On April 29 at 03:23 UTC, China launched a Long March 5B carrying the core module for the China Space Station from the Wenchang Satellite Launch Center on China’s Hainan Island. This high-profile launch was broadcast live in real-time online by China Central Television, the state television network.

This was only the second launch for the Long March 5B; it first launched about a year ago. It’s a bit different from the Long March 5. By omitting the large second stage from the Long March 5, the Long March 5B can launch really massive objects into low Earth orbit but no further. This also makes it a one-and-a-half stage vehicle just like the Atlas rocket that launched the Mercury capsules into orbit back in the 1960s. Both the rocket core and boosters are ignited on the ground, and the boosters are jettisoned when they have used up their propellant. The rocket core stage goes all the way into orbit with the payload.

The core module is named Tianhe, which literally translates to “Harmony of the Heavens”. The module is massive, weighing 22.5 metric tons (or 11,250 2-liter soda bottles), and it completely filled the cavernous fairing of the Long March 5B. The space inside the fairing is 20.5 meters long and 5.2 meters wide; our team thinks you can fit four school buses inside.

Tianhe itself looks externally like the Mir Core module with ISS-style solar panels on the sides. China’s entire space program is heavily influenced by Russia’s space program. The Chinese crewed spacecraft is essentially an adaptation of Soyuz, and their previous space stations were similar to the Soviet Salyut stations.

On the inside, the station is laid out reminiscent of the International Space Station module, with a clearly defined bottom and top and lockers on the sides. There are only so many ways to build a space station, so they all kind of end up looking the same. The Chinese station has two axial docking ports, one on each end, and four radial docking ports in a hub on the narrow end of the module. The docking ports resemble the ISS’s International Docking System Standard ports. (The technical specifications are freely available online for anyone to download, so you too can download a copy and build your own International Docking System port if you want.) Shenzhou — the Chinese crewed spacecraft — has docked to ports like this one on the previous Chinese space stations, the Tiangong 1 and 2. There is also an airlock for spacewalks in the core module.

China has an ambitious schedule of the future crew, resupply, and additional module launches for the next 18 months to fully outfit the station and populate it. The first of these is the Tianzhou 2 resupply spacecraft in May, followed by the crewed Shenzhou 12 mission later in June. Two other “Laboratory Cabin Modules” named Wentian and Mengtian will be launched on future Long March 5B’s in 2022. We’ll have reports for those launches after they occur.

One more note on this launch: according to Chinese sources, the core stage was supposed to conduct a deorbit burn to hasten its return to Earth. This would have been accomplished by venting excess propellants at just the right time and direction to slow down its orbit. As the core stage was still being tracked in its insertion orbit many hours after launch, the deorbit burn apparently did not happen. The core stage will have an uncontrolled reentry somewhere between 41 North and 41 South latitude, based on the inclination of the orbit, in the next days/weeks. This will be a major event wherever it occurs. 

The last Long March 5B core stage missed reentering over New York City by about two minutes of predicted reentry time. That core stage ended up reentering over the Pacific Ocean just off the Ivory Coast and showering a village with debris. As of May 4, this latest core stage was expected to reenter on May 9th at 04:37 UTC give or take about a day, so basically anywhere on Earth sometime next week. [Ed note: The core stage fell into the Indian Ocean at 03:24 UTC on May 9, near 72.47 degrees East and 2.65 degrees North.]

More Information

Planned space station details made public (China Daily)

China launches Tianhe space station core module into orbit (Xinhua)

CZ-5-8 Data Sheet (Space Launch Report)

Huge rocket looks set for uncontrolled reentry following Chinese space station launch (SpaceNews)

Bridenstine criticizes China for uncontrolled rocket reentry (SpaceNews)

Launch video