LIVE: Dnepr launch with DubaiSat-1 - July 29, 2009

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T-5 min

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T-1 min

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liftoff

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Stages separation

[anik]

Launch images

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We have now to wait for confirmation of a clean launch...

[William Graham]

Roskosmos reports that the launch was successful.
http://www.roscosmos.ru/NewsDoSele.asp?NEWSID=6920

[jcm]

Objects 2009-041A to J now cataloged.

Based on the (somewhat old) prelaunch info I have, the objects cataloged in orbit appear to be:
             
   A  Deimos 1      634 x 677 km
   B  Dubaisat-1    665 x 681 km
   C  UK DMC-2      623 x 677 km
   D  Aprizesat 4   606 x 677 km
   E  Nanosat 1B    586 x 677 km
   F  Aprizesat 3   565 x 677 km
   G  Dnepr gas-dynamic shield  541 x  678 km
   H  Dnepr rocket stage        668 x 1302 km
   J  Upper payload platform    641 x  677 km

The Dnepr rocket carries on burning as the satellites are dispensed,
so they end up at different heights and the rocket stage ends up with
a higher apogee.

[Danderman]

I am having a little trouble understanding the orbital elements as described above, in particular how the upper stage could be dropping off the various payloads on the way up, but with its perigee lower than the apogee of the payloads, and a much higher apogee. I find it difficult to imagine the required maneuvers to place all these payloads in orbits with a similar apogee, but with the upper stage having a much higher apogee.

[jcm]

I am having a little trouble understanding the orbital elements as described above, in particular how the upper stage could be dropping off the various payloads on the way up, but with its perigee lower than the apogee of the payloads, and a much higher apogee. I find it difficult to imagine the required maneuvers to place all these payloads in orbits with a similar apogee, but with the upper stage having a much higher apogee.

I think it's just that the upper stage keeps on burning after it's dropped off
the last payload. The payloads are released in order of increasing perigee
of course. The last one, Dubaisat, is in a 665 x 681 km orbit (vs 680 x 680 originally planned). Upper stage keeps going, eventually perigee becomes apogee and it ends up in circa 680 x 1300. Why perigee is in fact
only 668 vs 680 is another question  - not too hard to have happen if the thing is not burning quite horizontally.

[Satori]

Launch images from Roskosmos http://www.roscosmos.ru/NewsDoSele.asp?NEWSID=6920

[Danderman]

Why perigee is in fact
only 668 vs 680 is another question  - not too hard to have happen if the thing is not burning quite horizontally.

That kind of was my question. Why would "not burning quite horizontally" generate a perigee  that low?

[eeergo]

There's a nice factsheet with a cutaway diagram with information about Nanosat-1B following this link:

http://2.bp.blogspot.com/_b1AE8x4eLKI/SnDz3XbqKTI/AAAAAAAANbs/l5eHSl15cZY/s1600-h/Imagen+11.png

Source (in Spanish, with a very detailed summary about the Dnepr/R-36M): http://danielmarin.blogspot.com/2009/07/lanzamiento-de-un-dnepr-deimos-1nanosat.html

[jcm]

Why perigee is in fact
only 668 vs 680 is another question  - not too hard to have happen if the thing is not burning quite horizontally.

That kind of was my question. Why would "not burning quite horizontally" generate a perigee  that low?

If at the moment of engine cutoff, your velocity is locally horizontal (perpendicular to the line joining you to the Earth's center), then you are at perigee (assuming v > vcirc). For 680 km,  that is a velocity of 7.515 km/s if you want to stay in a 680 x 680 km orbit, or a velocity of 7.672 km/s if you want to arc up to 1302 km at apogee. The key point is that whenever you are at perigee or apogee, just from the geometry of the ellipse it's easy to see that your velocity is horizontal. Thus, if your velocity isn't currently horizontal, you must currently be higher than your perigee.

 
The Dnepr was actually heading down at an angle of 0.6 deg, with
a horizontal velocity of 7.673 km/s and a vertical downward velocity of
0.083 km/s. But it would actually make no difference to the apogee/perigee if the vertical velocity was upwards - that would just have meant it wouldn't get to the perigee until most of an orbit later.

Maybe think of it this way: nature has to put you somewhere on an ellipse such
that the semi major axis and eccentricity come out to give you the correct orbital period (via Kepler 3) and the correct angle to the horizontal at your current height. That's two constrains on two free parameters.

[Lewis007]

Additional pictures of the processing of UK DMC-2 and Deimos-1 can be found on the SSTL page: http://www.sstl.co.uk/News_and_events/UK-DMC2_launch_gallery

[Lewis007]

More information on Nanosat-1B is available on INTA's website (in Spanish): http://www.inta.es/NoticiaActualidad.aspx?Id=2021.
It includes some documents (English + Spanish) and photos.

[ostangen]

As Roscosmos puts it in English: The Satan on Peaceful Service.

http://tvroscosmos.ru/frm/vestidata/2009/vesti01_08_9_2.php

[JimO]

The military-civilian benefits flow both ways, and Dnepr launches are good training and verification exercises for their military sisters still on active duty. Extending the service lifetime of the 'Satan' has grown more critical with the latest debacle over the 'Bulava', pushing off the availability of Satan's successor farther into the indefinite future.

When I watched the Dnepr launch at Yasniy/Dombarovskiy two years ago, we never saw the military launch team members. They didn't even come to the post-launch party.

[sammie]

Not quite sure whether there is a direct link between the service life of the R-36 and the Bulava. There may have been talk about a new liquid fueled ICBM, but I don't think they ever got further then proposals from the manufacturers. Instead the Topol M (and it's MIRV'ed) brother will remain the mainstay of the Russian strategic forces, replacing the dwindling numbers of older liquid fueled ICBMs, such as the R-36.

Bulava is on a separate track, with little in the way of further Topol or land forces development. Besides the number of subs that can actually carry the Bulava are not much more then 1 or 2. R-29SM service life extension is more critical at this point of time.