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[Fwd: FGB and STS-88 launch times]



I found this discussion of the relationship between the Mir and ISS
orbits to be fascinating.  This makes it impossible to transfer, in
orbit, materials between Mir and ISS because of the energy required to
make this big an orbit plane change...

--
Will Marchant
kc6rol@amsat.org http://www.citizen.infi.net/~wmarchan/

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>From: jamesoberg@aol.com (JamesOberg)
>Newsgroups: sci.space.shuttle
>Subject: Re: FGB and STS-88 launch times
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>Date: 20 Oct 1998 12:08:02 GMT
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>
><<Policy views aside ;-) could you elaborate on the differences in orbital
>plane between ISS and MIR?  I'm sure some on this forum would be interested.>>
>
>The Russian side insisted from the beginning that ISS (FGB) be placed into an
>orbit where it would not interfere with Mir tracking for any single tracking
>site. All of one day's Mir (or FGB) passes needed to be completed, followed by
>about one hour of hardware reconfiguration time, before the day's FGB (or Mir)
>passes began. This requires them to be at least 140 degrees apart in terms of
>right ascension (longitude of ascending node). That gives a range of 140 to
>about 220 (which is 140 apart from the other direction). The Russians also
>preferred a four hour block of NO tracking on either vehicle in order to allow
>station down time for regular maintenance, so that pushed the alignment to one
>of the extrema. Since there was a small differential nodal regression due to
>differences in the altitude profile (THAT took a lot to determine), over the
>estimated six to twelve months of simo operation, there would be some shifting
>in this delta right ascension, but we came to the conclusion it should be
>disregarded. We also had our STS desirable mission features, with a sunlit
>landing high on the list (sunlit launch was nice but not a requirement).
>
>Scheduling the grapple activities was also a major challenge, since the crew
>had to wake up earlier and earlier every day until Day 4 in order to begin the
>sequence in time to complete it prior to the last Russian tracking pass of that
>day (FGB uses only ground sites, not TDRSS-style relay). But in the end it
>worked too.
>


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