Estimates vary as to when and where the 34ft long space station, which weights almost 10 tons, will crash - but it is believed to smash back down to Earth very shortly.
Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics, estimates that Tiangong-1 is the 50th most massive uncontrolled re-entry of an object since 1957, when the Soviet Union launched Sputnik 1 - the world's first artificial satellite.
Mr McDowell tweeted that Tiangong-1 is expected to land between 11pm to 5am United Kingdom time.
The Paris-based agency, which is managing the worldwide campaign to follow the laboratory's fall, said on Saturday that the time and place of its re-entry continues to be a "highly variable" prediction affected by the changing solar activity, reports Efe news.
Nasa's first space station, Skylab, fell to Earth in an out-of-control reentry in 1979, burning up harmlessly in the process.
So what might you see from Earth? China's chief space laboratory designer Zhu Zongpeng has denied Tiangong was out of control, but hasn't provided specifics on what, if anything, China is doing to guide the craft's re-entry. Space.com reports that Aerospace Corp., which is tracking the orbital fall of the space station, has estimated the crash to occur between March 31 and April, with an emphasis on 10:00 a.m. EST.
China was excluded from the 420-ton International Space Station mainly due to US legislation barring such cooperation and concerns over the Chinese space program's strong military connections.
The material is used as rocket fuel, but exposure to humans is believed to cause symptoms like nausea and seizures, with long-term contact said to cause cancer.
It poses only a slight risk to people and property on the ground, since most of the bus-size, 8.5-ton vehicle is expected to burn up on re-entry, although space agencies don't know exactly when or where that will happen.
Tiangong loomed just 90 miles above Earth by 3:30 p.m. Sunday, according to live-tracker Heavens Above.
"In the history of spaceflight, no known person has ever been harmed by re-entering space debris".
That has to do with the fact that the atmosphere can behave in odd ways - plus, no one has control of the space station. The delay was announced by the ESA which monitoring the station's movement.
"This means that re-entry may take place over any spot on Earth between these latitudes, which includes several European countries, for example".
Re-entry predictions will gain accuracy as the moment nears.