Have you ever felt like, okay, we had the space shuttle, so, what's next? Oh, we're going back to a capsule? Huh, it kind of seems like there should be some next evolutionary step in spacecraft design after the shuttle, but there isn't? Well, take heart. DARPA the Defense Advanced Research Projects Agency, has picked up the torch of spacecraft evolution. The often secretive agency has been developing a new space craft it called the XS-1 (X for experimental, S for spacecraft and 1 for the first of its kind.)
DARPA's main goals with the XS-1 are to finally make good on the original promises of the space shuttle: First, DARPA wants to create a totally re-usable spacecraft. Though reusability was one of the major selling points for the shuttle, it turned out that the entire launch system: the rockets and the external fuel tank were all one-use items. Also at least some of the heat shield tiles frequently needed to be replaced after every mission. The second goal of the XS-1 is to create a spacecraft with a very fast turn-around time. DARPA's stated goal is to be able to do ten missions with the XS-1 in ten days. By realizing both of these goals, DARPA will fulfill its ultimate goal, also a major promise behind the space shuttle: a much cheaper way into space. (DARPA is shooting for each launch of the XS-1, carrying payloads of between 3,000 and 5,000 pounds, to cost under five million dollars.
DARPA has some longer range goals in creating the XS-1 as well. They have in mind whole new lineages of technology. A DARPA announcement from November 2013 read: "Technologies derived from the XS-1 program will enable routine space launch capabilities with aircraft-like cost, operability and reliability."
Aside from creating a new, much cheaper launch vehicle, the aircraft-shaped XS-1 will also be a vehicle capable of exceeding Mach 10, or 10 times the speed of sound. "The long-term intent," DARPA's statement went on to say, "is for XS-1 technologies to be transitioned to support not only next-generation launch for government and commercial customers, but also global reach hypersonic and space access aircraft."
DARPA is still working out just exactly what shape the new craft will take, and how it will be launched. There are several companies that are competing for the contract to build the XS-1, but it is most likely that the craft will have wings and land on a runway like an airplane. It may be launched from atop a re-usable rocket, or from the back or belly of some sort of mothership aircraft that would take it to a high altitude, enabling the XS-1 make its way into orbit from there. In any case, DARPA's overarching goal with the XS-1 is to fundamentally change the way that we launch payloads into space. In our current way of doing things, space launches are hugely expensive and complex, requiring years of planning. "DARPA created its Experimental Spaceplane (XS-1) program," says DARPA, "to help overcome these challenges and create a new paradigm for more routine, responsive and affordable space operations."