Lacrosse 5 faints

From: George Roberts (
Date: Wed Aug 09 2006 - 13:25:15 EDT

  • Next message: Leo Barhorst: "Lacrosse 5"

    > This mystery has grabbed me, it begs solving.
    It seems to me there are 2 likely explanations for this 
    phenomenon (Lacrosse 5 dimmings).
    1) None or little of the satellite is white and instead it is made of mirror reflective
        surfaces such as gold foil.  In this case the right shape can cause dimmings.
        One example might be a cylinder capped not with half spheres but capped 
        with cones in turn capped with 1/3 spheres.
    2) There is a large flat surface that can put most of the rest of the satellite into shadow
       and this surface is either dark (like solar panel) or is flat and shiny (reflecting light
       back towards the sun or at least away from the earth).  Kind of like self-eclipse.
    I like possibility 2 as it seems more likely to me.
    There is a big observable difference between these 2 possiblities:
     #1 will result in the object going dark at different times for observers 
    in different locations along the path because this is determined not just 
    by the orientation of the satellite, but also by the observer-sat-sun angle.
    The dimming would move mostly along the ground path similar to
    a huge shadow (but not at the exact same speed because the satellite 
    is probably rotating as it orbits).
    #2 will result in the object going dark for everyone at the same instant
    because it only depends on the orientation of the satellite with respect
    to the sun and not the location of the observer.
    So if you can get 2 observers to observe the "faint" on the same pass with
    accurate timings (1 second should be fine for observers 20 miles apart,
    10 second accuracy for observers 200 miles apart) then we can possibly
    elminate one of the above 2 possibilities that I can think of.
    If it really does happen simultaneusly then the next step would be to try to
    figure out if there is some obvious axis of the satellite pointing to the sun
    at these times and try to be able to predict these dimmings based on sun
    position and guestimate satellite orientation.
    - George Roberts
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