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Re: STS-111 Launch Window



Udo Schneider wrote:
> > My prediction:  7:46:00 p.m. EDT (23:46:00 UTC) +/- a couple
> > of minutes.
>
> Helmut Strickner wrote:
> > I would like to know how you derived at that launch time.
> > According to my estimation the ISS is over the shuttle launch site at
> > 22:56:00 on 30 May 2002. I would assume that launch time is around
22:50:00.
> >
> > I cannot see an optimum launch time at 23:46:00 as you predicted.
> >
>
> Obviously you have used a tracking program to see when ISS
> is more or less over Cap Canaveral. But that's not so important.
> The shuttle must be shot into the orbital plane of ISS (Phil Karn
> has pointed out this a few weeks ago). So I have calculated for
> 30 May 2002 - using the last keps:
>
> 1. The RAAN (right ascension of ascending node) of ISS and
>
> 2. the siderial time for Cape Canaveral (Longitude 80.61 deg West).
>
> With an iteration in small time steps I have determined the time
> when the orbital plane goes through the launch pad. So I came
> to my prediction of 23:46:00 UTC +/-. I have written a program
> for that, but - as you know - Version 0.1 of a computer program
> has errors 8-(
>
> May be I'm wrong because of an error in my algorithm or my
> theory - let's see! The uncertainty in my theory is as follows:
> Is it better to correct the inclination of the shuttle's orbital
> plane or the height? It's a question of the quantity of fuel
> used for the maneuvers. Perhaps it's better when ISS is near KSC...
> In that case you would be right.
>
Hi Udo,
I have found out from searches done at KSC that the shuttle requires
aproximately eight minutes from lift-off to reaching the orbital plane of
the ISS. At that point the shuttle has about the same relative speed as the
ISS.
I could not find any specific information about any desirable earth orbit
injection point relative to the ISS. I assume that it would be desirable to
trail the ISS at a close distance at the point of orbit injection.

As a matter of interest I will try to make my own observations of the
STS-111 launch to find out how they done it. I make my estimate between
22:48:00 to 22:50:00 UTC.

Helmut VK4STR


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