The latest orbital mission of China's mysterious space plane may be nearing its end.
The hush-hush vehicle, which launched to Earth orbit on Aug. 4, ejected something on Monday (Oct. 31), according to astrophysicist and satellite tracker Jonathan McDowell, of the Harvard-Smithsonian Center for Astrophysics.
The newly released object "may be a service module, possibly indicating an upcoming deorbit burn," McDowell, of the Harvard-Smithsonian Center for Astrophysics, said via Twitter (opens in new tab) on Monday.
Related: The latest news about China's space program
The Chinese spaceplane launched on Aug 4 was in a 597 x 608 km x 50.0 deg orbit as of Oct 31; at around 1200 UTC it ejected an object (52418) that may be a service module, possibly indicating an upcoming deorbit burnNovember 1, 2022
That's not the only possible explanation, however.
The ejected object could also be "a small satellite for monitoring the space plane," SpaceNews' Andrew Jones wrote in a story that posted today (opens in new tab) (Nov. 2). "Chinese crew capsules have previously released 'Banxing' small companion satellites for monitoring purposes. It could also be a test for deploying small satellite payloads into orbit."
Whatever the object is, its release probably heralds the mission's impending end — if a single previous data point is a reliable guide, anyway. The Chinese space plane has one other orbital mission under its belt, a two-day jaunt in September 2020 that ended shortly after a similar ejection, as Jones noted.
Such speculation is pretty much all we have to go on, for China has said very little about the space plane or its activities.
For example, this is how China's state-run Xinhua news agency described the mission (opens in new tab) (in Chinese; translation by Google) just after it lifted off in early August:
"The test spacecraft will be in orbit for a period of time before returning to the scheduled landing site in China, during which reusable and in-orbit service technology verification will be carried out as planned to provide technical support for the peaceful use of space."
Western experts think the mysterious vehicle is roughly the same size as the U.S. Space Force's robotic X-37B space plane, which is about 29 feet (8.8 meters) long. The U.S. military is tight-lipped about the Boeing-built X-37B as well, revealing details about only a select few of the payloads the space plane totes on its orbital missions.
The X-37B is aloft now, and has been for quite some time: The program's sixth-ever mission lifted off on May 17, 2020. It's unclear when the X-37B will come back down to Earth.
Mike Wall is the author of "Out There (opens in new tab)" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall (opens in new tab). Follow us on Twitter @Spacedotcom (opens in new tab) or on Facebook (opens in new tab).