Orbital Focus - International Spaceflight Facts and Figures
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Tyneside, UK
2024 Jun 15
Saturday, Day 167

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Initial Orbital Manoeuvres

Spacetrack has identified seven items in orbit as emanating from the 2013-037 July 19 launch. As of August 10 it had still not managed to associate China's formal names with its own "Payload A", "Payload B" and "Payload C" names, introduced August 5 as a temporary measure. The upper stage of the CZ-4C launching rocket is 2013-037D and there are three debris items - tagged as E, F and G.

There has been not been any switching around of IDs in the database so it seems NORAD got them right at the first attempt. It has to be recognised that there is more than the radar and visual tracking of objects available to measure their orbits and establish their identity. Somewhere along the line here will have been some radio tracking that has enabled A, B and C to be recognised as payloads.

Payload C 'Comes Alive'

August 1, 2013-037C changed the height of its orbit, confirming itself up as being one of the three satellites. The change was quite small. A two-part manouvre eventually took the orbit height from 664 x 673 kilometres to 670 x 675 kilometres as of August 2. There was a very minor change in orbital inclination at the same time but it increased by less than .05°.

Further small orbit adjustments occurred August 3 and 4. A summary of the orbit history and Payload C can be found in the zarya.info launch list for 2013.

The obvious candidate to be Payload C is Shiyan 7 as it seems to be the payload with a robot arm to capture other satellites. It is engaged in joint manoeuvres with Payload B.

The plot illustrates the 2013-037C orbit change in terms of orbital period. It shows also that none of the other items has manoeuvred. Element sets for 037E stopped appearing August 1, shortly before 037C raised its orbit. They resumed August 5.

Data is added to the plot automatically as new orbital element sets are released by SpaceTrack. Periodic checks of this page will show any further changes.

SJ-15 Period

The rocket stage (2013-037D) is not shown because it moved away to a distinctly lower orbit once it had released the satellites.

Other Notes

Another measurement available from SpaceTrack is Radar Cross Section (RCS). Its value indicates how strongly an object reflects a radar signal. It is often an indication of size but not always because a small object might be coated in a material that reflects radar signals rather well.

The RCS values published August 3 by Spacetrack for items from this launch are 1.97 (2013-037A), 1.09 (037B), 2.94 (037C), 8.22 (037D - the rocket), 3.4 (037E), 0.03 (037F), 0.05 (037G).

Rocket stage aside, 2013-037C and 037E are the largest, initially pointing to the likelihood of them being payloads. Spacetrack's continued issuing of element sets identifying A, Band C as the payloads suggests that 037E is a bright radar reflector rather than something of significant size.

Page Date: 2013 Aug 10

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