Crash Landing

Earth’s gravity constantly pulls all objects in orbit toward the planet. Satellites that orbit Earth need this pull to keep them from flying off into space. But if a satellite slows down or shifts paths a little too much, it can fall back to Earth. That’s why satellites are equipped with small rockets to steer them and to keep them in orbit. When China lost contact with Tiangong-1, scientists could no longer use these tools to maintain the space station’s orbit. They predicted the space station would fall to Earth in late 2017 or early 2018. (Learn more about the prediction in a short news article from Science World.)

Large pieces of space debris—like Tiangong-1—fall from orbit back to Earth about once a year, passing through Earth’s atmosphere at very high speeds. The atmosphere is the layer of gases that surround the planet. Falling through the gases creates friction, a physical force that slows an object’s movement and creates heat. The heat becomes so intense that most space objects burn up on reentry.

But Tiangong-1 is larger than most space debris. Experts predicted 10 to 40 percent of the space station would make it to Earth’s surface. The China Manned Space Agency is uncertain how much of the station survived reentry. But don’t worry: The odds of a person getting struck by debris from the space station are less than 1 in 1 trillion.

Tiangong-1 isn’t the largest space station to fall out of orbit. In 1979, the U.S. space station Skylab crashed to Earth. It weighed 10 times as much as Tiangong-1. Pieces of it landed in Western Australia, but no one was hit by space debris. Most of the time, space debris lands in the oceans. Water covers 71 percent of the planet, so it’s much more likely that debris will land in water than on land.

Because there was no way to control Tiangong-1, it was very difficult for scientists to predict when and where it would land. People were on alert watching out for the spacecraft for many weeks leading up to the big crash. Initial predictions estimated that it could break apart over one-third of the planet, including large parts of North America.  

The odds of finding a piece of the space station are astronomically low, but if you do spot some debris, don’t touch it! Initially, the debris will be hot from passing through Earth’s atmosphere. It could also be sharp and possibly covered in toxic chemicals from rocket fuel. Instead, contact your local authorities—any debris is still the property of China!