HELSINKI — China’s experimental reusable spaceplane has been using a smaller spacecraft to test proximity operations, potentially even capturing the object.

China launched its spaceplane for the third time via a Long March 2F rocket Dec. 14, 2023. The spacecraft released an object into orbit, first cataloged by U.S. Space Force space domain awareness teams May 24, following orbit-raising and months of stable operation.

Analysis of orbital data and observations from Leiden, the Netherlands, by Marco Langbroek, a lecturer in optical Space Situational Awareness at Delft Technical University, suggest the spaceplane has used the spacecraft, “Object G,” to test rendezvous and proximity operations (RPO) June 7-8.

Such operations could be useful for retrieving, repairing and maintaining friendly satellites, or potentially nefarious counterspace operations against an adversary’s spacecraft.

After ejecting the object, the spaceplane performed an avoidance maneuver and later made additional maneuvers between June 5-7, Langbroek stated in his blog post. These brought it close to the object again June 8. 

“Some combinations of the orbital data for epoch 24160 do suggest that a potential very close approach at kilometer level or even less might have happened on 8 June near 14-15h UTC,” Langbroek wrote. 

“The rapid maneuvering evident from the clear orbital changes in successive elsets from June 8-9 makes it however difficult to validate true distances involved.” Elsets is short for “element sets,” which are used in the field of satellite tracking and orbital mechanics.

While it is unclear if the spaceplane briefly retrieved and re-released Object G, their close approach suggests intentional proximity operations. 

Jonathan McDowell, an astrophysicist and spaceflight activity tracker, told SpaceNews he reached similar conclusions to Langbroek regarding potential RPOs.

This would not be the first such activity for China’s spaceplane. Data from private firm Leolabs suggests that the spaceplane performed at least two and possibly three capture/docking operations with a co-orbiting object during its second flight in 2022-2023.

China has also conducted RPOs in geostationary orbit. Shijian-21 towed a dead satellite to a high graveyard orbit in December 2021. The GEO belt is also the stage for counterspace activities involving the United States, Russia and China. The U.S. military is looking to bolster its ability to detect and track potential threats in GEO.

Secretive spaceplane project

China has maintained strict secrecy around the mission. The country’s space authorities have not released images nor descriptions of the spacecraft. The only official Chinese report on the activity is a short launch report hours after the event. 

“During this period, reusable technology verification and space science experiments will be carried out as planned to provide technical support for the peaceful use of space,” the report stated.

The spacecraft is seen as China’s attempt to develop similar capabilities to the X-37B. It is currently on its third mission. Reusable spacecraft represent a significant advancement in space technology, offering the potential for reduced costs and increased frequency of missions.

The initial flight in 2020 lasted two days, while the second mission in 2022 extended to 276 days. Both missions included the deployment of an object while in orbit. The interval between the first and second missions was nearly two years, with the third mission following a seven-month gap.

The reusable spacecraft is intended to work in conjunction with a reusable suborbital first stage. This suborbital craft, which uses vertical takeoff and horizontal landing, was first tested in 2021. A second mission flew in August 2022.

The China Aerospace Science and Technology Corporation (CASC), which developed the spacecraft, announced plans for a fully reusable, two-stage-to-orbit (TSTO) space transportation system before the first launch. In 2022, CASC’s spaceplane project received national funding from the Natural Science Foundation of China.

Meanwhile, the U.S. Space Force’s X-37B spaceplane began its seventh mission on December 28 of the previous year. Launched on a Falcon Heavy for the first time, it is believed to have been sent to a highly elliptical, high-inclination orbit at a greater altitude than previous missions. The X-37B, a secretive and autonomous reusable vehicle, has been flying since 2010.

Andrew Jones covers China's space industry for SpaceNews. Andrew has previously lived in China and reported from major space conferences there. Based in Helsinki, Finland, he has written for National Geographic, New Scientist, Smithsonian Magazine, Sky...