China's oldest space station is going to fall out of space very soon
China's oldest long-term space station, the Tiangong-1, is due to fall from space and re-enter the Earth's atmosphere any day now, and no one knows exactly where it will land. Satellite trackers have only just discovered approximately when it's going to happen, but can only guess at where exactly it will impact - which is a little worrying for some.
As of mid-January, the spacecraft was travelling at about 280km altitude in orbit, but this will inevitably decay. Following the launch of the craft in 2011, the orbit steadily decayed due to the faint atmospheric drag present, which affects all satellites in low-Earth orbit. Regular orbital maintenance manoeuvres were executed to maintain operational altitude between 330 and 390km, but now it is too late.
It was China's first long-term space habitat, as well as the site of the country's first orbital docking and long-term space stays. The 8-ton satellite is said to drop sometime between March 24 and April 19 according to the European Space Agency earlier this month, but they are getting closer to the truth with each passing day. Presently, it's believed that the lab will fall within a few days of the end of March.
Dr Marco Langbroek, an archaeologist who also tracks satellites, predicted today that it will fall within three days of March 31, due to a geomagnetic storm giving it a "bump". This is close to the ESA's latest forecast issued on March 17, which said that the entry will occur between March 30 and April 6.
The space station is moving far too fast and chaotically for trackers to predict exactly where it will enter the atmosphere. All is known is that it will be somewhere between 43 degrees north latitude and 43 degrees south latitude, which is a huge range - covering everywhere from Boston to Brisbane. And according to the ESA, "At no time will a precise time/location prediction from ESA be possible".
Most of the populated world falls in this zone, but there is no need to worry about falling debris - unless you are severely unlucky. The ESA stated that "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".
Some spacecraft are designed to survive the intense heat from re-entering the atmosphere, but not the Tiangong-1. Most of it will break up in the atmosphere, but what does fall is very unlikely to land in a populated area given the amount of unoccupied land and ocean space on our planet.
Dr. Marco Langbroek is a little more hopeful about predicting its fall, however, writing on Twitter that "Only in the last few hours, some sort of estimate is possible". He also added that it is currently losing 2-3 km a day in altitude, with that value rapidly increasing as it gets closer to our planet over the next two weeks.