No antennae radiate all the power fed to them!
 

rickman wrote in :

Lol, radiation resistance is from the signal energy *leaving* the
antenna. It does not show up as heat!


I already posted that I wasn't talking about radiation resistance as used in
antennas. I just meant that some object, at some temperature, is limited in
how fast it can get rid of its heat. (Also, assuming that even in space a
thing may get heated a little by something, no matter how well someone tries
to shield it, and that it won't take much to prevent a superconductor
working).

No antennae radiate all the power fed to them!
 

rickman wrote in :

You need to read up on the temperatures involved. Space is near
absolute zero.

I read less than an hour ago that the interstellar medium has latent
temperatures of up to 100K. For a 'vacuum' it has a lot of stuff floating
around in it, too.

No antennae radiate all the power fed to them!
 

Lostgallifreyan wrote:
wrote in :

There is no undiscovered magic in superconductors.

There was no magic in any of the materials used for Gemini and Apollo either,
but countelss things were learned just by using them out there.

Care to name a few specifically from Genini and Apollo?

And BTW, 99.9% of the materials used is aluminum.


--
Jim Pennino

No antennae radiate all the power fed to them!
 

Lostgallifreyan wrote:
rickman wrote in :

You need to read up on the temperatures involved. Space is near
absolute zero.

I read less than an hour ago that the interstellar medium has latent
temperatures of up to 100K. For a 'vacuum' it has a lot of stuff floating
around in it, too.

That is for energetic stuff floating around in some particular place.

If you were causght in a CME it would be a lot hotter than that, but
again that is stuff.

The background temperature of space is 2.7 K.


--
Jim Pennino

No antennae radiate all the power fed to them!
 

No antennae radiate all the power fed to them!
 

No antennae radiate all the power fed to them!
 

rickman wrote in :

You are aware that a standing wave still moves up and down, no?

Ok, it looks like that is where I'm losing it. :) I look at some Youtube
video shows that in a tank this is happening. So aht is it I see when a
laminar flow hits a ceramic surface? Is it basically just a travelling wave
that matches (in reverse) the speed of the flow?

If that's all it is I'll let this rest.

No antennae radiate all the power fed to them!
 

On 11/2/2014 3:08 PM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:m36209$kk3$1@dont-
email.me:

No, I don't think any part of the ISS is in "constant shadow". I
believe it rotates as it orbits the earth, and different parts of it are
in the shade at different times. I could be wrong, though - I've never
been there :)


Fair enough. I know that Apollo used to do the 'barbeque roll', but as far as
I know there's less need of it on the ISS for whatever reason. Maybe they use
the solar panels for shade part of the time, there's a lot of those... Or
maybe it's in Earth's shadow often enough to get by... Or maybe it rolls
constantly and I just had no idea.

About particles, I don't know what sort of quantities there could be, or
energies involved, but I'll settle for the realisation that an amount capable
of causing heating would be long past rendering an antenna too noisy to use,
probably. I suspect heating by remnant of mass coronal ejection might be the
least of its worries. :)


Not many particles in a vacuum :)

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

No antennae radiate all the power fed to them!
 

On 11/2/2014 4:17 PM, wrote:
On Sunday, November 2, 2014 1:51:46 PM UTC-6, Jerry Stuckle wrote:

No, I don't think any part of the ISS is in "constant shadow". I
believe it rotates as it orbits the earth, and different parts of it are
in the shade at different times. I could be wrong, though - I've never
been there :)

Hard to say.. Some parts away from the sun may stay dark during a
daylight pass, but they may be lit on other passes, depending on
the direction and angles to the sun. I suspect they want to keep the
solar panels towards the sun as much as possible, but the panels
themselves may be steerable to some degree.
I've never been there in person, but I've been there via camera
on many an orbit. Watching the planet from that platform can be
good wholesome entertainment for the whole family. :)


I also don't know how steerable the solar panels are - but I would
expect them to be somewhat steerable. It wouldn't make a lot of sense
to keep having to adjust the position of the entire ISS to keep the
panels aimed at the sun.

The station itself does not really appear to roll at all.
Or at least that can be detected on a lit pass, and using the
earth as a "roll indicator" of sorts.


But if it keeps one direction pointed towards Earth, then it has to roll
- one rotation per orbit. Which means the solar panels have to be
steerable to some extent for maximum power.

But anyone can watch for themselves as long as they are in
contact, and not on a nighttime pass. The cameras they are using
don't seem to be too sensitive at night. IE: I hardly ever notice
the lights below on a dark pass. Of course, they zip around the
planet in about 90 minutes time.. So quite a few chances during a
day to see what parts of the station are lit, and which are not.
Some cameras, like the one I'm watching right now do not show the
station at all, while the one they were using a few minutes ago did.
At this moment they are fixing to pass into darkness over the Atlantic.

http://eol.jsc.nasa.gov/HDEV/
http://www.ustream.tv/channel/iss-hdev-payload


--
==================
Remove the "x" from my email address
Jerry Stuckle

==================

No antennae radiate all the power fed to them!
 

Jerry Stuckle wrote in news:m36b58$oee$1@dont-
email.me:

Not many particles in a vacuum :)


Well, I can't argue. :) I just think that in some big reach of space where
there is no sudden boundary between high material density, and high
rarifaction, that occasionally some surprising exceptions to expected local
conditions might occur. (And there was a time when 'space weather' was an
unhead of concept).