By Marina Malenic

The Air Force is preparing to launch a second experimental space plane into low earth orbit tomorrow after what service officials deemed a highly successful inaugural flight late last year.

The first X-37B Orbital Test Vehicle (OTV) spent 244 days, nine hours and 24 minutes in space before landing at Vandenberg AFB, Calif., on Dec. 3. The spacecraft, subject of much speculation, is designed to be a test bed for experiments that can be returned to Earth so that researchers can reexamine them, according to Air Force officials (Defense Daily, Dec. 7).

Like OTV-1, OTV-2 will launch aboard an Atlas 5 booster from Cape Canaveral Air Force Station, Fla., an Air Force spokesman said via e-mail. The two-hour launch window opens at 3:39 p.m. EST.

The military has to date only been able to conduct such space experiments on NASA’s space shuttle. The X-37 resembles the shuttle but is much smaller. According to the Air Force, two X-37s would fit into the shuttle’s bay. Unlike the shuttle, however, the unmanned X-plane is designed to remain on orbit for approximately nine months.

While funding details for the project are classified, the Air Force has purchased two spacecraft from prime contractor Boeing‘s [BA] Phantom Works division.

Originally built for a NASA program, the X-37B was taken over by the Air Force. The Air Force Research Laboratory and the Defense Advanced Research Projects Agency have participated in the Air Force development. The vehicles are operated by Air Force Space Command’s 3rd Space Experimentation Squadron based at Schriever AFB, Colo.

OTV-1 has not yet been scheduled for a second launch, but the Air Force anticipates it will return to orbit in the future.

“OTV-2 builds upon the OTV-1 on-orbit demonstration and expands the test envelop of the X-37B,” the service spokesman said via e-mail. “This second test mission furthers the development of the concept of operations for and fine-tunes technical parameters of an affordable, reusable space vehicle.”

Officials have said no significant changes were made to OTV-2 as a result of the OTV-1 flight. The vehicle’s main landing gear tire pressure was reduced slightly to avoid repeating the blown tire that OTV-1 experienced upon landing, the Air Force said.