The Air Force is working on a space vehicle that will allow government scientists to transport advanced technology into orbit, test its capability there, then bring it home to see how it fared in the harsh environment of space.

The X-37B Orbital Test Vehicle is similar to the space shuttle, except it's about a fourth the size and unmanned. The OTV can return from space on its own, said Lt. Col. Kevin Walker, an Air Force Rapid Capabilities Office program manager.

"All you do from the ground is send up the command for it to de-orbit, then stand back and it de-orbits itself," he said. "The OTV gets itself ready for re-entry, descends through the atmosphere, lines up on the runway, puts down its landing gear ... and it does it all on its own."

The vehicle will land at either Vandenberg or Edwards Air Force bases in California.

The OTV will serve as a test platform for satellites and other space technologies. The vehicle allows satellite sensors, subsystems, components and associated technology to be transported into the environment where they will be used -- space.

Scientists will prepare components in the OTV's experiment bay, and then the craft is launched into space aboard an Atlas V launch vehicle. Once in space, the OTV begins testing its payload. Colonel Walker said the doors aboard the craft could simply open, exposing the experiment bay, or mission scientists could design more elaborate experiments.

"You could design something to extend itself out of the experiment bay, or have it on a retractable arm, or it could just stay inside the bay," Colonel Walker said. "The OTV is a very flexible space test platform for any number of various experiments."

Being able to test parts in their actual operational environment will allow scientists to better judge how those parts will perform when deployed, so fewer redundancies may occur in future satellites.

"Rather than build unproven components into a high-cost satellite, with multiple layers of redundancy to make sure they work -- you can use the OTV to get those components into space to see how they respond to the environment, and make sure they work the way they were designed," Colonel Walker said. "When the OTV returns to Earth, you can inspect the tested component and use that information to potentially alter your design."

The Air Force's Rapid Capabilities Office has been tasked with acquiring, testing and demonstrating the OTV. Colonel Walker said much of the X-37B system vehicle is now being built and will soon move into a testing phase.

"We are getting into the subsystem and systems-wide testing, which will go on for about the next year," he said. "We are projecting our first launch for the beginning of 2008."

After a few flight tests in space, the OTV should be ready to begin experimentation in orbit, Colonel Walker said.

"The first flight or two will be to check out the OTV itself to make sure it works the way it is designed to," he said. "After that, you get into the realm of using it as a reusable space test platform -- putting space components into its experimental bay and taking them to space for testing."

Though the OTV is designed to provide a testing platform for new space technologies, it is made up of several advanced, untested technologies itself.

Randy Walden, RCO deputy and technical director, said there are a number of cutting-edge technologies on the OTV besides the auto de-orbit capability. It has new thermal protection tiles underneath and high-temperature components and seals throughout that need to be proven in orbit.

"There will be a great deal of extremely useful data coming from the OTV on its first flights,' said Mr. Walden. "Our plan is to share this data with other government agencies such as NASA."

The X-37 program, originally a NASA initiative, was transferred to the Defense Advanced Research Projects Agency in 2004. The Air Force's X-37B program builds upon the early development and testing conducted by NASA, DARPA and the Air Force Research Laboratory.

"We are honored to be developing this unique space platform," said David Hamilton, Jr., RCO director, "and very excited about the potential benefits to future space programs."