Re: TiPS tether visibility at 200 km

From: Bjoern Gimle (b_gimle@algonet.se)
Date: Wed Aug 09 2000 - 03:43:57 PDT

  • Next message: Bjoern Gimle: "Re: newbie sees flare"

    > did the math and found that the tether, 19 km long, would represent about
    > 50 sq. meters or about 540 sq. ft. if it was run back and forth to form a
    > solid partition. Still, the tether was very slim and  it was a long way
    away,
    > it didn't seem possible that it could be seen at 200 km without strong
    > magnification.
    
    It does not matter how the line is folded - it still reflects the same
    (considerable) amount of light !
    
    But contrary to your suggestion, magnification only spreads the light
    over a larger area, to make surface brightness lower, and the tether
    harder to detect. But: If you increase magnification 2x, BECAUSE the
    tether is so thin, it will be reduced to 50%, not 25%. If you at the
    same time can utilize twice the front aperture, you get 4x the light!
    (For an ordinary point-like satellite, magnification does not spread
    the light, so you only have the aperture benefit)
    
    In other words, a 40x50 tube is worse than 10x50 binoculars,
    but 40x200 really helps.
    ...
    >      My question is, would the the electron sheath produce a visible glow
    > that could account for a 2.6 mm tether being seen from great distances?
    > Several persons have noticed that the tether has become dimmer with time.
    >
    The original/maximum brightness corresponds well with the computed
    brightness. So, the main speculation is that the electrical(?)
    processes have made the surface darker.
    
    
    -- bjorn.gimle@tietotech.se (office)                         --
    -- b_gimle@algonet.se (home)  http://www.algonet.se/~b_gimle --
    -- COSPAR 5919, MALMA,    59.2576 N, 18.6172 E, 23 m         --
    
    
    
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