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RE: Re: AMSAT O-E



Rick:

You wrote:
" David,

AMSAT OSCAR-E is not to be deployed in a high orbit.  It is a LEO whose
orbit parameters will be determined by the launch, but you can assume
about 800Km height. There is NOT going to be "FM coverage to huge
areas." Operational and many design decisions are far from "concluded"
and I am soliciting inputs from everyone.

The satellite will have magnetic stabilization so it flips over every
time it crosses the equator. 

Power will be managed by limiting its transmissions to one or two
regions (about 20 minute segments) per pass.  These will be primarily
based on a geographic filter, and will also be mode dependant.

Rick
W2GPS "




That is MAGNETIC equator.  I might further point out that the
"geographic filter" and thus the need to maintain (COMPUTE)
information about the orbital state without having to load
this once per every orbit, MANDATES a computer such as the
V53 and the ability to update orbital elements and to
change the "earth footprint map" running this geographical
filter after you have figured out you have filtered
AMSAT's largest financial contributor in the sultanate
of Brunei.  ;-)

I know you are writing an article for the AMSAT journal but its
lead time is forever and we have started a big discussion
here.  About 90% of this discussion is based on assumptions
that we can fly a Cray supercomputer in the Mack truck we are
going to lift to geosynchronous transfer orbit in order to
be able point the 43% efficient solar perpetual motion
machine driven panels at the sun unless we are in eclipse then
we will take what little power we can get from reflected light
off the moon since we will need that power the required
1 Kilowatt transmitter and the EME array necessary to make
FM voice work in that orbit.


;-)


ALL of this baloney could die off if you would only take out the
pretty pictures in your upcoming article and the beautifully
derived tables and just give a small synopsis of the details.


FOR EXAMPLE:  We have PURCHASED, that is paid, hard earned
AMSAT volunteer dollars for a Microsat frame from Spacequest
and we have a contract of mythical details for same.  THAT
IS A DONE DEAL.

Almost all other aspects of the program can be INFERRED from
that fact but you might as well delineate them and place
emphasis on the fact that we are buying a multichannel
receiver with a transmitter of the Microsat variety, we will
have a TSFR (this space for rent) to experiment with an
ARM computer (maybe), etc.  These details will filter the
discussion into a random walk through idea space as usual,
but at least there will be a strong drift based on reality.
For example,  this almost totally determines the power
available from solar panel generation and thus limits the
useful orbits, etc. etc.  The spinning from solar pressure,
and tumbling from magnetic field, damped by the usual nutational
dampers lets one know you cannot point fold out solar panels
at the sun and we cannot operate FM from 25000 km apogee orbits
in that it almost completely determines what would be a useful
orbit.

Hey! At least there is a discussion AFTER we have purchased
the spacecraft about what to do with the 15% we can have
any control over whatsoever.  For that, we thank you.


Bob
N4HY



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