AO-73 : Funcube-1

Rotation Period

19 Feb 2021 = 23.6 seconds (from averaged panel temperatures)
20 Feb 2021 = 23.6 seconds (from averaged panel temperatures)
21 Feb 2021 = 19.9 seconds (from averaged panel temperatures)
22 Feb 2021 = 19.9 seconds (from averaged panel temperatures)
23 Feb 2021 = 18.9 seconds (from averaged panel temperatures)
24 Feb 2021 = 18.3 seconds (from averaged panel temperatures)
25 Feb 2021 = 18.3 seconds (from averaged panel temperatures)

AO-73 is now “rotating” about the Z-Z axis in a very indeterminate manner.

73 de Colin VK5HI.

AO-73 : Funcube-1

Rotation Period

12 Feb 2021 = 37.4 seconds (from averaged panel temperatures)
13 Feb 2021 = 35.9 seconds (from averaged panel temperatures)
14 Feb 2021 = 32.6 seconds (from averaged panel temperatures)
15 Feb 2021 = 30.3 seconds (from averaged panel temperatures)
16 Feb 2021 = 28.9 seconds (from averaged panel temperatures)
17 Feb 2021 = 27.1 seconds (from averaged panel temperatures)
18 Feb 2021 = 25.2 seconds (from averaged panel temperatures)

AO-73 continues to “wobble” about the Z-Z axis due to the uneven weight distribution about AO-73’s theoretical centre of mass. The influence of this “wobble” on the downlink signal over VK is very noticeable.

73 de Colin VK5HI.

AO-73 : Funcube-1

Rotation Period

05 Feb 2021 = 63.2 seconds (from averaged panel temperatures)
06 Feb 2021 = 58.3 seconds (from averaged panel temperatures)
07 Feb 2021 = 56.5 seconds (from averaged panel temperatures)
08 Feb 2021 = 50.4 seconds (from averaged panel temperatures)
09 Feb 2021 = 46.9 seconds (from averaged panel temperatures)
10 Feb 2021 = 43.6 seconds (from averaged panel temperatures)
11 Feb 2021 = 40.9 seconds (from averaged panel temperatures)

With reducing Spin Period AO-73 over the last two weeks has commenced to “wobble” about the Z-Z axis due to the uneven weight distribution about AO-73’s theoretical centre of mass. The affect of this “wobble” on the downlink signal over VK is now very noticeable.

73 de Colin VK5HI.

AO-73 : Funcube-1

Rotation Period

29 Jan 2021 = 111 seconds (from averaged panel temperatures)
30 Jan 2021 = 101 seconds (from averaged panel temperatures)
31 Jan 2021 = 90.3 seconds (from averaged panel temperatures)
01 Feb 2021 = 87.8 seconds (from averaged panel temperatures)
02 Feb 2021 = 79.1 seconds (from averaged panel temperatures)
03 Feb 2021 = 73.3 seconds (from averaged panel temperatures)
04 Feb 2021 = 67.5 seconds (from averaged panel temperatures)

73 de Colin VK5HI.

AO-73 : Funcube-1

Rotation Period

08 Jan 2020 = 507 seconds (from averaged panel temperatures)
09 Jan 2020 = 455 seconds (from averaged panel temperatures)
10 Jan 2020 = 411 seconds (from averaged panel temperatures)
11 Jan 2020 = 381 seconds (from averaged panel temperatures)
12 Jan 2021 = 340 seconds (from averaged panel temperatures)
13 Jan 2021 = 324 seconds (from averaged panel temperatures)
14 Jan 2021 = 290 seconds (from averaged panel temperatures)
15 Jan 2021 = 259 seconds (from averaged panel temperatures)
16 Jan 2020 = 235 seconds (from averaged panel temperatures)
17 Jan 2020 = 217 seconds (from averaged panel temperatures)
18 Jan 2020 = 197 seconds (from averaged panel temperatures)
19 Jan 2020 = 181 seconds (from averaged panel temperatures)
20 Jan 2021 = 166 seconds (from averaged panel temperatures)
21 Jan 2021 = 153 seconds (from averaged panel temperatures)
22 Jan 2021 = 175 seconds (from averaged panel temperatures)
22 Jan 2021 = 175 seconds (from averaged panel temperatures)
23 Jan 2021 = 145 seconds (from averaged panel temperatures)
24 Jan 2021 = 136 seconds (from averaged panel temperatures)
25 Jan 2021 = 161 seconds (from averaged panel temperatures)
26 Jan 2021 = 175 seconds (from averaged panel temperatures)
27 Jan 2021 = 125 seconds (from averaged panel temperatures)
28 Jan 2021 = 115 seconds (from averaged panel temperatures)

73 de Colin VK5HI.

AO-73 : Funcube-1

Rotation Period

01 Jan 2021 = 766 seconds (from WOD panel temperatures)
02 Jan 2021 = 714 seconds (from WOD panel temperatures)
03 Jan 2021 = 677 seconds (from WOD panel temperatures)
04 Jan 2021 = 626 seconds (from WOD panel temperatures)
05 Jan 2021 = 582 seconds (from WOD panel temperatures)
06 Jan 2021 = 557 seconds (from WOD panel temperatures)
07 Jan 2021 = 547 seconds (from WOD panel temperatures)

AO-73 continues to spin about the Z-Z axis with minimal Nutation.

73 de Colin VK5HI.

AO-73 : Funcube-1

Rotation Period

25 Dec 2020 = 820 seconds (from WOD panel temperatures)
26 Dec 2020 = 815 seconds (from WOD panel temperatures)
27 Dec 2020 = 805 seconds (from WOD panel temperatures)
28 Dec 2020 = 823 seconds (from WOD panel temperatures)
29 Dec 2020 = 808 seconds (from WOD panel temperatures)
30 Dec 2020 = 839 seconds (from WOD panel temperatures)
31 Dec 2020 = 808 seconds (from WOD panel temperatures)

AO-73 continues to spin about the Z-Z axis with minimal Nutation.

73 de Colin VK5HI.

AO-73 : Funvube-1

Rotation Period

18 Dec 2020 = 948 seconds (from WOD panel temperatures)
19 Dec 2020 = 880 seconds (from WOD panel temperatures)
20 Dec 2020 = 842 seconds (from WOD panel temperatures)
21 Dec 2020 = 812 seconds (from WOD panel temperatures)
22 Dec 2020 = 824 seconds (from WOD panel temperatures)
23 Dec 2020 = 827 seconds (from WOD panel temperatures)
24 Dec 2020 = 814 seconds (from WOD panel temperatures)

For the last week AO-73 has been spinning about the Z-Z axis with minimal Nutation.

73 de Colin VK5HI.

AO-73 : Funcube-1

Rotation Period

11 Dec 2020 = 1837 seconds (from WOD panel temperatures)
12 Dec 2020 = 2021 seconds (from WOD panel temperatures)
13 Dec 2020 = 1661 seconds (from WOD panel temperatures)
14 Dec 2020 = 1550 seconds (from WOD panel temperatures)
15 Dec 2020 = 1267 seconds (from WOD panel temperatures)
16 Dec 2020 = 1136 seconds (from WOD panel temperatures)
17 Dec 2020 = 1020 seconds (from WOD panel temperatures)

For the last five days AO-73 has been spinning about the Z-Z axis with minimal Nutation and the spin rate has increased steadily each day.

73 de Colin VK5HI.

AO-73 : Funcube-1

Rotation Period

04 Dec 2020 = 2655 seconds (from WOD panel temperatures)
05 Dec 2020 = 2760 seconds (from WOD panel temperatures) Reverse Spin
06 Dec 2020 = 3735 seconds (from WOD panel temperatures) Reverse Spin
07 Dec 2020 = 4500 seconds (from WOD panel temperatures) Best Estimate
08 Dec 2020 = 4200 seconds (from WOD panel temperatures) Best Estimate
09 Dec 2020 = 3300 seconds (from WOD panel temperatures) Best Estimate
10 Dec 2020 = 2153 seconds (from WOD panel temperatures)

This week’s analysis has indeed been very interesting.
For December 4th to 6th I used 24hour WOD’s supplied by Dave from the Warehouse Data to ascertain what was occurring with AO-73.
Late on the UTC day of the 4th AO-73 went into an attitude that indicated it was rotating about the Z-Z axis but the Z-Z axis was inclined at an angle to the normal direction of travel such that the -X and +Y planes were more illuminated than the +x and -Y planes. (Supposition on my part. Alternate theories welcome.)
Then later on the UTC day of the 5th December AO-73 resumed a more normal attitude but with reverse spin. Refer graphic below.

For the 7th to 9th December I have only had the retrieved WOD’s from the real-time telemetry to work with, hence my theoretical best estimates as AO-73 appears to have been in this complex attitude.
Fortunately the download over VK for the 10th December shows AO-73 has again stabilised with normal spin about the Z-Z axis. (Graphic below)

73 de Colin VK5HI.