China’s reusable space plane is circling Earth once again.
The Shenlong (“Divine Dragon”) spacecraft launched from Jiuquan Satellite Launch Center in the Gobi Desert on Feb. 6, kicking off the robotic vehicle’s fourth-ever orbital mission.
We don’t know for sure. The Chinese government has revealed few details about Shenlong, whose three previous flights to low Earth orbit (LEO) launched in September 2020, May 2023 and September 2024 and lasted two days, 276 days and 266 days, respectively.
The official line is vague and anodyne: Shenlong helps test technologies that “will pave the way for more convenient and affordable round-trip methods for the peaceful use of space in the future.”
That use case is similar to the one the U.S. military gives for its autonomous X-37B space plane, which Shenlong is thought to broadly resemble. And secrecy is a shared trait: Most X-37B payloads and activities are classified.
Analysts believe the Space Force owns two X-37B vehicles, each of which is 29 feet (8.8 meters) long and looks like a miniature version of NASA’s old space shuttle orbiters. The X-37B reached orbit for the first time in 2010 and is currently flying its eighth mission, which launched last August atop a SpaceX Falcon 9 rocket.
Though military officials have always insisted that the X-37B is merely a technology testbed, the vehicle has aroused suspicion in some quarters. Early in its flying days, for example, China apparently viewed it as a space weapon. But these fears are overblown, experts say.
“To date, the X-37B has never approached or rendezvoused with any other known space object and generally orbits far below the vast majority of operational satellites,” the nonprofit Secure World Foundation (SWF) wrote in its X-37B fact sheet. (There was one exception to that low-orbit rule, as the fact sheet notes: On the seventh X-37B flight, the vehicle got more than 24,000 miles, or 38,600 kilometers, from Earth on a highly elliptical orbit.)
The X-37B would also be a poor delivery system for space-to-ground weaponry, due to its small payload bay (about the size of a pickup truck bed) and limited power-generating capability.
“Hyperkinetic weapons dropped from the bay would need to be equipped with thrusters capable of performing a significant deorbit burn, which is unlikely given the available room,” the SWF fact sheet states.
“The X-37B itself reenters like the space shuttle, landing at an estimated 200 mph (321 kph), which means it travels in the atmosphere much slower than a nuclear reentry vehicle on a ballistic arc or a hyperkinetic weapon,” the fact sheet continues. “It thus would need to carry conventional explosives to do any significant damage. The X-37B after reentry would be a slow-moving, not-very-maneuverable glide bomb, easy prey for any air defense system along its path to the target.”
Much of this same reasoning holds for Shenlong. It’s thought to be roughly the same size as the X-37B, for example, so we shouldn’t worry about it raining bombs on Earth. However, unlike the X-37B, Shenlong has rendezvoused with other objects in space.
On each of its three previous missions, the space plane released one or more objects into orbit. We learned this not from the Chinese government but rather from the U.S. military, private space situational awareness companies and amateur astronomers, who have tracked Shenlong and its activities.
“The satellite deployed during the first mission demonstrated transmission broadcast capabilities, and the satellite deployed during Shenlong’s second mission is thought to have displayed independent propulsive capabilities,” the SWF wrote in its Shenlong fact sheet. “Shenlong has conducted numerous close maneuvers and capture/ docking operations with the deployed satellites.”
Indeed, such rendezvous and proximity operations (RPOs) — which we have not seen from the X-37B — may be a priority of the Shenlong program, as they seem to be for Chinese space officials overall.
“I think that tracks along with other things that they’re doing — you know, conducting RPOs in LEO and GEO,” said Victoria Samson, chief director of space security and stability for the SWF. (“GEO” is geostationary orbit, which lies 22,236 miles, 35,876 km, above Earth.)
“This is a skill set that they’re obviously interested in, as is Russia, as is the United States,” she told Space.com.
This interest is not exactly surprising: Mastery of RPO tech would allow operators to refuel, refurbish, upgrade and deorbit their own satellites — and, potentially, inspect and/or tamper with adversary spacecraft.
“It’s almost at the point now where, if you want to have space superiority, you need to be able to conduct RPOs,” Samson said.
Shenlong’s orbital work therefore worries some experts, who cite its anti-satellite potential. It’s tough to know how warranted such concerns are, given the secrecy — an argument you could make about the X-37B as well.
More information about each program would go a long way toward allaying some of these fears, if indeed they are unfounded, Samson said.
“I think a little more transparency would help fill in some of the blanks, because otherwise, people tend to just imagine the worst-case scenario,” she said.
