CAPE CANAVERAL, Fla., July 28 (UPI) -- Four teams selected by NASA to study options for unmanned cargo haulers to the International Space Station meet this week for in-depth technical briefings and to learn more about the agency's need for alternative vehicles to fly to the orbiting outpost.
"This program is increasingly important to NASA, especially with the shuttles down," Chris Hoeft, with Andrews Space and Technology of Seattle, Wa., said in an interview with United Press International.
Though the shuttles' hiatus from flight -- caused by technical concerns about fuel liners in the spaceships' propulsion systems -- is temporary, with flights scheduled to resume in late September or October, the grounding of the fleet underscores the problem of relying on one type of vehicle to ferry critical supplies, as well as experiments and equipment, to the space station.
At present, Russian Progress rockets periodically carry fuel and supplies to the outpost, but the international agreements for Russian resupply expire in 2006. By then, NASA hopes to have a new vehicle ready for its first test flight.
"The Russians really aren't part of this scenario," said NASA's Chris Crumbly, manager of the Alternative Access to Station project at the Marshall Space Flight Center in Huntsville, Ala. "They can be, if it works out that way, but we want more than one vehicle (in addition to the space station) to be considered."
From more than 10 proposals, NASA has selected four candidates for studies, which are scheduled to begin by the end of the month. The teams plan to meet in Houston Tuesday and Wednesday for detailed technical briefings about the space station and its docking equipment.
In its call for proposals, NASA did not detail what the vehicles should look like, how they would be launched, docked at the station or even if they would return to Earth.
"We tried to specify as little as we could get away with so that there'd be as much creativity possible," Crumbly told UPI.
The selected teams include two small commercial space firms -- Andrews and Constellation Services International of Woodland Hills, Calif. -- and two industry giants, Lockheed Martin of Denver and the Huntsville, Ala., branch of Boeing.
Lockheed plans to draw extensively on its work for NASA on a second-generation space shuttle, as well as its newly developed heavy lift expendable launcher, the Atlas 5, which is scheduled for its debut flight this summer.
Boeing plans to tap into its research for a Defense Department-backed program called Orbital Express, a proposed automated vehicle to service and refuel orbiting satellites.
Constellation is proposing to use a standardized container to haul cargo to the station that can be launched on a variety of unmanned boosters, including the Delta 2 and two rockets under study.
"We prefer to go straight to a demonstration project," said Constellation's Charles Miller, who declined to name the company that would provide what the firm calls its Leo Express.
The Andrews plan is to build cylinder-shaped modules that could be flown aboard an Atlas 5 or Delta 4 booster, attached to the station via the Russian or U.S. docking port or manually with the station's robot arm to a common port, and returned to Earth using an innovative system called a ballute.
The device inflates like a balloon to serve as a heat shield to protect the spacecraft during its fall through the atmosphere. A system of parachutes and airbags then takes over to cushion the impact of landing.
"The system could be partially reusable or expendable," said Hoeft, adding several sizes and concepts are under study.
The teams are to report back to NASA in a year. The agency's next step would be to choose one vehicle for a preliminary design, with test flights targeted for late 2005 or 2006.
