China’s doomed space station Tiangong-1 is about to return to Earth as a massive fireball. According to the European Space Agency (ESA), the 8-ton spacecraft will re-enter the atmosphere sometime between March 30th and April 2nd. Tiangong-1 is about the size of a European cargo spacecraft, such as the ATV-1 which itself re-entered in 2008. This re-entry video of the ATV-1 shows what the Tiangong-1 fireball might look like:
Tiangong-1 was launched in Sept. 2011 to establish a foothold in Earth orbit for China’s fledgling space program. It served as a temporary home in space for two crews, including China’s first female astronauts, and provided a testbed for automated rendez-vous and docking procedures. China lost control of Tiangong-1 in 2016 when a telemetry link failed. This made it impossible for mission controllers to guide the station to a re-entry over the South Pacific Ocean as originally planned. Instead, Tiangong-1 would re-enter on its own schedule as aerodynamic friction with Earth’s upper atmosphere slowly drained the station’s orbital energy.
Initially, Chinese officials speculated that re-entry would occur in late 2017. However, low solar activity delayed the splashdown. Sunspot numbers have plummeted recently as the solar cycle heads toward a deep solar minimum:
At the moment it is impossible to predict exactly where Tiangong-1 will re-enter. All we know is that it will disintegrate somewhere between +42.8 and -42.8 degrees latitude, the upper and lower limits of the station’s tilted orbit. This map from the ESA shows the re-entry zone:
Even with an uncontrolled re-entry, the odds strongly favor a descent over uninhabited land or ocean. According to the ESA, “[surviving fragments] will be scattered over a curved ellipsoid that is thousands of km in length and tens of km wide. The personal probability of being hit by a piece of debris from the Tiangong-1 is actually 10 million times smaller than the yearly chance of being hit by lightning.” Look at the ghostly images of the space station falling to Earth:
In other words, don’t worry. You’ll be lucky just to see the fireball. Approximately one day before the reentry, it will become possible to roughly predict re-entry ground tracks, and hence which regions on Earth might witness the disintegration. So keep your eyes wide open and turned toward the sky!