Dear Friends,
Please take a look at my article titled "The ARISSat-1 Power System" in the JAN/FEB 2011 AMSAT Journal. There is an interesting chart on page 10 "Figure 5. Power System Output."
My analysis, as shown in Figure 5, indicates that at certain "bad" sun angles, the solar panels may not provide enough power to run the satellite even in full sun.
The power from the panels can actually drop to as low as 2.5 watts at really bad angles but the satellite needs around 8 watts average to run in high power mode. This means that the satellite would have to draw current from the battery to run in high power mode even though it is in the sun.
This discharge would reduce the life of the battery so to minimize the damage and prolong the life of the satellite, it will switch itself to low power mode under these conditions.
I don't know for sure if this is what is happening but this condition is within the predicted nominal operation of the satellite.
73, Tony AA2TX --- On 8/11/2011 2:48 AM, Colin Hurst wrote:
ARISSat was in low power mode during the pass commencing at 0628UTC in full sunlight.
73
Colin VK5HI
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