Showing posts with label Australia. Show all posts
Showing posts with label Australia. Show all posts

Tuesday, 3 March 2026

The observed reentry of the Chinese CZ-2C upper stage 2018-054D over Australia on 28 February 2026

still from reentry movie. Click to enlarge. image (c) Robert H. McNaught, used with permission

On 28 February 2026 near 18:40 UTC, a Chinese CZ-2C upper stage (catalogue nr 43521, International Des. 2018-054D) reentered over southeast Australia.

Astronomer Robert H. McNaught filmed the early stage of the reentry from Coonabarabran (near Siding Spring Observatory), New South Wales. The event occurred low - about 10 degrees - above his northern horizon. His footage captures just over a minute of the early stages of the reentry, showing a single object sporting a clear plasma tail. After about a minute, the object moves behind cloud cover, only briefly to be seen again in a gap very low on the horizon. Above is a still from his movie, showing the rockert stage as a bright dot, sporting a bright plasma tail in its wake. Below is a snippet of footage from the movie:

 

 

Enough stars can be seen in the footage to do decent astrometry. I therefore measured several astrometric positions from the reentry movie, using AstroRecord.

Next, I used the last available orbit (dating from about 6h 45m before the reentry) to create a reentry model, using our open source TU Delft Astrodynamics Toolbox (Tudat). The goal was to see if I could recreate the trajectory as observed from Coonabarabran with our model.

Setting the mass at 3800 kg, I varied the drag area in the model untill I got a trajectory that indeed closely matches that filmed from Coonabarabran. 

Below is the result: red crosses are astrometric positions from the video footage, the blue line is the Tudat-modelled trajectory, and the blue numbers along the trajectory are the modelled atmospheric altitudes of the reentering object, in km. 

 

click diagram to enlarge
 

There is a discrepancy of about 20 seconds in time between the modelled trajectory and the observations, but otherwise it fits well in terms of the observed sky trajectory. 

The exercise provides information on the approximate altitude of the object during the reentry observations, and the geographic extend of the reentry trajectory. 

The footage picks the object up at an altitude of ~86 km, just as it begins to ablate, forms a plasma tail, and becomes incandescent, and before it starts to break up. The object is lost behind cloud cover at around 80 km altitude. Breakup likely occurred later, after the object went behind the cloud cover, once it reached 70-60 km altitude. By the time of breakup, from the reconstructed trajectory, it was likely already over sea: any remaining fragments fell into the ocean in front of the east coast of Australia.

In the map below, the blue line is the final trajectory: the yellow line is the part of the reentry trajectory that was above the horizon as seen from Coonabarabran (the part covered by the footage is shorter).

click map to enlarge
 

No final TIP was issued for this reentry by the US Space Force. The footage by Rob McNaught and this analysis is the only confirmation on where the object reentered. 

The  pre-reentry forecast by our Tudat model (see https://reentry.langbroek.org), based on a drag area that was slightly smaller than the result of the current analysis, had it reenter 20 minutes later, which given the almost 7 hours gap between the last available orbit and the moment of reentry, is actually not that bad an estimate.

With many thanks to Rob McNaught for communicating his observations, and for allowing me to use his imagery in this blogpost. Reentry footage (c) Robert H. McNaught.

Monday, 20 October 2025

[MULTIPLE UPDATES] Possible Space Debris found near Newman, Australia on Oct 18, might be Jielong 3 upper stage remains

click map to enlarge

On 18 October 2025 near 14:00 local time (= 18 October ~6:00 UTC), a strange object was found on or near a dirtroad in the outback of  the Pilbara region in Western Australia. The object, suspected to be space debris, was found some 30 km east of the small mining town of Newman, as reported by ABC.

The object (photo's in the ABC report) resembles a COPV (Composite-Overwrapped Pressure Vessel), a type of space debris that often survives reentry. It reportedly was burning when found (this seems to be visible in the first photograph in the ABC report), which is unusual and against expectations for space debris. Nevertheless, the character of the object and a good match of the find location to a reentry on 18 October does persuade me to conclude that this is space debris indeed.

A possible candidate for the origin of this apparent space debris is a Chinese Jielong 3 upper stage, catnr. 61237, COSPAR 2024-173L. This object reentered on October 18, although (again! See this recent reentry) no TIP was issued by CSpOC.

I identified the object (note: so independently did Ravi Jagtiani) by assuming the report it was burning, although odd, is true, indicating a very recent impact. Using the latest orbital catalogue I first checked which objects were in orbits below 250 km on October 17-18, i.e. close to reentry, and next I ran a SatEvo analysis on this set to further cull it down to objects that should have been near reentry around that time. Starlink satellites could be excluded given the character of the debris. This left only a handfull of candidates. Of these, only one was in an orbit that would match passing close to Newman in the early hours of October 18: the mentioned Chinese Jielong 3 stage in a 97.6 degree inclined polar orbit. Using a standard SGP4 propagation as a first check, the ground-track would pass some 20-30 km east of Newman around 4:40 UTC on October 18. The rocket stage approached from the north-northeast moving towards the south-southwest.

The last available orbit for 2024-173L is for epoch 25291.03873492 (18 Oct 00:55 UTC), a few hours before the Newman object was found. Using that orbit as a starting point and deploying the reentry model we recently created in the open source Delft University of Technology Astrodynamics Toolkit (Tudat), I tried whether I could get a reentry trajectory to end ~30 km east of Newman. 

Not much information is known about the Jielong 3 components in terms of size and mass: therefore, estimates for size and mass of the upper stage had to be used. I assumed a size of about 1.5 x 1.5 meter (cf Jonathan McDowell's catalogue) and then by trail-and-error varied the mass to get an impact point as close to 30 km due east of Newman as possible.

An impact point situated directly ~30 km east of Newman results when I use a mass of ~301 kg, which seems a reasonable value for a small solid fuel upper stage build from composite. The two maps below show the Tudat modelled reentry trajectory that results from a 2.5 m2 drag surface and 301 kg mass, with impact just after 4:40 UTC on 18 October (see also update II at the bottom of this post):

 

click map to enlarge

 

click map to enlarge

The modelled impact time is 1 to1.5 hours before the object was reportedly found. 

So it looks like the Jielong 3 upper stage 2024-173L is a good candidate for the origin of the possible space debris object found near Newman on October 18. Rather than a COPV from the stage, it could actually be (a significant part of) the upper stage itself, given the large size that the photo's suggest (and also given that the Jielong 3 upper stage is reportedly a solid fuel stage).

As we have seen with a number of recent reentries, CSpOC alas did not provide a TIP for this object (TIP = "Time of Impact Prediction", the reentry prediction by the CSpOC reentry model). They did however release an administrative "decay message" for 2024-173L for October 18 just after the reentry, indicating that it did reenter that day.

 

UPDATE I, 21 Oct 2025 00:20 UTC:

An EU-SST reentry analysis for the Jielong 3 upper stage 2024-173L is in good agreement with my Tudat analysis.

 

UPDATE II, 21 Oct 2025 15:45 UTC:

Using Tudat, I tried to fit the orbital evolution (based on US tracking data) for 2024-173L from July 1, 2025 to October 15, 2025 to the Tudat model, playing with mass and drag area, to get at empirical values for mass and drag area. One of the solutions that fits well is a mass of 300 kg and drag area of 2.2 m2 , which is close to the values I used to get it to reenter near Newman as described earlier in this blogpost. 

click diagram to enlarge

With a 300 kg mass and 2.2 m2 drag area, the Tudat reentry model has it nominally surviving untill ~5:17 UTC ± 65 min, nominally reentering half an orbital revolution after passing Newman: but passing Newman actually is well within the uncertainty window of this reeentry prediction (the blue line on the map shows the trajectory over the uncertainty window):

 

click map to enlarge

In other words: this too suggests that the object found near Newman could be (a part of) the Jielong 3 upper stage 2024-173L.

 

UPDATE III, 31 Oct 2025: 

A lone TIP has suddenly been issued for 2024-173L by CSpOC today: 18 Oct 2025 4:38 ± 1m UTC near nominally 18.1 S 121.2 E.  

This conforms well to the space debris being found in Newman, as the time and location likely are based (given the ± 1 minute uncertainty) on a satellite observation of the fireball, i.e. on the location at an altitude of 80-100 km. I have plotted the position in the map below, that also depicts our Tudat reentry trajectory with associated times.

 

click map to enlarge

Saturday, 15 June 2013

Fireball seen over Eastern Australia, 13 June 2013 6:05 pm AEST, was NOT the decay of Molniya 3-53

On June 13, 2013, near 6:05 pm local time (AEST - corresponding to 10:05 UTC), many people in Eastern Australia observed a bright fast light falling down in the sky. It was even recorded by one of those new-fangled dashboard-cams (one of these days, I must get me one for my bike).

The Australian news website "The Chronicle" claims it was a satellite decay - more exactly, that of the Russian Molniya platform Molniya 3-53 (2003-029A).

It was however most definitely not a satellite decay.

All descriptions talk about a fast object. The dashcam video shows a pretty fast fireball indeed.

It is much too fast to be a decaying satellite. The latter move at relatively slow speeds - 8.5 km/s. At that speed, it takes them several minutes to traverse your sky, not just a few seconds. As low over the horizon as the dashcam video shows it, it would have been very, very slow, taking several tens of seconds to traverse the distance it does in the video.

In addition to it being too fast to be a satellite decay, the proposed connection to Molniya 3-53 can be rejected right away.

First: Molniya 3-53 did not decay on June 13. Orbital data by Strategic Space Command ("NORAD") show it was still in orbit in the early hours of June 15 - two days after the Australian fireball. At the moment of writing (12 UTC, June 15), the last available orbit is for epoch 13166.42726929 ( = 15 June 2013, 10:15 UTC). The moment of decay is currently predicted as 15 June 14:04 UTC, with an uncertainty of 2 hours. [Update 22/6: SSC's final TIP-message issued 15 June 15:30 UTC gives 15 June, 14:10 UTC +/- 26 minutes for the moment of decay)

Now, given that the apogee of the satellite was at a very low altitude already, could it have been the case that it briefly started to burn but survived after it passed perigee?

The answer is "no" in this case and brings us to a second point against the identification with this satellite: Molniya 3-53 was not over Australia at June 13, 10:05 UTC. It was at very high altitude over Northern Europe at that time (see map below). It would not pass over (central) Australia untill 10:55 UTC (6:55 pm AEST), i.e. a full hour later than the fireball sighting.



So what was it then? Given the speed, it is very clear this was a meteoric fireball, a small piece of cosmic rock or ice (debris from a comet or an asteroid) entering the atmosphere.