China’s Tiangong-1 space station is due to re-enter the atmosphere in the coming weeks in what appears to be an uncontrolled descent, but where could it land – and will anything make it to the ground?
Tiangong-1 is currently dropping at a rate of 6 kilometers (3.7 miles) a week from its orbital height of around 280 kilometers (175 miles). Predictions at the moment suggest it will probably re-enter the atmosphere at some point between March 29 and April 9.
The orbit of the station takes it between latitudes of 42.8°N and 42.8°S. This takes it as far North as the US, Spain, and China, and as far South as Brazil, Australia, and South Africa. It definitely won’t land outside those zones, so places like the UK are safe.
However, as we don’t know exactly when the space station will re-enter, it’s impossible to know exactly where it might fall. We might not know until just hours before re-entry where it is going to come down.
What’s more, the space station isn’t that big – so it’s unclear how much of it, if any, will make it to the ground. The diagram below shows the possible places in green that the station could land. Those in yellow are at the highest risk, as it spends the longest time here in its orbit.
The station weighs about 8,500 kilograms (18,800 pounds) and measures about 10.4 by 3.4 meters (34.1 by 11 feet). As such, it doesn’t rank that highly on objects that have re-entered. An object of a similar mass even re-entered our atmosphere over Peru earlier this year, with little fanfare.
Nonetheless, there is still some cause for concern if the station is uncontrolled – China has said they have it under control, but others think otherwise.
This means the station could break apart over a populated region, with a small chance of debris making it to the ground – by some estimates 10 to 40 percent of it. Some of this material could also be hazardous, so it's advised that you don’t go near it if you do happen to find any.
Most of its orbit takes it over the ocean, though, with the station spending little time over inhabited regions. The odds of being hit by debris from Tiangong-1 are significantly less than your chance of being struck by lightning.
Still, it’s sure to garner a lot of headlines when it eventually does come down. Where that will be, well, we won’t know for a while.