Re: shuttle, please explain

From: j smith (zeus001002@earthlink.net)
Date: Mon Dec 20 2004 - 13:26:26 EST

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    >From: paul <astro@pgog.net>
    >Sent: Dec 20, 2004 12:59 PM
    >To: SeeSat-L@satobs.org
    >Subject: shuttle, please explain
    
    >haven't I also read that NASA is not sending shuttle to HST
    >for maintenance update because that is not safe.  it is safe
    >to repair ISS but not safe to repair HST.  what am I not
    >understanding?
    
    Its all about safety.  If the Shuttle is damaged during launch,
    it can hang out in a pressurized location (ISS) until it
    is fixed or there can be an emergency return of crew using
    the  Soyuz vehicles on ISS.  Also, the cameras on ISS will be
    used to inspect the external surfaces on the Shuttle.  No such
    inspection would be possible at the HST site.  Since inspection
    of the entire Shuttle surface is required for a safe return,
    this rules out going to HST.
    
    Why not go to HST from ISS or visa versa? 
    HST (500km/35 deg)  is at a different altitude /inclination 
    than ISS (400km/51 deg).  Because of the large inclination
    difference, the amount of fuel needed to move from one
    inclination to another is large.  It is unlikely to be able to
    go from HST to ISS (or visa versa) unless some kind of 
    thrusters are used on the Shuttle that are not planned.
    
    Note it is easy to launch a shuttle to the HST inclination
    (28 degrees inclination is typical for Shuttle launches) and 
    more fuel is used to launch to ISS, but the ISS inclination was 
    chosen as a compromise to have Russian participation.
    
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