WASHINGTON — A SpaceX Falcon Heavy rocket on Dec. 28 launched the U.S. Space Force X-37B spaceplane to orbit for its seventh mission. 

The triple-booster Falcon Heavy lifted off at 8:07 pm Eastern from Launch Complex 39A at NASA’s Kennedy Space Center in Florida.

The mission, designated USSF-52, was SpaceX’s 97th launch this year, and the Falcon Heavy’s ninth flight overall. 

USSF-52 was originally scheduled to lift off Dec. 10  but was delayed due to weather. The launch was again scrubbed Dec. 11 for unspecified technical issues. The Falcon Heavy was returned to the hangar Dec. 14. According to media reports, one or more engines had to be replaced on the rocket. 

The side boosters of the Falcon Heavy separated from the center core less than three minutes after liftoff, and the second stage separated about four minutes after launch.The side boosters flew back to Landing Zones 1 and 2 at Cape Canaveral Space Force Station about eight minutes after liftoff, marking the 257th and 258th landing of a SpaceX booster. The center core was expended and splashed into the Atlantic Ocean. After the boosters landed, SpaceX ended the live webcast and did not show any images of the payload.

The Falcon Heavy’s two side boosters return to Landing Zone (LZ)-1 and LZ-2 at Cape Canaveral Space Force Station after launching USSF-52. Credit: SpaceX

This was the first time the X-37B launched on a Falcon Heavy rocket. It previously launched five times on United Launch Alliance’s Atlas 5 and once on SpaceX’s Falcon 9. SpaceX was awarded a $130 million contract in June 2018 to launch USSF-52. 

The X-37B is an autonomous reusable vehicle, and has flown to space since 2010 for long missions that last years. Although it’s launched like a satellite, at the end of each mission it returns to Earth and lands on runways either at Kennedy Space Center or at Vandenberg Space Force Base, California.

X-37B space plane. Credit: Space Systems Command

The aircraft that was launched on Thursday — Operational Test Vehicle 7 — carries several U.S. military and NASA science experiments. The Air Force, in partnership with the Space Force, operates two X-37B spacecraft made by Boeing.

The target orbit for this mission is classified. Space watchers estimate that based on navigational warnings and the fact that it’s launching on a heavy rocket, the plane is headed to a highly elliptical, high inclination orbit, to a much higher altitude than previous missions. The X-37B is highly maneuverable, can change its orbit rapidly, making it difficult to track.

COMSPOC, a firm that tracks space objects, has developed video scenarios that illustrate what the X-37B space vehicle may look like in low orbit and highly elliptical orbit.

The 29-foot-long spaceplane will conduct a wide range of tests, including operating in new orbital regimes, experimenting with space domain awareness technologies, and investigating the radiation effects on materials provided by NASA, the Space Force said.

It carries NASA’s Seeds-2 mission, which will expose plant seeds to harsh radiation environments. Additionally, this mission will deploy the FalconSat-8 — a small satellite developed by the United States Air Force Academy for scientific experiments. 

The most recent X-37B mission, OTV-6, launched in May 2020 and landed in November 2022 after setting a new endurance record, spending 908 days on orbit.

Sandra Erwin writes about military space programs, policy, technology and the industry that supports this sector. She has covered the military, the Pentagon, Congress and the defense industry for nearly two decades as editor of NDIA’s National Defense...