Re: STS-133 astronaut ground-based observation; Update 1: frame processing into final result

From: Thierry Legault (
Date: Sun Mar 27 2011 - 16:47:14 UTC

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    hi all,
    I'm not sure if it's necessary to underline this fact because
    I know that members of this list are already conscious of it,
    but one cannot rely on a single raw image to show details
    at instrumental limits. What is pointed out in this image
    can be anything else than an astronaut and a robotic arm,
    and especially noise and/or distortion caused by turbulence,
    as I illustrated on this page:
    The four big and bright radiators (one on the top of the crop,
    one in the middle -partly in shade - and two on the bottom
    of the crop) are rectangular, with structures inside that are
    also rectangular (like chocolate bar) and much bigger than
    an astronaut. Nevertheless, on this image they look strongly
    distorted and their edges are fuzzy. Many elements along
    the ISS modules, many of them much bigger than an astronaut
    and a robotic arm, are distorted, hardly recognizable or even
    not visible at all, such as details at the end of Colombus.
    This is the case even for Discovery, the ATV and the
    Soyuz themselves, despite their size.
    Another evidence is that an image supposed to resolve details
    at the limit of instrumental capability shall show diffraction
    effects, under the form of variations of the Airy pattern:
    diffraction rings around bright spots and diffraction lines
    along bright lines. But this image does not show such effect
    at all.
    In addition, at this supposed level of details, a "real color"
    processing is meaningless since several pixels are necessary
    to show real color of each detail, because of the Bayer matrix.
    In the following picture of the ISS, where you can see the real
    shapes of the radiators and other elements, I have superimposed
    an astronaut somewhere:
    Can you find it without looking at the solution below?
    This comparison helps to realize the level of sharpness
    really needed to show an astronaut.
    In short, I am sorry to say that this image is far from having
    the sharpness and resolution necessary to show an astronaut
    and the robotic arm,  exactly as an image of Jupiter that hardly
    shows the Great Red Spot is unable to show details on its
    Thierry Legault
    At 23:38 22/03/2011, Ralf Vandebergh wrote:
    >Subject: STS-133 astronaut ground-based observation; Update 1: frame 
    >processing into final result
    >Update 1:  frame processing into final result
    >Hi all,
    >The image on the left side shows a part of the ISS with docked Space 
    >Shuttle Discovery in approach at a distance of still over 400 
    >km.  On the Port side we see a bright illuminated Payload Bay Door 
    >from Discovery and the Shuttle Robotic Arm Canadarm-1 (SRMS). At 
    >this point, Canadarm-2 (SSRMS), is weakly illuminated visible on the 
    >other side near the Columbus Module. (the module itself is mainly in 
    >shade). At the end of the Arm, STS-133 astronaut Steve Bowen is 
    >performing a spacewalk and just pops into view here as a small spot. 
    >As the distance reduces, about 20 seconds later, the small spot of 
    >the astronaut has grown and looks better resolved. The apparant size 
    >of the spacewalker seems comparable with the ExPRESS Logistics 
    >Carrier (ELC) mounted on the truss. On the image we can also see the 
    >newly, during the mission installed ELC-4 on the Starboard 3 truss. 
    >Also the two armed Robot Dextre (Special Purpose Dexterous 
    >Manipulator (SPDM), and the second Automated Transfer Vehicle
    >   (ATV) can be seen on the image.
    >For the full analysis see;
    >Best regards,
    >Ralf Vandebergh
    >[Non-text portions of this message have been removed]
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    Thierry Legault
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    This archive was generated by hypermail 2b29 : Sun Mar 27 2011 - 16:48:00 UTC