AO-73 : Funcube -1

First, my sincere thanks to Terry VK5GU for downloading and analysing the data in my absence over the last 3 weeks.
Secondly, thanks to Jason Flynn for the YouTube video detailing The Dzhanibekov Effect, which I believe precisely fits AO-73’s behaviour.

After viewing the video a number of times and following Dr Terry Tao’s logical explanation I can totally understand why AO-73 behaves as such.
In our case we just have to revise the axes, from those in the example discussed in the video.
I believe the +X and +Y Solar Panel Temperature Profiles neatly fit Dr Tao’s logic when it flips.

Spin Period
15 Nov 2019 = 18.2 seconds (from averaged panel temperatures)
16 Nov 2019 = 18.3 seconds (from averaged panel temperatures)
17 Nov 2019 = 18.4 seconds (from averaged panel temperatures)
18 Nov 2019 = 18.2 seconds (from averaged panel temperatures)
19 Nov 2019 = 19.5 seconds (from averaged panel temperatures)
20 Nov 2019 = 21.4 seconds (from averaged panel temperatures)
21 Nov 2019 = 21.4 seconds (from averaged panel temperatures)

On the 14th November AO-73 reversed it spin direction back to what we now as the norm.
On the 19th November AO-73 commenced randomly reversing direction.
On the 19th and 20th November based on the VK downloads it appeared to be randomly reversed on an orbit by orbit basis.
On the 21st November 1800utc onwards, AO-73 was reversing during each pass.
What awaits us this coming week?

Congratulations to AO-73 on its 6th Birthday.
What a magnificent and reliable satellite.

73 de Colin VK5HI.

AO-73 : Funcube-1

Spin Period
25 Oct 2019 = 25.5 seconds (from averaged panel temperatures)
26 Oct 2019 = 24.7 seconds (from averaged panel temperatures)
26 Oct 2019 = 23.7 seconds (from averaged panel temperatures)
28 Oct 2019 = 22.8 seconds (from averaged panel temperatures)
29 Oct 2019 = 22.4 seconds (from averaged panel temperatures)
30 Oct 2019 = 20.9 seconds (from averaged panel temperatures)
31 Oct 2019 = 20.6 seconds (from averaged panel temperatures)
01 Nov 2019 = 20.1 seconds (from averaged panel temperatures)
02 Nov 2019 = 19.9 seconds (from averaged panel temperatures)
03 Nov 2019 = 19.6 seconds (from averaged panel temperatures)
04 Nov 2019 = 19.8 seconds (from averaged panel temperatures)
05 Nov 2019 = 19.4 seconds (from averaged panel temperatures)
06 Nov 2019 = 18.8 seconds (from averaged panel temperatures)
07 Nov 2019 = 18.1 seconds (from averaged panel temperatures)
08 Nov 2019 = 16.6 seconds (from averaged panel temperatures)
09 Nov 2019 = 17.2 seconds (from averaged panel temperatures)
10 Nov 2019 = 17.0 seconds (from averaged panel temperatures)
11 Nov 2019 = 16.5 seconds (from averaged panel temperatures)
12 Nov 2019 = 15.7 seconds (from averaged panel temperatures)
13 Nov 2019 = 15.7 seconds (from averaged panel temperatures)
14 Nov 2019 = 16.3 seconds (from averaged panel temperatures)

73 de Terry VK5GU for Colin VK5HI.

AO-73 : Funcube-1

Spin Period
18 Oct 2019 = 28.3 seconds (from averaged panel temperatures)
19 Oct 2019 = 28.9 seconds (from averaged panel temperatures)
20 Oct 2019 = 29.4 seconds (from averaged panel temperatures)
21 Oct 2019 = 29.1 seconds (from averaged panel temperatures)
22 Oct 2019 = 28.0 seconds (from averaged panel temperatures)
23 Oct 2019 = 27.5 seconds (from averaged panel temperatures)
24 Oct 2019 = 26.8 seconds (from averaged panel temperatures)

AO-73 has continues to spin, reverse to what we know as the normal direction.

73 de Colin VK5HI.

AO-73 : Funcube-1

Spin Period
11 Oct 2019 = 21.1 seconds (from averaged panel temperatures)
12 Oct 2019 = 21.9 seconds (from averaged panel temperatures)
13 Oct 2019 = 22.7 seconds (from averaged panel temperatures)
14 Oct 2019 = 23.4 seconds (from averaged panel temperatures)
15 Oct 2019 = 24.2 seconds (from averaged panel temperatures)
16 Oct 2019 = 25.1 seconds (from averaged panel temperatures)
17 Oct 2019 = 26.7 seconds (from averaged panel temperatures)

Over the last week AO-73 has continued to spin, reverse to what we know as the normal direction.

73 de Colin VK5HI.

AO-73 : Funcube -1

Spin Period
04 Oct 2019 = 22.7 seconds (from averaged panel temperatures)
05 Oct 2019 = 21.9 seconds (from averaged panel temperatures)
06 Oct 2019 = 21.4 seconds (from averaged panel temperatures)
07 Oct 2019 = 20.9 seconds (from averaged panel temperatures)
08 Oct 2019 = 21.3 seconds (from averaged panel temperatures)
09 Oct 2019 = 20.8 seconds (from averaged panel temperatures)
10 Oct 2019 = 20.4 seconds (from averaged panel temperatures)

Over the last week AO-73 has continued to spin, reverse to what we know as the normal direction.
On the 8th October AO-73 started to exhibit a level of instability that indicated it was about to commence tumbling again.

73 de Colin VK5HI.

AO-73 : Funcube-1

Spin Period
27 Sep 2019 = 30.4 seconds (from averaged panel temperatures)
28 Sep 2019 = 29.3 seconds (from averaged panel temperatures)
29 Sep 2019 = 28.0 seconds (from averaged panel temperatures)
30 Sep 2019 = 27.0 seconds (from averaged panel temperatures)
01 Oct 2019 = 25.8 seconds (from averaged panel temperatures)
02 Oct 2019 = 24.8 seconds (from averaged panel temperatures)
03 Oct 2019 = 23.7 seconds (from averaged panel temperatures)

Over the last week AO-73 has continued to spin, reverse to what we know as the normal direction.
This week AO-73 has again maintained a high level of Nutation.

73 de Colin VK5HI.

AO-73 : Funcube-1

Spin Period
20 Sep 2019 = 40.8 seconds (from averaged panel temperatures)
21 Sep 2019 = 39.3 seconds (from averaged panel temperatures)
22 Sep 2019 = 37.8 seconds (from averaged panel temperatures)
23 Sep 2019 = 36.1 seconds (from averaged panel temperatures)
24 Sep 2019 = 34.5 seconds (from averaged panel temperatures)
25 Sep 2019 = 33.1 seconds (from averaged panel temperatures)
26 Sep 2019 = 31.4 seconds (from averaged panel temperatures)

Over the last week AO-73 has continued to spin, reverse to what we know as the normal direction.
This week AO-73 has again maintained a high level of Nutation.

73 de Colin VK5HI.

AO-73 : Funcube-1

Spin Period
13 Sep 2019 = 53.7 seconds (from averaged panel temperatures)
14 Sep 2019 = 52.3 seconds (from averaged panel temperatures)
15 Sep 2019 = 50.1 seconds (from averaged panel temperatures)
16 Sep 2019 = 48.4 seconds (from averaged panel temperatures)
17 Sep 2019 = 46.4 seconds (from averaged panel temperatures)
18 Sep 2019 = 44.5 seconds (from averaged panel temperatures)
19 Sep 2019 = 42.8 seconds (from averaged panel temperatures)

Over the last week AO-73 has continued to spin, reverse to what we know as the normal direction. This week AO-73 has maintained a high level of Nutation.

73 de Colin VK5HI.

AO-73 : Funcube-1

Spin Period
06 Sep 2019 = 66.4 seconds (from averaged panel temperatures)
07 Sep 2019 = 65.2 seconds (from averaged panel temperatures)
08 Sep 2019 = 63.6 seconds (from averaged panel temperatures)
09 Sep 2019 = 61.4 seconds (from averaged panel temperatures)
10 Sep 2019 = 59.5 seconds (from averaged panel temperatures)
11 Sep 2019 = 57.4 seconds (from averaged panel temperatures)
12 Sep 2019 = 55.5 seconds (from averaged panel temperatures)

Over the last week AO-73 has continued to spin, reverse to what we know as the normal direction. In recent days increased Nutation has developed.
Based on past observations we should expect AO-73 to commence tumbling in coming days.
This may or may not result in AO-73 returning to its normal spin sequence.

73 de Colin VK5HI.

AO-73 : Funcube-1

Spin Period
30 Aug 2019 = 52.2 seconds (from averaged panel temperatures)
31 Aug 2019 = 61.8 seconds (from averaged panel temperatures)
01 Sep 2019 = 66.3 seconds (from averaged panel temperatures)
02 Sep 2019 = 69.9 seconds (from averaged panel temperatures)
03 Sep 2019 = 71.7 seconds (from averaged panel temperatures)
04 Sep 2019 = 69.1 seconds (from averaged panel temperatures)
05 Sep 2019 = 68.8 seconds (from averaged panel temperatures)

By the 29th August AO-73 had achieved a very unstable tumble.
On the 30th August that tumble ceased with a resultant Spin Reversal but with minimal Nutation.
That spin reversal has been maintained since the 30th August.
With reference to the Z+ and Z- Sun Sensors values over VK, I have noted that the “flip” near the South Magnetic Pole appears to have negligible affect on the spin direction.
A download of telemetry from the Northern Hemisphere by Rocky, W2RTV helped my analysis significantly. Thank You Rocky.

The above analysis indicates AO-73 may be increasing in speed again.
?? Another tumbling period. -> spin reversal. ??

73 de Colin VK5HI.