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From: Pat Flannery on 20 Dec 2009 11:26
Sylvia Else wrote:
>> As has already come up, switching to batteries during eclipse isn't
>> practical because of the weight that would be involved to keep
>> microwave power transmission levels constant.
>
> Well, you wouldn't do it that way anyway. If you have suitable
> batteries, there's no point in putting them in orbit. You'd put them on
> the ground instead, to provide power when the rectantenna isn't.

Duh, hadn't thought of that one...
(Sheepish)

Pat :-)
From: Pat Flannery on 20 Dec 2009 11:41
Sylvia Else wrote:
> Pat Flannery wrote:
>>
>> Sylvia's multiple SPS constellation with the individual satellites
>> widely spaced certainly has simplicity on its side.
>
> If we're envisaging space antennae that can be steered just be changing
> the phase of the transmitting elements, then it seems sensible to use
> that mechanism to allow on SPS to transmit to different ground stations
> depending on demand. This would then not only be used to address the
> eclipse issue, but also make for more efficient use by changing where
> the power is delivered depending on loads (which are reasonably
> predictable over a period of a day or so).

That should work; the phased array radar used on modern fighter aircraft
can redirect the beam over a wide angle without moving, and do it in
milliseconds to boot.

Pat
From: jmfbahciv on 20 Dec 2009 10:13
jimp(a)specsol.spam.sux.com wrote:
> In sci.physics Pat Flannery <flanner(a)daktel.com> wrote:
>> David Spain wrote:
>>>> Using the concept of "If you can't raise the bridge, lower the river"
>>>> rectennas built not on flat land, but rather on the south-facing sides
>>>> of mountains would present a more perpendicular aspect to the incoming
>>>> microwave beam from a SPS in the southern sky.
>>>>
>>> Wouldn't that work regardless of which hemisphere it's constructed in North
>>> or South?
>> Yeah, in North America it would probably be out in the Rockies facing
>> south; in South America in the Andes facing north.
>
> What happens to the output when the antenna is covered with several feet
> of snow and ice?

Isn't that when the grad student gets to go outside on Mount Washington
and discover what real wind chill feels like?

/BAH
From: Pat Flannery on 20 Dec 2009 20:28
jmfbahciv wrote:
>> What happens to the output when the antenna is covered with several feet
>> of snow and ice?
>
> Isn't that when the grad student gets to go outside on Mount Washington
> and discover what real wind chill feels like?

You would have to mount the antenna elements far enough away from the
side of the mountain (on tall poles probably) so that they would stay
above the snow in winter.
Of course an avalanche wouldn't help things any. :-)

Pat
From: Dr J R Stockton on 20 Dec 2009 14:01
In sci.space.history message <UmXWm.89823$II.40825(a)newsfe22.ams2>, Sat,
19 Dec 2009 03:02:04, Androcles <Headmaster(a)Hogwarts.physics_q> posted:

>The Isle of Man is part of Great Britain but is not part of the United
>Kingdom. Same applies to Eire.

Neither of them is part of Great Britain.
<http://en.wikipedia.org/wiki/Great_britain> is correct.

--
(c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk Turnpike v6.05 IE 7.
Web <URL:http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, & links.
I find MiniTrue useful for viewing/searching/altering files, at a DOS prompt;
free, DOS/Win/UNIX, <URL:http://www.idiotsdelight.net/minitrue/> unsupported.
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