Developing the cis-Lunar economy and infrastructure

Terraformer · 2012-01-13 03:09:41

How far from the poles do we have to go to get to a point where we can use a direct link to GEO?

Grypd · 2012-01-13 04:52:45

You are forgetting that one of the advantages of the Moon is that it is tidal locked it always shows the same face to Earth and a transmitter placed on top of the right hill will face in the direction of Earth. There is no need for a satelite communication system at first. Well not in the Moons orbit anyway there is nothing to stop these communication dishes aiming for satelites in the Earths orbit.

This is further helped that any reasonable attempt to develop the Moon will use the Lagrange points 1 and 2 as a minimum depots and this helps communication.

It will only be when we are wanting to send exploration missions across the Moon that we will need out of site communication and it is perfectly possible that cheap mass produced communication satelites can be used to support these missions.

Glandu · 2012-01-13 05:11:55

Adaptation wrote:

I wonder how hard it would be to drape a light fiber optic cable across the surface of the moon as your land or take off. The from the deepest dark side base it would still take less than 2000 miles of fiber to reach the near side and setup a direct surface station.

mmmh, that would be an heavy baby to launch, transport, & deploy. Here on earth, it's already a tough job; you need a vehicle(truck or ship), skilled specialists, & probably a few other things. On the moon, the lack of proper mastery of the field would add, IMHO, a lot of headaches. A few sats would, I think, be muuuuuch easier.

louis · 2012-01-13 07:48:56

Glandu wrote:

Adaptation wrote:
I wonder how hard it would be to drape a light fiber optic cable across the surface of the moon as your land or take off. The from the deepest dark side base it would still take less than 2000 miles of fiber to reach the near side and setup a direct surface station.
mmmh, that would be an heavy baby to launch, transport, & deploy. Here on earth, it's already a tough job; you need a vehicle(truck or ship), skilled specialists, & probably a few other things. On the moon, the lack of proper mastery of the field would add, IMHO, a lot of headaches. A few sats would, I think, be muuuuuch easier.

What's wrong with relay stations? With no weather on the Moon couldn't you have light nylon telegraph poles with mini transmitters on them, transmitting data from one to another in a chain, with maybe a station every 10 miles (I am guessing on line of sight here). So if the distance is 1500 miles, that's 150 lightweight poles and transmitters.

Last edited by louis (2012-01-13 07:49:23)

Terraformer · 2012-01-13 10:07:00

Hmmm. 150 poles and transmitters... which given that you need power to them as well... you're looking at at least 200kg for each, probably much more. 30 tonnes to the Lunar surface, compared to 15 tonnes to Lunar orbit. It's easy to see which one is going to be best...

Mark Friedenbach · 2012-01-13 10:36:36

Terraformer wrote:

How far from the poles do we have to go to get to a point where we can use a direct link to GEO?

There are numerous peaks/ridges on the poles which offer near continuous line of sight to earth, sunlight, and in sime cases both. Ben Bussey's team has been studying this for a few years now.

louis · 2012-01-13 17:50:19

Terraformer wrote:

Hmmm. 150 poles and transmitters... which given that you need power to them as well... you're looking at at least 200kg for each, probably much more. 30 tonnes to the Lunar surface, compared to 15 tonnes to Lunar orbit. It's easy to see which one is going to be best...

No way do they need to be 200 kg each. I bet that's way out. The pole would probably be a few kgs max. - say 15kgs at the outside. How big a unit do you need to transmit 10 miles? I bet you can do that in under 10 kgs. Then you are down to solar panels, batteries and cabling... 30kgs max??? Total 55 kgs max. So your 30 tonnes is probably closer to 7.5 tonnes. And that is at the outside I would judge, since tiny lightwieght mobile phones send messages over several miles at least. It's probably no more than 1.5 tonnes in reality.

Adaptation · 2012-01-13 23:31:48

Louis your tiny light weight phones only work because there are cryogenically cooled receivers with big antennas and cpus doing signal processing on the other end. But I do agree with you in principle. Here is a break down of what I think it may take.

On the moon especially the dark side there is very little interference or need for you to restrict the bandwidth (RF) you use. On earth a consumer grade 0.4kg radio uses 15 watts and delivers 24mbps. If you broaden the band and use more expensive energy efficient technology you can probably get a few hundred mbps with about the same energy demand but lets say the heat resistant design takes two kg.

Lets assume the solar panels face straight up and there is no active tracking so we need to wait for the sun to poke up a bit more before we generate power so 17 days of dark and 12 of lite. Modest Li-ion batteries get about 150 Wh/kg with a decent reserve we end up at about 4kg. One kg for solar panels should be plenty.

A 0.5" x 35ft extruded carbon fiber rod would be another 2kg, with the lower gravity and no weather it should suffice. I think 10kg or less for each repeater site is entirely feasible.

I can think of two methods for instalation, you drive a rover across the surface or you hop along on a sub orbital rocket hopper. But none of this matters at all, the cost of installation will inevitably tip the scale to other methods of communication. Why not just unspool some fiber along the way with the rover or suborbital rocket and get a 300 gbps connection instead.

JonClarke · 2012-01-14 00:40:21

Hop wrote:

No, we don't.
I don't agree 9% = virtually no impacts.

Depends on your perspective. If you are flying airliners 9% failure is an appallingly large number. If you are testing geophysical models 9% is an unbelievably small number.

Hop · 2012-01-14 12:47:38

JonClarke wrote:

Hop wrote:
No, we don't.
I don't agree 9% = virtually no impacts.
Depends on your perspective. If you are flying airliners 9% failure is an appallingly large number.

If you are a retailer who benefits from holiday shopping, December isn't an inconsequential month. And December is only 1/12 (8.33%) of the year.

If only 1/12 of the metallic asteroids remain intact, there could be substantial ore bodies on the moon.

JonClarke wrote:

If you are testing geophysical models 9% is an unbelievably small number.

The small number of Apollo samples is a lot less than 9%. Yet from these vanishingly minute data points you seem convinced there are no lunar ore bodies.

Last edited by Hop (2012-01-14 12:49:26)

louis · 2012-01-14 14:31:20

Adaptation wrote:

Louis your tiny light weight phones only work because there are cryogenically cooled receivers with big antennas and cpus doing signal processing on the other end. But I do agree with you in principle. Here is a break down of what I think it may take.
On the moon especially the dark side there is very little interference or need for you to restrict the bandwidth (RF) you use. On earth a consumer grade 0.4kg radio uses 15 watts and delivers 24mbps. If you broaden the band and use more expensive energy efficient technology you can probably get a few hundred mbps with about the same energy demand but lets say the heat resistant design takes two kg.
Lets assume the solar panels face straight up and there is no active tracking so we need to wait for the sun to poke up a bit more before we generate power so 17 days of dark and 12 of lite. Modest Li-ion batteries get about 150 Wh/kg with a decent reserve we end up at about 4kg. One kg for solar panels should be plenty.
A 0.5" x 35ft extruded carbon fiber rod would be another 2kg, with the lower gravity and no weather it should suffice. I think 10kg or less for each repeater site is entirely feasible.
I can think of two methods for instalation, you drive a rover across the surface or you hop along on a sub orbital rocket hopper. But none of this matters at all, the cost of installation will inevitably tip the scale to other methods of communication. Why not just unspool some fiber along the way with the rover or suborbital rocket and get a 300 gbps connection instead.

Thanks for those informed calculations Adaptation - seems like my 1.5 tonnes guesstimate ended up being pretty close to your expert input.

I've been caught out with cable connections before...when you add up the mass of the cable and the spool, you are often (unpleasantly) surprised, but perhaps it would be worth it in this case.

Rune · 2012-01-15 09:44:30

Carbon fiber rods work at +100ºC? Really? Because that is news to me. In that case, they should have no problem with the -150ºC of nighttime. No "other side of the satellite" to sink the heat to (or the lack of it) in the moon's surface. You could "heatsink" your way a few meters underground, where it's cool all the time, of course, but that's more equipment and a good thermal conductivity on your rods, at least better than the ground's.

Same for the electronics, the moon is a harsh mistress. Haha, today I am on fire.

Anyhow, I don't doubt repeaters would be light. Who knows, they may even cover more than the single crater if you position them correctly (no atmosphere to attenuate signals, just distance and LOS). But taking them to the moon? Definitely more expensive than leaving the repeaters, solar panels and batteries on orbit, and they don't have to deal with the lunar environment dust, etc... Just the deep space one ^^'.

Rune. Someone has to try and plug holes in your plans, right? Otherwise they won't end up as good.

louis · 2012-01-15 10:47:25

Rune, I don't think anyone would deny that the Moon (and Mars) are a harsh mistress, but as far as I know, no-one has suggested that those Apollo flag poles are anything other than as upright as they were 40 plus years ago. What were they made out of? Unobtainium?

Obviously a cost benefit analysis has to be undertaken of what is the best coms system, but I was just arguing against those who said there was only one solution in effect. A ground system will be a lot easier to maintain for one thing.

Adaptation · 2012-01-15 13:29:41

Carbon fiber certainly can be used in harsh temperature environments the carbon itself can be used to 4000k. A pure carbon rod is kinda brittle so you use a carbon fiber composite and there are resins that will work much higher than 100°c

And I was actually arguing against a line of repeaters because of the installation cost.

Also maintaining the relay is going to be a beast. Traveling long distances across the lunar surface to reestablish communications with earth is not a fun prospect. My vote is for satellite at first and fiber optic later on.

Last edited by Adaptation (2012-01-15 13:33:03)

Hop · 2012-01-15 19:30:55

Rune wrote:

Carbon fiber rods work at +100ºC? Really? Because that is news to me. In that case, they should have no problem with the -150ºC of nighttime.

The most interesting sites are those that have volatile rich cold traps neighboring plateaus that enjoy nearly constant illumination.

The temperature swings at these polar plateaus are much milder than the lower lunar latitudes: -50 degrees C plus or minus 10 degrees.

See New Light on the Lunar Poles

Hop · 2012-01-15 20:06:18

Grypd wrote:

You are forgetting that one of the advantages of the Moon is that it is tidal locked it always shows the same face to Earth and a transmitter placed on top of the right hill will face in the direction of Earth. There is no need for a satelite communication system at first. Well not in the Moons orbit anyway there is nothing to stop these communication dishes aiming for satelites in the Earths orbit.

Indeed. People tend to forget earth is a moon synchronous satellite. It's not completely stationary as viewed from the moon's surface, it traces an analemma, but close enough.

The most interesting locations are plateaus that enjoy nearly constant illumination neighboring a volatile rich cold trap. I believe there are two such locations we know about.

The plateaus of nearly constant illumination have several advantages:

1) Mild temperature swings: -50 degrees C plus or minus 10 degrees
2) Constant solar energy
3) (maybe) Constant line of sight with the earth.

I don't know the third advantage for a fact. But it seems to me a high altitude polar plateau would be a good place to erect a communications tower. It might enjoy line of sight with the earth as well as the neighboring crater basin.

JonClarke · 2012-01-16 01:33:56

Hop wrote:

If you are a retailer who benefits from holiday shopping, December isn't an inconsequential month. And December is only 1/12 (8.33%) of the year.

Correct. How significant that is depends on the context.

If only 1/12 of the metallic asteroids remain intact, there could be substantial ore bodies on the moon.

What make you think that 12% of metallic asteroids will remain intact?

Even if they did, what makes you think they will be ores?

The small number of Apollo samples is a lot less than 9%. Yet from these vanishingly minute data points you seem convinced there are no lunar ore bodies.

You are conflating things here.

1) We can use Apollo geochemical data to draw conclusions about crustal scale evolution because geochemistry allows you to do that. We can test the conclusions against remotely sensed data, which show that the conclusions are generally correct. This is first year geology.

2) I have never said there are no lunar mineral accumulations of potenial economic interest. I have mentioned aluminium and titanium and of course the polar ice. These we know about. There may be others.

3) None of these accumulations are strictly speaking ore because they cannot be profitably mined (at present). Ore is an economic term, not a scientific one.

Hop · 2012-01-16 10:44:15

JonClarke wrote:

If only 1/12 of the metallic asteroids remain intact, there could be substantial ore bodies on the moon.
What make you think that 12% of metallic asteroids will remain intact?

I do not know the upper limit for velocity for an asteroid to remain intact. Besides impact velocity, there are other factors: size and shape of asteroid, structural strength, impact angle, etc.

This was in response to your contention that 9% is virtually no impacts.

(oh, and by the way, you just morphed 1/12 into 12%).

JonClarke wrote:

Even if they did, what makes you think they will be ores?

Potential ores. If a lunar base whose revenues exceed operating costs is achieved, growth is inevitable. This would create economic pressure to use ISRU materials rather than supplying the base with earthly materials. Metallic asteroids have lots of nickel and iron as well PGMs.

JonClarke wrote:

2) I have never said there are no lunar mineral accumulations of potenial economic interest. I have mentioned aluminium and titanium and of course the polar ice. These we know about. There may be others.
3) None of these accumulations are strictly speaking ore because they cannot be profitably mined (at present). Ore is an economic term, not a scientific one.

In the near term I believe the ice has the greatest potential for becoming ore. Propellant high on the slopes of earth's gravity well would break the exponent in Tsiolkovsky's rocket equation. Given one export, other local resources would become attractive for a lunar base seeking to reduce costly imports from earth.

And, given reduced transportation expense, PGMs and other lunar resources might eventually be profitably sold to earth markets.

Hop · 2012-01-16 11:00:36

Hop wrote:

3) (maybe) Constant line of sight with the earth.
I don't know the third advantage for a fact. But it seems to me a high altitude polar plateau would be a good place to erect a communications tower. It might enjoy line of sight with the earth as well as the neighboring crater basin.

I just suggested this to someone knowledgeable in the field. His response wasn't encouraging:

"As for Earth LOS comm, that's difficult due to the 5.5 degree latitude
libration -- you need about several hundred meters of tower to clear the
limb for each degree of elevation/latitude off the pole, so a tower that
encompasses all librational conditions based exactly at the pole would be
well over 2 km high. Possible, but not in any early stage of lunar
development. The preferred solution for initial lunar presence is a
constellation of relay satellites."

So back to Molniya relay satellites or pehaps constellations in halos about L1 or L2.

Adaptation · 2012-01-16 21:02:07

A constellations would also allow you to get precise location information. On earth GPS is often off by tens of feet, that's great for navigation but not so good for controlling robots. It would be good to get LPS accurate to a few inches so you can automate as much as possible.

JonClarke · 2012-01-17 04:11:42

Hop wrote:

I do not know the upper limit for velocity for an asteroid to remain intact. Besides impact velocity, there are other factors: size and shape of asteroid, structural strength, impact angle, etc.

I think we can safely meteorite fagments of any size, for several reasons. None have been found in over 130 km of traverse, despite several examples being found in much shorter taverses on Mars (where aerobraking does occur). No meteorite fragments more than a few 10s of microns have been found in any lunar regolith material. Even on Earth, individual meteorites never mass more than 100 tonnes, despite aerobraking. Even small impacts

(oh, and by the way, you just morphed 1/12 into 12%).

Thanks for picking that up.

Hop wrote:

JonClarke wrote:
Even if they did, what makes you think they will be ores?
Potential ores. If a lunar base whose revenues exceed operating costs is achieved, growth is inevitable. This would create economic pressure to use ISRU materials rather than supplying the base with earthly materials. Metallic asteroids have lots of nickel and iron as well PGMs.

Nickel, iron and PGEs are readily available on Earth in large amounts for a fraction of the cost of finding them on the Moon.

Potential ores are not ores. If we are going to talk about the economics of lunar mining we need to use the terms correctly.

"The words ‘ore’ and ‘reserves’ must not be used in describing Mineral Resource estimates as the terms imply technical feasibility and economic viability and are only appropriate when all relevant Modifying Factors have been considered." (JORC http://www.jorc.org/pdf/jorc2004web_v2.pdf)

Since we know neither technical feasibilty or the economic vaibility of any lunar mining then they are not ores. Nor are they mostly even Resouces. JORC again:

"A ‘Mineral Resource’ is a concentration or occurrence of material of intrinsic economic interest in or on the Earth’s crust in such form, quality and quantity that there are reasonable prospects for eventual economic extraction. The location, quantity, grade, geological characteristics and continuity of a Mineral Resource are known, estimated or interpreted from specific geological evidence and knowledge."

For most commodities of interest we don't have the required knowledge of location, quantity, grade, geological characteristics and continuity to define a resource - with the possible exception of titanium and aluminium.

Even these commodities are available in vast quantities on Earth for a fraction of the cost they would be on the Moon.

In the near term I believe the ice has the greatest potential for becoming ore. Propellant high on the slopes of earth's gravity well would break the exponent in Tsiolkovsky's rocket equation. Given one export, other local resources would become attractive for a lunar base seeking to reduce costly imports from earth.

You might be right, eventually. But at present we do not have the knowledge to justfy anything more than experimental ISRU. A lot has to happen before we can even define an ice resource to support a station, let alone an ore reserve for an explort industry.

And, given reduced transportation expense, PGMs and other lunar resources might eventually be profitably sold to earth markets.

How much will transport costs have to fall for lunar PGEs to complete with PGEs (produced essentially free) from the mining of nickel ores or from places like the Bushveld?

Adaptation · 2012-01-17 21:34:01

Kinetic launch from the moon to a remote shallow lake in Canada would have a rather small marginal costs. It may even be cheaper than transporting it from one side of the earth to another.

JoshNH4H · 2012-01-18 21:08:09

Hop and JonClarke-

I think the primary point that we're looking at here is that the concentrations of metals allegedly "discovered" by the LCROSS spectrometer would be very highly anomalous compared to the complete lack of these metals discovered anywhere else on the planet; further, because LCROSS only investigated one single location, while the Apollo missions investigated many different ones, it would be extremely surprising if LCROSS discovered one location with very high concentrations of rare elements while none of the Apollo samples had any similar finds.

Hop · 2012-01-19 16:24:09

JoshNH4H wrote:

I think the primary point that we're looking at here is that the concentrations of metals allegedly "discovered" by the LCROSS

Josh, the alleged 1.6% gold in the LCROSS ejecta is only one of several branches this thread has split into.

Terraformer · 2012-01-19 16:39:43

Well, actually, what I was hoping to do was to work out what the minimum we'd need to set up Lunar fuel production to allow much greater masses to be transported to Luna, and from there, what we'd need to develop a thriving infrastructure...

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