Lunar gravity assist may rescue Arabsat 4A

From: Ted Molczan (seesat@rogers.com)
Date: Thu Mar 02 2006 - 17:22:11 EST

  • Next message: Björn Gimle: "Re: Japanese Solar Sail"

    Alan Boyle, of MSNBC reports that the possibility of using a lunar gravity
    assist to manoeuvre Arabsat 4A to a useful GEO orbit is under consideration:
    
    http://www.msnbc.msn.com/id/11594666/#060301d
    
    As the article reminds us, this type of rescue was performed with Asiasat 3 in
    1998.
    
    Arabsat 4A's present orbit is about 51.5 deg, 500 X 14700 km. Raising its apogee
    to the radius of the moon's orbit requires a delta-V of about 1300 m/s.
    
    Arabsat 4A has plenty of delta-V available in the propellant that normally would
    have been expended to manoeuvre from its intended GTO (geostationary transfer
    orbit): 14.2 deg, 3150 x 35785 km, to a zero deg, 35785 km circular orbit. 
    
    A circularization burn, followed by an inclination change to zero deg inc, would
    have totalled 1968 m/s. That may be oversimplifying the actual manoeuvres, but
    it would appear that it has more than enough delta-V available to get to the
    moon. Additional delta-V could be obtained by using some of its station-keeping
    propellant.
    
    I imagine it may be months before the rescue will attempted; in the meantime, it
    may be worth the occasional optical observation to see whether or not, and how,
    the spacecraft is maintaining attitude control.
    
    Ted Molczan
    
    
    -------------------------------------------------------------------------
    Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive:  
    http://www.satobs.org/seesat/seesatindex.html
    



    This archive was generated by hypermail 2b29 : Thu Mar 02 2006 - 17:24:41 EST