While the US is developing hyper-sonic vehicles to deliver explosive payloads or to do surveillance, researchers at the German aerospace research center, Deutsches Zentrum für Luft- und Raumfahrt (or DLR) are working to develop something a bit more … peaceful: a sub-orbital, hyper-sonic passenger plane called SpaceLiner that will be capable of carrying 100 passengers from Europe to Australia in just 90 minutes.
DLR’s SpaceLiner will also be able to make the journey between Europe and the U.S. in about 60 minutes. Sound like science fiction? Well, at 20 times the speed of sound, travel times over what are considered today to be vast distances is completely doable.
The SpaceLiner’s basic design is reminiscent of the Space Shuttle. There are two parts: the orbiter, where the passengers will ride, and a booster. Except instead of an external fuel tank and two solid rocket boosters, the SpaceLiner will be carried aloft by a completely reusable launch vehicle, a mother ship of sorts. This mother ship will use environmentally friendly fuel: liquid hydrogen and oxygen which will produce only water vapor as a waste product.
Like the Space Shuttle, the whole rig will launch vertically. Then, in just 10 minutes the booster will accelerate the SpaceLiner to more than 20 times the speed of the sound. Once the pair reach their cruising altitude of about 50 miles, the orbiter will detach from the booster and start gliding down into the atmosphere at Mach 20, more than 15,000 mph. This is how the orbiter will be able to travel such huge distances in so little time. The booster will land autonomously at a pre-determined destination, optimally at the launch facility where it will be mated with another orbiter and prepared for another launch.
Researchers at DLR believe they could have the SpaceLiner designed and built within the next two decades. DLR’s head of Space Launcher Systems Analysis Sippel says: “We want to come up with a development road map. We need a mission definition and this year we will do that in Phase A. To make it more viable, DLR has also outlined a 100-seat version capable of 1-hr. intercontinental and transpacific missions. It is expected tickets would cost hundreds of thousands of dollars. We have several hundred million passengers traveling intercontinental distances each year and we think space should have a tiny portion of that. But even if the share will only be 0.2% why should we do it? From a space perspective that’s a potentially huge impact.”
One of the major design features DLR researchers will need to work hard at designing are the cooling technologies that will be needed to protect the structure of their SpaceLiner against intense heat produced by hypersonic flight. Keeping that and numerous other design, testing, and fabrication challenges in mind, DLR is predicting that commercial SpaceLiner service will not commence at least until 2040. Much like the Concorde, at first, the service will be extremely expensive. Therefore Sippel says that the SpaceLiner will be used by the rich and elite as a means of fast transportation. But over time DLR plans for the whole system to go into mass production, and the reusable booster will be available to ferry other vehicles and payloads into space or to soft-launch satellites into higher orbits, which will likely bring down ticket prices for human passengers over time.