Jerry Stuckle wrote in
:

Actually, high temperature superconductors have been found at
temperatures as high as -135C. And in the shade, space is very cold,
even at Earth's distance from the sun, shaded items are very cold. Even
the moon, which will hold some heat, cools to -233C at night time.


I wonder if the ISS might be a place capable of doing tests like these. Parts
of that must be in constant shade, so maybe some test of a space-based
superconducting antenna is feasible. (I'm not ignoring what Jim said about
having space to build a big, normal antenna, it's just interesting that there
might be scope now to try this just to see what can be done with it. Also,
given the cost of sendign heavy stuff out there, it might be viable anyway
if it saves the need to do that so often).

I think the odds of this happening between now and the end of the solar
system are pretty slim. If a small wire could so easily be hit by a
micrometeorite, our satellites, space stations, rockets, etc., all much
bigger, would be in deep doo-doo.


Ok. Besides, never mind stretching, the superconductor would be brittle,
probably. Would a swarm of partcles redirected from sun via some magnetic
field, passing the antenna wire, be enough to heat it to the point of
supercondcuting failure? I have no idea about this, it just seems that there
might be a lot of energy, even if thinly distributed..

On Sun, 2 Nov 2014 05:30:14 -0000, wrote:

Jeff Liebermann wrote:
On Sat, 01 Nov 2014 18:47:32 -0400, rickman wrote:

I think you are confusing need with practicality. There is nothing to
stop you from making a superconducting antenna. There just isn't a need
for it unless you live in Gareth's world. Hmmm... wasn't that a movie?
Gareth's World?
(...)
I believe there are rather cold temperatures in space. A
superconducting antenna could be used there with *no* supporting
"apparatus".

You don't need to go to outer space to see cryogenic radios in
operation.

You can see space a lot better with a cryogenic radio.

On the ground, cooling the LNB is easy enough but how do you cool the
dish? The LNB is looking at the entire dish, which is sitting there
radiating at ambient temperature. Paint is low emissivity white?

Incidentally, I tried making my own LNB cooling derangement back in
the days of 100K C-band LNB's. Peltier 6 pack beer cooler plumbed
with copper ice maker line and an aquarium pump. The signal would
look great for about 10 minutes, and then slowly fade away. It seems
that cooling also causes water to condense on the "mica" waveguide
window. Add a small heater and fan. When I replaced it with a 25K
LNB, the cooler and fan went away. At least in outer space, there is
no condensation problem.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Lostgallifreyan wrote:
Jerry Stuckle wrote in news:m35chg$mlv$1@dont-
email.me:

What would cause the superconductors to warm up? They have no
resistance, so it wouldn't be from internal means. And kept shaded,
there would be very little external heat applied.


Not much, maybe. I just figured that their state would not be stable, that it
would take very little, from any source, to heat them to the point where the
problem started getting rapidly worse. Maybe it wouldn't be an issue if the
superconductor were 'hot' enough. -196?C is 77?C above absolute zero, so
maybe some of them will always stay cold enough with nothing but shade.

Heat sources might be unexpected though. If a thin wire got hit my a
micrometeorite, it would likely get stretched and heated pretty fast. So the
question might be what kind of margins exist for safe operation.

The only external heat source in space is the Sun; solution, sun shade.

If shaded, things get quite cold in space, cold enough for known
superconductors to work.

A hit by a micrometeorite would be rare, but likely catastrophic; heat
wouldn't be your main problem.

But again, the question is why bother?


--
Jim Pennino

wrote in news
But again, the question is why bother?


Well, to add to your list of Eternal Questions of the Past Century, you can
add that one. It's far older actually, and has been asked of air travel,
mountian climbing, exploring West Africa, Antartica, and probably bungy
jumping. The jury's still out on that last one. The simple answer is: because
it hasn't been done, or at least not by the person most wanting and able to
do it. A better answer is: to find out what can be learned along the way,
given that the destination is a new one. Most of science was built that way.

Lasers were (in)famously a solution waiting for a problem for over 50 years,
and if in all that time people had said 'why bother?' we'd still be without
compact optical storage and several other things. No inertial confinement
fusion experiments, no eye surgery except by scalpel or needle, and likely no
high precision clocks. Big Pharma is asking 'why bother' investing in new
antibiotic research, and the odds are that because it IS asking that question
in the negative, millions, perhaps billions of people will die. Of course,
given the population crisis, any surving descendents may actually be thankful
for this!

Point taken about shade. I still wonder if magnetically guided swarms of
particles might get at it even if there is a shade directly between the sun,
but I guess not many, and so long as the sun is hidden while the distant
signal point is not, then it works, same as it does now without
superconductors.

On 11/2/2014 10:49 AM, Lostgallifreyan wrote:
Jerry Stuckle wrote in
:

Actually, high temperature superconductors have been found at
temperatures as high as -135C. And in the shade, space is very cold,
even at Earth's distance from the sun, shaded items are very cold. Even
the moon, which will hold some heat, cools to -233C at night time.


I wonder if the ISS might be a place capable of doing tests like these. Parts
of that must be in constant shade, so maybe some test of a space-based
superconducting antenna is feasible. (I'm not ignoring what Jim said about
having space to build a big, normal antenna, it's just interesting that there
might be scope now to try this just to see what can be done with it. Also,
given the cost of sendign heavy stuff out there, it might be viable anyway
if it saves the need to do that so often).


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

I think the odds of this happening between now and the end of the solar
system are pretty slim. If a small wire could so easily be hit by a
micrometeorite, our satellites, space stations, rockets, etc., all much
bigger, would be in deep doo-doo.


Ok. Besides, never mind stretching, the superconductor would be brittle,
probably. Would a swarm of partcles redirected from sun via some magnetic
field, passing the antenna wire, be enough to heat it to the point of
supercondcuting failure? I have no idea about this, it just seems that there
might be a lot of energy, even if thinly distributed..


Those particles, although moving quickly, would be too small to have
much effect.

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

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

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.

Lostgallifreyan wrote:
wrote in news
But again, the question is why bother?


Well, to add to your list of Eternal Questions of the Past Century, you can
add that one. It's far older actually, and has been asked of air travel,
mountian climbing, exploring West Africa, Antartica, and probably bungy
jumping. The jury's still out on that last one. The simple answer is: because
it hasn't been done, or at least not by the person most wanting and able to
do it. A better answer is: to find out what can be learned along the way,
given that the destination is a new one. Most of science was built that way.

Apples and oranges; we already know what will happen if one were to build an
antenna from a superconductor.

Fire up EZNEC and set material loss to zero; done.

snip more apples and oranges


--
Jim Pennino

wrote in :

Apples and oranges; we already know what will happen if one were to
build an antenna from a superconductor.

Fire up EZNEC and set material loss to zero; done.


Yeah, anyone with a map could say a great deal about the shape of West Africa
based on ocean travel. My point isn't so much about antennas, as about
exploring the easy availability of cold environments for superconductors in
space. Not having to lug heavy coolers up there might be an offer someone
cannot refuse, and that someone might come back with all kinds of
discoveries, things no models or predictions are going out there to find.

wrote in news
The only external heat source in space is the Sun; solution, sun shade.


Maybe not. I just did a bit of Googling for 'superconductors in space' minus
quotes. There's a lot of statements abotu space missions ended because
required helium or hydrogen coolant ran out, and also of space having latent
temperatures up to 100K, so a sun shade won't help a lot there with current
materials. Also, show me the 100% efficient sun shade. Maybe the James Webb
scope's shield might set some new precedents if that gets launched.

Basically, any worth in the idea will come out of some compromise between
ambient conditions and new higher temperature superconductors. And if they
end up cheaper to lug up there than the current materials for antennas and
matching networks, they may get used anyway. Without knowing what materials
become available, and the needs for them, we can't assert a lot about what is
possible.

Lostgallifreyan wrote:
wrote in :

Apples and oranges; we already know what will happen if one were to
build an antenna from a superconductor.

Fire up EZNEC and set material loss to zero; done.


Yeah, anyone with a map could say a great deal about the shape of West Africa
based on ocean travel.

Again, apples and oranges as we know EXACTLY and in DETAIL what would happen.

My point isn't so much about antennas, as about
exploring the easy availability of cold environments for superconductors in
space.

Easy availability measured in thousands of dollars an ounce to get
stuff there.

Not having to lug heavy coolers up there might be an offer someone
cannot refuse, and that someone might come back with all kinds of
discoveries, things no models or predictions are going out there to find.

The only thing that makes a superconductor different is the lack of
resistance.

We already know exactly what that means and what we would do with them
if room temperature superconcductors were available.

Here are a couple of things: electric motors and generators that would
be very close to 100% efficient, small, light, and lossless power
transmission lines, lossless transformers, big honking magnets.

--
Jim Pennino