reflecting sunlight onto the Moon?

In article , ulrich.schreglmann@t-
online.de says...
"Hop David" wrote in message ...
Ool wrote:

So finding a spot that's perpetually in sunlight isn't such a bad
idea, be it a mountain on the south pole or L1...

Is there such a mountain?


I think the highest spots along the crater rims are in sunlight 86% of
the time. That would be 24 Earth days of light, 4 days of darkness.
It would diminish the need for heavy batteries or flywheels considera-
bly...

But I'm not sure you could get that much sunlight all in one spot and
wouldn't have to connect several sites with kilometers of power ca-
bles...

Do you think that kilometers of power cables would be less massive than
just a wireless power transmitter like a laser or a printed circuit
board rectenna? Not that it matters much either way. There are bigger
technical problems for moon colonization, I'm sure .

--
Quibbler (quibbler247atyahoo.com)
"It is fashionable to wax apocalyptic about the
threat to humanity posed by the AIDS virus, 'mad cow'
disease, and many others, but I think a case can be
made that faith is one of the world's great evils,
comparable to the smallpox virus but harder to
eradicate." -- Richard Dawkins

In article , ulrich.schreglmann@t-
online.de says...

The idea is to live in an inflatable habitat buried under an insulat-
ing layer of regolith. (Which is very insulating. Only about half a
meter down in the ground there's a stable -20=C2=B0C, as opposed to -140=
=C2=B0C
or +100=C2=B0C on the surface.)

Heck, with those kinds of differences you could just operate a closed=20
cycle heat pump . =20


=20

--=20
Quibbler (quibbler247atyahoo.com)
"It is fashionable to wax apocalyptic about the=20
threat to humanity posed by the AIDS virus, 'mad cow'
disease, and many others, but I think a case can be=20
made that faith is one of the world's great evils,=20
comparable to the smallpox virus but harder to=20
eradicate." -- Richard Dawkins

In article ,
says...
is there no advantage to using a nice nuclear reactor to provide power?..

There are certainly advantages if you don't want to be dependent on
sunlight. But reactors are expensive and you're going to have to jump
through hoops to shield it or put it far enough away so that it's safe.
Plus, it will eventually need new fuel rods, depending on how it's
designed. On earth reactor rods are replaced every couple years and is
something of a pain. You could more easily use radioisotope thermal
generators for heating and minimal electricity supply, but they're also
expensive and low efficiency. I think the reason folks are going with
solar is because it's by far the most abundant source on the moon and
scales better than most other options. Ultimately, when there's a power
grid in the moon it won't be a big deal to send power to colonies on the
night side.

--
Quibbler (quibbler247atyahoo.com)
"It is fashionable to wax apocalyptic about the
threat to humanity posed by the AIDS virus, 'mad cow'
disease, and many others, but I think a case can be
made that faith is one of the world's great evils,
comparable to the smallpox virus but harder to
eradicate." -- Richard Dawkins

quibbler wrote:

Plus, it will eventually need new fuel rods, depending on how it's
designed. On earth reactor rods are replaced every couple years and is
something of a pain.

The space reactor will almost certainly be designed to operate
for much longer than three years, and to not be refueled.
It will probably be a fast reactor, and metal fuel elements
in fast reactors can achieve burnups of 20% or better.


You could more easily use radioisotope thermal
generators for heating and minimal electricity supply, but they're also
expensive and low efficiency. I think the reason folks are going with
solar is because it's by far the most abundant source on the moon and
scales better than most other options. Ultimately, when there's a power
grid in the moon it won't be a big deal to send power to colonies on the
night side.

PV arrays on the moon can be illuminated during the lunar night by
lasers from Earth. Since electricity and labor are so cheap here,
this may well be the least expensive approach for many years to come.

Paul

In article , says...
quibbler wrote:

Plus, it will eventually need new fuel rods, depending on how it's
designed. On earth reactor rods are replaced every couple years and is
something of a pain.

The space reactor will almost certainly be designed to operate
for much longer than three years,

Sure. I was just trying to highlight some of the many issues which are
often neglected when people treat a nuclear reactor as though it's a
black box for making energy.


PV arrays on the moon can be illuminated during the lunar night by
lasers from Earth.

I was wondering about this myself. Clearly though we would need
stations all around the world, including some backup locations in case
it was cloudy. Do you have any figures on the number of sites needed
and the size/energy requirements for the lasers?

--
Quibbler (quibbler247atyahoo.com)
"It is fashionable to wax apocalyptic about the
threat to humanity posed by the AIDS virus, 'mad cow'
disease, and many others, but I think a case can be
made that faith is one of the world's great evils,
comparable to the smallpox virus but harder to
eradicate." -- Richard Dawkins

"quibbler" wrote in message t...
In article , ulrich.schreglmann@t-
online.de says...

The idea is to live in an inflatable habitat buried under an insulat-
ing layer of regolith. (Which is very insulating. Only about half a
meter down in the ground there's a stable -20°C, as opposed to -140°C
or +100°C on the surface.)

Heck, with those kinds of differences you could just operate a closed
cycle heat pump .


Well, like I said, you have to just find some way of fusing the rego-
lith together into something that absorbs huge amounts of thermal en-
ergy. Then keep it from releasing the heat again during the night by
insulating it before the sky becomes cold. Harness the heat flow and
you can keep your base warm, have a Stirling engine produce electrici-
ty, etc.

And it's not particularly high tech. You can probably produce such a
slab of dirty glass simply by focusing enough sunlight on the rego-
lith, melting it into something non-porous.

Have another slab freeze down to -140°C during the night and keep it
cold during the day and you have one mother of a heat sink for keeping
oxygen liquid, etc.


Energy is cheap in space. Near Earth orbit space has the advantage
that the side towards the Sun is extremely hot while the side towards
deep space is extremely cold. So causing extreme temperatures either
way by just shielding yourself off against one side is easy. The
problem is that there's nothing around to build things with.

The Moon has the advantage of plenty of building matter but a two-week
cycle between extremely hot and extremely cold.

Asteroids are the best of both worlds but they're rather far away on
erratic orbits.


So even if there were no ice on the Lunar poles it might not be such
a bad location after all for all sorts of things, with the night side
close by and the day side close by and enough resources under your
feet to harness the energy flow.

We'll see...



--
__ "A good leader knows when it's best to ignore the __
('__` screams for help and focus on the bigger picture." '__`)
//6(6; ©OOL mmiv :^)^\\
`\_-/ http://home.t-online.de/home/ulrich....lmann/redbaron \-_/'

"quibbler" wrote in message t...
In article , says...

PV arrays on the moon can be illuminated during the lunar night by
lasers from Earth.

I was wondering about this myself. Clearly though we would need
stations all around the world, including some backup locations in case
it was cloudy. Do you have any figures on the number of sites needed
and the size/energy requirements for the lasers?


I'm sure astronomers will be ecstatic. And you thought your local
disco's searchlights were causing light pollution...!



--
__ "A good leader knows when it's best to ignore the __
('__` screams for help and focus on the bigger picture." '__`)
//6(6; ©OOL mmiv :^)^\\
`\_-/ http://home.t-online.de/home/ulrich....lmann/redbaron \-_/'

In article , ulrich.schreglmann@t-
online.de says...
"quibbler" wrote in message t...
In article , says...

PV arrays on the moon can be illuminated during the lunar night by
lasers from Earth.

I was wondering about this myself. Clearly though we would need
stations all around the world, including some backup locations in case
it was cloudy. Do you have any figures on the number of sites needed
and the size/energy requirements for the lasers?


I'm sure astronomers will be ecstatic. And you thought your local
disco's searchlights were causing light pollution...!

I guess we could use microwave beams too, but the idea was probably to
get double duty out of the PV. Actually, I suppose if the light were
concentrated enough it may not be too terrible for astronomers.

--
Quibbler (quibbler247atyahoo.com)
"It is fashionable to wax apocalyptic about the
threat to humanity posed by the AIDS virus, 'mad cow'
disease, and many others, but I think a case can be
made that faith is one of the world's great evils,
comparable to the smallpox virus but harder to
eradicate." -- Richard Dawkins

quibbler wrote:

I was wondering about this myself. Clearly though we would need
stations all around the world, including some backup locations in case
it was cloudy. Do you have any figures on the number of sites needed
and the size/energy requirements for the lasers?

Geoffrey Landis has looked into this sort of thing.

http://www.sff.net/people/Geoffrey.Landis/laser.htp
http://powerweb.grc.nasa.gov/pvsee/p...aser_moon.html

Paul

Ool wrote:

I'm sure astronomers will be ecstatic. And you thought your local
disco's searchlights were causing light pollution...!

Narrowband light pollution is fairly easy to filter out.

Paul