WASHINGTON — In just five years, astronauts may journey to the International Space Station in a stripped-down four-seater instead of the mammoth — and aging — space shuttle.
In effect, NASA hopes to commute to orbit in a sleek sedan instead of an 18-wheeler.
NASA Administrator Sean O'Keefe announced plans for the Orbital Space Plane before space shuttle Columbia came apart over Texas and killed seven astronauts on Feb. 1. But the tragedy has added a powerful incentive to find a cheaper, simpler and more dependable way to ferry astronauts between the space station and Earth.
It's a plan applauded by the Columbia Accident Investigation Board, which chided the nation for not already having a new spacecraft in production.
Eventually, NASA hopes to build a next generation shuttle, a more dependable heavy-lift cargo carrier to replace Columbia's three surviving sister ships. But it may be more than a decade before such a craft gets serious consideration.
For now, the space agency is rushing to design, build, test and fly a simple four-person craft that can more cheaply haul people and light cargo to the space station.
"The focus is to keep it simple and flexible," said Dennis Smith, the Orbital Space Plane program manager at the Marshall Spaceflight Center. "We're doing everything we can to get it up by 2008."
It is, Smith admitted, "a very ambitiously rapid schedule." But he noted NASA pulled off such magic in the early days of the space program.
"Mercury, Gemini and Apollo all did things faster than that," he said.
The key to the project, Smith said, is to keep the spacecraft simple and use technology that already has been developed. That also makes its cheap.
The design phase of the program is budgeted at $2.4 billion, inexpensive by space standards. Smith said the craft will be built with existing technology and existing materials. Some earlier, more ambitious NASA programs required fundamental technical advances that never developed but cost billions.
Such a simple approach has been used in the past to create some of the classic designs in transportation. Vehicles such as the World War II Jeep and the DC-3, a durable air transport that flew for more than 50 years, endured because they were they were simple, flexible, durable, dependable and relatively cheap.
The space plane will have only two missions: to carry people up and down from the space station, and to act as a standby lifeboat, parked at the space station for the evacuation of astronauts if there is an emergency.
"The two biggest reasons that schedules slip and costs increase is that you change the requirements or you're counting on technology that didn't pan out," Smith said. "That's why we have a very focused set of requirements that we don't intend to change. We're going to set it up for the primary mission of crew rescue and crew transport."
He said they are resisting unnecessary bells and whistles and not holding out for "some material like 'unattainium' that isn't in existence."
Preliminary studies have settled on some candidate designs. One is flat, resembling a manta ray, with upward folded wings. Others are long and slender, with stubby wings. Those could all land on a runway, as does the space shuttle.
Another design resembles a bell-shaped capsule, rather like the craft of NASA's early days. That craft would descend by parachute, the same way the Mercury, Gemini, Apollo and Russian Soyuz spacecraft landed.
NASA expects to settle on a final design within a few months.
With a capacity of four people, the plane will make it possible for the first time to put more than three long-term residents aboard the space station. Now, the Soyuz, a three-seat craft, is the only escape vehicle available if an emergency develops on the orbiting laboratory. With four more rescue seats, the station could accommodate seven astronauts safely.
Smith said the space plane initially will be launched by either Atlas or Delta boosters. These American rockets are among the most dependable, each with decades of success. Later, NASA hopes to develop another booster system.
Unique to American spacecraft, the plane will be designed to fly either manned or unmanned. Smith said an auto guidance system will allow the plane could be flown remotely to rendezvous and dock with the Space Station, and then return to Earth. With no humans aboard, the craft could be used to haul light cargo to the orbiting lab.
On the Net:
Orbital Space Plane: www.ospnews.com/planeart.html