I haven't been monitoring this thread for a few days. Whew! did you guys
get off on a tangent, or what?!?!?! As for batteries, I would like
to state that these systesm are NOT the first satellites ever
to experiance an eclipse. Eclipse durations vary over the
time of day, and time of year. The G* orbit, at about 100 min per
rev, is going to see eclipses from probably 0 minutes to maybe
35 minutes. This is an educated guess. If people are serious,
I can dig out some software from my school days andjury rig it
and calculate the precise numbers for a 1400 Km orbit.
BUT. Trust me when I say that designers have figured this one out
long ago. You know the saying "It aint rocket scince?" Well,
that is sort of antiquated, because rocket scince is actually
pretty old hat nowadays. I can say that cuz I are one.
Anyway, designers take all this into account when take this
into account during the inital design pahse. The general rule
of thumb is that satellite batteries are designed for 1~5%
depletion for every 1 minute of expected eclipse duration.
Eclipse duration is a function of orbital altitude, so it is a known
quantity up front. Then, the next general rule of thumb is to not
let your batteries go below about 65% of their capacity. These
parameters are what I learned in school, and real satellite power
engineers, which I am not one, may use somewhat different
numbers.
But all satellites go through eclipses regularly, especially LEO's
like G* and Iridium. They have been designed for their particular
orbital altitude/eclipse duration without going below about
65% of their battery capacity. |
