Re: ISS Flight Mode

From: Robert Reeves (
Date: Mon Jan 06 2003 - 20:38:49 EST

  • Next message: John locker: "Re: ISS Flight Mode"

    > Hi everyone
    > I got an image of the ISS on Sunday morning, which showed it to be flying
    > in -XPOP mode. This was not quite what I expected since the sun angle was
    > low enough for it to be in XVV. The current rules I have are XVV if sun
    > angle (beta) is less than 37 degrees. ISS passed this value (decreasing)
    > January 2nd. Does anyone know if the rules have been altered or whether
    > are just a bit late in implementing the change.
    > Thanks
    > Phil
    I received an email today from Don Pettit, the curent Science Officer on
    ISS, which mentioned the attitude the station is in.  Perhaps this clip from
    that email will explain the ISS attitude you saw.
    I have been experimenting with wide field astrophotography out the Lab
    window.  I have not yet completed my barn door so I have no tracking
    capability yet.  However,  station is currently in a solar inertial attitude
    with torque equilibrium hold which means it can wobble around a few degrees
    as it orbits the earth so as to minimize spent momentum from our control
    moment gyros.  This means the station makes for a pretty stable platform
    with camera mounted solid.  It also means that for the night pass the lab
    window points away from earth which give fantastic views of a black dark
    star field.  I have film cameras and have talked to you about storing my
    Fuji 800 in the water bags.  Before I expend my rolls of film, I wanted to
    BTW, the message is related to "amateur" astrophotography from the ISS.  Don
    is an amateur astronomer and had purchased my book "Wide-Field
    Astrophotography" several years ago.  He and I have been in contact since
    then and have discussed various ways he can conduct celestial photography
    from the station with the Nikon cameras they have aboard.  He sent me some
    shots he took with the Nikon digital that were pretty good, but I have to
    keep them to myself until they are "officially" released on the NASA web
    Robert Reeves            
    520 Rittiman Rd.         
    San Antonio, Texas 78209    210-828-9036
    USA                                     29.484  98.440  200 meters
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