Re: [FPSPACE] SZ 4 recovery - competition time !

From: Sven Grahn (
Date: Sun Jan 05 2003 - 03:04:01 EST

  • Next message: Edward Lyons: "Re: Shenzhou 4 TLEs"

    At 18:45 2003-01-04 +0000, Phillip Clark wrote:
    >Regarding the SZ 4 high orbit, way back in 2000 as an exercise I ran some
    >software to calculate the repeating orbit patterns for SZ orbits, and for a
    >31 circuit repeater at 42.4 minutes the repeating orbit period is 91.212
    You must mean nodal period = 91.098 min, i.e. mean motion = 15.7871549 revs/day
    >Using USSPACECOM data, SZ 4 manoeuvred straight into this orbit,
    >and the decay rate (or lack of, compared with SZ 2 and 3) makes me wonder
    >whether the Chinese are using regular low thrusts to maintain altitude.
    >There was a manoeuvre announced for January 2nd, but the change in altitude
    >was only of the order of 1-2 km - not 5-10 km as seen on the earlier
    Yes, it sure looks that way. The three latest elsets all show increasing 
    period (see my little SZ-4 article:
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