Back to the Future A new series of X vehicles is setting the stage for the next generation of space flight By Hoyt Coffee
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n this era of "better, faster, cheaper" projects, NASA scientists are deciding the shape of spacecraft to come by taking some hints from the past. As they did with the experimental airplanes of the 1950s and early '60s—rocket-powered craft that just nudged the threshold of space—researchers today are designing and testing a new series of "X" vehicles, laying the groundwork for spacecraft of the next millennium. "You can almost say it is 'back to the future,'" says Curtis McNeal, AE '72, chief engineer and deputy program manager on the DC-XA program. "When we look back at the rate at which advancements were made in the '50s and '60s—to be honest they were kicking butt. They had a lot of new frontiers back then to tackle, and they tackled them on multiple fronts and relatively inexpensively. "One of INASA Administrator DanJ Goldin's guiding visions is that we need to go back to the way we used to do business, which is to design small, low-cost vehicles to tackle individual problems, rather than one vehicle to do everything for everybody."
A Plume of Flame Originally called the Delta Clipper, the 43-foot DCXA that McNeal worked with before moving on to improved booster technology was itself something of a throwback: a rocket that took off—and landed—on its tail. "Everybody from the '50s and maybe even the '40s remembers Buck Rogers taking off and landing on a plume of flame," McNeal says. "That had always been everybody's dream, everybody's ideal of how to do it. In fact, that is how we landed on the moon. But it had never been done here on Earth until we did it." After a series of Air Force tests, NASA flew the Clipper four times, as few as 26 hours apart, before a landing accident ended the trials. The DC-XA lifted off the launch pad, flew as high as 10,300 feet and hovered. Controllers put the craft through a variety of maneuvers, rotating through large angles, 74
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twisting, even flying sideways, "which is another thing that rockets don't typically do and which really twists your mind when you see it done for the first time," McNeal says.
An X-15 for the '90s While it completed all but one of its technologydemonstration goals and set some ground rules for maintaining a single-stage rocket, the DC-XA was limited to lower altitudes and speeds. Expanding that envelope falls to a follow-on of the Clipper, the X-34. Designed and engineered by Orbital Sciences Corp., the X-34 can be considered "an X-15 for the '90s," says John Hudiburg, AE '83, who was chief engineer on the project. Like the X-15, the new experimental craft is launched from underneath an airplane, rockets up to about 250,000 feet—roughly the altitude reached by Alan Shepard on the first Mercury flight—and Mach 8, then lands on a runway. Unlike the X-15, the X-34 does this without a pilot: it is intended to be totally autonomous, thanks to computer technology that vastly outpaces even that used on the space shuttle. "X-34 is an experiment in building rockets and planes, rocket planes in this case, that is significantly more cost effective than anything we've done before at NASA," says Hudiburg, who worked on the International Space Station before taking on the X-34 project. "Its goal is to enable truly low-cost reusable launch vehicles." With space shuttle launches costing between $200 million and $400 million each, Hudiburg says the X-34, as well as the X-33/VentureStar project to come, aims to cut the "fire and smoke" component of space flight to about a tenth of the shuttle's cost. There is a trade-off in capability, however, even though the X-34 is not intended as an actual launch vehicle. "A shuttle can launch very large satellites in orbit," Hudiburg says. "This can only carry about a 400-pound payload, and it's suborbital at this point; it won't go into a full Earth orbit. It's just for