Top Secret X-37B U.S. Space Plane Makes 4th Flight

The secretive United States Air Force vehicle is currently undertaking its fourth space trip.

Details about the unmanned X-37B spacecraft are hard to come by, and the Air Force has not released any details about the mission. The craft is similar in shape to NASA’s retired space shuttles, but is slightly smaller, writes Kenneth Chang for The New York Times.

Top Secret X-37B U.S. Space Plane Makes 4th Flight

X-37B contains experimental payload

“The test mission furthers the development of the concept of operations for reusable space vehicles, and fine-tunes technical parameters for an affordable, reusable space vehicle,” said Capt. Christopher M. Hoyler, a spokesman for the Air Force.

Two of the X-37B spacecraft were built by Boeing, and the first launched in April 2010. Since it was first seen, commentators have speculated as to what its purpose may be. The Pentagon has denied that it has anything to do with space weapons.

The rocket launched from Cape Canaveral, Florida on Wednesday morning. The Air Force has mentioned an experiment that will work on an upgraded version of an electric thruster, which are more efficient than conventional chemical thrusters. It is hoped that electric thrusters will one day be used to power cargo ships to Mars, although significant improvements in performance need to be made.

Materials and CubeSats also undergoing testing

NASA will also use the flight to measure how materials react to space conditions. Almost 100 different materials will be analyzed as they experience the high levels of radiation and extreme swings in temperature that the craft will experience in orbit.

Among the materials are thermal spacecraft coatings, clear materials which could be used for windows and ink made to resist the ravages of space. The information gathered during the experiment will help inform the choice of materials for future spacecraft components.

As well as the X-37B, the rocket also launched with 10 small satellites on board. The devices are known as CubeSats, and will be testing new technologies related to propulsion and communication.

One of the models is known as LightSail. Although it may only be as large as a loaf of bread upon launching, it will unfurl a sail and four 13-foot booms, and be propelled by sunlight. Further testing of the LightSail is scheduled for next year during a SpaceX test.