[UPDATED] Identifying a reentry over the Canary Islands on 16 October as the reentry of the Chinese satellite Xinjishu Yanzheng 7 (XJY-7)

click to enlarge

In the early local morning of 16 October 2025 around 1:56 UTC, a spectacular phenomena appeared in the sky over Tenerife in the Canary Islands. A bright, slow, fragmenting fireball moved from south to north over the sky. Sonic booms were heard and registered by several seismic stations on Tenerife. The event clearly was a reentry of artificial space debris. For footage, see here and here. The all-sky image on the left above is from the Izana Atmospheric Research Center on Tenerife (the plotted sky map on the right is by me, for comparison, see discussion below).

I was alerted to the event by my Spanish colleague Josep Trigo (ICE-CSIC/IEEC) in the morning of October 16, who asked if I could identify which object was reentering here. A check on the CSpOC portal Space-Track did not yield a TIP that would match - as it turns out, the object in question never received a TIP, which is odd as it was heavy and large, as we will see.

So in order to identify it, I had to do some additional research. I selected all orbits from the orbital catalogue with perigee below 200 km. Next, I used SatEvo software to see which of these orbits would have a predicted reentry on October 15-16. From the handfull of candidates left, I next checked which of them would be over the Canary Islands near the time of the event (1:56 - 1:57 UTC on 16 October 2025). One object stood out - and it was one for which no TIP had been issued: the Chinese satellite Xinjishu Yanzheng 7 (XJY-7, 2020-102C), launched in 2020.

All sky imagery showing the reentry trail in the sky against a starry background had meanwhile been published on Twitter by the Izana Atmospheric Research Center on Tenerife. The general location of the trail amidst the stars in the sky and the direction of movement matched those expected for XJY-7 well. It was clear we had found our culprit.

Not much is known about XJY-7. Jonathan McDowell lists bus dimensions of about 3 x 5 x 9 meter and a dry mass near 3000 kg for this object in his catalogue. ESA's DISCOS lists similar dimensions but a mass of 5000 kg (perhaps a wet mass).

The last available orbit for XJY-7 was for epoch 25288.77158679, or 15 October 18:31 UTC, some 7h 25m before the event. To investigate further, I used the reentry model that my colleague Dominic Dirkx and I made some time ago (see earlier posts) in the Open Source Delft University of Technology Astrodynamics Toolkit (Tudat) to see whether I, with trial-and-error, could get a reentry model for XJY-7 to end over the Canary Islands. As it turns out, I could, for a mass of 2717 kg (close to 3 tons) and a drag area of 37.44 m² (the maximum drag surface listed by DISCOS), using past and current space weather.

The map below shows the resulting reentry groundtrack and times for this model integration. Note that the model does not take fragmentation and mass loss into account, so it has limitations and is an approximation only. I had the model terminate at 20 km altitude.

The figure below the map, compares the sky trajectory resulting from this model for the location of the Izana Atmospheric Research Center, to that registered by the all sky camera at Izana. They match well.

Click map to enlarge

 

click to enlarge

 

It is curious that no TIP was issued for this reentry by CSpOC. This was a large heavy object: 3 x 5 x 9 meter and 3 tons in mass. CSpOC apparently overlooked this reentry - a few hours post reentry, they however did add an administrative "decay message" for October 16 to the catalogue for this object, but without any further details. 

We recently have seen a complete lack of TIP's being issued for any object, for over a month. Only recently, CSpOC resumed issuing TIP's. CSpOC is currently clearly having some issues with their system. Luckily, we were nevertheless able to identify the object responsible for this spectacular reentry, by some diligent analysis.

 

UPDATE 17 Oct 2025  22:00 UTC:

Click map to enlarge (map updated to correct typo)

I played a little bit more with the reentry model, tinkering the area to mass ratio to get an even better fit to the sky trajectory as seen from the Izana camera station. Here is an updated plot of the modelled sky trajectory (numbers next to trajectory are atmospheric altitudes in km according to the simulation):

A mass of 2715.5 kg creates a very good fit, except for the end of the trail. That is no surprise: the reentry model is a simple model without mass loss and fragmentation, while in reality there is massive mass loss and fragmentation (meaning: changing area to mass ratio's for various fragments). When solid parts survive, heavy relative to their size, these have a lower area to mass ratio meaning they lose altitude less quickly.

Here is the improved model trajectory overlayed on the Izana camera image:

Click image to enlarge

(I thank Josep Trigo (ICE-CSIC/IEEC) and the Spanish SPMN for data and discussions)

A Trident-II D5 SLBM launch in the Atlantic on 21 September 2025: analysis of footage from Puerto Rico (UPDATED)

frame stack of movie by SAC station Anasco, Puerto Rico

 

click map to enlarge

On 15 September 2025, Navigational Warnings appeared that pointed to an upcoming Trident-II D5 SLBM (Submarine Launched Ballistic Missile) unarmed test launch in the Atlantic between 17 and 22 September 2025, from a submarine of either the US Navy or UK Royal Navy positioned some 400 km out of the coast of Florida (update 24 Sept 2025: according to this US DoD bulletin it was an American test launch from an unnamed Ohio-class SSBN (Ballistic Missile submarine). The submarine test-launched four Trident missiles between Sept 17 and 21). I have posted about such tests and the typical pattern of Navigational Warnings associated to them earlier, in an analysis of a Trident launch that was inadvertently captured on camera in a time-lapse by an amateur astronomer on La Palma in September of 2013.

And now we have another case of inadvertant capture on camera of such a launch, and a second opportunity for analysis! 

In the evening of 21 September 2025 near 23:30 UTC, eyewitnesses in Puerto Rico saw a fuzzy object and what looked like expanding missile exhaust clouds move through the sky, consistent with a rocket or missile launch. The event was captured by amongst others a meteor camera of the Caribbean Astronomy Society (SAC) near Anasco, Puerto Rico. 

Eddie Irizarry of SAC was so kind to send me the video footage for identification and analysis. Immediately, it was clear to me that the video showed the Trident test launch we expected.

In top of this post is a frame-stack from the footage. Below it is a map I prepared showing the northern part of the sky as seen from the camera station in Puerto Rico, with the blue line representing the sky trajectory expected for this Trident launch for an assumed (but see below) apogee altitude of 2200 km. They compare well (note: the video stack shows a part of the trajectory only, up to about azimuth 30 degrees, while the sky map shows the full trajectory).

Here is the video footage itself (courtesy of  Eddie Irizarry, used with permission):

 

 

The trajectory for this Trident test launch is known, as it can be reconstructed from the Navigational Warnings that have been issued for it. Below is the Navigational Warning, and a map where I have plotted the exclusion zones A-D from it, and a fitted ballistic trajectory:

151958Z SEP 25
HYDROLANT 1538/25(GEN).
ATLANTIC OCEAN.
DNC 01, DNC 16.
1. HAZARDOUS OPERATIONS 171830Z TO 220136Z SEP
   IN AREAS BOUND BY:
   A. 28-34.00N 076-29.00W, 29-07.00N 076-28.00W,
      29-05.00N 075-33.00W, 28-30.00N 075-35.00W.
   B. 28-37.00N 075-51.00W, 28-55.00N 075-44.00W,
      27-44.00N 070-28.00W, 27-05.00N 070-28.00W.
   C. 16-28.00N 044-01.00W, 17-01.00N 043-43.00W,
      14-36.00N 038-46.00W, 13-37.00N 039-33.00W.
   D. 10-35.00S 001-40.00W, 10-05.00S 001-25.00W,
      12-01.00S 002-21.00E, 12-45.00S 002-55.00E,
      13-11.00S 002-20.00E, 13-01.00S 002-02.00E,
      13-04.00S 002-00.00E, 12-38.00S 001-15.00E.
   E. 26-58.00N 070-28.00W, 28-14.00N 070-28.00W,
      25-56.00N 063-20.00W, 24-34.00N 063-50.00W.
2. CANCEL THIS MSG 220236Z SEP 25.

click map to enlarge

 

On the map, I have undicated the part of the trajectory that was captured by the SAC camera on Puerto Rico as a yellow line. 

Area A is the launch area where the submarine is located. Areas B, E and C are respectively the splashdown zones of the first, second and third stages of the missile. Area D is the RV (Reentry Vehicle) target zone. The switched designations for the C and E area are probably a clerical error.

The launch area, 400 km out of the Florida coast is one of two well established launch locations for Trident tests in the Atlantic (see my earlier investigation here). Likewise, the target area in the southeastern part of the Atlantic, 900 km east of St Helena at a range of about 9500 km from the launch site, is a well known target location for these test launches.

What cannot be well gleaned from Navigational Warnings alone, is the apogee altitude of this test. 

In this post, I will however reconstruct it from a combination of the known missile flight trajectory and measurements of the missile's sky track in the video footage from Puerto Rico, in a similar way as I analysed the earlier 2013 Trident observation from La Palma. For that 2013 test, I found an apogee at ~1800 km.

The video (the original is higher resolution than the version posted in this blogpost) provides plenty of reference stars to do astrometry on the missile path through the sky. So I measured the missile's position with respect to the stars for several frames from the video. Plotting  these observed positions (in RA/DEC) on a star map along with the expected sky trajectories in RA/DEC for various assumed apogee altitudes (based on the trajectory from the Navigational Warnings), it is clear that an apogee of 2200 km fits best. Red crosses in the plot below are the measured positions from the video: the blue lines provide the expected missile tracks for various apogee altitudes:

click map to enlarge

(note that I choose to plot RA on the Y-axis rather than X-axis, in order to get a plot orientation that is most easily compared to the video footage).

Earlier, while similarly analyzing the Trident launch seen from La Palma in 2013, I found an indicated apogee of ~1800 km, some 400 km lower than seems to be the case with this latest test launch. Both values are significantly higher than the ~1200 km that is often taken as a canonical value for an intercontinental missile apogee. These tests in the Atlantic therefore appear to be a bit "lofted", perhaps simply to keep the Reentry Vehicle (RV) impact area sufficiently out of the African coast.

From the timing of the Puerto Rico video, the actual launch time was likely somewhere near 23:27 UTC (Sept 21) from a location  near 28.8 N, 76.3 W, with a flight time near 41 minutes from launch to RV impact. As seen from Puerto Rico the missile cleared the horizon while at ~150 km altitude, steadily climbing to  ~800 km when it left the field of view of the CAS camera station (while continuing its ascend towards apogee). The closest slant range to the camera station was ~1300 km. The big cloud of exhaust gas seen in the early part of the video likely stops upon ejection of the second or third stage. The various smaller "pufs" of exhaust cloud that can be seen later emanating from the fuzzy object, are probably due to either the third stage or post-boost vehicle orienting itself.

(With thanks to Eddie Irizarry/CAS for sending me the footage and for his permission to use it in this blog) 

UPDATE 24 Sept 2025: 

According to this US DoD bulletin the missile was launched from an unnamed US Ohio-class Ballistic Missile submarine (SSBN). The submarine reportedly test-launched as much as four Trident missiles of the 5DLE variety between Sept 17 and 21. The below image was published, showing a Sept 21 nighttime launch, the missile that was seen from Puerto Rico:

 

Sept 21 2025 Trident missile launch. Photo US Navy/Shelby Thompson

X-37B OTV 8 and Limasat (the USSF-36 payloads) imaged

 

This morning (early 24 August 2025) weather finally cooperated and I managed to observe both of the USSF-36 payloads, two days after launch: the X-37B Spaceplane OTV 8 (2025-183A) and  LIMASAT (2025-183B). Limasat was about half a minute in front of OTV 8.

Above is footage from this pass, showing both objects. The footage was obtained from my home in Leiden, the Netherlands, using a WATEC 902H2 Supreme camera with a Samyang 1.4/85 mm lens filming at 25 frames/second. This was an early twilight pass low in the south-southwest (27 degrees maximum elevation).

Below are framestacks from parts of the footage (both framestacks are 51-frame stacks):

Limasat (stack of 51 frames)

 

X-37B OTV 8 (stack of 51 frames)

 

Current observations show OTV 8 in a 331 x 342 km, 49.5 degree inclined orbit. Limasat is in a 330 x 341 km, 49.5 degree inclined orbit. Limasat was probably carried piggyback on the X-37B Service Module before being released.

X-37B Spaceplane mission OTV 8 located on orbit

OTV 8 imaged by Kevin Fetter 5 hours after launch. Image (c) Kevin Fetter, used with permission

OTV 8, the 8th mission of the US Space Force's X-37B Spaceplane, launched on 22 August 2025 at 03:50 UTC. It has been catalogued as 2025-183A (cat. nr. 65271) under the name of  'USA 555', along with a second payload, called LIMASAT (2025-183B, 65272). The latter has probably been dispensed from the OTV 8 service module.

Five hours after launch, Kevin Fetter managed to observe OTV 8. Above is one of his images, showing OTV 8 as a short bright trail in a partly cloudy sky. 

A preliminary orbit fit suggests that OTV 8 is in a 327 x 334 km, 49.5 degree inclined orbit [update 25 Aug 2025: the latest improved orbit update shows it in a 331 x 342 km, 49.5 degree inclined orbit]: a slightly (~20 km) lower orbital altitude than my initial pre-launch guess but otherwise a quite comparable orbit.

Click image to enlarge

 

An overview of the OTV missions so far: 

MISSION  ORBITER  LAUNCH   INCL   ORBIT   DURATION
--------------------------------------------------
OTV 1    I        2010     40.0   LEO     224 days
OTV 2    II       2011     42.8   LEO     468 days
OTV 3    I        2012     43.5   LEO     674 days
OTV 4    II       2015     38.0   LEO     717 days
OTV 5    II       2017     54.5   LEO     780 days
OTV 6    I        2020     45.0   LEO     909 days
OTV 7    II       2023     59.1   HEO     435 days
OTV 8    I        2025     49.5   LEO         tbd
--------------------------------------------------

Bad weather in the Netherlands has so far precluded me from trying to observe the latest launch.
 

EDIT (24 August 2025): 

I imaged both the USSF-36 payloads (OTV 8 and Limasat) in the early morning of 24 August, see this follow-up blogpost with footage. 

An upcoming Hypersonic Missile Test (repeat of FT-3) from Kodiak to Kwajalein [UPDATED]

Click map to enlarge

Navigational Warnings have been published that point to a Hypersonic Missile Test (a repeat of the failed FT-3 from 2021) from the Pacific Space Port at Kodiak Island, Alaska, to the Ronald Reagan Test Site at Kwajalein, Marshall Islands, between August 22-26, 2025. The range is about 6350 km.

Navigational Warning NAVAREA XII 520/25 defines three hazard zones (A, B and C in the map above), one near Kodiak Island and two in the mid Pacific, for the splashdowns of the three rocket booster stages. Navigational Warning HYDROPAC 2097/25 defines a hazard area at Kwajalein Atoll for the Hypersonic payload impact area. I have plotted the areas in the map above.

The test appears to be a repeat of the failed FT-3 test from 2021. This test was scrubbed in June 2021 and next failed on a second attempt on 21 October 2021, reportedly when one of the booster stages failed in flight.

Details on FT-3 can be found in this US DoD document. A three-stage STARS (Strategic Target System) launch vehicle consisting of two Orion stages and a C4 stage would launch the hypersonic payload from the Kodiak Pacific Space Port Complex and (based on Navigational Warning HYDROPAC 2097/25) target the Northeast Deep Water Impact Zone near Gagan island on Kwajalein.

Here is the text of the Navigational Warnings:

080912Z AUG 25
NAVAREA XII 520/25(16,19).
GULF OF ALASKA.
NORTH PACIFIC.
ALASKA.
1. HAZARDOUS OPERATIONS 220400Z TO 221000Z AUG, 
   ALTERNATE 0400Z TO 1000Z DAILY 23 THRU 26 AUG
   IN AREAS BOUND BY:
   A. 54-12.00N 156-36.00W, 54-03.00N 156-14.00W,
      55-16.00N 153-14.00W, 56-32.00N 152-01.00W,
      57-29.00N 152-06.00W, 57-32.00N 152-20.00W,
      56-59.00N 153-06.00W, 57-00.00N 153-30.00W.
   B. 46-32.00N 167-23.00W, 46-24.00N 167-05.00W,
      45-43.00N 167-45.00W, 45-51.00N 168-03.00W.
   C. 37-36.00N 175-36.00W, 37-19.00N 175-00.00W,
      32-19.00N 178-40.00W, 32-41.00N 179-12.00W.
2. CANCEL THIS MSG 261100Z AUG 25.


080852Z AUG 25
HYDROPAC 2097/25(81).
NORTH PACIFIC.
MARSHALL ISLANDS.
DNC 12.
1. HAZARDOUS OPERATIONS 220400Z TO 221000Z AUG, 
   ALTERNATE 0400Z TO 1000Z DAILY 23 THRU 26 AUG
   IN AREA BOUND BY
   09-43.00N 167-47.00E, 09-36.00N 167-59.00E,
   09-11.00N 167-44.00E, 09-17.00N 167-33.00E.
2. CANCEL THIS MSG 261100Z AUG 25. 

 

UPDATE 23 Aug 2025:

The launch happened on 22 August 2025 at 06:10 UTC. Footage of the launch shot from Seward, Alaska, by Seth Andrzejewski is here on twitter.  

The upcoming launch of the X-37B Spaceplane mission OTV 8

X-37B mission OTV 6 after landing (Image: US Air Force)

Navigational Warnings have appeared for OTV 8, the 8th launch of the secretive X-37B spaceplane by the US Space Force (launch USSF-36). The launch, on a SpaceX Falcon 9, will be from Cape Canaveral launch pad 39A. The window of the Navigational Warning runs from 22 to 28 August 2025, with a time window of 08:30 - 10:30 UTC 03:40 - 08:03 UTC for August 22 (August 21 local date in Florida). There is something odd with these times by the way, on which more later.

Navigational Warnings NAVAREA IV 877/25 and HYDROPAC 2096/25 define two hazard zones. One is the immediate launch hazard zone on the Florida coast. The other is the deorbit area for the Falcon 9 upper stage, in the Eastern Pacific, near the end of the first revolution. 

While the direction of the first hazard zone on the Florida coast suggests a 42 degree inclined orbit, the location and direction of the Falcon 9 upper stage deorbit area is incompatible with this. Rather, it fits a 49.5 degree inclined orbit. The location and the time difference of the deorbit window start compared to that for the launch area, strongly point to launch into a Low Earth Orbit, with an orbital altitude likely near 350-400 km, just like the first six missions (remember that mission OTV 7 surprisingly was sent into a Highly Elliptical Orbit, see several previous posts, e.g. here).

I have plotted the two hazard zones and a launch trajectory for a 49.5 degree inclined, ~350 km altitude orbit in the map below. Numbers next to the trajectory refer to the flight time in minutes after launch:

 

Click map to enlarge

 

Below are the two Navigational Warnings:

142327Z AUG 25
NAVAREA IV 877/25(11).
NORTH ATLANTIC.
FLORIDA.
1. HAZARDOUS OPERATIONS, ROCKET LAUNCHING 
   220340Z TO 220803Z AUG, ALTERNATE
   230400Z TO 230823Z, 240420Z TO 240843Z,
   250440Z TO 250728Z, 260500Z TO 260748Z,
   270345Z TO 270808Z AND 280540Z TO 280833Z AUG
   IN AREA BOUND BY
   28-40.25N 080-38.57W, 28-50.00N 080-22.00W,
   28-39.00N 080-11.00W, 28-27.24N 080-31.58W.
2. CANCEL THIS MSG 280933Z AUG 25.


141931Z AUG 25
HYDROPAC 2096/25(83).
PACIFIC OCEAN.
DNC 06, DNC 13.
1. HAZARDOUS OPERATIONS, SPACE DEBRIS
   220500Z TO 220911Z, 230520Z TO 230931Z,
   240540Z TO 240951Z, 250600Z TO 250836Z,
   260620Z TO 260856Z, 270505Z TO 270916Z
   AND 280700Z TO 280941Z AUG 
   IN AREA BOUND BY
   09-55.00N 120-25.00W, 10-41.00N 121-25.00W,
   07-44.00S 135-45.00W, 08-30.00S 134-45.00W.
2. CANCEL THIS MSG 281041Z AUG 25.

Note the shift in launch time with date: 03:40 - 08:03 UTC for the 22nd, 04:00 - 08:23 UTC for the 23rd, etcetera: a shift forward in time of 20 minutes per day. [edit: as noted by Ted Molczan, the times next suddenly shift to - nearly - the initial times again by August 27. I still cannot make sense of it]

The direction of this shift is odd. It is forward, to a later time each day: if a particular orbital plane is aimed for, it should however shift backwards, to an earlier time, each day. I wonder if this is a mistake and someone added corrections into the wrong direction...

The X-37B spaceplane (there are actually two of them) is the subject of a lot of conjecture and wild tales. My interpretation is that it is a technology testbed, not some space weapon such as the Russians and Chinese would have it. 

The rumoured "high manoeuverability" is often misunderstood: in flight, the X-37B does not change its orbital plane (see this earlier post from 2019). It does change orbital altitude frequently, and during the last mission (OTV 7) into HEO, it used Aerobraking (briefly dipping into the upper atmosphere during perigee) near the end of its mission to reduce orbital speed and altitude in preparation for landing. It manoeuvered almost daily during that mission. However, and I want to re-emphasize this as it is a common misunderstanding, it does not swirl and manoeuver like an X-wing Starfighter or Tie-fighter, changing orbital plane at will. In many ways, on-orbit it is just another satellite, moving in a fixed orbital plane (this is how we trackers find it back after an orbit raising or lowering manoeuver: we do a plane scan). The wings only function in the atmosphere, not in space.

According to this Space Force bulletin, mission OTV 8 will experiment with laser communications with "proliferated commercial satellite networks in Low Earth Orbit" (read: Starlink). It will also test a new navigation device, a "quantum inertial sensor" which works by "detecting rotation and acceleration of atoms without reliance on satellite networks like traditional GPS". This experimental technique is important to be able to continue navigating in space when GPS is being jammed/spoofed, and will become an important means of navigation in XGEO (CisLunar Space) in the future.

The SatTrackCam (B)log is 20 years old!

 

On 6 August 2005, this blog saw its very first post. This means that the SatTrackCam blog is now

20 Years Old! 

 

Since that first post, we are now 20 years and over one-thousand blogposts further. 

To quote the Talking Heads: "And you may ask yourself, "Well, how did I get here?"

Originally it started out as a mere observers activities log, documenting my baby steps into satellite tracking. Most of the early blogposts were very simple, descriptive and brief (and sometimes naive), and contain a lot of complaining about the Dutch weather.

Over the years, as I built up more knowledge, insight and expertise, I started to post more elaborate posts, including increasingly elaborate analysis of observations, events, data, and satellite life histories. It also included occasional Off-Topic posts on asteroids and comets and astrophotography (it still does every now and then). Some 13 years ago, a growing interest in the North Korean Space and Missile program and a chance observation by a German amateur astronomer on La Palma of what eventually turned out to be a Trident-II SLBM launch (see original post here - still containing misinterpretations - and a later revisit post and analysis here), lead to a broadening of the scope of the blog to also include Missile tests.

I can truely say that writing this blog changed my life. With hindsight, this post from July 2014 on a very tragic event (the shootdown of flight MH17, and whether US SBIRS satellites could have seen and geolocated the firing of the missile) was a turning point. It was picked up by Dutch politician Pieter Omtzigt, which one-and-a-half year later, in January 2016, led to me being invited to provide an expert opinion during a Dutch Parliamentary Committee Hearing on the subject. Little did I know at that time, that this was to profoundly alter the course of my professional life, and the beginning of a switch from an essentially amateur hobbyist interest to professional involvement in (military) Space Situational Awareness. It led to warm and ongoing contacts with the Defense Space Security Center (DSSC) of the Royal Netherlands Airforce, and to the initiation of a series of projects around building an optical satellite tracking capacity for the DSSC. In the period 2017-2022 I got a series of small positions at the Astronomy department of Leiden University in the context of these projects. 

Eventually, three years ago in June 2022, it culminated in what is by now a permanent position at the Aerospace Engineering faculty of Delft University of Technology, where I am currently employed as a part-time (0.5 fte) Lecturer in Space Situational Awareness as part of the section Astrodynamics and Space Missions. 

The second half of the 20 years since I started this Blog truely has been a rollercoaster in this sense, and I am still wildly amazed (and somewhat in disbelief) where it has brought me (apart from landing the academic position,  I found myself at a small invitation-only UNIDIR expert meeting at the United Nations in Geneva just three months ago for example). I never envisioned that to happen, when I decided to make my first blogpost on a rainy August day 20 years ago. It blows my mind.

The blog is no longer the only venue through which I share my thoughts, analysis and observations (but still an important one). There always was the Seesat-L mailing list; and over the past 15 years I grew a large twitter account (sorry, refuse to say 'X") that I still maintain because I do not want to leave the 21.6K followers I still have there (including a lot of journalists). I also have an account with 3.4K followers on BlueSky, and recently have become much more active on LinkedIn as well. I occasionally publish topical analysis in The Space Review, and I am frequently featured in the media (including Dutch, and occasionally foreign, tv and radio, as well as Dutch and international written press and online news media). And then there are of course publications in professional scientific journals as well.

But it all started with this blog (and contributions to the SeeSat-L mailing list), very modestly, now 20 years ago. 

I want to thank all of you who have read my blogposts, who shared insights, and have supported and encouraged me over the past 20 years. A blog is nothing without an audience.

I specifically want to thank Ted Molczan, Jonathan McDowell, Bart Hendrickx, Scott Tilley, Bob Christy, Mike McCants, Cees Bassa, Nico Janssen, Bram Dorreman, Leo Barhorst, Greg Roberts, Paul Camilleri, Jeffrey Lewis, Alice Gorman, Trevor Paglen, Bill Gray, Ankit Panda, the late Pierre Neirinck, and twitter contributor @Dutchspace, plus several members of the Seesat-L list and Twitter's Missile and Space communities, for much appreciated feedback, discussions, suggestions, corrections, and food for thought over all these years.

Now, let's continue towards 25 years!

RPO Galore: the complex proximity operations of Kosmos 2581, Kosmos 2582, Kosmos 2583 and 'Object F'

click image to enlarge

Some 590 km above our heads, a complex series of multiple Rendezvous and Proximity Manoevers (RPO) by multiple Russian military spacecraft has been going on the past months, weeks and days.

On 5 February 2025, Russia launched three satellites from Plesetsk, into a 82 degree inclined orbit: Kosmos 2581, Kosmos 2582 and Kosmos 2583 (2025-026A, B and C). Kosmos 2581 was initially placed in a 595 x 578 km orbit; Kosmos 2582 in a 597 x 576 km orbit; and Kosmos 2583 in a 597 x 580 km orbit.

The diagram below sums up what has unfolded over the past few months: a complex series of manoeuvers and approaches to each other.

Click diagram to enlarge

 

About two weeks after the launch, both Kosmos 2581 and Kosmos 2582 were manoeuvered to a slightly higher orbit: Kosmos 2582 did so on 15 February and Kosmos 2581 on 19 February. 

On 24 February, Kosmos 2582 manoeuvered again, this time slightly lowering its orbit to the same orbital altitude as Kosmos 2581, for the initiation of first of a long series of complex proximity manoeuvers. They made a very close approach (1 km or less) on 24 February around 21:44 UTC. They stayed in each others close vicinity for the next three months, manoeuvering to and fro, with Kosmos 2582 doing the manoeuvering and Kosmos 2581 acting as the target..

Meanwhile, on 18 March 2025, the third satellite from the launch, Kosmos 2583, surprised by releasing a fourth object, 'Object F' (2025-026F). This object appears to be passive (i.e. it does not appear to be manoeuvering), but starting in April, Kosmos 2583 has subsequently been doing RPO manoeuvers with it, manoeuvering to and from it repeatedly, untill late May, so perhaps it is not merely debris. 

On 26 May, Kosmos 2583 manoeuvered away from 'Object F' to a higher orbit. It subsequently made a series of manoeuvers that made it closely approach Kosmos 2581 to a few hundred meters or less on June 10 near 9:42 UTC. It next stayed in the close vicinity of Kosmos 2581, approaching it again very closely in the days around June 19.

While Kosmos 2582 meanwhile had stayed in the wider vicinity of the other two, following them at a  distance of several hundreds of kilometers, it manoeuvered on June 23 in order to get close, within kilometers, to the by then close pair of Kosmos 2581 and Kosmos 2583. As a result, all three objects were now orbiting closely together.

 

click image to enlarge

The framestack above is from video footage I shot from Leiden, the Netherlands a few nights later during a near-zenith pass in twilight on 28 June 2025, when the three objects were still in close vicinity, albeit less close than the days before (during the days before, they were so close that I generally could not resolve them). Kosmos 2581, 2582 and 2583 are all visible in the framestack, the latter however being very faint.  

Kosmos 2581 and Kosmos 2582 were at about 1.2 km from each other at the time of observation. Kosmos 2583 was at about 3.6 km from Kosmos 2581.

Below is the actual video footage the framestack was derived from: the two brighter objects are Kosmos 2581 and 2582 (Kosmos 2581 leading), and just in front of them is Kosmos 2583, barely visible (look closely at full screen during the first 4 seconds of visibility). It was shot from my home in Leiden, the Netherlands, with a WATEC 902H2 Supreme and Samyang 1.2/85 mm lens.

'Object F' meanwhile, has drifted to quite a distance from the other three objects. Below is a framestack showing it, from video observations obtained on 17 June 2025: it was faint and might show some brightness variation.

Click image to enlarge

 

This is one of the most complex RPO exercises Russia has been conducting in LEO in decades. The RPO appears to be ongoing, and it will be interesting to follow it: for example, will we see that at one point 'Object F' is becomes the subject of an RPO again or not?

 

Post scriptum: more on another recent event with another Russian satellite, Kosmos 2558, releasing an object in another blogpost from today. 

Kosmos 2558 released an object on orbit on June 26 [UPDATED]

Object C (click image to enlarge)

 

Kosmos 2558 (2022-089A, cat nr. 53323) is a Russian military satellite that was launched from Plesetsk three years ago, on 1 August 2022. It was launched into the orbital plane of an American ADVANCED CRYSTAL spy satellite, USA 326. It is therefore believed to be a 'Nivelir' type 'inspection satellite' (see also this earlier discussion of several of such missions, and Bart Hendrickx' Space Review article on the Nivelir program  here).

As I recently wrote, there have now been four of these missions in a five-year timespan. Apart from Kosmos 2558 discussed here, these are: Kosmos 2542/2543 launched in the orbital plane of USA 245 in 2020;  Kosmos 2576 placed in the orbital plane of USA 314 in 2024 (see this earlier blogpost); and very recently, Kosmos 2588 placed in the orbital plane of USA 338 (see this earlier blogpost). 

With the exception of Kosmos 2542/2543, which have been deorbitted, all three remaining missions are still dedicatedly shadowing their American targets, keeping their orbital altitude and inclination difference such that the rate of RAAN (node) precession matches that of their target. This ensures that the orbital planes do not drift apart.

While mostly seen as 'inspection missions', I have repeatedly voiced a concern that these missions might be the positioning of 'dormant' on-orbit Anti-Satellite (ASAT) weapons. To me, the long, ongoing shadowing of what are some of the most prized US military space assets, their KH-11 Advanced Enhanced Crystal high-resolution optical IMINT satellites, is odd for 'just' an inspection mission. What is there still left to inspect after 3+ years? The satellites make only periodic close approaches (every few days) so monitoring of attitude (pointing) or radio signals is not an explanation.

Understandibly, the 'stalking' behaviour of these Kosmos satellites on their satellites makes the US military nervous. And now they have yet another reason to get even more nervous: on 26 June 2025 near 12:03 UTC (according to my analysis), Kosmos 2558 released  a second object, currently designated as 'Object C' (2022-089C, cat nr. 64627). 

The release is actually visible in the orbital elements for kosmos 2558, as a sudden slight lowering of the orbit:
 

Click diagram to enlarge

 

This is the third time we see this kind of 'Matrushka Doll' behaviour from Russian military satellites in five years time. 

Shortly after reaching orbit in 2020, Kosmos 2542 released a sub-satellite too, Kosmos 2543, which next in turn fired what is interpreted as a projectile, 'object E' (the latter was widely seen as an ASAT technology test at the time). 

In addition, more recently, Kosmos 2583 released an object, 'Object F' (2025-026F), on 18 March this year, as part of a complex series of RPO's (Rendezvous- and Proximity Operations) between Kosmos 2581, Kosmos 2582, Kosmos 2583 and said 'Object F'. I will publish a separate blogpost on these later [edit: separate post now available here].

In 2020 and more recently with Kosmos 2583 and 'Object F', this spawning of other objects happened within weeks after the launch of the parent satellite. But this time with Kosmos 2558 and 'Object C', the release of a second object happened almost three years after launch.

I observed Kosmos 2558 and the newly released 'Object C' last night. 'Object C' reached magnitude +8. The images below are 1-second frame stacks from video observations I made from Leiden, the Netherlands, on the night of 28-29 June 2025, two-and-a-half days after 'Object C' was released. At the time of observation, 'Object C' was some 143 km distant from Kosmos 2558, passing the camera FOV some 16-seconds after it. The first framestack shows 'Object C'; the second shows Kosmos 2558.

 

Object C (click image to enlarge)

 

Kosmos 2558 (click image to enlarge)

Below is the video footage of the pass in question. The first to pass through the FOV is Kosmos 2558 as a bright object: then, some 16 seconds later, 'Object C' passes through the FOV as a fainter object. The footage was shot from Leiden, the Netherlands, with a WATEC 902H2 Supreme camera and Samyang 1.2/85 mm lens.

 

 

It will be interesting to see whether any manoeuvering between the two objects is happening over the coming weeks.

 

UPDATE 4 July 2025:

Since release, Object C has been manouevering with respect to Kosmos 2558. While initially manouevering back to Kosmos 2558, it lowered its orbit significantly (by 15 km) on July 3 near 18:42 UTC. See diagram below.

Click diagram to enlarge

The reentry of the Chinese Zhuque-2E upper stage 2025-103G over Kazachstan on 5 June 2025

still from one of the fireball movies posted on Twitter by @Buggy__Bugler

 

In the evening of 5 June 2025 around 22h local time (17h UTC), a slow profusely fragmenting fireball was seen and filmed from several cities in Kazachstan, including Astana, and Bishkek in neighbouring Kirgistan. It had all the well-known characteristics of a satellite or rocket stage reentry. Indeed, as it turns out, this was a rocket stage reentry: the reentry of the upper stage of a Chinese Zhuque-2E (ZQ-2E) rocket, 2025-103G, from a multiple satellite launch on May 17.

Unfortunately, some Russian and Ukranian language twitter accounts started to disseminate the footage with the wildly wrong suggestion that this was a failing Russian Oreshnik IRBM breaking up. This misinformation next proliferated very quickly via various social media, and later also traditional media (e.g. Newsweek). This while it is not a Russian Oreshnik missile at all, as already mentioned.

I was alerted to the event somewhat later that evening when several of my social media followers tagged me and asked me for my opinion. It didn't take me long to identify the event as a space-launch related reentry rather than a Russian missile. Indeed, the Kazachstan MoD had meanwhile also deemed it a space debris reentry, per various news outlets.

The object in question was 2025-103G (cat. nr. 64054), the Zhuque-2E (ZQ-2E) upper stage from a Chinese satellite launch on 17 May 2025 from Dongfeng (Jiuquan). The upper stage from this launch was left in an in initially 600 x 175 km, 96.1 degree inclined orbit.

The CsPOC TIP for this object's reentry available at that time (it was updated later), had forecast reentry at 5 June 2025, 15:40 UTC with an uncertainty of  ± 3 hours. The Kazachstan event (~17h UTC) hence was within the reentry window. When I checked the trajectory over this full window, it showed that the object would make a south-to-north pass over eastern Kazachstan around 17:10 UTC, very close in time to the Kazachstan event (which was reportedly around 10 pm local Astana time = around 17 hr UTC). Direction of movement in the various videos of the event matched well.

Later, CSpOC published a final TIP placing the reentry at 5 June 2025 17:08 UTC  ± 1 min, near 36.6 N, 73.5 E. Given the 1 minute accuracy, this is likely based on a DoD satellite observation of the reentry fireball. The TIP position is just south of Kazachstan, but a reentry is a process of several minutes duration. Moving south-to-north, the fireball created by the fragmenting space debris would move northwards, over eastern Kazachstan, in the minutes directly after this time mark. In other words, this final TIP matches the event quite well.

Below is the trajectory over the final revolution of the ZQ-2E upper stage, based on the last available TLE (epoch 25156.48638369) which dates from ~5 hours before the reentry:

 

Click map to enlarge

I next ran a reentry model with our Delft Technical University open source Astrodynamics package Tudat. The ZQ-2E upper stage has a dry mass of approximately 5000 kg and measures 12 x 3.4 meter. Using 60% of the maximum drag area for that dimension, a value usually representing the average drag surface of a tumbling (and hence showing a variable drag surface) elongated rocket stage well, the Tudat model predicts reentry near 17:03 UTC ± 1.1 hr (remember, this is based on a 5 hour old orbit), the nominal value being well in line with the Kazachstan event and nominally within 5 minutes of the CSpOC final TIP.

Next I ran the model again adjusting the drag area slightly, via trial-and-error, such that the model would conform to the estimated start of visibility of the reentry fireball, at just below  ~100 km altitude, at the time/location of the CSpOC TIP (17:08 UTC). 

I get a reasonable match when I reduce the drag area to about 58% of the maximum drag area. Below is a map showing the resulting estimated reentry trajectory (movement is from south to north):

click map to enlarge

When I use this Tudat-estimated reentry trajectory to generate a sky track for Astana, Kazachstan, I get this approximate sky trajectory (movement is from left to right, i.e. south to north, low through the west):

Click map to enlarge

This conforms quite well to some of the video footage of the reentry (several of which show the reentry fireball pass the waxing moon), e.g.:

 

still from one of the movies posted on Twitter by @Buggy__Bugler

The predicted sky track for Astana of course depends on how accurate our Tudat-modelled atmospheric altitudes of the reentering rocket stage are. If they in reality are a bit lower than we modelled, the trajectory will be located slightly lower in the sky (and vice versa, slightly higher if the altitudes are in reality a bit higher). It is very clear however that the general direction and location of the trajectory in the sky matches well with what was seen and filmed.

As usual, I feel some frustration about the general absence of information on camera locations and time of the footage regarding the imagery of this event distributed via various social networks. Those data are important but almost never included. These matches of observations with reentry data would get so much easier if people posting footage would include the geographic location and the time. So please people: next time you post something like this, include these important data.

This event once again also showed the failure of AI as a reliable source of information for answering questions regarding events like this (we earlier saw that with the Kosmos 482 Descent Craft reentry too). Twitter's AI "Grok" generated some profound nonsense (i.e., misinformation) when people asked it to identify the character of the event, likely partly as a result of the large amount of disinformation already doing the rounds on social media about this event.

Raiders of the Lost Venus Probe: a post-mortem of an interesting reentry and the confusion it left

On 10 May 2025, an unusual object, the Kosmos 482 Descent Craft, had an uncontrolled reentry (see this earlier post).

With my TU Delft colleague Dominic Dirkx, I have written a 'post mortem' for this reentry for The Space Review of 27 May 2025, titled:

 "Raiders of the Lost Venus Probe: a post-mortem of an interesting reentry and the confusion it left"

It can be read here.

(the Tudat script we used for our reentry analysis can be downloaded here. Tudat itself can be downloaded here). 

Kosmos 2588 has been placed in the same orbital plane as the US spy satellite USA 338: another RPO?

click image to enlarge

 

Russia launched a new military satellite from Plesetsk today (23 May 2025), Kosmos 2588 (cat nr. 64095, COSPAR 2025-109A). It was placed in a 73-degree inclined, approximately 464 x 481 km orbit.

As first noted by Bart Hendrickx, the orbital plane is very close to that of a US military optical reconnaissance satellite, USA 338 (2022-117A). This can be seen in the diagram above. 

The difference in RAAN is only 0.11 degrees, the difference in inclination is a mere 0.6 degrees. Kosmos 2588 orbits just above USA 338. They can come to within 100 km of each other in this orbital configuration.

This is the fourth time in the last five years that Russia has placed a military satellite in the same orbital plane as and very close in orbital altitude to that of a US military optical reconnaissance satellite. 

The first time was in 2020 when they placed Kosmos 2542/2543 in the orbital plane of USA 245. That had the appearance of an 'inspector satellite' mission (although Kosmos 2543 later fired a projectile). The second time was in 2022 when Kosmos 2558 was placed in the orbital plane of USA 326. The third time was in 2024, when Kosmos 2576 was placed in the orbital plane of USA 314 (see my earlier blogpost here). 

The latter two occasions were different from the first, in that the Russian satellites in question stayed co-planar with the US satellites, rather than paying a relatively brief visit as Kosmos 2542/2543 had done. Rather than being inspector satellites, we might perhaps be seeing a counterspace capacity (a sleeping co-orbital ASAT capacity) being positioned in the latter two cases.

Which makes the current fourth instance highly interesting: the plot thickens. It will be interesting to see whether they keep this one co-planar as well.

It is possible that, as was the case with the launch of Kosmos 2576 a year ago, multiple payloads have been put in space. So far (less than a day after launch) only one has been catalogued.

We are seeing more and more of these RPO activities (in LEO as well as GEO) lately. Things in space are clearly getting more confrontational and passive-aggresive. A very worrying trend.

The tumbling behaviour of the mysterious Kosmos 2553 satellite

Framestack (530 frames) showing variable brightness of Kosmos 2553. Click image to enlarge

Over three years ago, on 5 February 2022, Russia launched a mysterious military satellite, Kosmos 2553 (2022-011A), into an unusual orbit at approximately 1995 km altitude, the outermost margin of Low Earth Orbit. Very few satellites orbit there.

Early 2024, US Congressman Michael R. Turner, chairman of the House Intelligence Committee, wrote an unprecedented public letter to House members in which said he had concerns about a "serious national security threath", urging then President Biden to declassify the information. Subsequently, various US news sources quoted various of the proverbial "anonymous sources", with often conflicting information about the nature of the threath, but all indicating some kind of Russian space weapon. And moreover: a nuclear weapon, alledgedly. See my earlier 2024 blogpost here. Based on statements that a kind of prototype of the satellite in question was in Low Earth Orbit 'in a region not used by any other spacecraft', Kosmos 2553 was identified as the likely suspect.

More recently, in April 2025, various news sources (e.g. here and here) reported that as of late 2024, Kosmos 2553 had started to tumble, indicating a possible loss of attitude control.

I imaged Kosmos 2553 on May 20, 2025, and it indeed shows a brightness variation that was not present when I imaged it a year earlier. The image above is a 530-frame (21.2 second) stack, and the brightness variation can be clearly seen in it. Below is a sequence of the actual video footage:

 

We can compare this to video footage from a year earlier (20 May 2024) when the object was steady:

 

I extracted almost 9 minutes of photometric information from the 20 May 2025 video. This shows a prominent flash cycle of (peak-to-peak) 2.22 seconds, with a regular pattern consisting of a brighter flash followed by a fainter flash, ad infinitum. 

Below is a diagram of the full 9-minute photometry series, and a detail of a part of the curve which shows the pattern of the brightness variation: the red line is a fitted multi-sinusoid who's main period is 2.22 seconds. Gaps in the data are moments the camera was repositioned, or the object was closely passing a star.

Click diagram to enlarge

 

 

Click diagram to enlarge

The datapoints in the diagrams are 5-frame running averages. The data in the two diagrams above have been corrected for range and phase angle variation, i.e. to absolute magnitude (normalisation to 1000 km range and 90 degree phase angle). 

The apparent observed magnitude varied between magnitude +5.7 and +9.4. Below are these apparent photometric measurements uncorrected for phase angle and range (note that a calibration of the data to the Visual band has been done to correct for instrument spectral sensitivity):

 

Click diagram to enlarge

The imagery was made from my home in Leiden, the Netherlands, with a WATEC 902H2 Supreme camera and Samyang 1.4/85 mm lens, filming at 25 frames/second. 

The photometry clearly supports reports that Kosmos 2553 has started a tumble or spin. Whether this means it is no longer operational, is another question that is less easily answered. Given the regularity of the flash period, the flashing could be due to spin stabilization. On the other hand: why did this only become apparent some 2 years into the mission?

In orbital data for Kosmos 2553, a sudden subtle change in orbital altitude can be seen starting around 15-16 November 2024 (see diagram below). Perhaps this is when the tumbling or spin started.

Click diagram to enlarge

Multiple analysts, including myself, believe Kosmos 2553 to be a (Radar) imaging satellite (possibly 'Neitron'). It has a ground track that after four days closely repeats itself, which would fit an imaging satellite. It is not clear why some in US Government circles believe that Kosmos 2553 is connected to a 'nuclear space weapon' program (presumably Ekipazh). That suspicion must be based on undisclosed HUMINT.

Russia itself has stated that Kosmos 2553 is a "technological spacecraft […] equipped with newly developed onboard instruments and systems for testing them under the influence of radiation and heavy charged particles". That explanation does not sit entirely well with several analysts: yes, at 2000 km altitude the radiation regime is different and more severe compared to a more typical Low Earth Orbit: but not thát much different and severe, really.