Markus Mehring wrote:
>
> On Wed, 4 Dec 2002 16:54:54 -0000, you ("John locker"
> <satcom@cybase.co.uk>) wrote:
>
> >The latest elements from celestrak (338.25) give me a pass around the same
> >time as ISS (1740ish) ......which doesnt look right.....anyone have more
> >accurate data please ?
>
> No, that ought to be about right. It seems both objects are still
> comparably close together, previous missions certainly saw a much greater
> separation during post-undocking days than this one. These are the latest
> elset that I have, all comparably close together, making passes with fairly
> small timely separation. MEPSI is leading, followed by Endeavour, followed
> by the ISS:
>
Very crude computation gives separation rate between ISS and Endeavour
cca. 20 km per orbit. as the difference in M dot is 0.00729381 (2 x
3.14159... x 6770 km x 0.00729381 = 310 km per day, divided by M dot
gives 19.93 km per orbit).
The first maneuvre, starting the quarter loop inspection flight was
naturally small posigrade burn, transferring STS into orbit with
somewhat higher apogee (in the order of hundreds of meters). After
reaching the point directly above ISS, retrograde separation burn 0.9
m/s (ie. 3 fps) was performed. Sometimes another orbit shaping burn,
further lowering STS orbit (and adding to separation rate) is performed
some hours after separation burn, with the aim to better shape ground
track for landing (crossrange optimization). According to the
information available, no such maneuver was planned on STS-113 mission.
Shorter than usual roundfly was probably due to necessity to maximize
delta V for ISS orbit corrections. (During roundfly is rather big
consumption of RCS propellant, as I guess).
Mgr. Antonin Vitek, CSc.
Office: Main Library, Academy of Sciences of the Czech Republic
Narodni 3, CZ-11522 Praha 1 - Phone: +420/221 403 255, fax +420/224
240 611
Home: Kytin 127, CZ-25210 Mnisek p. B., Czech Republic
Phone: +420/318 592 865, cell +420/603 148 201 - Coord.: 14.2194 deg E,
49.8488 deg N, 442 m ASL
My satellite home page: http://www.lib.cas.cz/www/space.40/index.html
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USE ALTERNATE ADDRESS: vitek1@lib.cas.cz
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