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 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.

An artist rendering released by NASA shows four concepts being considered for the design of the Orbital Space Plane. Clockwise, from bottom left: a capsule, a lifting body, a sharp body with wings and a blunt body with wings. Boeing Phantom Works, Lockheed Martin Corp.; and a team including Orbital Sciences Corp., and Northrop Grumman are the contractor teams designing potential candidates for the vehicle.

The key to the project, Smith said, is to keep the spacecraft simple and use technology that already has been developed. That also makes it cheap.

The design phase of the program is budgeted at $2.4 billion, inexpensive by space standards. Smith said the craft would 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 DC3, a durable air transport that flew for more than 50 years, endured because 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.