RE: A person and a Robot seen from Earth!

From: Paul Grace (
Date: Tue Apr 19 2011 - 23:28:38 UTC

  • Next message: Brad Young: "BY Classfd Apr 20"

    Mr. Legault, I am not expressing an opinion on the photos, as I have not
    traced their acquisition.  However, your composite image isn't a reasonable
    test comparison.  For one, the "astronaut" image was shown in silhouette,
    sunlight-lit, against black space.  Your image is not similar.  
    Second, from mission logs, the location of an astronaut on the ISS and the
    silhouette of the ISS during spacewalk can be determined, and compared to
    the imagery for confirmation.  
    Third, Comparing the silhouette of a two-meter astronaut three hundred
    kilometers away to the details of the surface of a Jovian satellite
    600*10^6km away seems equally misplaced, as comparatively, the astronaut is
    roughly  the same size as Io, Europa, or Callisto (Hardly a "detail").
    Finally, although I could be mistaken, the image could be a composite of
    several frames, and that could dramatically improve S/N, resolution, and
    color, in the result.  
    It is up to the author of the photos to explain the methodology, and if he
    does not, then we need not accept any particular conclusions.  But
    suggesting the image cannot be what it purports to be seems unhelpful.
    -----Original Message-----
    [] On Behalf Of
    Thierry Legault
    Sent: Tuesday, April 19, 2011 13:58
    Subject: Re: A person and a Robot seen from Earth!
    hello, '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 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. On 
    the contrary, many "details" visible on this image do not exist at all.
    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 satellites.
    For those who want to know how looks like the ISS in reality, I 
    recall that they can have a look at my last images and video 
    At 15:14 12/04/2011, Ralf Vandebergh wrote:
    >Subject: A person and a Robot seen from Earth!
    >Special for todays 50 years Human in Space; A PERSON & A ROBOT seen 
    >from Earth. Since Yuri Gagarin, we have accomplished quite 
    >something. An even more Human-like robot was brought with to the 
    >ISS, but this one is inside (Robonaut).
    >This result is one of my best resolution ISS images so far. The 
    >image shows also resolved detail within Robot Dextre and the ELC 
    >elements. Dextre (SPDM) is here still visible at its old location, 
    >before it was grappled by the Canadarm-2 later, see the other image sent
    >Ralf Vandebergh
    Thierry Legault
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