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"
(the Tudat script we used for our reentry analysis can be downloaded here. Tudat itself can be downloaded here).
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| 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.
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| 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.
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| Click diagram to enlarge |
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| 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):
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| 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.
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| 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.
