China Aerospace Engineering Bureau said it expected the lab to re-enter the atmosphere between March 31 and April 4, and burn it.
Alan Duffy, a researcher at the Center for Astrophysics and Supercomputers at the Swinburne Technical University in Australia, said China's secrecy on the space mission made the risks difficult to assess.
"The international community does not know what the ship is made of, and that makes the danger more difficult as heavy fuel tanks can reach the ground, whereas lightweight panels do not," he said.
Space Station Prototype
In its UN submission to the plane's crash to earth, China said the likelihood of "jeopardizing and harming aviation and ground operations is very high."
In January, Zhu Zongpeng, the chief designer of the space laboratory, told China Youth Daily that China was monitoring the Tiangong-1. He predicted that most of it would burn if it entered the atmosphere while the rest would fall into the sea.
Markus Dolensky, the technical director of the International Center for Radio Astronomy research in Australia said that if the sky is clear, witnesses may be able to see a "series of fireballs crossing the sky".
"It is now approaching its fiery demise as it is gradually decelerated from the edges of the upper Earth's atmosphere," he said.
It is not uncommon for space debris such as spent satellites and rocket stages to fall to earth, though ships that are capable of sustaining human life are much rarer.
Experts said that it is difficult to pinpoint where the space laboratory will fall, but it is expected to fall within a latitude of 43 degrees north and south of the planet Equator crashes.
"Some parts of the upper atmosphere are thicker than others, which means that the ship will unpredictably slow down and because it moves around the earth in just 90 minutes, even a two-minute uncertainty can cause the ship to go somewhere along a 1,000 kilometer route. " Said Duffy.