Leonard David's INSIDE OUTER SPACE

Artist’s concept of the Tiangong-1 in Earth orbit.
Credit: CMSA

The United Nations Office for Outer Space Affairs (UNOOSA) has reissued a notification by China on the future uncontrolled re-entry of the country’s Tiangong-1 space lab.

On March 16, 2016, the Tiangong-1 ceased functioning and to date the spacecraft has maintained its structural integrity.

The space lab’s operational orbit is under constant and close surveillance by China. Its current average altitude is 217 miles (349 kilometers) and it is decaying at a daily rate of approximately 525 feet (160 meters), according to the notification.

Re-entry date

The lab’s re-entry is expected between October 2017 and April 2018. According to the calculations and analysis that have been carried out, most of the structural components of Tiangong-1 will be destroyed through burning during the course of its re-entry.

“The probability of endangering and causing damage to aviation and ground activities is very low,” the notification adds.

Artist’s view of Tiangong space lab
Credit: CMSE

Taking measures

The notice advises that China attaches great importance to the re-entry of Tiangong-1 and will take the following measures in terms of monitoring its fall and providing public information:

— China will enhance monitoring and forecasting and make strict arrangements to track and closely keep an eye on Tiangong-1 and will publish a timely forecast of its re-entry

— China will make use of the international joint monitoring information under the framework of the Inter-Agency Space Debris Coordination Committee in order to be better informed about the descent of Tiangong-1.

— China will improve the information reporting mechanism. Dynamic orbital status and other information relating to Tiangong-1 will be posted on the website of the China Manned Space Agency (www.cmse.gov.cn) in both Chinese and English. In addition, timely information about important milestones and events during the orbital decay phases will be released through the news media

— As to the final forecast of the time and region of re-entry, China will issue the relevant information and early warning in a timely manner and bring it to the attention of the United Nations Office for Outer Space Affairs and the Secretary-General of the United Nations by means of “note verbale” through diplomatic channels.

Leftovers

Tiangong-1 was launched into Earth orbit on September 29, 2011. It conducted six successive rendezvous and dockings with spacecraft Shenzhou-8 (uncrewed), Shenzhou-9 (piloted) and Shenzhou-10 (piloted) as part of China’s human space exploration activities. The vehicle weighed  (18,740 pounds (8,500 kilograms) at launch.

Credit: The Aerospace Corporation’s Center for Orbital and Reentry Debris Studies (CORDS).

According to the Aerospace Corporation, based on Tiangong-1’s inclination, the lab will reenter somewhere between 43° North and 43° South latitudes. As for leftovers, “it is highly unlikely that debris from this reentry will strike any person or significantly damage any property,” adding: “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 Aerospace Corporation will perform a person and property risk calculation for the Tiangong-1 reentry a few weeks prior to the event.

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