The European Space Agency (ESA) Sunday updated its latest time prediction for Tiangong-1 re-entry into Earth's atmosphere, saying it would take place within a four-hour window centered on 01:07 UTC Monday night.
The agency had originally forecast re-entry between midday Saturday UTC and Sunday, later adjusting their prediction to between Sunday afternoon and Monday morning. The change in day in the defunct Chinese space lab's predicted return to Earth was due to changes in the conditions of solar activity, ESA said in a blog post.
A high-speed stream of sun particles failed to materialize as expected, leading to calmer space weather and no increase in the density of the upper atmosphere, which would have pulled the 8.5-metric-ton (9.4-ton) Tiangong-1 down toward Earth at a faster rate.
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ESA said the spacecraft could land anywhere between 43 degrees north latitude and 43 degrees south latitude. However, the agency emphasized the uncertainty around predicted re-entry information, stating: "At no time will a precise time/location prediction from ESA be possible."
Tiangong-1, or "Heavenly Palace," was launched into orbit in September 2011. A controlled return guided by ground engineers to Earth became impossible after the lab ceased functioning in March 2016.
Re-entry forecast: fiery with a chance of debris showers
The spacecraft will mostly burn up as it re-enters Earth's atmosphere due to the heat generated by its passage, ESA said.
However, it added that some craft parts could survive the atmospheric re-entry and reach the Earth's surface. The pieces could land over an area "that is thousands of kilometers in length and tens of kilometers wide," but the agency highlighted that "a large part of the Earth is covered by water or is uninhabited."
"Hence the personal probability of being hit by a piece of debris from the Tiangong-1 is actually 10 million times smaller than the yearly chance of being hit by lightning," ESA said.
Chinese authorities said that the spacecraft's fiery disintegration will provide a "splendid" show similar to a meteor shower, AFP reported.
Scientists at the Fraunhofer Institute for High-Frequency Physics and Radar Technology (FHR), located just south of the western German city of Bonn, is assisting ESA with radar technology and will be following Tiangong-1's fiery return to Earth. The institute will be regularly checking to see whether the descending lab remains intact or whether pieces have broken off.
As of Sunday morning, the FHR said there had been no damage to the craft.
The FHR said that Germany faces no risk from Tiangong-1's flaming fall to Earth.