Author Topic: Kosmos 2519/2521/2523 - Soyuz-2.1v/Volga - Plesetsk - June 23, 2017  (Read 475060 times)

Online Alter Sachse

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The whole thing is mysterious.
I thought K2519 is the target and K2521 the inspector.
Now the target is running to the hunter ??
One day you're a hero  next day you're a clown  there's nothing that is in between
        Jeff Lynne - "21century man"

Offline russianhalo117

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The whole thing is mysterious.
I thought K2519 is the target and K2521 the inspector.
Now the target is running to the hunter ??
they are independent spacecraft testing multiple hardware for likely future spacecraft.

Online Alter Sachse

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Cosmos 2521 has fallen from 350/369 km to 347/362 km due to natural influences.
One day you're a hero  next day you're a clown  there's nothing that is in between
        Jeff Lynne - "21century man"

Offline Phillip Clark

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Another Cosmos 2519 manoeuvre downwards:

Jul  9.596    97.855 deg      95.227 min     436-623 km    303 deg
Jul 10.522   97.856 deg      94.932            410-621         304

Maybe a point will be reached that perigee is kept almost constant and apogee reductions begin?

And as comparisons (these have not manoeuvred since April 2018 and October 2017 respectively:

Cosmos 2521:   Jul 10.783    97.901      91.627     347-362    261

Cosmos 2523:   Jul 10.792    97.850      96.872     553-665    106
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Offline Phillip Clark

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After a day's pause, Cosmos 2519 once more lowers its orbit:

Jul 11.753    97.856 deg      94.933 min     410-620 km    300 deg
Jul 12.503    97.859            94.651            387-617         300
I've always been crazy but it's kept me from going insane - WJ.

Offline Phillip Clark

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Cosmos 2519:

Jul 12.873    97.860 deg      94.653 min     387-617 km      299 deg
Jul 13.464    97.857            94.369            363-613           301

Well that has matched the Cosmos 2519 perigee with the Cosmos 2521 apogee: I wonder if they will start to bring the Cosmos 2519 apogee down and match it to the Cosmos 2521 perigee?   Or maybe match the Cosmos 2521 perigee first and then start to bring down the apogee?   Or. of course, neither of these options!

The orbital planes of the satellites are currently 14 degrees apart (and increasing) so this will need to be correcting - expensive on propellant unless the Russians can reverse the drift between the planes.
« Last Edit: 07/14/2018 03:53 pm by Phillip Clark »
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Offline Phillip Clark

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The Cosmos 2519 perigee is now below the orbit of Cosmos 2521:

Jul 14.776    97.862 deg      94.372 min      363-613 km    296 deg
Jul 15.496    97.847            94.072             337-610         295
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Offline Phillip Clark

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Cosmos 2519 doesn't appear to be matching the Cosmos 2521 orbital altitude:

Jul 15.823    97.855 deg      94.076 min     337-610 km    295 deg
Jul 16.541    97.848            93.778           312-606          295

Maybe it will be lower that C2521 to give the orbital planes a chance to drift close over time?   But apogee needs to come down first.
I've always been crazy but it's kept me from going insane - WJ.

Offline Phillip Clark

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The ups and downs of Cosmos 2519.   After a pause for a day, it has now manoeuvred up .......

Jul 17.714    97.850 deg      93.777 min     312-606 km    291 deg
Jul 18.562    97.855            94.103            315-635         288

I've always been crazy but it's kept me from going insane - WJ.

Offline Phillip Clark

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Cosmos 2519 still going up .......

Jul 18.889    97.855 deg      94.104 min     315-635 km    287 deg
Jul 19.544    97.859            94.428           317-664          285

The new apogee is matching that of Cosmos 2523.   But for how long?
« Last Edit: 07/20/2018 07:12 am by Phillip Clark »
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Offline Phillip Clark

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Now we have Cosmos 2521 on the move.   No manoeuvre from Cosmos 2519 yesterday but instead Cosmos 2521 converted its perigee to a new apogee:

Jul 19.827    97.899 deg      91.613 min     346-362 km    223 deg
Jul 20.583    97.901            90.929           292- 348           93

Nothing from Cosmos 2523, in case you are wondering: yet, anyway,
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Offline Phillip Clark

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From my rather large Cosmos 2519-2521-2523 spreadsheet, the orbital periods and altitudes of Cosmos 2519 and Cosmos 2521.
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Offline Phillip Clark

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No new manoeuvres to report today but I have just noticed that the orbital planes of Cosmos 2519 and 2523 are only three degrees apart and this is decreasing.   And the apogee altitudes are closely matched, although the apogee directions will need to be aligned .........

Oh, and the maximum nodal separation was June 26, a day or two before Cosmos 2519 started its manoeuvres.   Of course, I could well be coincidence-hunting!
« Last Edit: 07/22/2018 01:30 pm by Phillip Clark »
I've always been crazy but it's kept me from going insane - WJ.

Offline B. Hendrickx

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Phil, first of all, thank you for your almost daily updates on this mission.

With Kosmos-2519 and 2521 now both performing maneuvers that are seemingly not designed to get them back in each other's vicinity, I'm wondering if their orbits are being set up to make joint long-distance observations of other objects in space (with Kosmos-2523 possibly serving as one of the targets). I don't know if the current orbital geometry of the satellites would make that possible, but combining images from two space surveillance satellites in slightly different orbits is a technique that has been discussed in Russian literature to accurately determine the orbits of orbiting objects.

For instance, the technique was proposed in a PhD dissertation written by Andrei Treshchalin, who is affiliated with an optical company called NPO Lepton. The dissertation's main theme was the use of space-based optical equipment to determine the orbits of space debris. As part of his PhD research, Treshchalin used a camera aboard NPO Lavochkin's Zond-PP (MKA-FKI (PN1)) remote sensing satellite (launched in July 2012) to observe objects in space.  The camera (called FGMB) was built by NPO Lepton, but was not the satellite's main payload. In the final chapter of his PhD, Treshchalin discusses the possibility of performing joint observations of orbiting objects from two observation satellites in slightly different orbits. Using a technique called epipolar geometry, this would make it possible to increase the accuracy of orbital measurements twofold. 

The PhD thesis is here:

http://ipg.geospace.ru/ref/DS/00000003/disser.pdf


I should add that there is no evidence that NPO Lepton is directly involved in the Kosmos-2519/2521/2523 mission.  It is interesting to note though that Treshchalin's PhD was reviewed by specialists of the TsNIIKhM institute, which is known to be involved in this mission (see Reply 241).

http://ipg.geospace.ru/ref/DS/00000003/ЦНИИХМ.pdf

Earlier this decade NPO Lepton also worked on a star tracker called ZKL-1312 for a constellation of small space surveillance satellites (Trek SK-1) proposed by a company known as Tekhnologii Geoskan. However, that project never materialized.

https://en.ppt-online.org/261889

Online Alter Sachse

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That's an interesting theory.
But are the 3 objects (C 2519/2521/2523) not far from each other?
One day you're a hero  next day you're a clown  there's nothing that is in between
        Jeff Lynne - "21century man"

Offline Phillip Clark

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Thank you for your comments Bart!

Do you remember something that Sven Grahn said at the BIS meeting in June? - that the different satellites in the Cosmos 2519 "stack" might be carrying different sets of sensors for tracking/observing each other, and part of the mission objectives would be seeing how these different sensors worked in flight.

Certainly the manoeuvres which Cosmos 2519 has completed in the last month must rule out the "Earth observation" role for the satellite as a serious mission objective!   Although of course, imaging other objects in space was also mentioned as an objective (this was when the three satellites of the stack were still attached to each other).

I could imagine both Cosmos 2519 and Cosmos 2521 being "active" inspector satellites, possibly with Cosmos 2523 being a non-manoeuvring (apart from the single perigee-reduction manoeuvre after deployment from Cosmos 2521) target.   Of course, this would not rule out Cosmos 2523 also carrying its own sensors to track/observe either/both of the other two satellites at varying distances.   The orbit of Cosmos 2523 had apogee above both Cosmos 2519 and 2521 and perigee below both satellites until April this year.   So maybe it was being tracked both against a stellar background and against the Earth - although I would imagine that for a small satellite the latter would be difficult to do.

There are plenty of "known unknowns" and "unknown unknowns" with this fascinating mission.   I just hope that they pause in about ten days so I can draw a line across the second Spaceflight article and get it submitted!   I think that David Baker might have a heart attack when he sees the list of manoeuvres ..........
I've always been crazy but it's kept me from going insane - WJ.

Offline Phillip Clark

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All has been quiet with these satellites for nearly a week, but of course it is far too soon to suggest that the manoeuvres are over.

This week what seems to be the annual "data transmission problem" reappeared with Space-Track, which means that they are issuing only the latest set of orbital data each day, not every element set generated that day, and even then the reduced data are being issued a day later than normal.   No-one ever explains what the problem is with transmitting the data, but last year it lasted for around three months before the problem was sorted.
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Offline Star One

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All has been quiet with these satellites for nearly a week, but of course it is far too soon to suggest that the manoeuvres are over.

This week what seems to be the annual "data transmission problem" reappeared with Space-Track, which means that they are issuing only the latest set of orbital data each day, not every element set generated that day, and even then the reduced data are being issued a day later than normal.   No-one ever explains what the problem is with transmitting the data, but last year it lasted for around three months before the problem was sorted.

Been catching up on my issues of Spaceflight so have now read your article on this topic and it was much appreciated and informative. That’s the most recent issue I’ve read so have you written a follow up letter as you indicated you were going to?

Offline Phillip Clark

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Been catching up on my issues of Spaceflight so have now read your article on this topic and it was much appreciated and informative. That’s the most recent issue I’ve read so have you written a follow up letter as you indicated you were going to?

Thank you for your comments.

My "Letter to the editor" quickly grew into a second article which I planned to send in at the beginning of this month.   Then Cosmos 2519 started to manoeuvre at the end of June!

So, unless further manoeuvres begin, my plan is to draw a line across events on July 31st and send in the article in about a week's time.   I just hope that David Baker, the editor, does not have a heart attack when he sees the length and the table with all of the manoeuvres listed!
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Offline Star One

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Been catching up on my issues of Spaceflight so have now read your article on this topic and it was much appreciated and informative. That’s the most recent issue I’ve read so have you written a follow up letter as you indicated you were going to?

Thank you for your comments.

My "Letter to the editor" quickly grew into a second article which I planned to send in at the beginning of this month.   Then Cosmos 2519 started to manoeuvre at the end of June!

So, unless further manoeuvres begin, my plan is to draw a line across events on July 31st and send in the article in about a week's time.   I just hope that David Baker, the editor, does not have a heart attack when he sees the length and the table with all of the manoeuvres listed!

Do you think we can expect more satellites like 2519, is it just the first in a series or is it an experimental one off?

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