A secretive Space Force plane completed its longest mission yet

Loud booms heard in Florida marked the return of the X-37B, the U.S. Space Force's uncrewed orbital test vehicle, after the secretive space plane's sixth and longest mission yet.

After 908 days in orbit, the Boeing vehicle touched down at NASA's Kennedy Space Center in Florida early Saturday morning.

NASA conducted a number of experiments during the trip, the Space Force said in a statement.

It was also the first X-37B mission to include a service module, which the Space Force described as "a ring attached to the rear of the vehicle expanding the number of experiments that can be hosted during a mission."

Beyond that, not much is known about the X-37B's missions. Officials have released scant information about a few experiments that took place aboard the latest flight.

One of the experiments, in partnership with the Naval Research Laboratory, involved converting solar power into microwave energy. Another aimed to test the durability of certain materials exposed to space conditions. A third experiment was designed to study the long-term effects of space radiation on seeds, in order to explore crop production and "the establishment of permanently inhabited bases in space."

"The X-37B continues to push the boundaries of experimentation, enabled by an elite government and industry team behind the scenes," said Lt. Col. Joseph Fritschen, the X-37B program director for the Air Force Department's Rapid Capabilities Office. "The ability to conduct on-orbit experiments and bring them home safely for in-depth analysis on the ground has proven valuable for the Department of the Air Force and scientific community."