Space Shuttle: The Next Generation

Illustration by Bob Sauls/Frassanito & Associates FLYBACK
Northrop Grumman's proposal employs two liquid-fueled flyback boosters and a central rocket to push either a crew- or payload-carrying vehicle into orbit. The central rocket and fuel tank also return to Earth for future use, creating a completely reusable system. By contrast, the current shuttle's external fuel tank burns up as it reenters the atmosphere after being jettisoned. Illustration by Bob Sauls/Frassanito & Associates

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Last November, NASA took decisive action on its two-and-a-half-year-old plan to replace the aging space shuttle.



It cut the heart out of the project.



Abruptly and quietly, NASA scrapped the shuttle-replacement portion of its so-called Space Launch Initiative (SLI)—the latest in a string of development programs conceived in the wake of the 1986 Challenger disaster—and shifted most of the nearly $5 billion the agency had already earmarked for the program to pay for current shuttle improvements. Among them: safety upgrades that it hoped would let the shuttle fly accident-free until 2020 or beyond. And with plans for a new shuttle on hold, NASA announced that SLI would focus mostly on building an Orbital Space Plane, a modest, relatively inexpensive reusable vehicle that could hold a small crew (and little else) and would be launched by an expendable rocket. NASA hopes that when OSP is ready in 2010, it will serve as an interim, alternative transport, a "space taxi" until the agency can produce a next-generation shuttle.



NASA's decision was a last resort. The agency's latest estimates for designing and building a new shuttle had mushroomed from $6 billion to $35 billion. And even that was only a best guess, says Garry Lyles, NASA's Next Generation Launch Technology program manager. The gap between the figures, Lyles says, reflects NASA's difficulty with budget forecasts: "We need to develop a technology program that provides accurate data for our cost models." While so much uncertainty surrounded SLI's price tag, the shuttle's cost—$500 million per launch—was at least a known quantity. Consequently, NASA officials believed they had no choice but to place yet another bet on the 30-year-old system.



But three months later, Columbia broke up on reentry, killing its crew of seven, and the agency's decision to shelve the new shuttle program took on a troubling cast. The three surviving shuttles are now grounded, and when they fly again, they'll cost more to operate than before. Safety, maintenance and inspection protocols will be added, and because there's one fewer shuttle the total number of flights will be reduced while fixed personnel and infrastructure costs remain the same. The upshot: With so many economic and engineering questions weighing on the shuttle concept, NASA's plans to fly it for another 20 years suddenly smacks of blind optimism.



Which means that NASA must face far sooner than ex-
pected the considerable challenge of what will replace the shuttle. There's no shortage of ideas. The SLI and its precursor shuttle replacement programs were ended primarily because NASA insisted that any new system be a huge improvement over the shuttle instead of being merely more efficient and cost-effective. That often made these projects overly expensive and ambitious. But many of these proposals contained critical technological information that points to the feasibility of building a more durable, less complicated reusable spacecraft—with improved rocket engines, streamlined ground-support procedures and modern safety-enhancing diagnostic systems, among other things—for less money than the $35 billion figure NASA feared. "There's been one proposal practically every year for a new space launch system like the shuttle since the shuttle first flew," says Bob Parkinson, who managed the now defunct Hotol reusable launch vehicle project for British Aerospace in the 1980s. "And all of them would have been better than what we have."