Saving the Shuttle

Marked for death in 2010, the troubled space shuttle could find new life as a rocket to the moon and Mars.

Established in January, the office is defining requirements for a fleet of exploration vehicles to fulfill President Bush's vision for a series of missions to send robots, then humans, back to the moon and on to Mars. It can choose from shuttle derivations and a variety of rockets, including Boeing's Delta 4 and Lockheed Martin's Atlas 5 heavy lifters. The office plans to outline its vision no earlier than September, setting the stage for a summertime contest that is right in line with Bush's competitive sourcing initiative.

Shuttle program managers began making their case in February at a summit of government, industry and academic leaders who meet annually to review progress on proposed improvements designed to keep shuttles flying. Convening a year after the Columbia disaster, this year's summit focused on developing a suitable plan to ensure the remaining three shuttles are safe, capable and robust on their last flights. "It is very important [to] keep looking forward," Lee Norbraten, the chief of shuttle development at NASA's Johnson Space Center told the Texas gathering. "We are going to build something based on strength, rather than . . . on the retirement of a program some perceive to be past its prime."

In announcing his vision for space exploration in January, Bush said NASA can continue using the shuttles until sometime around the end of the decade to finish assembling the international space station. Then the agency must retire the shuttle, making way for a safer launch vehicle to be developed with existing technology. "Certainly our world has changed," says Michael Kostelnik, NASA's deputy associate administrator for shuttle and station programs. "There's nothing more important in this agency than what we have to do . . . to return to flight and complete the mission. We're the first step in the vision." Shuttle strategists are promoting three mission models they say are consistent with the exploration vision. All three are based on flying the shuttle until the space station is assembled with components furnished by 15 international partners.

Mission Model 1 achieves only that construction milestone. It proposes the minimum improvements necessary to operate the reusable orbiters safely and retire them in good working order. Afterward, private industry would assume responsibility for launching crews and cargo on disposable rockets developed for the Air Force. The second and third mission models envision a future for the shuttle beyond Bush's deadline for decommissioning it.

Mission Model 2 gradually adds technology to enable the shuttle to fly without a crew. By 2007, only two astronauts instead of the usual seven would be needed to park a winged orbiter at the space station to deliver components or supplies. The other five would ride back and forth in a multipurpose capsule called a Crew Exploration Vehicle, launched atop a commercial heavy lifter. Within a few years, the autonomous shuttle would carry only cargo and all astronauts would use the CEV.

Mission Model 3 derives crew and cargo vehicles from existing hardware, ground infrastructure and management systems. Today's shuttle "stack," in NASA vernacular, consists of a winged orbiter riding piggyback on a bullet-shaped fuel tank with two candlestick-style booster rockets at either side of the tank. The orbiter is missing from blueprints for the future stack. They depict astronauts being launched in a capsule atop a single booster, augmented with an upper stage engine for extra thrust. For cargo flights, the rest of the stack remains intact. In the conceptual drawings, a cargo capsule is either stacked on top of the fuel tank or mounted where the orbiter sat.

From the fact that the Mercury and Gemini projects made possible the moon landings of Apollo, Norbraten takes his belief that the space shuttle and international space station should enable the next human activity in space. "The agency does not have the luxury, nor do I believe it has the skill, or the resources, or the budget, to start a new program from a base of zero," he says. "It had better start from the base of knowledge and capabilities that we already have."