#Change5 DRO state vector estimate with rationale.

Amateurs lost signal ~2021-12-03. About 3 integer periods of ~13 days, which is around the optimal DRO period. We appear to be seeing spacecraft at eastern elongation now. So... (1/n)
From what I understand of DRO insertion geometry one likes to enter DRO from one of the elongation points not the EM-L1 or EM-L2 points. This insertion burn occurred ~ 2021-12-03. SOURCE: ntrs.nasa.gov/api/citations/…
Location of #Change5 this evening is within error bars of rough location of a hacked together state vector estimate is. (2/n)
Epoch = 30 Nov 2021 05:45:00 UTC
X = -67449.18744845511
Y = -17483.7843354477
Z = 6702.56651251734
VX = -0.08113647071667798
VY = 0.3191833891179148
VZ = 0.01610495268014363

• • •

Missing some Tweet in this thread? You can try to force a refresh

Keep Current with Scott Tilley

Scott Tilley Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!


Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @coastal8049

9 Jan
Could #Change5 be in a Distant Retrograde Orbit (DRO) of the Moon pulling off a space first?

CE5 is ~15deg east of the Moon suggesting it is ~100000km distant from the Moon. I made a model DRO in GMAT seeded it with a start from EM-L2 around 2021-12-01 00:00 UTC, Hmmm... (1/n)
Examining papers on the upcoming #NASA SLS EM-1 mission that will use a DRO reveals the geometry somewhat fits the limited observations we have of #Change5 since it was recovered a couple of days ago. (2/n) SOURCE: ntrs.nasa.gov/api/citations/…
Range estimates based on SNR of #Change5 X-band signal appear to be consistent with it being approximately at a lunar distance. If it is in a DRO this would be a first scoping the upcoming #NASA SLS EM-1 mission. (3/n)
Read 4 tweets
9 Oct 21
March 2021 - 18SPCS reported that YUNHAI 1-02 [44547, 2019-063A] had broken up. Since the breakup report, amateurs have monitored radio emissions on 1704MHz. As the spacecraft straddles the terminator it was lost in the glare of daylight until now...
@18SPCS reported that YUNHAI 1-02 broke up and amateurs noticed it continued to emit. The following thread should catch you up on some of these facts.
@planet4589 later noted an anomolly in the @SpaceTrackOrg catalogue with a report indicating 48078, 1996-051Q: "Collided with satellite". See this great thread to learn more about his analysis and the tie to YUNHAI 1-02.
Read 7 tweets
16 Jan 21
Well well well, the mystery of what the signal on ~992.4MHz/~1000.44MHz and FM audio on ~998.94MHz from the Meridian satellites is resolved. It's SECAM TV channels from Turkmenistan. SECAM channel spacing is 8MHz and video carrier to audio carrier is 6.5MHz which matches.
I mused a few weeks about about the curious nature of the 15.625MHz sub-carriers around the primary.
Here you can find some info on the SECAM channel frequencies. Look up France, Eastern Europe, Former Soviet Union, French overseas territories and former French colonies in Africa, North Korea, Vietnam...
Read 7 tweets
15 Dec 20
Steffan Watkins provided a wealth of AIS data from MarineTraffic about the journey of Yuan Wang 3 to the #Change5 re-entry skip point in the Arabian Sea. The data reveals that the ship did some interesting stop and goes prior to arriving on station to look at what? THREAD.
2020-12-10 UTC between 18:30 & 22:30, Mars was at the zenith when they stopped and set just before they got underway again. Perhaps providing support for TIANWEN-1 on the way to Mars?
2020-12-11 UTC between 14:20 & 22:05 more TIANWEN-1 watching at the zenith again it appears. The Mars bound probe has a big signal on X-band which is also used by #Change5.
Read 8 tweets
15 Dec 20
Here's a plot of an estimated ground track for the #Change5 re-entry.
This THREAD will discuss:
- Evidence supporting this ground track,
- Alternatives that have been excluded,
- 'Skip' re-entry profile visibility characteristics,
- State vector confirmation of timings/position.
Two possible re-entry ground tracks have been explored. The one presented is favoured because the tracking ship Yuan Wang 3 is now presently at the 'skip re-entry perigee'. Using AIS data dug up by @steffanwatkins the ship has been loitering in the area for a day or so now.
@Cosmic_Penguin noted the following graphics posted during pre-launch coverage of training efforts which showed the location of Yuan Wang 3 and the major re-entry event locations. Despite some oddness in the presented data the plan looks solid.
Read 14 tweets
14 Dec 20
I consulted with Astrogator Mike and we are getting closer to a ground track estimate for #Change5 during re-entry. The s/c will skip off the atmosphere over Yemen. The timing of this is directly related to TCM corrections and the accuracy of our model so should improve. THREAD
#Change5 like the Apollo capsules will use the atmosphere to steer itself. Thus creating a lot of complexity and uncertainty in modelling the actual ground track to aid observers. We are looking at a few ways to spit ball a ground track for those living in the general area.
As it will be night time over this part of the world it should be a spectacular show for those lucky enough to see it.
Read 4 tweets

Did Thread Reader help you today?

Support us! We are indie developers!

This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!


0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy


3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us on Twitter!