After losing control of their decommissioned space station Tiangong-1 last year, the Chinese space program announced that the station is slowly crashing back to Earth in a decaying orbit. The exact timing and location of this protracted death is near impossible to predict, but it now seems likely that it will occur towards the end of March or beginning of April.
It is not in any way unusual for space junk to fall back to Earth, as satellites that have ended their lifespan frequently re-enter the atmosphere. But these are often small or designed in a way that means they are more likely to burn up in the atmosphere, minimizing the risk of big chuncks hitting the ground.
The difference with Tiangong-1 is its size. The space station weighs around 8,600 kilograms (19,000 pounds) and is made of dense material, thus increasing the likelihood that some substantial bits of the craft might make it down to the surface still intact. Usually for such large crafts, the operators use thrusters to control the re-entry to make sure it occurs over water. However, as the Chinese have lost control of it, the craft is now in freefall.
“You really can’t steer these things,” Harvard astrophysicist Jonathan McDowell told The Guardian last year. “Even a couple of days before it re-enters we probably won’t know better than six or seven hours, plus or minus, when it’s going to come down. Not knowing when it’s going to come down translates as not knowing where it’s going to come down.”
The only thing known for certain so far is that it will crash down somewhere between 43 degrees North and 43 degrees South latitude. Most of this area is covered by water, meaning that the chance it will hit land is low and the odds it will crash into a settlement even smaller.
This, however, hasn’t stopped people from trying to predict where it might touch down. The website Satview, which tracks the location of satellites as they whizz around our planet, posted an update this week as to what their best estimate it.
According to their forecast, Tiangong-1 will likely re-enter in around three months, with their rather exact prediction being Wednesday, April 4, at 15:36 UTC. This, it almost goes without saying, should be taken with a pinch of salt, as there can be a host of external factors that could alter it. But, if Satview are indeed correct, it means that re-entry would occur over land despite all odds, with Venezuela and Colombia being in the firing line.
As if it hasn't been said enough already, the decaying orbit is incredibly unpredictable. We'll just have to wait and see what happens.