SB SPACE @ ARL $ARLS003 ARLS003 AO-40 Report Suggests Damage to Antenna Systems ZCZC AS03 QST de W1AW Space Bulletin 003 ARLS003 From ARRL Headquarters Newington, CT January 16, 2001 To all radio amateurs SB SPACE ARL ARLS003 ARLS003 AO-40 Report Suggests Damage to Antenna Systems 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. NNNN /EX