[ExI] More ranting on power sats

[John Clark]

On Sun, Aug 12, 2012 at 3:27 PM, spike <spike66 at att.net> wrote:

*>>…*solar power satellites…wouldn't work for up to 72 minutes a day when
>> the earth eclipses anything in geosynchronous orbit…   John K Clark
>>
> ** **
>
> Indeed sir?  Did you forget that the plane of the ecliptic is tilted 23
> degrees from the orbit plane of the earth’s orbit about the sun?  Of course
> for a few days in March and a few days in September, your comment is partly
> right, if you don’t consider the penumbra all the way out there.
>

Between February 28 and April 11 and between September 2 and October 14 the
sun will be eclipsed by the earth every day for anything in geosynchronous
orbit, the time in shadow varies reaching a maximum of 72 minutes at the 2
equinoxes. It's particularly unfortunate that it occurs at around noon
local time the busiest part of the day, assuming the gigantic receiving
antenna was aimed at the satellite that was highest in the sky so it went
through the least amount of atmosphere. This blackout is not such a big
deal for communication satellites because they can run on chemical
batteries for a hour or so, but the problem is not as easy to solve for
power satellites, and even so battery aging is the main thing that limits
the lifetime of communication satellites.

  John K Clark
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