There have been past discussions about the best place for a lunar base/colony/outpost, but since it has been a while I thought to refresh the topic with or without the likelihood of a lunar expedition in the immediate future (ask this question again with the next US president or Congress and I'll bet the chances change once again).Previously, the Lunar poles garnered attention since the presence of ice is confirmed. While this is logical for long-term sustained settlement, if we're talking the first 20 years it is not so much. I state this because it will be some time before we figure out what to do with the ice, partly because we aren't fully certain if it's fluffy space snow or thin veins in a rocky matrix. Add to that, neither the north or south poles are friendly places to land blindly since they are, for better or worse, crater quagmires. Regarding the poles, definitely study them both with robots and astronauts but hold off on any fledgling lunar cities.
The "Best Region for a Base/Outpost" is in LLO, not on the surface. From there, sorties to all regions of interest can be carried out, samples gathered, tests performed and instrumentation laid. Only if that location is worth hanging around for or is ideal for testing surface equipment for other (Mars?) operations should a surface base/outpost be established. From a previous post of mine, the LLO temporarily-manned base/outpost;For maximum scientific, modular and reuse capability with minimum size, fuel use and cost I've gone with polar LLO, possibly 86 degrees as that appears to be highly stable. I've calculated delta-v at 2.014 for obit between 85 - 103km with inclination/plane change budget of 15 - 10 degrees, respectively, to cover the entire polar regions. The polar regions with their possibility of ice are a must, the far side equator prime for radio telescopes and the Apollo 15 site the most geologically interesting.All these are readily accessible from the PLO mentioned, as well as much more. Since then I've buttoned down and tweaked the orbit to be elliptical, but the fundamentals and reasons remain: "Anytime return" from all areas of interest, lowest fuel requirements for multi-sortie missions, shortest duration (safest) and smallest craft to LLO return, greatest downmass capability especially if delivered via SEP, etc.
For any base to survive it needs power 24/7. A nuclear power supplied base can be placed anywhere. In case of solar power it needs to be near a pole for higher sunshine hours. During lunar nights a solar power system will be running on batteries or fuel cells.
I don't think any other location comes close to the poles in desirability, and that makes it the #1 initial base location to obtain "propriatory" rights.
And when the Sun has one of its hissy fits?
Quote from: Andrew_W on 03/12/2014 06:11 amI don't think any other location comes close to the poles in desirability, and that makes it the #1 initial base location to obtain "propriatory" rights.Desirable yes, practical another question. We don't know how to mine lunar ice and landing on or near a shadowed crater is not easy. However, landing at one of the mares near the north pole would be possible, and either by rovers or short-range rocket jumps venturing into the polar craters themselves to build up confidence.
Pros. A solar satellite beaming power maybe able to deliver enough power on each pass to keep a hibernating base alive for lunar night.Cons. Solar satellites don't exist so it would have to be developed. Between satellite and ground station this base has suddenly become complicated and expensive.
Apollo went for large flat areas because hitting a predesignated specific landing spot was near impossible...
Quote from: Andrew_W on 03/12/2014 08:43 pmApollo went for large flat areas because hitting a predesignated specific landing spot was near impossible...False. Apollo 15 was one hairy ride between a mountain and canyon that produced excellent science. Apollo 17 went into a hilly region with serpentine valleys. Suggesting large flat spaces are required is completely incorrect.
Quote from: TrevorMonty on 03/12/2014 05:26 pmPros. A solar satellite beaming power maybe able to deliver enough power on each pass to keep a hibernating base alive for lunar night.Cons. Solar satellites don't exist so it would have to be developed. Between satellite and ground station this base has suddenly become complicated and expensive.The essential tech for a solar power sat has all been demonstrated so I doubt it is too much of a problem and it is arguably simpler to leave the power production system in orbit as opposed to locating it on the Lunar surface since you don't have to land it. The surface part of the base is actually simpler than one that must generate its power on the surface. A series of solar power sats could provide continuous power and open up the entire Moon for exploitation while providing BPP, GPS(LPS?), and communication as well as power. Any base involved in ISRU will likely produce oxygen as a byproduct and a craft using beam powered propulsion could use this waste product for propellant which I think is kind of elegant. The issue it seems to me is whether the intent is to have a base or prepare for large scale activity all over the Moon.
Amateurs.....
Quote from: Warren Platts on 03/13/2014 01:57 amAmateurs.....We have better maps now. And certainly would have the advantage of better computers & software.Still, the Apollo 12 landing near the Surveyor was pretty impressive.
Quote from: rusty on 03/12/2014 11:04 pmQuote from: Andrew_W on 03/12/2014 08:43 pmApollo went for large flat areas because hitting a predesignated specific landing spot was near impossible...False. Apollo 15 was one hairy ride between a mountain and canyon that produced excellent science. Apollo 17 went into a hilly region with serpentine valleys. Suggesting large flat spaces are required is completely incorrect.Both Apollo 15 and 17 had target landing sites in places with tens of square kilometers of flattish ground.
Locate a base where there are good deposits of thorium. Plan on using it to fuel a LFTR.
Quote from: clongton on 03/16/2014 01:06 pmLocate a base where there are good deposits of thorium. Plan on using it to fuel a LFTR.I don't think you'd find any place like that on the Moon. Much easier to bring thorium from Earth. Of all the things you'd make from in-situ material, I would imagine fissionables to be at the very bottom, since fissionables are so incredibly value-dense.
Quote from: Robotbeat on 03/17/2014 05:45 amQuote from: clongton on 03/16/2014 01:06 pmLocate a base where there are good deposits of thorium. Plan on using it to fuel a LFTR.I don't think you'd find any place like that on the Moon. Much easier to bring thorium from Earth. Of all the things you'd make from in-situ material, I would imagine fissionables to be at the very bottom, since fissionables are so incredibly value-dense.See attached
Quote from: clongton on 03/16/2014 01:06 pmLocate a base where there are good deposits of thorium. Plan on using it to fuel a LFTR.I hope you're joking as it's a bit like saying, "Find Helium3 to build a fusion reactor."
Agreed in the sense it's a bit too early to utilize either thorium or helium3 ...
Thought this would interest some:http://blogs.telegraph.co.uk/finance/ambroseevans-pritchard/100026863/china-going-for-broke-on-thorium-nuclear-power-and-good-luck-to-them/We developed it and made it work efficiently in the 60's.Then Nixon killed it because you couldn't make bombs from the waste.He wasn't interested in electrical power - just weapons.But the Chinese want it for electrical power, and they're going to get it, because a LFTR just isn't that hard.These can be made small and modular.Yes, they can be on the moon and would be safer than the reactors we run today.And no I didn't assume a full blown mining operation already there.I was thinking that it would be a good idea to build a base there because EVENTUALLY mining could be done there. The whole moon could eventually be powered by Thorium, fueled from this one place - economically.
The Chinese want it for electrical power, and they're going to get it, because a LFTR just isn't that hard.These can be made small and modular. ...The whole moon could eventually be powered by Thorium, fueled from this one place - economically.
Zoomable map of the lunar north pole recently released - since many believe the poles a prime location worth posting here: http://lroc.sese.asu.edu/gigapan/
'Shrapnel' Risk to Future Moon Surface Missions http://www.astrowatch.net/2014/03/shrapnel-risk-to-future-moon-surface.htmlGive us this day our daily FUD.
To your point, Redliox; It's by no means "too early to utilize Thorium." In the most literal sense, Thorium power is "shovel ready" and can immediately begin replacing all coal and nuclear powerplants as quickly as it can be mined and the plants built.
Deeper you can bury the base the better. There was an article on one of the moon threads about creating an underground base using robotic mining equipment.
Quote from: rusty on 03/19/2014 10:31 amTo your point, Redliox; It's by no means "too early to utilize Thorium." In the most literal sense, Thorium power is "shovel ready" and can immediately begin replacing all coal and nuclear powerplants as quickly as it can be mined and the plants built.Here's some very good commentary on the current state of thorium power technology.http://energyfromthorium.com/2014/03/21/the-molten-salt-reactor-race-will-america-join-the-race/China looks to be the new front runner, with a hope of being "shovel ready" in 10 years.
China looks to be the new front runner, with a hope of being "shovel ready" in 10 years.
If you'd like more info [...] try;http://www.world-nuclear.org/info/Current-and-Future-Generation/Thorium/
The China Academy of Sciences in January 2011 launched an R&D program on LFTR, known there as the thorium-breeding molten-salt reactor (Th-MSR or TMSR), and claimed to have the world's largest national effort on it, hoping to obtain full intellectual property rights on the technology. The TMSR Research Centre has a 5 MWe MSR prototype under construction at Shanghai Institute of Applied Physics (SINAP, under the Academy) with 2015 target for operation.
Speaking of blogs, the blog post to which I linked above is listed at http://energyfromthorium.com/kirk-sorensens-corner/. Many here on the nasaspaceflight forums hold Kirk Sorensen in high esteem. He was an early contributor to many discussions here. Since kfsorensen endorses Jon Morrow's Mar 21, 2014 post and its reporting of the thorium situation in China, I'm going to believe it is basically correct. That said, I expect it will be a long, long time before thorium mined on the Moon is used as fuel in any sort of reactor!
Space Based Solar Power (SBSP) would be best IMO. A game-changing Moon base will need several tens of megawatts. Now we could put in a nuke plant--if we could figure out a way to cool the thing. Not trivial. It's old fashioned, dinosaur tech if you ask me! Or we could use solar. Now of course a peak of permanent light would get pretty much 24-7 light. But, it would be awful to try and set up km2 sets of solar panels that would wind up shading each other. You know, the mass to keep them stood up and moving around 360 degrees per month. Terrible.So why waste the rocket propellant to land them on the Moon in the first place when they could be set up in orbit at an L-point and the energy beamed to the Moon?This would be a great trial run for eventual SBSP on Earth. That would be a lot better than nukes IMHO....YMMV
... Now we could put in a nuke plant--if we could figure out a way to cool the thing. Not trivial. ...
IIRC, a megawatt power-rectifier antenna would be about a 1km diameter wire grid. Add the suspension poles in (capable of withstanding Lunar gravity instead of Earth) and it sounds like a metric tonn of wire and a couple of tonns max for the poles and conditioning equipment.Randy
Quote from: Warren Platts on 03/26/2014 01:52 am... Now we could put in a nuke plant--if we could figure out a way to cool the thing. Not trivial. ...Assuming we'll have some type of robotic bulldozer on the Moon for clearing LZs or roads, mining, etc. burying habs seems a foregone conclusion for protection and insulation. Even if we don't and even if we don't have bulldozers to work with - burying radiators isn't difficult and should be used for habs and power systems.
Quote from: Andrew_W on 03/28/2014 06:51 pm... soil is a great insulatorNot as good as a vacuum
... soil is a great insulator
Quote from: RanulfC on 03/27/2014 07:22 pmIIRC, a megawatt power-rectifier antenna would be about a 1km diameter wire grid. Add the suspension poles in (capable of withstanding Lunar gravity instead of Earth) and it sounds like a metric tonn of wire and a couple of tonns max for the poles and conditioning equipment.RandyOn the Moon, since it's in a vacuum, we wouldn't have to have huge microwave rectennas. The power could be beamed directly with lasers, so the footprint of the receiver would be A LOT smaller.
1) Wrong. As the temperature of your radiator increases it radiates more effectively in a vacuum, http://www.endmemo.com/physics/radenergy.php Bury it, and you'll melt your radiator.
2) Earth soil has water in it, which helps its heat conduction. Lunar regolith will be bone dry.
Maybe I should do some of the math for you, if your radiator is at 480K, and if at 1m away the regolith is at 180K you have a temperature gradient of 300K/m, so for each square meter of radiator you'll radiate 300W* in regolith (assuming a generous conductivity of 1W/m/K), compare that to the 3009W* from radiating to a vacuum with the radiators at 480K. As the temperature of the regolith in the vicinity of the radiator increases the heat loss from the radiators will decline until eventually, if you keep pumping heat into them, they'll melt, soon after that your nuclear reactor will also melt.* On each side of the radiator
Heat retention of regolith soil is important part of base design/location as it needs to be buried for radiation protection. What would be useful is knowing temperature fluctuations of something buried at various depths over lunar day cycle. If a depth can be found where the temperature doesn't fall below -20C then most equipment should be able to hibernate without external heating being required.
Thanks Andrew for link.I've just found some results from Apollo 15 tests of regolith temperature at various depth. At 80cm temperature is stable at 250k (-23C). With an underground base robotic equipment shouldn't require any heating to survive lunar night.
Come night time Rover drivers into shelter and closes entrance off.
Here's a chart showing thermal conductivity through various materials, I'd expect regolith to have conductivity of less than 1W/m/K http://en.wikipedia.org/wiki/List_of_thermal_conductivities
Quote from: TrevorMonty on 04/02/2014 08:13 pmCome night time Rover drivers into shelter and closes entrance off.In case you haven't seen it:Heather Jones, John P. Thornton, Ramaswamy Balasubramaniam, Suleyman A. Gokoglu, Kurt R. Sacksteder, and William (Red) L. Whittaker, "Enabling Long-Duration Lunar Equatorial Operations With Thermal Wadi Infrastructure," 49th AIAA Aerospace Sciences Meeting, January, 2011http://www.ri.cmu.edu/publication_view.html?pub_id=6946
The spiderfab maybe one solution to building a lunar base. http://www.tethers.com/SpiderFab.htmlThis could build a Dome or tunnel house structure from Trusses then cover with a material and finally with 2-3m of regolith.
While researching Polaris I discovered it can survive a lunar night on surface. There was no information on how it does this, but we can eliminate radioactive isotope heating.
IMO it would not be a great problem for a larger and nuclear powered rover to run night and day. [...]but the most interesting areas are in those [polar] craters, so back to nuclear again
If you are postulating two bases you are probably thinking further ahead than the astrobotic rovers.
Also IMO (for HSF precursors) the poles are more interesting than other areas hands down, and there are probably large areas there where you can get significantly larger ratios of daytime to night time.
in the best of circumstances you would have more money.
QuoteAlso IMO (for HSF precursors) the poles are more interesting than other areas hands down, and there are probably large areas there where you can get significantly larger ratios of daytime to night time.Hmm. What's "significantly larger?" On Earth polar regions have asymmetric illumination because the rotational axis is considerably non-perpendicular to the plane of the Earth's orbit around the sun. But that's not so true for the Moon. Do you have values handy for the ratio of day and night at lunar poles?
Quote from: sdsds on 04/10/2014 06:27 pmQuoteAlso IMO (for HSF precursors) the poles are more interesting than other areas hands down, and there are probably large areas there where you can get significantly larger ratios of daytime to night time.Hmm. What's "significantly larger?" On Earth polar regions have asymmetric illumination because the rotational axis is considerably non-perpendicular to the plane of the Earth's orbit around the sun. But that's not so true for the Moon. Do you have values handy for the ratio of day and night at lunar poles?According to Spudis there are a few areas that are illuminated a little more than 80% of the time.These place are thought to be -50şC ± 10ş.However the sunlight grazing angle is very small. The solar arrays would need to be nearly vertical. Vertical arrays are a problem. With the long shadows of the location, it's hard to position the arrays so they don't cast shadows on their neighbors.
Quote from: sdsds on 04/10/2014 06:27 pmQuote[polar] areas there where you can get significantly larger ratios of daytime to night time.What's "significantly larger?" [...] Do you have values handy for the ratio of day and night at lunar poles?According to Spudis there are a few areas that are illuminated a little more than 80% of the time.
Quote[polar] areas there where you can get significantly larger ratios of daytime to night time.What's "significantly larger?" [...] Do you have values handy for the ratio of day and night at lunar poles?
[polar] areas there where you can get significantly larger ratios of daytime to night time.
These place are thought to be -50şC ± 10ş.
However the sunlight grazing angle is very small. The solar arrays would need to be nearly vertical. Vertical arrays are a problem. With the long shadows of the location, it's hard to position the arrays so they don't cast shadows on their neighbors.
QuoteThese place are thought to be -50şC ± 10ş.Is the implication that the thermal cycling in these locations is relatively benign?
QuoteHowever the sunlight grazing angle is very small. The solar arrays would need to be nearly vertical. Vertical arrays are a problem. With the long shadows of the location, it's hard to position the arrays so they don't cast shadows on their neighbors.You're thinking of an array farm, as for a substantial base, not just a single vertical mast like for a rover?
According to Spudis there are a few areas that are illuminated a little more than 80% of the time.These place are thought to be -50şC ± 10ş.However the sunlight grazing angle is very small. The solar arrays would need to be nearly vertical. Vertical arrays are a problem. With the long shadows of the location, it's hard to position the arrays so they don't cast shadows on their neighbors.
Quote from: Hop_David on 04/11/2014 02:59 amAccording to Spudis there are a few areas that are illuminated a little more than 80% of the time.These place are thought to be -50şC ± 10ş.However the sunlight grazing angle is very small. The solar arrays would need to be nearly vertical. Vertical arrays are a problem. With the long shadows of the location, it's hard to position the arrays so they don't cast shadows on their neighbors.This is one reason I see mountainous areas, including the heavily-cratered poles, as a disadvantage logistically. Plenty of sunlight but sharp angles on sharp terrain. With 1/6 gravity something like a 100-foot mast tower might be feasible, but in turn there's two problems 1) It might be assembled in 1/6-G, but it will still be launched from Earth at a full 1 G. Depending on how hefty the support structure is, this might be less cost-effective than a bank of flat solar panels on the ground.2) Using astronauts to assemble a 100-foot tower would be cumbersome at best even with new suit technology, and telerobotics with human hands might prove time-consuming. I wouldn't recommend tower construction on the Moon during the first 10 years; possibly after metal production is enabled but not initially because of risking either an astronaut falling off, the tower falling on an astronaut, and because there are simpler solutions requiring less labor.Again guys, talk about the terrain or region that might work best, not simply "Oh this solar mirror in orbit would blah blah". This is about using the environment, the landing site, the Moon and identifying the pros and cons of settling here, there, and elsewhere on the Lunar surface (not low orbit, not LaGrange points). The Moon has a surface area equating to the New World smushed into a rock - we haven't even explored the area of Connecticut up there!
Quote from: Hop_David on 04/11/2014 02:59 amAccording to Spudis there are a few areas that are illuminated a little more than 80% of the time.These place are thought to be -50şC ± 10ş.However the sunlight grazing angle is very small. The solar arrays would need to be nearly vertical. Vertical arrays are a problem. With the long shadows of the location, it's hard to position the arrays so they don't cast shadows on their neighbors.Again guys, talk about the terrain or region that might work best, not simply "Oh this solar mirror in orbit would blah blah".
Again guys, talk about the terrain or region that might work best
Quote from: redliox on 04/11/2014 08:24 pmAgain guys, talk about the terrain or region that might work bestOr about the approach to take in finding the best terrain/region. I was impressed by the method Vanoutryve et al. used. See e.g."An Analysis of Illumination and Communication Conditions near the Lunar South Pole based on Kaguya data"http://solarsystem.nasa.gov/docs/pr404.pdf
If you are having problems with shadows can we find an arrangement in which no more than half the solar panels are shaded at any time? We just need twice as many poles.
Quote from: A_M_Swallow on 04/12/2014 08:01 amIf you are having problems with shadows can we find an arrangement in which no more than half the solar panels are shaded at any time? We just need twice as many poles.A cylindrical surface would be constantly illuminated, no matter if the sun was in the south, east, north or west. But then the watts per square meter of array would fall by a factor of pi.Also when a given part of the surface swings between full sunlight and complete shadow, you once again have to deal with destructive temperature swings.But a cylinder would be more stable than a rotating mast.And I suppose the panels on the sunside could send heating electricity to the shadow side of a cylinder. Since they're insulated by perfect vacuum. the heating expense may not be high.
or any of a zillion components that might slowly or suddenly fail due to extreme temperature changes.
Talking about solar panel design and installation does no good until the fundamental question is answered: "how much continuous electrical power will be required to power the base"? Only then will anyone have any idea how large the array must be.One needs to know how large the array is before one can design its installation.
Quote from: KelvinZero on 04/13/2014 01:09 amor any of a zillion components that might slowly or suddenly fail due to extreme temperature changes.There are no real extreme temperature changes at the poles to speak of. The sun is at a pretty consistent angle of ~1.5 degrees for the entire lunar month, just constantly changing direction. The subsurface temperature, whether in sunlight or shadow, remains around -110 degrees C, more or less. Inside the permanently shadowed craters is a different story but on the average surface temperatures are fairly constant at the poles.
Quote from: clongton on 04/13/2014 01:25 amQuote from: KelvinZero on 04/13/2014 01:09 amor any of a zillion components that might slowly or suddenly fail due to extreme temperature changes.There are no real extreme temperature changes at the poles to speak of. The sun is at a pretty consistent angle of ~1.5 degrees for the entire lunar month, just constantly changing direction. The subsurface temperature, whether in sunlight or shadow, remains around -110 degrees C, more or less. Inside the permanently shadowed craters is a different story but on the average surface temperatures are fairly constant at the poles.Im pretty sure you would get extreme temperature changes, though the situation is better than at the equator. If there are permanently shadowed areas then I expect there are many more areas that are shadowed only half the month. I don't see why these should be much warmer than lunar night at the equator.
One of the reasons I was impressed by the Vanoutryve paper linked in a prior post was how they made "operationally actionable" thermal assumptions. In particular they assumed the thermal control system and batteries would support loitering through periods of darkness lasting up to 55 hours without sustaining damage.I Am Not A Thermal Engineer, but I have faith in modern thermal engineering design practices. As regards the "illuminated on one side; shadowed on the other" problem, I assume thermal engineers can design, build (and test) equipment that will meet reasonable requirements. Some amount of internal heat transfer is going to occur from the lit side to the dark side; clever design can maximize the usefulness of that. I'm not saying that design work will be easy or cheap; just that it will be valuable!
These lava caves look like a great place a base, there are hundreds to choose from. At up to 900m across it would be possible to land a Bigelow module in one then drive it inside.Some of the XPrize Landers in development could land in one and explorer it with a small rover.http://www.parabolicarc.com/2014/07/21/lunar-pits-shelter-future-explorers-settlers/