, even running the printing presses at the Mint flat out, they weren't going to give NASA everything they asked for. No, no matter how important it was to keep military-quality engineers employed, and no, no matter how many lost-to-Japan factory jobs they created. (Any engineering or scientific spin-offs were dismissed out of hand; Congress believed, rightly or wrongly, that throwing that much money at any scientific or engineering project would produce a similar number of breakthroughs. Given that DARPA funding into communications research all-but created the modern desktop computer and the Internet as we know as its spin-offs, I'm not sure they were wrong.)

The first ultimatum that NASA was given was this. You want a space shuttle, a new generation heavy lift booster, and an orbiting space platform? Pick two. As far as Congress was concerned, given how badly the US economy was doing, giving them two of the things they wanted was generous. In fact, it was considered to be so generous that even that with those sacrifices, the resulting appropriations almost didn't make it through Congress at all. There were, and still are, a lot of people who, if the government is going to run any kind of a jobs program, would rather see that money spent to employ non-white poor people than upper-middle-class white engineers.

NASA never seriously considered abandoning the space station as a long-term goal. Without the space station as a platform for building more permanent stations, bases, and long-range exploration craft, the whole manned space program was pointless. That left them having to choose between newer conventional disposable rockets, or a brand new kind of "space plane." But the thing is this: if you send people up in a disposable rocket, you still have to bring them down. Water splashdowns, like we used from 1961 to 1973, are both expensive and dangerous. Parachuting uncontrolled capsules onto dry land like the Russians do is cheaper, but still felt way too dangerous. (In hindsight, it's worth pointing out that the Soyuz has a better safety record than the Shuttle. But at the time, the Shuttle seemed safer.)

So if they were going to keep the program at all, they had to make the Shuttle do the job of both the crew ferry and the heavy-lift rockets. It also meant that it had to be relatively huge, compared to what they originally wanted, because they would no longer have disposable fuel tanks in orbit to build the space station out of. That meant that the Shuttle's cargo bay had to carry a completely assembled space station module, both size and weight. But as I explained the other day, when you add weight to a rocket, that means adding more fuel, which adds more weight, which means adding more fuel, ad infinitum. So NASA went back over to the "dark side" of rocketry: solid fuel boosters.

Solid fuel rocket boosters seem like a good idea. They're the oldest kind of rockets we have, going back hundreds of years. They don't require elaborate pumps, spray nozzles, liquid fuel tanks, or chillers to keep the liquid oxygen and whatever fuel liquid. You just mix the solid fuel with a solid oxidizer, pack it into a cylinder, and then figuratively stick a fuse in one end and bake it solid. But solid rocket boosters have two huge drawbacks that made all of us hard-core space aficionados cringe when we saw them attached to the Shuttle. The second scariest thing about a solid fuel rocket booster is that if anything goes wrong, you can't turn it off. But the single scariest thing about solid fuel rocket boosters is that they have a terrible safety rating, a long history of blowing up during launch if there's the slightest defect. A lot of us said at the time that sooner or later, one of those solid fuel rocket boosters was going to blow up and take an entire Shuttle full of people with it. In 1986, we were proven right. But was there an alternative? Other than cost, the other real problem with liquid fuel rocket boosters is that the engine itself weighs tons. Those tons of extra weight were at a real premium, and so were costs, so NASA engineers felt that they had no real alternative. Even after adding that gigantic flimsy disposable external fuel tank, they just plain needed the lift, so they got it the only way they could. And it still wasn't enough. They had to give up on lifting the station components all the way to geosynchronous orbit, and settled for what they hoped was a minimum stable orbit, just barely high enough to keep it from falling down from atmospheric drag the way that Skylab had. And still it wasn't enough ... so that meant a lot less fuel left over when they got to orbit.

A lot less fuel left when they get to even low orbit meant one other huge problem, too. Von Braun's original design for the crew shuttle assumed that there would be plenty of maneuvering fuel left. That way the shuttle would have been able to brake hard before dropping into the atmosphere. Because von Braun knew that if you didn't do that, you'd come in so fast the the heat from the friction of the atmosphere would heat the shuttle up so much that any known metal alloy would melt. But when NASA got around to designing their shuttle, because they'd had to so inflate the cargo load, they didn't have enough fuel to properly brake the thing, and that meant coming in hot. Unfortunately, their engineering team thought they had a brilliant solution. Anybody who's ever used a kiln knows that there are ceramics that can take much more heat than any metal alloy known. So they would coat the outside of the Shuttle with lightweight temperature-resistant ceramic. And since it turned out to be impractical to cast huge slabs of curved ceramics at the time, well, all that meant was hundreds and hundreds and endless hundreds more of little bitty ceramic tiles, glued on.

When we got our first glimpse at the final design for the Space Shuttle, every hard-core space buff in American groaned in terror. We knew for a fact that sooner or later, one of those solid rocket fuel boosters was going to blow up, because that's what solid fuel rockets do. We knew that sooner or later, either one of those tiles was going to crack or the glue was going to fail on one of them and it would fall off during re-entry, and then the Shuttle would blow up. These were easily made, rock solid, 100% reliable predictions that have since, unfortunately, both come true. But the only alternative was not to have a manned space program at all. It wasn't a choice between this shuttle and a better shuttle, let alone a choice between this shuttle and a smaller, more practical shuttle plus a new generation of big dumb boosters. In the mid 1970s when all of these decisions were made, nobody had the foresight to predict commercial space flight would within 25 years produce better disposable rocket boosters than we had back then, because communications satellites would be that big a business. If they had known that, then a case could have been made for waiting until commercial heavy lift capabilities reached the level where the orbital platform components could be lifted on commercial rockets, and having NASA concentrate on building a smaller, lighter, and more reliably engineered passenger-only shuttle. But if we had waited thirty years between Apollo and the resumption of manned space flight, would we have resumed manned space flight by now? NASA administrators felt that the Apollo program had built up a momentum, a reservoir of public enthusiasm. They felt that stopping the manned space flight program, even for a few years, let alone for a few decades, would wipe out that momentum. Then, without the spur of fear of the Soviet Union, we might never go at all. And I'm still not sure that they were wrong about that part.

We have the technology now, we've had it for years, to scrap the current low-orbit, too-small space station and the current unreliable, too-heavy space shuttle. We could now scale up any of several of the X-Prize competitors, or any of the last several Single Stage To Orbit trials like the Delta Clipper, into something capable of reliably carrying passengers to high orbit, and we could do it for a lot less than what the Shuttle costs to fly. But it would probably mean letting yet another space station fall out of the sky. And it would mean a lengthy gap, even longer than the last two shuttle-explosion-related gaps, in our manned space flight tradition, maybe as long as another ten or twenty years. After ten or twenty years of doing without, would there still be enthusiasm for opening a new frontier in space? Maybe. But perfectly reasonable people, thinking clearly, with all the facts available at their disposal, decided not to risk it.

And that's why 14 astronauts have now died, why 40% of the Shuttle fleet has already exploded, and why there's serious doubt as to whether the remaining 60% of the fleet will ever resume flight. What's more, even before last week's cancellation of the "Return to Flight" shuttle launch, there was a big red warning flag over the space station program. The projected end of flight, the date on which the entire Shuttle fleet loses its FAA air-worthiness certificates, is only a couple of years away. Even if they could maintain the launch rate of the best year in NASA history, even if last week's Shuttle launch hadn't been scrubbed, there was only time to fly another 15 or fewer Shuttle missions before the vehicles have to be grounded for good. And unfortunately, there are more than 15 loads of station parts and assemblies to go up. Nor is it realistically an option to send them up on Russian (or even American, or European) disposable rocket boosters, because they were precision-engineered to fit into the Shuttle's cargo bay. So we'd have to re-engineer them, or re-engineer the launch vehicle, to send them up in another vehicle. So the program is basically doomed.

If the public thought that von Braun's promise that space was going to be conquered soon turned out to be as big a cheat, as big a hoax, as the promise of meals in a pill, disposable high-fashion clothing, energy too cheap to meter, cures for cancer and the common cold, and flying cars, all of which were also promised "soon" back in the early 1950s, well, it's going to turn out that they were right. Did it have to turn out that way? Well, frankly, given the economics of the situation, probably yes. We might, yet, be able to start the whole thing over, maybe even in my lifetime (but I'm not betting on it), using commercial launch vehicles. But it will take that, a completely fresh start, and I completely decline to predict whether or not America, or even the human race, will choose to attempt the project ever again.