Re: DSCS circularization burn visible?

Date: Tue Mar 11 2003 - 23:28:50 EST

  • Next message: "Re: DSCS circularization burn visible?"

    In a message dated 3/11/2003 5:31:20 AM Eastern Standard Time, writes:
    > Jonathan McDowell wrote:
    > "... DSCS III A-3 and its IABS (Integrated Apogee Boost 
    > Subsystem) apogee stage  into a 234 x 35780 km x 25.5 
    > deg. [orbit]. The IABS will fire its twin R-4D 
    > bipropellant engines on Mar 13 to circularize the orbit, 
    > and separate from DSCS after a final burn around Mar 15."
    > I was just wondering if this burn, and separation, might 
    > be visible to someone somewhere.  With the Centaurs, as I 
    > saw for myself last year in Mike's telescope, it wasn't 
    > just the venting of the excess fuel that was visible.  
    > Other events were fairly obvious.  I don't know how the 
    > IABS would compare to a Centaur, but maybe the 
    > circularization burn might be fairly similar.  Of course 
    > we would need to know the location (equator above the 
    > Indian Ocean, about 85 east? -- looking at the 
    > ground-track map on and time of the 
    > burn....
    I've not been able to find transfer orbit TLEs for the vehicle (I believe its number is 27691).  However, based on earlier information on the Boeing page, and that from Jonathan's report earlier today, I've managed to piece together a couple of rough transfer orbits to help bracket things.  
    Not knowing exactly where it's supposed to be finally stationed, there appear to be 3 apogee / ascending node opportunities for DSCS 3 on Thursday 13 March.  These occur at approx. 00:35 at 171 E (visible from Australia and the Far East) longitude, at approx. 11:03 at 14 E longitude (visible from Africa, Europe and the Middle East) and at approx 21:30 at 142 W longitude (visible from North and Central America and Western South America).  
    Unfortunately, they all occur in daylight since the line of apsides seems to point almost directly at the sun with apogee in the daylight.  Too bad, I remember a few years ago watching the Centaur injection burn (maybe it was a propellant dump) of a Milstar (I think) on one our few clear winter nights.
    Daryl Bahls
    Seatte, WA
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