The BBC has a news article saying: "Mystery Russian satellite's behaviour raises alarm in US". But the article doesn't say how or why the behavior is "abnormal".

And the linked transcript of Remarks on Recent Russian Space Activities of Concern merely states:

Mr. President, in October of last year the Russian Ministry of Defense deployed a space object they claimed was a “space apparatus inspector.” But its behavior on-orbit was inconsistent with anything seen before from on-orbit inspection or space situational awareness capabilities, including other Russian inspection satellite activities. We are concerned with what appears to be very abnormal behavior by a declared “space apparatus inspector.”...

(emphasis added)

So, what's so special/different about this (unnamed) satellite's orbit?

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    $\begingroup$ Based on the comments alone, it's impossible to say for sure. If I had to take a wild guess, I'd say proximity operations near unfriendly vehicles would be a likely candidate. Want to deny an IMINT satellite access to its tasked location? Park a vehicle in front of it, in classic "you make a better door than a window" fashion. That's a total WAG though. $\endgroup$
    – Tristan
    Aug 15, 2018 at 19:13
  • $\begingroup$ @Tristan Correct me if I'm wrong, but the article's mention of anti-satellite capabilities brings to mind the possibility that it could be used to destroy or disable satellites: anywhere from parking in front of a satellite to wiping it out. $\endgroup$
    – called2voyage
    Aug 15, 2018 at 19:16
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    $\begingroup$ @called2voyage Generally correct. I would look at this as the space equivalent of Russia's practice of sending fighters and bombers to encroach on our airspace from time to time. $\endgroup$
    – Tristan
    Aug 15, 2018 at 19:40
  • $\begingroup$ It's likely that the orbit will be fluctuating, possibly with disregard to potential impacts with other satellites, or more likely, manoeuvres that seem to bring it close to US intelligence satellites. This will have been triggered as the advertised nature of the satellite implies a specific pattern of behaviour and the satellite is not displaying said behaviour. $\endgroup$
    – david_c
    Aug 16, 2018 at 9:42
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    $\begingroup$ CLASSIFIED $\endgroup$
    – gerrit
    Aug 16, 2018 at 10:44

1 Answer 1


Soyuz-2-1v, launched June 23, 2017, had a payload which attained orbit on the same day. The payload received the designation Kosmos-2519.

On August 23, 2017, the Russian Ministry of Defense announced that a miniature vehicle designed to inspect other satellites in orbit had been released from a military spacecraft launched two months earlier.

In its official registration to the United Nations, Russia reported that the satellite separating from Kosmos-2519 on Aug. 23, 2017, had received an official designation Kosmos-2521. Then, on October 30, 2017, Kosmos-2521 also released a sub-satellite, which was officially named Kosmos-2523.

emphasis added

So the satellite that was deployed in October was Kosmos-2523. The satellite that was announced as an orbital inspector was Kosmos-2521, the satellite that Kosmos-2523 deployed from. The official purpose of Kosmos-2523 is unknown. Perhaps that is the unusual behavior? A launch occurred and deployed a payload. That payload contained a secret payload that then deployed and was announced later. Then that secret payload deployed another payload in October the intentions of which were unspecified.

CNN describes the "nested" satellites here:


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    $\begingroup$ Well, she did say abnormal behavior, so I guess it doesn't have to be maneuvers like I was thinking. Is there any way to know if 2523 was flitting about in new or dangerous ways (other than its "sneaky" launch)? $\endgroup$ Aug 16, 2018 at 18:49
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    $\begingroup$ @BrockAdams Someone more qualified then me would have to look at its orbital data. $\endgroup$
    – called2voyage
    Aug 16, 2018 at 18:50
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    $\begingroup$ Of course the Russians would do this. en.wikipedia.org/wiki/Matryoshka_doll $\endgroup$
    – Mark Adler
    Aug 17, 2018 at 19:01

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