RE: Shuttle launch-UK observation

Date: Wed Oct 02 2002 - 13:55:44 EDT

  • Next message: Sebastian Stabroth: "RE: Shuttle launch-UK observation"

    The launch time prediction was calculated from the latest Twoline Orbital Elements set. The calculation is based on the time when the Earth's rotation carries the launch site through the orbit plane, and an adjustment to allow for the climb to orbit.

    Using a constant daily increment to calculate the time is a good basic method over a few days but but there are many variables to account for, including variations in orbital parameters and the effects of orbit adjustments.

    With the new delay to October 7, the launch time computes as 19:44 GMT. This may still not produce visibility over the UK.

    As far as I can tell, launch time is normally set for the middle of the launch window (usually about ten minutes in duration). The reason for this is to use the most efficient ascent trajectory. Going early or late involves a dog-leg manoeuvre. The actual lift-off time can be varied on the day - STS-105, for example, was launched 5 min early to avoid deteriorating weather.

    On 2 Oct 2002 at 9:51, Bill Mitchell wrote:

    > > Predicted time for the middle of the launch window for STS-111, based
    > > on the most recent ISS element set:
    > >
    > > October 3 21:19 GMT
    > How do you do that?  Skymap?
    > Subtracting 23 mins. 42 secs. each day since last launch I get 22:02:04 GMT.
    > Thanks,
    > Bill
    On 2 Oct 2002 at 7:22, Dale Ireland wrote:

    > Don't they usually set the time for the start of the 10 minute launch
    > window? Or the middle?
    > Dale


    Robert Christy
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