Kosmos 2558 keeping its orbit close to USA 326 [UPDATED]

 [updated 9 Sept 2022 20:00 UTC]

In a series of previous blogposts (here, here and here) I wrote about a cat-and-mouse game going on in space, where the recently launched Russian satellite Kosmos 2558 (2022-089A) is stalking the US spy satellite USA 326 (2022-009A).

That game of cat-and-mouse is still ongoing. Over the past week, Kosmos 2558 has been making adjustments to its orbital inclination (see the diagram above). 

At first glance, you would say that it is apparently moving its orbit away from USA 326, as it is increasing the difference in orbital inclination.

But that is deceptive. The difference in orbital inclination between the two objects is actually very small (currently 0.2 degrees), and so is the difference in RAAN (currently 0.26 degrees). The two objects basically share the same orbital plane.

So why the adjustments in orbital inclination? If you look at the diagram below, which depicts the effects of the orbital inclination adjustments on the precession of the RAAN (i.e. the drift of the node of the orbit), you will note that the effect is that the RAAN precession starts to more closely match that of USA 326.

In other words:  the adjustment is actually in order to get the precession of the two orbital planes synchronised, i.e. to make sure the orbital planes do not drift too far apart. This ensures that the two objects will continue to share virtually the same orbital plane.

 

Click diagrams to enlarge

 

 

Because Kosmos 2558, while sharing the same orbital plane as USA 326, is orbiting at a slightly lower orbital altitude than USA 326 (on average some 60 km lower), its orbital inclination needs to be slightly different from that of USA 326 in order to maintain a similar RAAN precession: the rate of RAAN precession depends on both the inclination and orbital altitude.

The fact that it is making adjustments to synchronize its rate of RAAN precession with that of USA 326, again makes clear that the launch of Kosmos 2558 into the orbital plane of USA 326 is no coincidence.

The image below shows how closely the orbital planes match: the main difference is a relatively small difference in altitude. This results in slightly different orbital periods for both satellites, and as a result Kosmos 2558 is 'taking over' USA 326 every 5 days, resulting in flyby's at distances of 60 to 80 km each 5 days.

 

click image to enlarge

 

UPDATE 9 Sept 2022 20:00 UTC:

Kosmos 2558 made an orbit raising manoeuvre on 8 September 2022 around 11:10 UTC, raising apogee by 5.5 km and perigee by 1 km. It also adjusted its orbital inclination again, to get the RAAN precession closer to that of USA 329:

 

click diagram to enlarge

click diagram to enlarge

The flyby of USA 326 by Kosmos 2558 on August 4: a post-analysis

click image to enlarge

In a previous post I discussed the launch of Kosmos 2558 (2022-089A), a Russian military satellite which was launched from Plesetsk on August 1, 2022. 

As I pointed out, it was inserted into the same orbital plane as the American classified military satellite USA 326 (2022-009A, an electro-optical reconnaissance satellite launched in February 2022), at an orbital altitude only a few tens of kilometers below it. 

And that was probably no coincidence: Kosmos 25578 is likely an 'inspector' satellite meant to surreptitiously check out USA 326.

 

click image to enlarge

 

The two satellites had a relatively close flyby on August 4. I did a post-encounter analysis based on orbits from before and after the flyby, to assess the time and the distance of the flyby.

I find that the close flyby happened near 14:16:27 UTC (August 4, 2022), give or take a few seconds, at a nominal distance of ~67 km. Most of that distance (about 64 km) is in altitude. 

The flyby happened in daylight near 42.3 N, 25.9 W, over the mid-Atlantic, while both objects were southbound. USA 326 was at an altitude of about 518 km at that time, and Kosdmos 2558 at an altitude of about 453km.

Below is an animation of the flyby, as seen from two viewpoints (first lateral, than oblique):

 

~67 km is a clear safe distance and therefore no cause for worry (although it worried some generals in the Pentagon perhaps), but nevertheless close enough to make it interesting. I strongly suspect that Kosmos 2558 was imaging USA 326 at the time, in an attempt to gather information on the character of the satellite.

The diagram below gives the distance with time between Kosmos 2558 and USA 326 around the time of the approach.

click diagram to enlarge

It will be interesting to follow the two objects and see whether a new flyby happens at some point. In a previous similar case in early 2020, another Kosmos satellite, Kosmos 2542, was sent to check out the US military satellite USA 245, and released a second satellite, kosmos 2543, that chased the US satellite for a while.

 

Added comment:

Fred Jansen made a pertinent remark: from launch to operational in a mere 3 days would be awfully fast.
Another issue, brought up by Allan Thomson, is that the Sun-Kosmos 2558-USA 326 angle was quite low during this encounter, which is  not ideal.

However, as the two objecst share the same orbital plane, these encounters repeat at intervals: so even if it was not ready and fully operational yet during this approach, there will be other opportunities in the future. It will be interesting to see whether Kosmos 2558 will raise its orbit at some point, or will do other manoeuvres to keep the precession of its RAAN in line with that of USA 326.

(Note: the orbital elements for USA 326 used in this analysis are based on optical tracking data by an international group of  Independent Space Observers, including myself, Cees Bassa and Russel Eberst)

A stalker and its prey (Kosmos 2558 and USA 326)

 

In my previous post I discussed the newly launched Russian military satellite Kosmos 2558 (2022-089A), that was launched on August 1 into the orbital plane of the US military IMINT satellite USA 326 (2022-009A). There are indications that it is an 'inspector' satellite that is going to take a detailed look at USA 326.

Last night I observed them both, passing about half an hour after each other. Over the enxt 24 hrs Kosmos 2558 will approach USA 326, to a distance of ~75 km on August 4 ~14:47 UTC, if they do not manouvre in the mean time.

Above are framestacks from the captures (in the image with USA 326, a flaring Starlink, Starlink-1349, is also visible, in the lower left corner).

Below is the video footage. It was taken with a WATEC 902H2 Supreme with a Pentax 1.2/50 mm lens at 25 fps.

It will be interesting to follow this Cold war cat-and-mouse game above our heads over the coming days and weeks....

 

 

Kosmos 2558, a Russian inspector satellite targetting the US IMINT satellite USA 326?

 

click image to enlarge

On August 1, 2022, at 20:25 UTC, Russia launched a Soyuz 2.1v carrying a military satellite from Plesetsk into a Polar orbit. It has since been catalogued under nr 53323 (COSPAR ID is 2022-089A). It will probably receive the designation Kosmos 2558. 

Directly after launch it was in a 435 x 452 km, 97.25 degree inclined orbit. The Volga upper stage was catalogued in a 284 x 425 km orbit.

Before the launch, there was a rumour that this was another 'inspector' satellite - a snooping satellite meant to covertly inspect another satellite. After some speculation about the potential target arose, I pointed out that the middle of the launch window as indicated by NOTAM's for the launch, 20:30 UTC, was close to the moment that the orbital plane of the classified US electro-optical IMINT satellite USA 326 (2022-009A) passed over Plesetsk, at 20:25 UTC. 

And sure enough, it did indeed launch at 20:25 UTC, into the orbital plane of USA 326. And as it turned out, into an orbital altitude that is close as well.

The apparent target, USA 326, was launched in February and is widely believed to be a new generation electro-optical IMINT satellite. It moves in a 97.4 degree inclined, 489 x 518 km sun-synchronous polar orbit. 

The RAAN of the newly launched Kosmos 2558 matches the RAAN of USA 326 closely, with a difference of only 0.04 degree (changing by about 0.01 degree/day). The close correspondance of the two orbital planes can be seen in the diagram above. The orbital altitude of Kosmos 2558 is about 60 km lower than that of USA 326, but that might change if any post-launch manoeuvres are done the coming days and weeks.

With the current orbit, Kosmos 2558 will make a relatively close approach to USA 236 at August 4 near 14:47 UTC. The approach distance is ~75 km, almost all of that (73 km) is in altitude.

 [EDIT: a post-encounter analysis on 6 Aug 2022 based on orbits closer to the approach moment gives 4 August ~14:16:27 UTC for the approach, and a nominal distance of 67 km, most of this in altitude]

In early 2020, Russia did something similar with Kosmos 2542/2543, directing it towards the KH-11 electro-optical reconnaissance satellite USA 245.

It will be interesting to follow both satellites the coming weeks, to see what happens.