[amsat-bb] AO-16 update 11 November 2008
Mark L. Hammond
n8mh at embarqmail.com
Tue Nov 11 05:30:52 PST 2008
An update on AO-16 is long overdue, so please accept my apologies for the tardiness of the post. (Life is good, but busy!)
AO-16 has been in continuous voice operations since commanded back ON and configured in voice mail on 15 Sept 2008 at 10:58 UTC. Our predictions regarding sustained activities seem to be right on the mark. Recording your observations about AO-16 at http://oscar.dcarr.org has been, and will continue to be, very helpful to us. Please keep this up, especially over the 4 weeks.
Many of you will recall that the "best guess current model" is that a hardware timer in AO-16 is firing when the craft is at a certain temperature, currently around 15 deg C or cooler. When the space craft temperature is over 15 deg C, the hardware timer behaves and continuous operations are sustained. The craft temperature is dependent upon solar illumination. It appears that around 85% illumination is the "magic number." If the orbit puts AO-16 with less than 85% illumination, the watchdog timer restarts the satellite, and the transmitter shuts down.
Illumination projections (and subsequent temperature predictions) suggest that we might be able to sustain operations until sometime in the window of November 22 until December 4, 2008. So, if you want to make some AO-16 contacts, you had better get them as soon as possible!!!
Long term orbital projections suggest that if the satellite hardware remains fundamentally unchanged (i.e., no deterioration of components on-board), it will be nearly 10 years before AO-16 receives sufficient illumination to warm up the spacecraft enough to again support sustained operations! You can be sure that we'll continue to probe the craft with commands, in hopes that we something will change in a good way that will allow us to use the bird for operations of some sort.
It is possible that the transmitter on AO-16 will turn OFF sometime in the next few days/weeks; this requires some commanding to get it running again, which means a pass over the Eastern US coast is required for a change in operational status. We expect that as the spacecraft cools down, transmitter shutdowns will become more frequent.
Enjoy this grand old bird while you can!
Current operational mode for AO-16:
Mode FM Voice Repeater ( Downlink is DSB)
Uplink : 145.9200 MHz FM
Downlink 437.0260 MHz SSB
On behalf of the command team,
Mark L. Hammond [N8MH]
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