Tiangong-1 Reentry


Tiangong-1 is currently predicted to reenter the Earth’s atmosphere around April 1st, 2018 ± 4 Days.

Object Description

Type: Payload
Int’l Designation: 2011-053A
NORAD Number: 37820
Launched: 2011 September 30 @ 03:16:03.507 UTC
Site: Jiuquan Satellite Launch Center, China
Mission: Tiangong-1, First Chinese Space Station
Mass: 8500 kg at launch (18,740 lbs)
Length: 10.5 m (34 ft)
Diameter: 3.4 m (11 ft)
Solar panels: 2 panels (approx. 7 m x 3 m)



Diagram of Tiangong-1 – Image credit: Wikimedia Commons


Reentry Information


Tiangong-1 is predicted to reenter in around April 1st, 2018 ± 4 Days*.

This prediction was performed by The Aerospace Corporation on 2018 March 20.

*Note: This prediction assumes an uncontrolled reentry (no thrusting).


Orbit of Tiangong-1 as of 2018 March 13 @ 00:00:00.000 UTC. The Apogee (highest point in the orbit) = 259 km while the Perigee (lowest point in the orbit) = 231 km. For reference, the International Space Station is in a 400 km circular orbit.


Tiangong-1 Reentry Hazard

There is a chance that a small amount of Tiangong-1 debris may survive reentry and impact the ground. 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.

When considering the worst-case location (yellow regions of the map) the probability that a specific person (i.e., you) will be struck by Tiangong-1 debris is about one million times smaller than the odds of winning the Powerball jackpot. In the history of spaceflight, no known person has ever been harmed by reentering space debris. Only one person has ever been recorded as being hit by a piece of space debris and, fortunately, she was not injured.


Tiangong-1 Altitude Prediction


Tiangong-1 Altitude History & Adjustments

Dotted lines indicate dates of probable orbital maneuvers.


*Prediction and altitude history graphics updated weekly*



Mission Background

  • Tiangong-1 is the first space station built and launched by China.
  • It was designed to be a manned lab as well as an experiment/demonstration for the larger, multiple-module Tiangong station.
  • The spacecraft was launched aboard a Long March 2F/G rocket on 2011 September 30 UTC.
  • There are 2 modules that compose Tiangong-1: A habitable experimental module and a resources module.
  • It has a habitable volume of 15 cubic meters.
  • Tiangong-1 is equipped with 2 sleep stations for astronauts.
  • The first Chinese orbital docking occurred between Tiangong-1 and an unmanned Shenzhou spacecraft on 2011 November 2.
  • 2 manned missions were completed to visit Tiangong-1: Shenzhou 9 and Shenzhou 10.


Manned Visits to Tiangong-1

Shenzhou 9 Shenzhou 10
Launched 2012 June 16 with 3 astronauts Launched 2013 June 11 with 3 astronauts
China’s first female astronaut (Liu Yang) was aboard First Chinese orbital maintenance completed
Completed 2 dockings – 1 computer-controlled, 1 crew-guided More docking tests executed
13 day mission, 11 days spent at station 15 day mission, 13 days spent at station

Has There Been a Loss of Control?

On 2016 March 21, an official Chinese statement declared that telemetry services with Tiangong-1 had ceased. Based on The Aerospace Corporation’s analysis of Two-Line Element set data from the JSpOC, the last orbital adjustment for Tiangong-1 was made in December 2015. Likewise, amateur satellite trackers have been tracking Tiangong-1 and claim it has been orbiting uncontrolled since at least June 2016. On 2016 September 14, China made an official statement that they predict Tiangong-1 will reenter the atmosphere in the latter half of 2017.  China later updated its prediction via an announcement to the UN’s Committee on Peaceful Uses of Outer Space on December 8, 2017.  It was not mentioned whether the reentry was to be targeted or remain uncontrolled.



Where will Tiangong-1 reenter?

It is a well known scientific principle that any measurement or prediction will always have an associated uncertainty. In the case of most reentering objects, the uncertainty associated with predicting reentry location is extremely large and precludes an accurate location prediction until shortly before the reentry has occured. In general, it is much easier to predict an accurate reentry time rather than an accurate reentry location. Based on Tiangong-1’s inclination, however, we can confidently say that this object will reenter somewhere between 43° North and 43° South latitudes.

How Difficult is it to Accurately Predict a Reentry?

Due to the uncertainties involved it is very difficult to predict the exact timing of a space object’s reentry. There are several sources of uncertainty which include: 1) significant variation in the density of the upper layers of the atmosphere, 2) significant uncertainties in the orientation of the space craft over time, uncertainties in some physical properties of the spacecraft such as the exact mass and material composition, and 3) uncertainties in the exact location and speed of the space station. When aggregated, these factors translate into a reentry timing uncertainty that is roughly 20% of the “time to go” (the time between the date of the prediction and the predicted date of reentry).

Will objects from this reentry hit me or my property?

It is highly unlikely that debris from this reentry will strike any person or significantly damage any property. The only known case of space debris striking a person is Ms. Lottie Williams of Tulsa, Oklahoma who was struck by a small piece of space debris in 1996 but was not harmed in any significant way. The Aerospace Corporation will perform a person and property risk calculation for the Tiangong-1 reentry a few weeks prior to the event.

Is this a controlled reentry?

It is unlikely that this is a controlled reentry. Although not declared officially, it is suspected that control of Tiangong-1 was lost and will not be regained before reentry.

Are there people on board? Are they in danger?

No, no astronauts are currently on board Tiangong-1. The last manned mission departed from Tiangong-1 in June 2013.

Can I see the reentry?

It may be possible to see Tiangong-1 reentering depending on your location, the time of day, and visibility during reentry which will not be known until a few days prior to the event. A more detailed predicted reentry region will be provided a few days prior to the reentry time frame. Visibly incandescent objects from this reentry will likely last tens of seconds (up to a minute or more) in contrast with the vast majority of natural meteors which last mere seconds.

What will this reentry look like?

Depending on the time of day and cloud visibility, the reentry may appear as multiple bright streaks moving across the sky in the same direction. Due to the relatively large size of the object, it is expected that there will be many pieces reentering together, some of which may survive reentry and land on the Earth’s surface. Some examples of reentries can be found here: video 1, video 2.

Are there hazardous materials on board?

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.

Should I report a sighting of the reentry? If so, to whom?

Yes. Contact CORDS at http://www.aerospace.org/cords/contacting-cords/ – Please report your location and time of the sighting, a description of what you saw, and provide any images or videos you may have captured of the reentry.

Is this the largest man made object to ever reenter from space?

No. The largest object to reenter is the Mir space station at 120,000 kg which reentered on 2001 March 23. In comparison, Tiangong-1 is only 8,500 kg. For further space debris reentry information, consult the table on this page.


Tiangong-1 European Space Agency (ESA) Blog

Tiangong-1 FAQ

Tiangong-1 Reentry Update

Tiangong-1 Captured via Telescope

Reentry Test Campaign Announcement


Tiangong-1 in the News

Basic Tiangong-1 background info

Official statement regarding Tiangong-1 telemetry ceasing

Official statement regarding Tiangong-1 reentry

Amateur satellite trackers claim Tiangong-1 likely uncontrolled

Controlled vs. uncontrolled reentries

General reentry info



New York Times

Reuters: Tiangong-1 is not out of control

China’s Manned Space Program



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