Tiangong-1 space laboratory containing hazardous substance to crash to Earth in March

An artist’s rendering of the Shenzhou 9 spacecraft docking with Tiangong 1 space laboratory in 2012. Image Credit: Keith McNeill / Space Models Photography

According to new calculations, China’s space laboratory, Tiangong-1 will fall to Earth in March of 2018. While most parts of the spacecraft are likely to burn up in the atmosphere, there are concerns that some pieces, containing highly-toxic chemicals, may hit the ground.

Beijing lost control over Tiangong-1 on March 16, 2016. It is believed that the space station ceased functioning due to a dysfunctional battery charger. Since then, the module has been unable to recharge its batteries from its two solar arrays. However Chinese officials provided little information stating only that the laboratory had started to descend gradually and would eventually fall to Earth.

China finally confirmed in mid-September of 2016 that the spacecraft was heading for an imminent re-entry, but they still did not disclose whether the station’s descent is controlled or not. First announcements made by the China Manned Space Engineering Office (CSME) indicated that Tiangong-1 was (at that time) orbiting at an average altitude of 230 miles (370 kilometers) and was descending for its fiery reentry into Earth’s atmosphere in late 2017.

In May of 2017, China informed the United Nations (UN) that Tiangong-1’s orbit had decreased to an altitude of some 217 miles (349 kilometers) and that it was decaying at a daily rate of approximately 525 feet (160 meters). This indicated that the re-entry of the spacecraft is expected sometime between October 2017 and April 2018.

Now, a new report issued by Aerospace Corporation, a non-profit corporation that provides technical guidance and advice on all aspects of space missions, predicts that Tiangong-1 will fall to Earth in March 2018, most likely in the middle of the month. Perhaps what is the most alarming aspect of this report is that it warns that parts of the spacecraft, which could survive the re-entry, may contain hydrazine – a highly-toxic material used in rocket fuels.

“Potentially, there may be a highly toxic and corrosive substance called hydrazine on board the spacecraft that could survive reentry. For your safety, do not touch any debris you may find on the ground nor inhale vapors it may emit,” the warning issued by Aerospace Corporation’s Center for Orbital and Reentry Debris Studies (CORDS) reads.

Hydrazine is used as a propellant for the maneuvering thrusters of spacecraft. Other variants of hydrazine that are used as rocket fuel are monomethylhydrazine and unsymmetrical dimethylhydrazine. According to the U.S. Environmental Protection Agency, short-term exposure to high levels of hydrazine may include irritation of the eyes, nose, and throat, dizziness, headache, nausea, pulmonary edema, seizures, coma in humans. Moreover, long-term exposure to this substance is believed to cause cancer in humans.

In the report, CORDS also provided some insights regarding the possible location of the imminent Tiangong-1 re-entry. Its experts predict that the spacecraft will re-enter the atmosphere somewhere between 43 degrees North and 43 degrees South latitudes, most likely at higher latitudes.

This large swath of Earth includes Northern parts of the U.S., and countries such as Spain, Italy, Turkey, China, North Korea or Japan in the Northern hemisphere. When it comes to the Southern hemisphere, most probably it would re-enter over Chile, Argentina, Southern Australia or New Zealand.

Over all, CORDS’ report delivers more detailed information about Tiangong-1’s re-entry than the latest note that China sent to the UN on December 8, 2017. The brief document only informed the organization that the fall of the spacecraft is expected between the first 10 days of February and the last 10 days of March 2018. Beijing added that until November 26, the laboratory had been orbiting at an average altitude of 184 miles (296 kilometers) and insists that the Tiangong-1 and the fuel it contains, will not harm those on the ground.

“Based on analysis, the remaining small amount of fuel will be burned and destroyed along with its structural components during the course of re-entry and will therefore not cause any damage on the ground,” the note states.

As was the case with previous note to the UN, China again assured that it is committed to further monitoring and forecasting the descent of Tiangong-1 and will inform the public as soon as more information is available.

Tiangong-1 (“Heavenly Palace” in Chinese) is China’s first space laboratory. With a mass of about 8.5 metric tons, Tiangong-1 measures some 34 feet (10.4 meters) long and has a diameter of approximately 11 feet (3.4 meters). The station was launched in September of 2011. Nine months later, in June, 2012, three Chinese taikonauts docked their Shenzhou-9 spacecraft to the station for the first time. The module was visited again in June 2013 when the Shenzhou-10 spacecraft transported another trio of taikonauts.

Besides being used as a laboratory for space research, Tiangong-1 also served as an experimental platform from which China could demonstrate orbital rendezvous and docking capabilities. The orbiting laboratory was also used as a stepping stone to pave the way for the nation’s future space stations, the next of which the country plans to complete in 2022. Along with its predecessor, Tiangong-2 (launched in September 2016), Tiangong-1 helped test technologies deemed critical for this planned modular orbital outpost.

Tagged: China China National Space Administration Lead Stories Tiangong-1

Tomasz Nowakowski

Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski's generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.