is ssto coming back from the brink of death?
Single stage to orbit spacecraft have been mothballed for decades. But with the potential of space tourism, there may be an incentive to take another run at designing them.
Remember the good old days of the late 1980s and early 1990s when plans for reusable space planes were circulating around space agencies, and while the ESA was thinking about HOTOL, NASA was experimenting with the X-34, a prototype of what was supposed to be an SSTO, or single stage to orbit, spacecraft? As we all know, gravity is a harsh mistress and overcoming it takes a lot of power, so when things predictably got really complicated and the delays and mechanical gremlins piled up, NASA decided to strap some rockets and an enormous tank loaded with over a million pounds of fuel to the space shuttle and launch that into orbit, letting the two X-34s it had sit in a hangar. On the other side of the Atlantic, as soon as the problems with brand new Ariane rockets were resolved, the ESA promptly dumped HOTOL and let its designers go on their merry ways, trying to design their SABER hybrid engine for the new iteration of their dream project, the Skylon. The SSTO planes were all but dead. But now, with the advent of adventurous space tourism companies, it seems that the death of the orbital space plane may have been greatly exaggerated. Just ask NASA and the Air Force.
As regular readers may recall, I’ve pretty frequently beat up on Constellation, calling it a huge leap backwards for the space agency because it relied on the old capsule concept with no reusable components. It was big, wasteful, and so technically conservative, NASA might as well have ordered five brand new shuttles and had much more advanced spacecraft by the end of the day. In fact, its secondary plans to reengineer the shuttle into a heavy lift or high capacity crew vehicle were far better than the dual rocket approach. But ultimately, if you want to make space travel cheaper and more reliable, you need an SSTO craft. Because it would entirely reusable and require only a really long runway, you save on infrastructure costs and you don’t have enormous rockets and fuel tanks to build for every new flight. And because your SSTO plane is one orbiter, rather than a collection of parts held together by explosive bolts, there are fewer things that can go wrong during takeoff and landing. Financially and technically it makes far more sense than rockets. Just imagine driving to the store in your car, then driving back home and buying another car to drive to the store again when you run out of milk. It sounds ridiculous, right? Well, that’s basically what the philosophy behind Constellation called for us to do in the next five years, selling this as the future of space exploration.
Now, of course, going into space isn’t exactly as easy as driving to the store and you need engines that could generate a whole lot of trust to get into orbit, so for a while, rockets were the only way to go. But today, with the successful flight of the USAF’s X-37B, we’ve shown that we have the means to get into orbit without strapping an enormous rocket to our orbiters. Encouraged by this fact, NASA took its X-34s out of cold storage and very gingerly towed them into the desert so aerospace companies could take a look at it and assess if there’s still hope for the X-34 to be reengineered to get into orbit. That’s right, SSTO is once again attracting attention and engineering talent. Just imagine what could be done when instead of having to pay over a billion dollars for each and every launch, your spacecraft only need to be maintained and fueled. How many missions could you fly? How many experiments could you launch? And imagine what could happen if the craft’s turnaround is fast enough to be lent to private customers who want to launch satellites or people eager to take a look at the planet they inhabit from a hundred miles up. Why the vehicle could pay for itself in just five to ten years! Going from more than $1 billion per flight to as little as $75 million would be huge. Aerospace companies building a fleet of space planes would be flush with cash, NASA could greatly expand its scientific programs, and all this wouldn’t necessitate a huge space exploration budget. Or at least it wouldn’t in theory.
Realistically, there would have to be a consistent flow of cash for years until the space planes have been built and tested. The companies that would develop SSTO craft couldn’t just get their hands on the X-37B because it’s a classified spacecraft and even if the defense contractor which built it (which would be Boeing) would set out to build another space plane, the teams would most likely be unable to share important information. Or if in a more likely scenario, the job gets handed back to the X-34’s original designers, Orbital Sciences, there’s going to be a re-learning curve since new technologies would mean that the new craft would have to be built from nearly scratch. Let’s keep in mind that the X-34s were suborbital planes, not mini-shuttles. If the funding to keep the project going, work out all the bugs, and properly test the results gets cut off, SSTO is once again shelved for civilians. And even if the effort is successful, we’ll still need big rockets to do the heavy lifting. Most space planes would only be able to carry propellant, basic supplies, and their crew or light cargo. All massive shipments or craft designed to go to another would would need a lot more horsepower than any space plane could muster unless a significant quantity of positrons are added to its fuel mix, a rather expensive, risky, and complicated engineering effort. But at least for now, things are looking up for SSTO, and let’s hope that NASA still has the drive and the vision to go forward with its plans to revive its space plane ambitions…