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Anton Petrov's new video Another Satellite Collided in Space, But Everyone Missed It Until Now (below) is fun to watch, and links to Jonathan McDowell's tweet string which begins

Space-Track catalog updated today with a note for object 48078, 1996-051Q: "Collided with satellite".
This is a new kind of comment entry - haven't seen such a comment for any other satellites before. Let's look a bit closer:

Then Johnathan McDowell's August 15, 2021 tweet

37 debris objects (green) have been cataloged so far from the breakup - there are likely to be more. This looks to be the first major confirmed orbital collision in a decade.

Johnathan McDowell tweet 37 debris objects (green) have been cataloged so far from the breakup - there are likely to be more. This looks to be the first major confirmed orbital collision in a decade.

and tweet:

Nevertheless it appears that the Yunhai satellite is still under control and able to make orbit adjustments (blue dots) so the collision was not catastrophic?

Johnathan McDowell tweet Nevertheless it appears that the Yunhai satellite is still under control and able to make orbit adjustments (blue dots) so the collision was not catastrophic?

show a cluster of green squiggly lines from April through August 2021 that seem to be somehow associated with a conjunction event involving Yunahi-1.

What are these green squiggly lines? What do they mean?


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From McDowell tweet of Aug. 15th, 7:17AM

37 debris objects (green) have been cataloged so far from the breakup - there are likely to be more.

the most obvious interpretation is that the green lines represent the altitude vs time of the fragments. The blue line corresponds to the altitude of Yunhai 1-02 (which shows its in-orbit maneuvers after the impact in the zoom in second chart).

I don't know what the red line means.

EDIT(1st Sep.)

From NASA debris quaterly-June 2021, the Gabbard plot:

enter image description here

Somebody familiar with in-orbit collision may be able to correlate the two sets of data.

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  • $\begingroup$ Thanks! I'm confused how I'd read past the "37 debris objects (green)" without it sinking in, I suppose that's a personal anomaly. I'd assumed that red, green, blue were periapsis, semimajor axis and apoapsis but it's just a guess and that doesn't explain why blue can vary so much while both of the other two remain constant. The rapid evolution of the green squiggles over a few months at altitudes as high as 900 km is perplexing unless they are elliptical with low periapsese. $\endgroup$
    – uhoh
    Aug 31 at 22:53
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    $\begingroup$ @uhoh, There is at least one green curve that doesn't correspond to a fragment from the collision, since it started long before March 2021.The red curve could be the altitude of another satellite that the author of the plot cares about collision with one of the fragments. I have added a Gabbard plot (for forensic experts!). $\endgroup$
    – Ng Ph
    Sep 1 at 8:28
  • $\begingroup$ Interesting! Okay I'll at least scratch my head about it. $\endgroup$
    – uhoh
    Sep 1 at 12:47

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