The X-37B Orbital Test Vehicle, which looks like a small version of the manned space shuttles retired in 2011, will be launched from Cape Canaveral in Florida on May 16, the Air Force said.

Once in orbit, it will deploy a small FalconSat-8 research satellite and, for the first time, also carry a service module that will expand its capacity for experiments.

Experiments carried by the spacecraft include tests for NASA of the impact of radiation on seeds and other materials.

Another test for US Navy researchers involves transforming solar power into radio frequency microwave energy, which could then be transmitted to the ground, according to a statement.

The "space plane" as it is called, has spent a cumulative 2,865 days in space, including 780 days in orbit on its last mission, which ended in October 2019.

"This X-37B mission will host more experiments than any prior missions. This launch also demonstrates the department's collaboration that pushes the boundaries for reusable space systems," said Secretary of the Air Force Barbara Barrett.