Leonard David's INSIDE OUTER SPACE

Tiangong-1 altitude decay forecast as of March 21.
Credit: ESA

The latest reentry forecast for China’s Tiangong-1 space lab has been provided by the European Space Agency’s (ESA) Space Debris Office in Darmstadt, Germany.

In a March 21 update, the Tiangong-1 reentry window forecast is now roughly March 30 to roughly April 2, with the Space Debris Office noting that this is highly variable.

Credit: The Aerospace Corporation/CORDS

Tiangong-1 was lofted in late September 2011. The first Chinese orbital docking occurred between Tiangong-1 and an unpiloted Shenzhou spacecraft on November 2, 2011. Two piloted missions were completed to visit Tiangong-1: Shenzhou 9 and Shenzhou 10.

Docking of China’s Shenzhou 10 spacecraft with the Tiangong-1 space station June 13, 2013.
Credit: CCTV

Test campaign

Meanwhile, ESA will serve as host and administrator of a test campaign regarding the reentry of China’s space lab, conducted by the Inter Agency Space Debris Coordination Committee (IADC).

IADC comprises space debris and other experts from 13 space agencies/organizations, including NASA, ESA, European national space agencies, Japan’s JAXA, India’s ISRO, Korea’s KARI, Russia’s Roscosmos and the China National Space Administration.

IADC members will use the fall of Tiangong-1 to conduct their annual reentry test campaign, during which participants will pool their predictions of the time window, as well as their respective tracking datasets obtained from radar and other sources. The aim is to cross-verify, cross-analyze and improve the prediction accuracy for all members.

Artist’s view of Tiangong space lab
Credit: CMSE

Two modules

There are two modules that compose Tiangong-1: A habitable experimental module and a resources module. It has a habitable volume of 15 cubic meters and is equipped with sleep stations for astronauts.

The space lab’s mass at launch was over 9 tons (18,740 pounds; 8,500 kilograms).Tiangong-1’s length is 34 feet (10.5 meters) and sports a diameter of 11 feet (3.4 meters) It is outfitted with two solar panels that are roughly 7 meters by 3 meters.

There is a chance that a small amount of Tiangong-1 debris may survive reentry and impact the Earth’s surface. Should this happen, any surviving debris would fall within a region that is a few hundred kilometers in size and centered along a point on the Earth that the station passes over. The map below shows the relative probabilities of debris landing within a given region. Yellow indicates locations that have a higher probability while green indicates areas of lower probability. Blue areas have zero probability of debris reentry since Tiangong-1 does not fly over these areas (north of 42.7° N latitude or south of 42.7° S latitude). These zero probability areas constitute about a third of the total Earth’s surface area.
Credit: The Aerospace Corporation’s CORDS

Where on Earth?

As to where on Earth Tiangong-1’s will reenter, that’s an unknown. But given the spacecraft’s inclination, this object will reenter somewhere between 43° North and 43° South latitudes.

Owing to the Chinese station’s mass and construction materials, there is a distinct possibility that some portions of Tiangong-1 will survive and reach the Earth’s surface.