Re: Double Iridium Flares at the South Pole

From: Gerhard HOLTKAMP (
Date: Sat May 14 2005 - 17:32:29 EDT

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    >We are having the May 14 and 15 -8 flares (actually they will be flaring 
    >at -8 in about 3 hours) that Gerhard Holtkamp mentioned in his e-mail you 
    >sent me, he mentioned that the flare was going to be from front antenna 
    >which is unusual, because all flares are caused by the right rear antenna 
    >and he said there would be no difference on the appearance on the ground, 
    >but there is a big difference. I am seeing double flares.
    I'm puzzled. I've never seen double flares like that, no matter what surface 
    they came from (I alway keep track on which antenna causes the Iridium 
    flare). Actually, it was May 10 that had the front antenna flares at the 
    South Pole. May 14/15 and further dates this season will feature the  antenna 
    pointing 120 to the rear. I checked all three antennas for both dates but 
    only the one indicated was anywhere near to flare. Also a solar panel 
    pointing to the sun would have been too far off. In order to get another 
    flare 15 seconds later the new flare surface would have to be just 3 offset 
    from the old one. Does anyone have a detailed drawing of Iridium satellites?
    One thought that occurred to me was that there actually should be a difference 
    between the front and the rear antenna (but this should not cause a double 
    flare). The front surface should see faster erosion as it faces the full 
    impact of whatever atomic oxygen, micrometeorites etc. is left up there, 
    while the rear surfaces are sheltered. This might cause a decrease in 
    reflectivity, the smaller the Iridium number (the longer the satellite is up 
    there) the more pronounced the effect should be. But it's probably too weak 
    to be observed visually? 
    Gerhard HOLTKAMP
    Darmstadt, Germany
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