A reponse I received from Telesat Canada

From: Kevin Fetter (kfetter@yahoo.com)
Date: Thu Feb 09 2006 - 11:19:34 EST

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    I sent a email to telesat canada, who have control over some geo sat's, like the boeing HS702 one
    called Anik F1.
    
    Here's the response I recieved
    
    The solar panels are always aligned north & south with the Earth's
    rotational axis.  Since geo satellites sit over the same spot on the
    Earth, the satellite goes around the earth once a day.  The solar panels
    rotate on the body to track the sun 24 hrs a day while the body
    continues to point at the earth.
    
    In the winter and summer when the sun is at a declination of about 23
    degrees to our equatorial orbit, we do not usually tilt the solar panels
    to compensate unless we are very very low on power.  Only some
    satellites have that capability.  The maximum we have ever tilted the
    solar panels toward the sun though is 10 to 15 degrees.  Current
    satellites are designed to have panels large enough that they can
    operate with no problems during that period of reduced solar power.
    
    We do however rotate the north or south solar panels a little off the
    sun to reduce the amount of solar pressure that the satellite receives
    from the sunlight hitting the panel.  This small force is sometimes
    enough to create a tipping imbalance if more light is hitting one panel
    over the other, or one surface is just naturally more reflective than
    the other.  By rotating the panel a couple of degrees relative to the
    sun we reduce the size of the panel as seen by the sun, and reduce the
    force from the light reflecting on it, to balance the satellite better.
    
    
    
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