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Re: AMSAT Special Bulletin 008.01

Thank's for your efforts to restore AO-40 .

----- Original Message -----
From: Dan James <DanJ@marvin.com>
To: 'Amsat BB' <amsat-bb@AMSAT.Org>
Sent: Monday, January 08, 2001 12:34 PM
Subject: [amsat-bb] AMSAT Special Bulletin 008.01

> SB SAT @ AMSAT $ANS-008.01
> BID: $ANS-008.01
> AMSAT-DL President AMSAT-DL President Karl Meinzer, DJ4ZC,
> provided ANS with the latest information about AMSAT OSCAR 40:
> Greetings,
> Since my report from late December, command stations have
> implemented the strategy which I had outlined. The first priority was
> to determine which command-uplink channels were available. This
> work was difficult, very time consuming (and for the satellite) somewhat
> dangerous due to the unknowns. The command stations did a
> magnificent job! Due to their combined efforts I can report the
> following findings:
> 1. After some blind transmissions to test the omni-antennas around
> apogee (that failed to produce a response), the scheduler was activated
> and programmed in such a way as to prevent lock-out. This strategy
> turned out to be very prudent and the scheduler-operation went smoothly
> and resulted in no additional anomalies.
> 2. The scheduler then took AO-40 through a number of modes, which
> allowed the P3D team to determine the following:
> a. V, U and L-1 receivers work
> b. V, U and L high-gain antennas work
> c. U and L low-gain antennas do not work
> d. the status of the V-band low-gain antenna has not
> been finally
>       determined. Apogee blinds tests are in progress as I
> write this
>       to accurately determine the status of this antenna
> 3. The V-band transmitter was operated for one MA-unit. It demonstrated
> a marked temperature increase, but no signal was heard. This was a
> quick-look test and this result should not be considered final. Further
> tests
> will be necessary (including the need to determine if the matrix was set
> properly). These tests will have to wait until the spin rate is reduced to
> ensure that the satellites heat-pipes will be able to handle the
> for extended periods.
> 4. Magnetorquing was started to reduce spin and the first indications are
> loss of around 0.5 rpm - roughly consistent with theoretical predictions.
> can conclude that the system works. In order to use Earth-sensing data, a
> small additional program needs to be installed which stores data at apogee
> for later recovery when telemetry reception becomes available.
> What's next?
> During the next days the attitude control system should be returned to
> functionality. It will be used to reduce the spin to a value consistent
> heat-pipe operation and also with the requirements to change attitude.
> These changes are necessary for sun-angle constraints, communication
> access and also to reduce the effect of our ongoing mass-loss on perigee
> altitude. Newer model calculations show that the mass loss could be larger
> than my previous estimates; thus it would be prudent to use the resulting
> thrust to increase perigee altitude (right now it is decreasing it).
> Once the spin/attitude situation is under control, we will continue the
> check-out of other systems (such as):
> 1. Determine the status of the V-band transmitter (controlled experiments)
> 2. Determine the status of the U-band transmitter
> 3. Determine the serviceability of the ATOS (Arcjet) to determine if it
>     be planned on for a strategy toward an improved orbit
> 4. Test the momentum wheels to determine if AO-40 can be put into a
>     three-axis mode which would greatly reduce the impact of the loss of
>     omni-antennas
> Present data so far indicates that although we have lost some systems
> in AO-40, there has been no further deterioration after the second
> In particular, if ATOS and three-axis stabilization are still serviceable,
> AO-40 will still be able to produce a large fraction of the Amateur Radio
> service expected from it.
> Personally, I am optimistic and I believe that the command-and
> engineering team stand a good chance of turning AO-40 into an
> extremely useful Amateur Radio satellite.
> 73, Dr. Karl Meinzer, DJ4ZC
> Stay tuned to ANS, the official source of information on AMSAT
> OSCAR 40.
> [ANS thanks AMSAT-DL and AMSAT-NA for this information]
> /EX
> ----
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