April 11, 2018

Last week, on April 1, China’s first space station, Tiangong-1, returned to its home planet in a fiery “uncontrolled return” through Earth’s atmosphere. Tiangong-1 (Heavenly Palace-1 in English) was launched in 2011 and ceased operating in 2016. The remnants of the unoccupied space station—the parts that did not disintegrate on reentry—crashed into the South Pacific Ocean.

This illustration shows the uncontrolled return of the Tiangong-1 space station on April 1, 2018. Credit: © Alejo Miranda, Shutterstock

The spacecraft’s demise was tracked closely by the United States National Aeronautics and Space Administration (NASA), the U.S. Air Force, and other space agencies and air forces around the world. The end of Tiangong-1 could have posed a threat to highly populated areas, and the derelict craft’s reentry position was continually updated as it spun through its final orbits. At last, Tiangong-1 hit the atmosphere over a wide expanse of empty sea. Most of the spacecraft was incinerated, but pieces of it did strike the water at Earth’s surface.

Tiangong-1 was launched aboard a carrier rocket from the Jiuquan Space Launch Center in northern China in September 2011. The modest space station, two cylindrical sections with a docking port, was about 39 feet (12 meters) long and 11 feet (3.3 meters) wide. The spacecraft was used mainly to carry out rendezvous and docking tests in preparation for the construction of a larger and longer-lasting space station scheduled for completion and launch in the early 2020′s. Tiangong-1 settled into an orbit about 217 miles (350 kilometers) above Earth, slightly lower than the orbit of the much larger International Space Station.

In early November 2011, the robotic Shenzhou-8 (Divine Craft-8) spacecraft visited Tiangong-1, executing China’s first-ever orbital docking. In June 2012, three taikonauts (Chinese astronauts) aboard Shenzhou-9 gave the heavenly palace life for about two weeks. A year later, three more taikonauts spent a fortnight aboard Tiangong-1. The spacecraft continued some Earth-observation work after that, but contact and control of Tiangong-1 were lost in March 2016. A successor craft, Tiangong-2, was launched in September 2016 and is currently in operation.