Thursday 28 July 2022

CZ-5B rocket stage 2022-085B: reentry forecasts

 (this post is periodically updated when new tracking data become available and have been analyzed)

last updated 30 July 19:05 UT   

My latest forecast is: 30 July, 17:10 UTC +- 15m

The latest CSpOC forecast was:  30 July, 16:49 UTC +- 10m 

The FINAL CSpOC TIP is 16:51 UTC +- 1m, near 3.4 N, 113 E

A possible reentry observation has been made from Kuching (Sarawak, Borneo) near 16:50 UTC 

Click diagram to enlarge


On 24 July 2022, China launched a CZ-5B rocket carrying the Wentian module to the Chinese Space Station. The huge CZ-5B core stage, 2022-085B, with a dry mass of 18 tons and a length of 33 meter, is now set for an uncontrolled reentry on July 30.

The diagram above shows the evolution of apogee and perigee altitudes so far.

I am running reentry models in the General Mission Analysis Tool (GMAT) for the CZ-5B stage, that currently point to reentry in the second half of July 30 UTC. At this point in time it is still too early to pinpoint a more precise time or location - and for this reason I do not give geographic coordinates for the nominal reentry point yet.

The map below shows the current risk area, based on the latest forecast and its uncertainty window. Within the uncertainty window, the rocket stage can come down anywhere on the blue line in the map. The yellow circle is the nominal reentry position, i.e. the center of the uncertainty interval, but not necessarily the most likely location.


Current risk area. Click map to enlarge

Movement of the spacecraft is from west to east = left to right on the map. Cities between 41.5 N and 41.5 S with 1 million or more inhabitants are shown as yellow dots.

Below is a diagram of the evolution of the reentry forecast so far. Below the diagram is the same data in tabular form, with the most recent forecast at the bottom of the table.

- My latest GMAT based forecast (black dots) is: 30 July, 17:10 UTC +- 15 m

- The last pre-reentry CSpOC TIP forecast (red dots) is: 30 July, 16:49 UTC +- 10 m

- The FINAL CSpOC TIP is 16:51 UTC +- 1 m, near 3.4 N, 113 E

The latter time, with its 1 minute uncertainty, and position are likely based on an infra-red detection of the reentry fireball by a SBIRS Early warning satellite. So it seems my last forecast was about 20 minutes off. It reentered more or less at the start of my uncertainty window.

Below is a map with the final revolution and actual reentry location:


click map to enlarge

Each dot is a prediction based on a new orbit release. On the x-axis is the date/time (in decimal days) of the orbit on which the forecast is based. On the y-axis is the predicted reentry time/date resulting from a GMAT model run using  this orbit. These too are given in  decimal days (e.g., "30.5" = "30 July, 12:00 UTC". Note: for dates beyond July 31, "July 32.0" means "August 1, 00:00 UTC" etc.). 

Error bars show the uncertainty in the prediction. Note how the uncertainty window become smaller once we get closer to the reentry.

The black dots are the results of my GMAT model runs. The red dots are predictions by CSpOC, the US Military tracking organization (and "the" authoritive source of orbital tracking data), given for comparison.

click diagrams to enlarge

My reentry modelling in GMAT uses the MSISE90 model atmosphere, current, predicted and past spaceweather, a dry mass of 18000 kg and a drag surface of 62% of the maximum value, which is the best estimate for the average drag surface of a tumbling rocket stage of these dimensions. The depicted uncertainty window is a fixed 20% of the timespan between orbit epoch and the reentry time forecast resulting from the orbit.


GMAT model forecasts:


 25-07 11:52:33    31-07 08:28  +-  28.1 h
 25-07 13:01:55    31-07 02:51  +-  26.8 h
 25-07 14:30:57    31-07 02:42  +-  26.4 h
 25-07 17:29:00    31-07 02:45  +-  25.9 h
 25-07 19:29:01    31-07 02:08  +-  25.3 h
 26-07 03:04:47    31-07 02:39  +-  23.9 h
 26-07 11:16:28    31-07 03:40  +-  22.5 h
 26-07 13:11:03    31-07 02:22  +-  21.8 h
 26-07 15:43:05    31-07 02:34  +-  21.4 h
 26-07 18:40:46    31-07 02:44  +-  20.8 h
 26-07 19:12:28    31-07 01:04  +-  20.4 h
 27-07 14:41:30    30-07 21:29  +-  15.8 h
 27-07 15:55:00    30-07 20:57  +-  15.4 h
 27-07 17:18:31    30-07 21:01  +-  15.1 h 
 27-07 18:20:32    30-07 23:39  +-  15.5 h
 28-07 17:05:39    30-07 23:46  +-  10.9 h
 29-07 01:18:22    30-07 21:36  +-   8.9 h
 29-07 08:55:31    30-07 20:12  +-   7.1 h  
 29-07 13:03:52    30-07 19:20  +-   6.1 h   
 29-07 16:34:29    30-07 18:58  +-   5.3 h  
 29-07 18:00:07    30-07 19:00  +-   5.0 h  
 30-07 01:31:37    30-07 20:06  +-   3.7 h 
 30-07 08:22:22    30-07 17:50  +-   1.9 h  
 30-07 09:54:18    30-07 17:29  +-   1.5 h  
 30-07 12:28:44    30-07 17:28  +-   1.0 h 
 30-07 12:58:01    30-07 17:30  +-    54 m  
 30-07 14:17:27    30-07 17:20  +-    37 m   33 N 126 W  
 30-07 15:48:42    30-07 17:09  +-    16 m   40 N 178 E
 30-07 15:57:24    30-07 17:10  +-    15 m   41 N 173 W  latest


UPDATE 30 July 17:15 UT:

Footage purportedly shot today from Kuching (Sarawak, Borneo) appears to show the reentry of 2022-085B. It would place reentry near ~16:50 UTC. The footage is here, in a tweet by Nazri Suleiman.
I say 'purported' because for the moment the footage has not yet been verified. But it seems likely it is the reentry indeed.


UPDATE 30 July 19:05 UT:

CSpOC gives a final TIP of 16:51 +- 1m UTC near 3.4 N, 113 E, which matches the Kuching sightings well (multiple video's from the Kuching region have since turned up on social media, so it is now quite certain that this was the reentry).

The map below gives the final orbital revolution and location of reentry over Borneo.


click map to enlarge


Other forecast sources:

CSpOC  (

Aerospace Corporation  (

Josep Remis  (

ESA  ( 



Added note on 'Live' satellite tracking websites

BEWARE: contrary to what many people think, purported 'Live' satellite tracking websites such as are NOT showing you satellite locations based on 'live' tracking data!

In reality, they show predictions based on older orbital element sets, that can be hours old actually.

This can be deceptive. They sometimes happily show an object apparently still "on orbit" after it in reality already reentered!

Thursday 7 July 2022

A failed US missile test on July 7


click to enlarge

In the first week of July, two Navigational Warnings appeared (NAVAREA XII 431/22 and HYDROPAC 1811/22) that indicated an ICBM-type missile test in the Pacific for a multiple day window starting July 7, with launch from Vandenberg AFB in California and target the Reagan Test Site at Kwajalein.

These are the Navigational Warnings in question:

030348Z JUL 22
NAVAREA XII 431/22(18,19).
   A. 34-47.00N 120-37.00W, 34-51.00N 120-36.00W,
      34-52.00N 121-25.00W, 34-39.00N 121-25.00W,
      34-40.00N 121-01.00W, 34-47.00N 120-37.00W.
   B. 34-56.00N 123-14.00W, 34-51.00N 123-57.00W,
      34-05.00N 123-49.00W, 34-10.00N 123-06.00W,
      34-56.00N 123-14.00W.
   C. 35-01.00N 124-11.00W, 34-48.00N 126-00.00W,
      33-40.00N 125-47.00W, 33-54.00N 123-59.00W,
      35-01.00N 124-11.00W.
   D. 34-34.00N 128-22.00W, 34-17.00N 130-07.00W,
      33-03.00N 129-49.00W, 33-20.00N 128-05.00W,
      34-34.00N 128-22.00W.
   E. 33-04.00N 136-33.00W, 32-51.00N 137-30.00W,
      31-54.00N 137-11.00W, 32-06.00N 136-15.00W,
      33-04.00N 136-33.00W.
2. CANCEL THIS MSG 111344Z JUL 22.

030450Z JUL 22
HYDROPAC 1811/22(81).
DNC 12.
   ALTERNATE 080600Z TO 081258Z JUL
   A. 09-16.00N 167-22.00E, 09-23.00N 167-33.00E,
      09-32.00N 167-26.00E, 09-37.00N 167-29.00E,
      09-37.00N 167-45.00E, 09-38.00N 168-00.00E,
      09-37.00N 168-03.00E, 09-07.00N 168-05.00E,
      09-05.00N 168-03.00E, 08-56.00N 167-34.00E.
   B. 08-56.00N 163-29.00E, 09-14.00N 165-41.00E,
      09-03.00N 166-19.00E, 08-18.00N 166-49.00E,
      07-25.00N 166-58.00E, 06-18.00N 166-54.00E,
      06-00.00N 165-11.00E, 06-15.00N 164-09.00E,
      07-30.00N 163-18.00E, 08-10.00N 163-12.00E.
2. CANCEL THIS MSG 081358Z JUL 22.

The number and geographic locations of the hazard areas indicated to me that this was not a standard Minuteman-III test. In the map below, blue are the hazard areas from the 7 July Area Warnings; red that for a typical Minuteman III test (shown example is the 29 Oct 2020 test). Near California, the number and positions of the hazard areas are clearly different.

click map to enlarge

As it turns out, this indeed was not a Minuteman-III launch, but a test launch of a Minotaur-II with a new experimental reentry vehicle, the Mk21A developed by Lockheed Martin. This warhead is a future  replacement for the W87 warhead on the future LGM-35 Sentinel missile being developed by Northop-Grumman.

The launch at 6:01 UT on July 7, was a failure: according to a press release from Vandenberg, the missile exploded about 11 seconds in flight, starting a fire in the area.

Rearrangements in the USA 328 - 331 'train'


click image to enlarge

In front of the 'train' USA 328 to USA 331 launched last month (see previous posts here and here), things are changing, and objects are being rearranged.  The train is streching out too. It now takes the train almost 6 minutes to pass, and the bright F object is no longer the last trailing object.

On the night of 5/6 July, USA 328 and USA 329 were very close to each other. The image above is a stack of 100 video frames (4 seconds)  showing both objects. The brightness difference of almost 2 magnitudes between (the objects we dubbed) USA 328 and USA 329 was remarkable.

Below is a video of this pass. The footage was made with a WATEC 902H2 Supreme + Samyang 1.4/85 mm lens.  The two objects were some 2 km apart in reality.