The Pacific Ocean Takes the Hit

Tiangong-1, the ‘Heavenly Palace,’ was an unmanned space lab launched on September 29, 2011. (Image:  CMSE)
Tiangong-1, the ‘Heavenly Palace,’ was an unmanned space lab launched on September 29, 2011. (Image: CMSE)

The Chinese space lab, Tiangong-1, was in the news for all the wrong reasons. The media frenzy over the school bus-sized space station suggested that bits of its debris could very well fall anywhere between 43 degrees north and 43 degrees south latitudes, practically all of Earth’s most populated area. The “uncontrolled” fall of a space module this big had many questioning China’s space technology; however, the remains of Tiangong-1 were ultimately absorbed by the Pacific Ocean.

What was the Tiangong-1?

Tiangong-1, the “Heavenly Palace,” was an unmanned space lab launched on September 29, 2011. It was made of two sections — a resource module that contained the solar-power and propulsion systems, and the experimental module for visiting astronauts and their work units. The mission was built to establish a docking station for China’s permanent space station in the Earth’s orbit planned for 2023. It played host to two successful manned space missions, which also included China’s first female astronauts.

Chinese contact with Tiangong-1 was cut off in 2016 as it began to move  slowly toward Earth. The module was only meant to be “active” for two years and China had planned to de-orbit it in a controlled manner. However, as the link got cut off and China stopped receiving data from the module, the fall was no longer under control.

Tiangong-1 was made of two sections: a resource module that contained the solar-power and propulsion systems, and the experimental module for visiting astronauts and their work units. (Image: CMSE)

Tiangong-1 was made of two sections: a resource module that contained the solar-power and propulsion systems, and the experimental module for visiting astronauts and their work units. (Image: CMSE)

It was announced by many space agencies that most of Tiangong-1 would break apart and burn up in the atmosphere, however, it was also possible for some of its “harder” parts to survive re-entry and land on the Earth’s surface. Multiple estimates suggested that the pieces were more likely to enter an ocean, with the odds of the debris hitting any human to be less than 1 in 1 trillion.

Much ado about nothing?

Space debris falling to Earth is no longer uncommon, whether the fall is controlled or not. During a controlled fall, it is easier to ensure that the object and its parts enter the ocean or fall on unpopulated areas to avoid harm. In an uncontrolled situation, Earth’s atmospheric drag drives the fall, making it inconsistent and unpredictable. There was chaos over Tiangong-1’s landing until the very end, showing how difficult tracking can be. Having said that, Tiangong-1 was certainly not the biggest uncontrolled space-object to enter Earth. An example of a previous larger one was NASA’s 152,000 pound Skylab that hit Australia in 1979.

The final orbit of Tiangong-1 above the Pacific Ocean with 10 minute markers. (Image: Tomruen via wikimedia CC BY-SA 4.0)

The final orbit of Tiangong-1 above the Pacific Ocean with 10-minute markers. (Image: Tomruen via wikimedia CC BY-SA 4.0)

On the other hand, China’s lack of transparency, as usual, over the whole matter has left a sour taste. This secrecy has made it difficult for other space agencies to assess risk. Without knowing the composition of the spacecraft — that is, information on the material buildup of hard and lightweight components — the international community had to assume the worst. An uncontrolled fall also meant that China was unprepared for such an outcome.

Additionally, China had been denying the loss of control for the longest time. China also has been previously reprimanded by the international community in 2007 for using a missile to destroy a Chinese satellite that wasn’t in use. The missile collision with the satellite had created a “large and potentially dangerous cloud of debris.” With continued risks and Tiangong-2 still in orbit, China needs to own up and take more responsibility for what they put in space.

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