The US military's reusable X-37B spaceplane will launch on the next flight of SpaceX's Falcon Heavy rocket, scheduled for December 7, officials announced on Wednesday.
This was unexpected because the spaceplane's six previous missions launched on medium-lift Atlas V or Falcon 9 rockets. This next mission, the seventh by an X-37B spaceplane, will fly on a heavy-lift launcher for the first time.
The payload for the next Falcon Heavy rocket was a secret before the military's announcement on Wednesday. The mission was known simply by the designation USSF-52, and it will take off from NASA's Kennedy Space Center in Florida.
In a statement, the Space Force said the seventh X-37B mission will have a "wide range of test and experimentation objectives." The Pentagon wants everyone to know the X-37B spaceplane exists, but military officials are mum about the details of the vehicle's missions. The Space Force's statement Wednesday was similarly vague on details of the upcoming flight.
"These tests include operating the reusable spaceplane in new orbital regimes, experimenting with future space domain awareness technologies, and investigating the radiation effects on materials provided by NASA," the Space Force said.
Shrouded in secrecy, the automated X-37B spaceplane can deploy small satellites, host experiments, and pursue other classified objectives. Flying without any astronauts on board, the vehicle generates electricity with a solar array and autonomously guides itself to a runway landing at the end of each mission.
Expanding the envelope
The X-37B program is a partnership between the Space Force and the Air Force Rapid Capabilities Office. Military officials have acknowledged there are two X-37B vehicles built by Boeing, and each has flown multiple times.
The spaceplane measures about 29 feet (8.9 meters) long with a wingspan just shy of 15 feet (4.5 meters), about one-quarter the size of one of NASA's space shuttle orbiters. It has a cargo bay inside the fuselage for payloads, plus a disposable service module that was flown for the first time on the most recent X-37B mission, providing additional capacity for experiments.
The spaceplane fits snugly within the nose cone of a Falcon or Atlas rocket, allowing the X-37B to take off on top of a conventional launch vehicle just like any other satellite payload.
The X-37B flew into orbit for the first time in 2010. Its most recent flight ended a year ago this week with a return to NASA's old space shuttle landing strip in Florida, wrapping up nearly 30 months in orbit, the longest X-37B flight to date. All of those missions flew a few hundred miles above Earth in mid-inclination orbits, following paths that took the vehicles between about 55 degrees north and south latitude on each lap around the planet.
Next month's launch will "expand the envelope" of the X-37B's capabilities and will again fly with a service module mounted to the rear of the spaceplane, said Lt. Col. Joseph Fritschen, the X-37B program director. He said in a statement that the X-37B will fly "multiple cutting-edge experiments for the Department of the Air Force and its partners."
The military's talk of expanding the envelope and operating in new orbital regimes seems to suggest the next X-37B mission will fly in a higher orbit than its predecessors. That makes sense with the spaceplane launching on top of a Falcon Heavy rocket, with significantly more lift capability than the Falcon 9 or Atlas V used to launch the previous X-37B missions. The spaceplane weighs about 11,000 pounds (5,000 kilograms), not including the additional weight of its service module.
A military solicitation document released when the Air Force procured the rocket for the USSF-52 mission—which we now know will launch the X-37B—said this mission would require a lift capacity of around 14,000 pounds (6,350 kilograms) into a geostationary transfer orbit, a highly elliptical loop around Earth ranging some 22,000 miles (35,000 kilometers) from the planet. That would be a big change from the past missions of the military's mini-space shuttle.
But this document is now more than 5 years old, and the circumstances of the mission may have changed. The military typically doesn't publish the orbital parameters of its space missions, but watchful amateur sleuths can estimate altitude and inclination with publicly available information like airspace and maritime warning notices associated with a rocket launch. Those are usually released closer to the launch date.
An Air Force spokesperson declined a request from Ars for additional information about the orbit for the next X-37B mission.
Launching the X-37B on a Falcon Heavy rocket will drive more speculation about the military spaceplane. US military officials have released information about some of the experiments the X-37B has flown, including electric thruster and advanced thermal control technologies. But past X-37B missions have deployed small satellites, both covertly and overtly, and the military has provided only vague descriptions of the spaceplane's other activities.
Some observers, including Russia and China, have claimed the X-37B might be a weapons platform or could approach other satellites in orbit for inspection. There's no evidence this has occurred on the X-37B missions to date, according to the Secure World Foundation. China has twice launched its robotic spaceplane that appears to be similar in size and shape to the X-37B.
The Space Force's mention of space domain awareness technologies on the next X-37B mission suggests some of its experiments will be used to observe other objects in orbit, at least from a distance. The NASA experiment on the X-37B mission will expose plant seeds to the harsh radiation environment of long-duration spaceflight, the Space Force said.
In June, the former vice chief of space operations, Gen. David Thompson, said the X-37B spaceplane "has been a remarkable testbed and experimentation vehicle." He also hinted at new things for the winged vehicle.
"We have grown its mission set, in terms of the types of technologies that we’re testing, some associated experiments with operational concepts," Thompson said in a forum hosted by the Mitchell Institute for Aerospace Studies. "It has proven itself to be a remarkably flexible and versatile platform, and I would tell you you’re only beginning to see some of the exciting things that we have planned for the X-37."
