When satellites and space craft have outlived their lifespan, they are frequently brought hurtling back to Earth. The smaller crafts breakup and disintegrate in the atmosphere, but bigger ones manage to make it all the way down to the surface, and often end up in what is now known as the spacecraft cemetery.
In order to minimise the chance that any falling bits of space debris might accidentally hit someone, which amazingly has been avoided to date, the space agencies in control of the re-entry picked the most remote part of Earth furthest from any land and, thus, people.
Known as the oceanic pole of inaccessibility, or “Point Nemo”, it is located in the southern Pacific Ocean some 2,688 kilometers (1,670 miles) from the nearest bit of land, which is Ducie Island of the Pitcairn Islands, Motu Nui of the Easter Islands, and Maher Island of Antarctica. This isolation, coupled with the fact that the currents move in such a way that there are few fish, and so few fisherman, means it has in effect become a spacecraft cemetery.
It is now thought that the sea floor of Point Nemo is the last resting place for at least 260 satellites scattered over an area roughly 1,500 square kilometers (580 square miles) in size. But it is not only satellites that are brought down over this patch of ocean. Somewhere in this watery grave lies the burnt out and broken up remains of the Mir space station.
Another of the most well-documented re-entries of any space kit is that of the space freighter ATV Jules Verne, which was flown by the European Space Agency on a mission to resupply the International Space Station in March 2008. As it came hurtling back to Earth in September of that year, it gave scientists an incredible opportunity to watch its re-entry and break-up as they flew in two planes alongside the spacecraft, documenting the event in astonishing detail.
But the ability to get the space junk to accurately re-enter over Point Nemo is reliant on the space agency involved still having control over the satellite or spacecraft, something that isn’t always possible. When America’s first space station, Skylab, came hurtling back down to Earth in 1979, the mostly uncontrolled re-entry saw the huge piece of equipment come crashing down over the Australian outback, with massive chunks touching down not far from the town of Esperance.
Now, as the China's first space station starts to lose orbit, it seems that a similar fate awaits Tiangong-1 since contact with it has been now been lost. The exact location of where Tiangong-1 will strike will not be known until a few hours before impact, but it will be somewhere in the latitudes of Spain and Australia.