Return To The Moon, Everything Old is New again Options

[monitorlizard]

I thought I read somewhere that the new manned landers are being baselined to return 80 kg to Earth on each flight. I assume that refers to 80 kg total, for samples, film magazines (if we're not all-digital by then), and any other items returned, which could include hardware from engineering tests. So, there wouldn't be as much in lunar samples returned as on later Apollo flights, but if we could actually establish a long-term manned lunar program, that wouldn't be critical. Also, with one-week surface stay time by three astronauts, more could be done to choose the very best samples to return to Earth.

[hendric]

That said, is the technology currectly available for microwave transmission of power? Or is this one of those technologies NASA will need to develop first?

Microwave? You're on an airless body. Just mount a few mirrors with sun tracking systems and you can get power 28 days a week(or whatever the 24x7 equivalent is for the moon). Plus, some solar cells can tolerate amplified sunlight, so you could use concentration mirrors or multiple mirrors pointing back to the base to boost the power. Another advantage is that you could setup some of the mirrors to provide ambient light around the base.

In fact, you could even setup a "network" of mirror farms, with a couple mirrors of the farm pointing to "dark" farms to provide them power for their systems when they are in the dark. Maybe something like this:

3 farms, each farm has 1 smaller mirror for pointing to any farm in the dark, 1 small solar cell for local power, 1 slightly inverse parabolic mirror for spreading light around the base, an additional inverse parabolic mirror for spreading light around the current work area, and the rest of the mirrors pointing to the base solar cell farm.

With the lighter gravity and no wind to stress the mirrors, the assemblies can be very large, and/or very light.

[Stephen]

Microwave? You're on an airless body. Just mount a few mirrors with sun tracking systems and you can get power 28 days a week(or whatever the 24x7 equivalent is for the moon). Plus, some solar cells can tolerate amplified sunlight, so you could use concentration mirrors or multiple mirrors pointing back to the base to boost the power. Another advantage is that you could setup some of the mirrors to provide ambient light around the base.

In fact, you could even setup a "network" of mirror farms, with a couple mirrors of the farm pointing to "dark" farms to provide them power for their systems when they are in the dark. Maybe something like this:

3 farms, each farm has 1 smaller mirror for pointing to any farm in the dark, 1 small solar cell for local power, 1 slightly inverse parabolic mirror for spreading light around the base, an additional inverse parabolic mirror for spreading light around the current work area, and the rest of the mirrors pointing to the base solar cell farm.

With the lighter gravity and no wind to stress the mirrors, the assemblies can be very large, and/or very light.

Sounds overly complicated to me. NASA would be wiser to practice K.I.S.S. (==Keep it Simple Stupid) unless it wants its astronauts to periodically spend their time playing repair detail than than being explorers.

Besides, the term "mirror farms" produces visions of something like in the movie "Gattaca", or akin to those so-called wind farms--meaning acres of mirrors and associated paraphrenalia all of which would have to be carted up to the moon and presumably unloaded & set up by somebody, presumably the astronauts. Such a thing may well be useful further down in the track once a more permanent settlement was set up, but surely not for an initial base.

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Stephen

[dvandorn]

Actually, my understanding is that one reason for setting up an outpost at Shackleton is precisely because there are locations along the rim which get sunlight most of the time. Which means they *can* erect a solar panel farm up in the permanently sunlit potion of the rim that will power the outpost and any water mining installations.

I'm pretty sure they'll need to simply run power lines and not use transmitted power of any kind (including reflected sunlight), since they will need to power installations in the adjacent permanently shadowed lands just inside the rim. Beaming microwaves or concentrating sunlight would have the tendency to drive the volatiles out of the adjacent soils -- and our engineering isn't good enough to prevent significant energy leaks along the borders of beamed power routings. We don't want to boil the volatiles into space, we want to gather and use them!

-the other Doug

[hendric]

Ok, I see your points, but it still might be a good idea just for the directed sunlight. You could use it for lighting, and the volatile extraction is a bonus! Just put up a conveyor belt in a glass building placed in the dark portion of the crater, and you get free solar energy to extract volatiles and nice cold regolith to recover them.

[helvick]

It's interesting to consider just how hard all of this is going to be.

Just running power lines is not going to be a trivial task on the Moon. Running a power line any significant distance over this sort of unfriendly terrain is going to be mega hard.

The rated (safe) current carrying capacity of a 5mm diameter copper cable is about 60 amps. Assuming you can drive it at 1kv you can deliver about 60kwatts fairly safely over that on earth. A kilometer of that cable contains about 160kg of copper and maybe as much again of insulation\shielding and armouring. Using aluminium saves you about 50% mass for the same current carrying capacity but it is bulkier and harder to install which are possibly going to be equally important characteristics.

That said if you could get 50-100kw of power then you could probably do a lot with it in terms of mining and refining in situ resources if you were reasonably patient.

[dvandorn]

One good thing to remember is that the Moon's original crust is made up primarily of aluminum. You won't do this at the beginning, of course, but eventually you will be able to use the anorthositic rocks to refine aluminum in situ -- and then a building boom can truly begin.

-the other Doug

[Greg Hullender]

On the bright side, at least you don't need insulation; in fact, you can probably just lay the wire on the ground.

--Greg

[Stephen]

On the bright side, at least you don't need insulation; in fact, you can probably just lay the wire on the ground.

But would you necessarily want unshielded cabling scattered across the lunar surface, especially a surface probably in perpetual darkness? Sounds like an accident waiting to happen.

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Stephen

[nprev]

Uh...I don't know about that, Greg. Over a fairly long cable run, it doesn't seem safe to assume that the soil along the full length is a perfect dielectric. (Nightmare scenario: Part of the uninsulated run goes over a patch of volatiles, which just happens to run a few feet deep and along an ancient chunk of nickel/iron that has held its original charge from landing for lo these many eons...throw the switch, and ZAP!...cable's severed, glowing orange at the ends...)

If nothing else, no insulation would only increase sporadic, minor transmission losses, which is not good esp. if aluminum is the material of choice; it's lossy enough already, which is why it's not more widely used than copper.

BTW, and not to get too engineering-geeky here, what about solar disturbance effects on lunar medium-haul power lines, insulated or not? Got no magnetic field to protect them from the brunt of the surge; might need some serious surge supressors and isolation transformers to avoid blowing all the equipment in the station!

So, unfortunately, it appears to me that not only will the power cables require insulation but also heavy shielding with single-point Moon-grounds for same... ...not cheap, nor light, nor particularly easy to install working in a surface suit.

[dvandorn]

First, if the power cables are manufactured on Earth and taken whole to the Moon (which will happen for quite some time to come), then they'll probably have some type of organic-material insulation, such as plastic or rubber. In the future, when we're making aluminum power cables from lunar resources, I'd imagine we'll find a way of making insulation from the silicate slag that's left over from smelting the rocks.

I also think they will probably bury the cables to avoid interference from the lunar radiation environment. Yes, they'll have an up-and-down path, since you can't go more than a few meters on the Moon without running into a crater of some size, and they'll skirt larger (10+ meter) craters. But I can vey easily see a vehicle fitted with a trencher that digs a trench, lays the cable into it, and covers it over in one smooth operation. I think you could probably lay cable no more than 20 to 30 cm below the surface and it will be well insulated from the lunar radiation environment.

EDIT: I will point out that the ALSEP stations endured several powerful solar flares and none encountered serious issues from power surges in their power or data cables. So, while it's something to take into account, the radiation environment may not be as much of a problem as we might think.

-the other Doug

[nprev]

I will point out that the ALSEP stations endured several powerful solar flares and none encountered serious issues from power surges in their power or data cables. So, while it's something to take into account, the radiation environment may not be as much of a problem as we might think.

-the other Doug

Good info as usual, oDoug...but must respectfully submit that the ALSEPs didn't require 100m+ cable runs of maybe 4-gauge wiring or better packing 60 KV & a whole lot of amps. High-voltage power transmission systems with long cable runs are much more vulnerable to these effects; they just have a lot more 'exposure potential' to them, if you know what I mean.

Burying them as deep as possible would of course do quite a bit to obviate this...but we're going to have to fly a really good ditch-digger for sure...probably with anchor lines to the surface in order to gain enough leverage to dig out the soil and rock deeply in the low gravity...

Just trying to point out that establishing the first lunar power station will NOT be a trivial effort in terms of systems engineering or labor; there are many, many critical dependencies to consider, and I'm sure we've barely scratched the surface here...

[dvandorn]

...I'm sure we've barely scratched the surface here...

I assume you weren't aware of that pun -- considering we're discussing how to bury power cables -- or else I would have to kill you...

-the other Doug

[nprev]

...well, LA's pretty big...and you don't know my address...

[PhilHorzempa]

Phil, my understanding is that once the transportation system is in place, one out of every three or four manned landings will be sortie missions that will land at various locations to do some true exploration. A majority of the work at the polar outpost will be to pioneer the engineering techniques required for humans to survive on a planetary surface other than Earth's for extended periods.
But, please, hear me now -- engineering research is still scientific research. It may not be the kind of science you're interested in, but it is most definitely scientific research.
-the other Doug

My question is - Why do we need to pioneer the techniques for extended stays on a planet's
surface? Mars is NOT the Moon and survival on its surface should be a heck of a lot easier than
surviving on the Moon - Mars has lots of water ice, less deadly dust, 24-hour "sol," etc.
As for learning how to operate a manned spacecraft for months or years at a time - I thought
that is what the ISS is meant to do. Why do we need a clone of the ISS on the Moon?

As for doing good science at the Moon's S. Pole, I agree that we will learn a lot from that
location, but that area is just a small spot on the Moon. The Moon is a WORLD - you will not
"know" that world by hunkering down in one spot. OK, all of you in UMSF-world, imagine if
Opportunity simply "hung around" Eagle crater for the last 3 years. Sure, we would have
gained some new knowledge of Mars - but you all know how many surprises we would have missed.
We go to the Moon or Mars to EXPLORE.

Why go through all of the effort to develop a way to return people to the Moon when all
that they will do there is build a chalet and a garage? In the past, Griffin himself said (at
the First Exploration Conference in early 2005), after a while, exploration without science
will begin to look like a STUNT, and then, as he continued, we won't have it anymore (implying
that it would lose public support).

I urge all of those on UMSF to go to my earlier post, in this thread, and actually
read the description of the 24 landing sites on the Moon that are suggested by Don Wilhelms,
perhaps the foremost living lunar expert.
These sites are the MINIMUM necessary to actually understand the Moon as a world. I think that
many believe that the data from Apollo basically answered all of our questiions about the Moon.
That would be an erroneous assumption - recall, for example, the Orange Soil, discovered on the last Apollo mission, by accident. How many more "shock and awe" discoveries await us?

We will not know if we are limited to a paltry 1 Sortie mission per year.


Another Phil