Re: 97 20E,F elsets

Bjoern Gimle@tt-tech.se (Gimle@tt-tech.se")
Wed, 07 May 1997 11:46:56 +0200

Ron Lee wrote to me:
> 
> According to what I saw on iridium's web page, the five satellites
> were deployed and solar arrays also deployed within two hours of
> launch.
> 
Thanks, Ron,
	I shouldn't have jumped to conclusions, but the confusion
and/or lack of orbit info makes speculation almost inevitable.

I tried to search for info on the web, and found mostly references
to 75 degree inclination, and 780 km height.

What is "Iridium's web page" ? I found
http://leonardo.jpl.nasa.gov/msl/QuickLooks/iridiumQL.html
and http://www.iridium.com/systm/systm.html
The latter says 420 nm (=780 km !?)

I am not as satisfied as you are with our pre-launch elsets.
Using the actual elsets I posted, I find your set 1m45s late,
mine 4m late on the first orbit.

The satellites would "have passed" W.of Vandenberg at 14:56:35,
the F object E. of Vandenberg 14:53:40. Both are "too early",
but the F object can be explained by assuming its orbit was raised
near lat. 30S after two orbits. Possibly the satellites' "early start"
is explained by a circularization on the second orbit ?

Rob Matson's COLA on my F elset, and the others', give the closest
approach as 1.9-5.2 km for A to D initial and later elsets,
9.6 km for the later E elset.
All occur 16:41:16.3-16:41:50.5, i.e. near perigee after ONE orbit.
So, the timing of all objects could be explained by a low first
half-orbit, an elliptic half-orbit with apogee S of Vandenberg,
circularized after the first full orbit, and the F object raised
shortly afterwards.

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