Re: progress tle , high drag factors

From: Sebastian Stabroth (
Date: Wed Aug 29 2001 - 16:28:54 PDT

  • Next message: Paul Gabriel: "az/el compass"

    > If a drag factor in an elset is higher than the true drag experienced by
    > the object traveling through the upper atmosphere, then if the observer
    > looks for the object based on an ephemeris generated by a propagator
    > using the elset, then the observer will see the object later than
    > expected.
    Oh, now I see that I at first incorrectly interpreted your statement. Thanks for your
    > Btw: Can someone explain how to derive the ballistic coefficient B (mass/(drag
    > factor*cross-sectional area)) from the Bstar drag term in the 2line elsets? The
    > Spacetrak report says something like: B=rho/(2*Bstar) with rho=2.461*10^-5
    > kg/m^2/Earth radii. But with the Progress TLE above (Bstar=0.70872*10^-3 in
    > 1/Earth radii) I realy don't think that B=0.017.. kg/m^2 is right! The ballistic
    > coefficient of a Progress freighter should be around 200 kg/m^2 in the worst case.
    And, I forgot to multiply 'rho' by the value of Earth radius (~6378 km). So, the
    ballistic parameter for Progress is around 100 kg/m^2 for this 2line elset - really
    (too) high drag as you said, Walter.
    Unsubscribe from SeeSat-L by sending a message with 'unsubscribe'
    in the SUBJECT to

    This archive was generated by hypermail 2b29 : Wed Aug 29 2001 - 16:29:56 PDT