a rocket-launched spaceliner: combining the worst of both worlds

If you ever explored the pages of popular science magazines from the heady days of the Space Race, inspired by novels of the Golden Age of science fiction, you’ve no doubt seen proposed ads for space planes taking busy commuters around the world in mere hours. It sounds like the perfect solution to spending as much as a day locked inside a flying metal tube filled with stuffy recycled air. And the Noodly One forbid you have to make the trip in coach. Ugh. Unfortunately, hypersonic jets are really difficult to build and the sonic booms they would create would quickly run afoul of local noise ordinances. This is not to mention that airport runways would have to be a lot longer to help them build up speed and the air and space routes would have to be mapped in completely new and different ways. But all this we could deal with to make sure that a venture designed to shuttle people around the world in no time at all is a viable business and taking any space plane is as easy as taking a commercial jet liner today, although a lot pricier.

Yes, making suborbital flight an easy and convenient proposition is diffciult and expensive. But that doesn’t mean that a European start-up’s plan to attach a space plane to a rocket, fire it off like a space shuttle, and have it glide back down to Earth at 15,000 miles per hour is any better than having to redesign major airports to support hypersonic planes. According to the company, using proven rocket technology would mean that the plane would begin daily service in 2050. If we actually do a little research about hypersonic flight and rocket launches, it would mean that a plan resembling anything like the venture proposed is dead on arrival and should come with an obligatory DNR order. This idea effectively combines the biggest, most expensive hindrance to cost-effective suborbital, and adds a layer of regulatory issues, as well as logistical pains which would drive potential customers to simply fly on an existing aircraft because they would get there much faster. It’s in no way commercially viable or safe for the passengers since there’s a really, really high chance that the space plane will disintegrate as it glides back down to Earth.

But let’s backtrack for a moment. Consider the issue of starting a trip with a rocket launch. Last time most of us checked, rockets cost millions and get thrown away after each use. SpaceX has been working on reusable rockets, so that may bring down costs substantially, but there would only be so many flights it could make before the repeated stresses render both it and the space plane unusable. Furthermore, it means that the proposed SpaceLiner would have to launch in a small time window at a spaceport built well out of the way as not to interfere with air traffic over a major city or transport hub, precisely the places where you should be offering the flights to make it easy to get to the space plane. If you miss a window due to a mechanical issue, you could end up wasting the entire day rather than just reschedule for the next flight since the next window for the trajectory you need may not come for the next few days. By this point, if you were willing and able to spend the hundreds of thousands of dollars for a SpaceLiner ticket, $15,000 for a typical long haul first class flight on a conventional aircraft would sound like a decent bargain.

And, of course, there’s the whole possible disintegration thing. You see, gliding at 15,000 miles an hour through the atmosphere isn’t exactly what happens when you’re going that fast. No, it’s more like plowing through miles of gas that’s exponentially increasing in density while the heat generated by air compression is trying to engulf your craft. DARPA tried the exact maneuver the SpaceLiner is expected to do with one of the most advanced hypersonic bullets ever built. It did not end well. The entry vehicle’s skin came off its body. There’s a non-zero chance that even a shielded SpaceLiner would face stresses that would either melt its skin right off, or kill whoever was on on board should the glide back down to the ground hit a rough patch somewhere. Again, the slow jet sounds like a good deal, doesn’t it? Especially an advanced supersonic design that muffles the noise of its sonic boom by its shape and the angles of its flight surfaces which would let it catch on in a way that the Concorde never could due to its engines’ piercing shriek.

And if that supersonic jet could get you halfway across the world in five hours from your nearest airport with a much, much smaller chance of a fiery, explosive death as it blazes through the air during its descent, why would you want to pay about ten times the price of a first class ticket on such jets to schlep out to the middle of nowhere to try and catch a rocket and shave off three or four hours of the final leg of your trip if you do manage to launch in your window? By the time it’ll touch down at another spaceport in the middle of nowhere, you could have been relaxing in your hotel room or home half a world away for hours. Other than the novelty and complexity of going by SpaceLiner, you would’ve gotten nothing out of the trip that a supersonic plane couldn’t have given you safer, cheaper, and more efficiently. Now if you were going to the Moon or an orbital hotel room, that would be a different story. Maybe the company behind the SpaceLiner proposal would want to take aim at the Skylon concept rather than trying to challenge Virgin Galactic and every major airline with a caveat-laden offer to its potential customers 37 years from now. Then again, it’s likely that today’s space tourism companies would dominate that market by then…