Space lab re-entry expected by Monday

China's Tiangong I space lab is expected to re-enter the atmosphere between Saturday and Monday, according to the China Manned Space Agency.

The latest announcement, posted on Thursday afternoon on the agency's website, said Tiangong I was still in orbit at an average altitude of 196.4 kilometers on Thursday, which means it had descended 5.9 km since Wednesday. It also narrowed the earlier predicted window from the Beijing Aerospace Control Center, which had estimated that the re-entry would take place between Saturday and Wednesday.

Sources close to the matter told China Daily that it is extremely difficult to predict the exact time and location of the spacecraft's re-entry due to a host of factors such as the unpredictability of upper atmospheric drag and the ultrafast speed of the spacecraft.