The U.S. Air Force on Friday made its first public confirmation that the X-37B unmanned space shuttle will be launched next month on the fourth flight of an Orbital Test Vehicle.

The 8-million-pound mobile service tower is retracted from around the Atlas 5 rocket, revealing the 19-story-tall vehicle for liftoff from Vandenberg Air Force Base, California, on NROL-55.

NASA is sending into orbit Monday night a spacecraft to test a safer type of rocket fuel, an ultra-precise atomic clock that could change the way missions navigate in deep space, and an experiment to examine the resiliency of electronics to radiation.