Interesting thread regarding MET and ARISSat-1 switch on. Someone made the very good point that the transition in or out of sunlight (eclipse) is not an on/off event. I remember many MIR visuals, and as she passed from sunlight in the west to darkness in the east there was a significant time, perhaps a minute or more when she changed colour from bright and silver white to orange then disappeared into blackness. I always interpreted that as passing through the penumbra, or semi shadow area. ARRISat-1 is at at around 370km, does anyone know how to find the width of the penumbra at that altitude? Working out the transit time through that region might be informative. 73 John G7HIA
Using Orbitron 3.71 software, I can tell that the penumbral duration today was 9 seconds. However, this will vary in the future as the angle of the orbit to the sun changes. However, the first sunlight the satellite will get will be very red (due to the blue light scatter caused by the atmosphere). I have observed that ARISSat-1 doesn't start transmitting for a further 14 minutes.
To be more precise, I am seeing the Mission Elapsed Time (MET) counter start counting from zero about 40 seconds after coming out of eclipse, and the first BPSK telemetry frame has a MET=808. The first KURSK experiment data isn't transmitted until MET=945. However, since 12th September the KURSK experiment appears to have failed and is only sending null data.
73s, Simon G7WIQ
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John Heath -
Simon Pack