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SB SPACE @ ARL $ARLS026 ARLS026 AO-40 still silent

24.12.2000 10:12:17

ZCZC AS26 QST de W1AW Space Bulletin 026 ARLS026 >From ARRL Headquarters Newington, CT December 19, 2000 To all radio amateurs

SB SPACE ARL ARLS026 ARLS026 AO-40 still silent

AMSAT OSCAR-40 remains silent, and command stations on the ground still have been unable to reestablish contact with the Amateur Radio satellite. It had been hoped that an onboard computer timeout expected on or about December 16 would restart the beacon telemetry and give the ground crew some clues as to why AO-40 suddenly stopped transmitting on December 13.

AMSAT-Germany's Peter Guelzow, DB2OS, of the AO-40 team, said nothing was heard over the weekend, and command stations tried to re-establish communication by sending blind commands. If the reset had occurred, the satellite would have been restored to its post-launch configuration and attempt to transmit on 70 cm. However, the 70-cm transmitter has been problematic, and the satellite likely still would need to be reconfigured for 2-meter transmission at that point to be heard on Earth.

The AO-40 team is continuing to investigate reports of weak signals on the 2-meter downlink frequency of 145.898 MHz that seem to be coming from AO-40, but it has discounted reports of telemetry heard there as a hoax. Other reports persist of a weak, unmodulated carrier, however.

Guelzow said today that the AO-40 team is encouraged by a report from the North American Air Defense Command--NORAD. The report indicates that AO-40 was found to be in one piece, that the orbit was exactly were it should be, that the radar cross-section was as expected, and that no other pieces were found. Guelzow said the NORAD data counter rumors ''which no one on the inner team believed'' that AO-40 might have exploded.

AMSAT-NA President Robin Haighton said ground controllers were exploring several options.

When and whether the satellite will be heard from again depends, in part, on whether AO-40 has picked up any of the ''blind commands'' sent by ground controllers. Guelzow says that if no commands were accepted by the IHU-1 onboard computer since contact was lost December 13, then a ''command-assist'' watchdog routine on December 21 will cycle the satellite through various receive, transmit, high-gain and low-gain antenna modes. If AO-40 did pick up some commands, Guelzow said, the command-assist watchdog will be reset for another 10 orbits. That could extend the wait until sometime after Christmas.

Guelzow says the ''watchdogs'' are software resets. Ground controllers want to avoid doing a hard re-boot of the main computer, which is considered a last resort. ''There is no need to hurry, and the command team doesn't want to miss any option,'' he said. NNNN /EX

* Origin: ---=== RA9LO Station at MO27SC ===--- (2:5077/39) __________________________________________________________________ Alexander

RZ6HGG Stavropol FidoNet: 2:5064/11.30 24 декабря 2000 г. 6:57:38

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