Tiangong-1 Reentry

Tiangong-1

The world watched and waited as the Chinese space station Tiangong-1 hurtled towards a fiery reentry. Please visit our media kit page for background information.


Reentry Information

Tiangong-1 was predicted to reenter the Earth’s atmosphere on April 2nd, 2018 00:30 UTC ± 1.7 hours. The reentry has been confirmed as 2018/04/02 00:16 UTC. Reentry occurred in the Pacific Ocean.

This prediction was performed by The Aerospace Corporation on 2018 April 1.

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)

Reentry Dashboard: Where is Tiangong-1 now?

(Click on image to view full-size image.)

Reentry Overview Video


Tiangong-1 Altitude Prediction


Tiangong-1 Altitude History & Adjustments

Dotted lines indicate dates of probable orbital maneuvers.


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.

tiangong_1_drawing

Diagram of Tiangong-1 – Image credit: Wikimedia Commons

 

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.

 

FAQs

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.

As reentry gets closer, we are able to narrow possible reentry locations to a collection of specific ground tracks instead of broad regions of the globe. As the reentry time gets closer, the number of ground tracks will diminish until we are left with only one, and after that with only a portion of a single ground track. Areas not within the ground tracks are clear. The exact statistical likelihood of you or your property being struck by reentering debris is constantly changing. Potential reentry points and whether the final ground track is over inhabited or uninhabited areas will determine the risk to a specific location. Even so, the likelihood of any one person (i.e. YOU) being struck by debris is still far less than winning the Powerball Jackpot.

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.

Has anyone been harmed by reentry debris?

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 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

Newsweek

Wired

New York Times

Reuters: Tiangong-1 is not out of control

China’s Manned Space Program

 

 

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