ARRL

ARRL Satellite Bulletin ARLS001 (2001)

SB SPACE @ ARL $ARLS001
ARLS001 AO-40 Recovery Continues

ZCZC AS01  
QST de W1AW  
Space Bulletin 001  ARLS001
From ARRL Headquarters  
Newington, CT  January 4, 2001
To all radio amateurs

SB SPACE ARL ARLS001
ARLS001 AO-40 Recovery Continues

Efforts continue to assess the status of AO-40 following a
resumption of telemetry transmissions. AO-40 went silent December
13, but ground controllers successfully reset the main computer on
Christmas Day and got the satellite transmitting again.

Ground controllers now are analyzing the telemetry sent via the S2
beacon on 2401.305 MHz. AMSAT-NA President Robin Haighton, VE3FRH,
says the command team worked through the holidays in an effort to
determine just what went wrong aboard AO-40. Among other things,
ground controllers would like to know what actually happened on
December 13 and why, as well as which telemetry functions are known
to be correct and which data are suspect and why. The satellite went
silent during maneuvers to test its onboard 400-Newton propulsion
system following an earlier orbit-shifting burn.

Ground controllers also want to know the spacecraft's actual
attitude with respect to Earth--and if it has changed attitude.
Other parameters they'll be examining include spin velocity, the
status of batteries, battery chargers and regulators, and what
happened to the onboard computers, IHU-1 and IHU 2, and why.

The AO-40 command team also wants to find out if all the antennas
are operational and what can be done next to improve communications,
and if there are any risks involved in attempting to restart onboard
systems. So far, the 2-meter beacon transmitter has remained off the
air since AO-40 was returned to ground control on Christmas Day.
It's believed that problems with the 70-cm transmitter developed
shortly after launch. The 2.4 GHz transmitter appears to be
operating ''nominally,'' however.

''When questions such as these--and others--are answered, it may be
possible to determine the working capability of the spacecraft, and,
if appropriate, to start to try operation on other bands,'' Haighton
said. He said critical decisions will be made over the next week or
two ''based on the results of the analysis and much discussion among
the command team.''
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