FWD [forteana] Shuttle Sensor Anomalies / Ground Tracking Photo

From: Terry W. Colvin (fortean1@mindspring.com)
Date: Mon Feb 10 2003 - 10:14:18 MST

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    A colleague has just passed these URLs on to me. It shows the state of the
    sensors
    during Columbia's post re-entry phase, together with the routing of the
    associated
    wiring. It is quite revealing.

    < http://www.nasa.gov/columbia/COL_sensor_wire_030207.pdf >

    There's also a better image of this ground tracking camera photograph:

    < http://www.nasa.gov/columbia/COL_image_030207.html >

    It's interesting that sensors in the main undercarriage bay show temperature
    anomolies while sensors that have cables that run past the bay simply stop
    sending.
    The sensors that show normal readings but simply stop suggest a problem with the
    wiring, while sensors that go off scale appear to still be functioning until the
    sensors themselves fail. The first indicates a problem remote from the sensor,
    the
    second indicates a problem close to the sensor.

    Looks like whatever happened to the wing was around the short section of wiring
    that ran across the front and outer side of the bay. And look how the anomolous
    sensors start at the back of the bay and work forward. By the time the forward
    sensors start showing unexpected readings, they start to fail almost
    immediately,
    suggesting a sequential aft-to-forward build-up of heat in the bay.

    The photo is interesting, but it's a pity the resolution is so poor. Even
    accounting for variance in pixel brightness, it *does* look more than just
    jitter
    in the data. With a bit of looking-sideways-at-the-picture-through-narrowed-eyes
    you might just convince yourself that the delineation in the profile matches the
    wing leading-edge kink just forward of the 90-degree bend in the sensor cable
    run.
    Mind you, this is going to have to be studied long and hard by people with much
    more experience at interpreting these pictures than me before a definite
    conclusion
    can be reached (you'd need to compare pictures taken of known objects to
    calibrate
    the camera, for a start, to see if this image is real and not just a
    camera/lens/processing effect).

    More useful information might be gleaned from better details of the positions of
    the UC sensors in 3D space and a photo of the sensor cable lay-up, which might
    indicate which had greater shielding (by virtue of their position in the cable
    bundle). This could point to where the cable failures started to occur.

    It is another symptom - it still doesn't solidly identify the cause, though.
    Still
    could be leading edge failure with progressive burn-through of the front or side
    of
    the wheel well, undercarriage bay door loss or even the failure of the upper
    skin.

    Cheers,

    Robin Hill, STEAMY BESS, Brough, East Yorkshire.

    -- 
    Terry W. Colvin, Sierra Vista, Arizona (USA) < fortean1@mindspring.com >
         Alternate: < fortean1@msn.com >
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