AO-40 Report Suggests Damage to Antenna Systems

Discussion in 'Amateur Radio News' started by Guest, Jan 16, 2001.

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  1. Guest

    Guest Guest

    From the ARRL Space Bulletin...



    The latest information on AO-40 suggests that the satellite might
    have suffered antenna system damage when it went silent last
    December 13. The satellite stopped transmitting while ground
    controllers were testing the 400-newton propulsion system.



    AMSAT-DL Vice President and AO-40 team member Peter Guelzow, DB2OS,
    reports that efforts to restart the 2-meter transmitter continue to
    be unsuccessful. The satellite had been sending telemetry via the
    2-meter transmitter when it quit transmitting last month.



    Guelzow said this week that while the 2-meter, 70 cm and 1.2 GHz
    receivers are working on the high-gain antennas, none of them will
    work on the omnidirectional antennas. He speculated that either the
    omnidirectional antennas or the cabling or the antenna relays are
    damaged. Additional tests will be carried out, he said, including
    testing the VHF transmitter using the omnidirectional antennas.



    Plans also call to test the 70-cm transmitter on both the high-gain
    and omnidirectional antennas, once the spacecraft's spin rate has
    been reduced and AO-40's heat-dissipation mechanism is working
    again.



    Guelzow said that AO-40's attitude control system is fully
    functional--something that would be critical to keeping the
    satellite in orbit on a long-term basis. But, the sun sensor's
    electronics have quit working, and, Guelzow said, without sun and
    attitude information, no magnetorquing can be performed.



    AO-40 team leader Karl Meinzer, DJ4ZC, was reported to be developing
    a software fix that does not rely on data from the sun sensor. It
    will be tested soon.



    Guelzow expressed the hope that once the sun angle and
    antenna-pointing capabilities have been established, the ground
    crews will have a better chance to check out the status of the 2
    meter and 70 cm transmitters through ''better-controlled and suitable
    experiments.''



    He indicated that AO-40's arcjet thrusters and the reaction wheels
    also will undergo testing as soon as possible.
     
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