Sorry, I am just now reading about the AO-7 orbit "count turn over" question.
Assuming a 99,999 orbit turn over as calculated by Space-Track:
Yes, this will be the second time the data has exceeded the 99,999 orbit count limit in the SpaceTrack TLEs. Just a short history: AO-7 was launched on November 15, 1974. AO-7 became non-operational mid 1981 (after 7 years) due to battery failure. In 2002, one of the shorted batteries became open and AO-7 could then be powered without the battery by its solar panels when in sunlight. The AMSAT digital KEPs distribution system started operation sometime in 1991 with Dick Campbell (N3FKV) as Orbital Data Manager. At that time AO-7 had already gone silent due to the battery short in 1981. When I was handed the KEP distribution baton in 1993, AO-7 had been silent for about 12 years and was NOT in the KEP distribution list. But, due to loss of that battery short sometime before June 20, 2002, it came back! I first added AO-7 back in the KEPs on June 20, 2002 after 21 years of being silent. The orbit count, at that point, was 26,363 orbits. This indicates that AO-7 had already crossed its first 99,999 orbit "count turn over" sometime while it was out of service. Currently, we are at 99,696 orbits and counting on July 6, 2018.
Yes, nothing will happen after the orbit "count turn over" (like Y2K - HI). As previously noted, most if not all tracking programs do not use the orbit number data for anything. Maybe display only??? Note: The orbit count is calculated by Space-Track and is not an actual count of orbits completed. It is an indicating number that excludes many factors (particularly orbit drag). Alan (W4SCA) is right, it is just an odometer giving an indication, not an exact data point. And NOT as accurate as the odometer in your car.
And yes, what an amazing satellite and a great testimony to its builders! AO-7, the little satellite that could!
I think a 200,000 orbit celebration is warranted!
What should we do?
Ray Hoad WA5QGD AMSAT-NA Orbital Elements Manager
-----Original Message----- From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of E.Mike McCardel Sent: Tuesday, July 3, 2018 19:25 To: Pedro Converso pconver@gmail.com Cc: AMSAT BB amsat-bb@amsat.org; APBIDDLE@mailaps.org Subject: Re: [amsat-bb] AO-7 orbit count.
I ran a simulation on my cell phone app HamSat. I know it isn’t perfect. I found that orbits rolled over from 99999 to 100000 at 04:13:28 EDT (091228 UTC). The resultant map shows it over Mongolia. So, I’m just letting my curiosity run rampant and thinking out loud. Considering that it’s period has changed over time, what constitutes an orbit? How does the software account for that?
73 EMike
EMike McCardel, AA8EM Rotating Editor AMSAT News Service Sent from my iPhone
On Jul 2, 2018, at 2:05 PM, Pedro Converso pconver@gmail.com wrote:
Hi all,
Nice idea to celebrate AO-7 200th orbit anniversary, our beloved grandfather bird merits it.
Looks that 200k orbit will happen around August the 1st see: http://amsat.org.ar/ao7-200k.gif .
http://amsat.org.ar/pass?satx=ao-7 account for orbits above 100k.
We hams should be thankful to have AO-7 alive, duly recognizing those that made it possible .
73, LU7ABF, Pedro
On 7/2/18, Alan wa4sca@gmail.com wrote: Greg,
Fortunately this is not a TEOTWAWKI Y2K issue. Unlike most of the other numbers in the Keps, the orbit count has nothing to do with predicting the orbit, and can be completely ignored. Some programs do that. Others compute backwards and forwards from the reference epoch and orbit number in the Keps they are using. I am most familiar with SatPC32, and when working on prelaunch Keps recently, I found that if you ran it backwards in time before the launch, it will happily show negative numbers. ;)
The problem is that when the specification for the Keps we use was created, it only allowed 5 digits for the orbit count. That seemed enough, and comes from Space Track that way. So like an odometer it just rolls over. In principle, software could look for that, and automatically compensate.
I can't speak for all the software out there, but in most cases they will just roll over and keep on tracking.
73,
Alan WA4SCA
<-----Original Message----- <From: Greg D [mailto:ko6th.greg@gmail.com] <Sent: Monday, July 02, 2018 11:29 AM <To: APBIDDLE@MAILAPS.ORG; 'Tom Schuessler' tjschuessler@verizon.net <Cc: 'AMSAT BB' amsat-bb@amsat.org <Subject: Re: [amsat-bb] AO-7 orbit count. < <Hi Alan, < <Other shoe, please? What happened to the world's prediction software <(if, indeed, we even had any back then) when it rolled over? What is <expected this time? < <We survived Y2K, but did we learn anything from it? < <Greg KO6TH < < <Alan wrote: <> Tom, <> <> It has in fact turned over once already. <> <> 73, <> <> Alan <> WA4SCA <> <> Sent from my Waring blender. <> <> <> <-----Original Message----- <> <From: Tom Schuessler [mailto:tjschuessler@verizon.net] <> <Sent: Monday, July 02, 2018 09:03 AM <> <To: APBIDDLE@MAILAPS.ORG <> <Cc: AMSAT BB amsat-bb@amsat.org <> <Subject: Re: [amsat-bb] AO-7 orbit count. <> < <> <12.5×365×45 equals 205,312..5. Based on that you think it had Brolley a <> <diameter the second time already but it might have been hiring slower <when <> <originally launched. <> < <> <Sent from my iPhone <> < <> <> On Jul 2, 2018, at 02:47, Alan wa4sca@gmail.com wrote: <> <> <> <> Tom, <> <> <> <> According to the Keps, AO-7 makes 12.54 orbits per day. It will hit 99999 <> <> on the 30th or so. You can use the Preview function to find out exactly <> <> when. <> <> <> <> 73, <> <> <> <> Alan <> <> WA4SCA <> <> <> <> <> <> <-----Original Message----- <> <> <From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of <> <> <tjschuessler@verizon.net <> <> <Sent: Sunday, July 01, 2018 23:56 PM <> <> <To: 'AMSAT BB' amsat-bb@amsat.org <> <> <Subject: [amsat-bb] AO-7 orbit count. <> <> < <> <> <Now I see looking at SatPC32 that it shows AO-7 in the 99,625 range in <> <> orbit <> <> <count. If memory serves me right though, doesn't the TLE orbit count <roll <> <> <over at 99,999 (Just like a car odometer), so that would mean that we <> <would <> <> <be coming up to the 200,000th rev is that right? If I am right, then this <> <> <will be coming up in less than a month. Does anybody know exactly <when <> <> that <> <> <will be? I am doing a presentation for a local club and would like to <> <> throw <> <> <out that fact if I could. Also the day of that event would be good AO-7 <> <> <operating day I would think. <> <> < <> <> <73 <> <> < <> <> <Tom Schuessler, N5HYP <> <> <EM12ms <> <> < <> <> < <> <> < <> <> <_______________________________________________ <> <> <Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum <> <available <> <> <to all interested persons worldwide without requiring membership. <> <Opinions <> <> <expressed <> <> <are solely those of the author, and do not reflect the official views of <> <> AMSAT- <> <> <NA. <> <> <Not an AMSAT-NA member? Join now to support the amateur satellite <> <> <program! <> <> <Subscription settings: http://www.amsat.org/mailman/listinfo/amsat- <bb <> <> <> <> _______________________________________________ <> Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum <available <> to all interested persons worldwide without requiring membership. <Opinions expressed <> are solely those of the author, and do not reflect the official views of <AMSAT-NA. <> Not an AMSAT-NA member? Join now to support the amateur satellite <program! <> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
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_______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb