Some personal thoughts on this subject. On the 14th December AO-73 was placed back in Transponder mode after having been in Educational Mode for many months to examine the performance of AO-73 in full sun. AO-73 is currently experiencing its second full sun encounter which will last until April 2019. The first experience was earlier this year when a number of observations were noted in AO-73's attitude. A controlled experiment has been undertaken during the first stage of this current full sun encounter to understand and quantify those previous observations.
Simply put, while in full sun AO-73 slowly speeds up due to Propeller Effect and reaches a point where due to an offset Centre of Gravity the Nutation becomes excessive and AO-73 finally ceases to rotate about its Z-Z axis.
Points of clarification. Educational Mode 300 milli-watts Beacon downlink. Transponder Mode 30 milli-watt Beacon. Propeller Effect occurs from the Materials Experiment on AO-73. Schools STEM Initiative. https://funcube.org.uk/education-outreach/ The fading you are currently seeing is medium to high Nutation (Wobble about the Z-Z axis). AO-73 has not ceased to rotate about the Z-Z axis or start tumbling. For past history please refer to Mike's Blog and in particular. http://www.dk3wn.info/p/?cat=79
73 Colin VK5HI
-----Original Message----- From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Jean Marc Momple Sent: Tuesday, 18 December 2018 04:15 To: Hasan al-Basri Cc: amsat-bb@amsat.org; corvanheiningen@outlook.com Subject: Re: [amsat-bb] A0-73
Dear All,
Also noticed quite a difference on AO-73 reception this side, it used to be 100% reliable but less decodes theses day, I have not investigate same but for sure there is a degradation somehow.
Just FYI
73
Jean Marc (3B8DU)
On Dec 17, 2018, at 8:35 PM, Hasan al-Basri hbasri.schiers6@gmail.com
wrote:
Agreed, severe QSB even with RHC rx antenna. Also, I'm not rx anywhere near the number of TLM frames since the xponder was turned on.
Hasan
On Mon, Dec 17, 2018 at 7:19 AM Cor van Heiningen < corvanheiningen@outlook.com> wrote:
Have the last days qso s made via AO-73 sat the rx goes from s 9 to 0 sometimes with a lot of QRM. I think the sat turned around its axis faster than a few months ago. Many stations have problems with QSO S via this sat. 73 PE1NIL