Our first lunar mining machines

[Rhyshaelkan]

Well we have to start somewhere. The general consensus is to start with fuel production. If we can eliminate the need for fuel to be brought from Earth for the trip from LEO to lunar landing, we can make use of that much more mass for each rocket launch. In addition, with the fuel, OTV/Lander, or OTV and Lander we could always loan out the system to other organizations. Which will generate funds for our ongoing project(s).

Two possible fuels.

1. Crack lunar ice into hydrogen and oxygen for standard LH2 LO2 rocket engines.

2. Per the website/paper here (http://www.wickmanspacecraft.com/moon1.html), we could make an Al/LO2 mono-propellant.

For the first option. We will need to know in what form the the hydrogen detected by the LRO mission is. Ice? Frozen ammonia? Once we know that we can understand what machinery to send up to claim this resource. As side publicity, depending on our timing, we could possibly earn an X-Prize for our findings.

Second option is to forgo the hydrogen for now(and it is a short 'for now'). Concentrate on what we know. Due to the powdery texture of lunar regolith we could possibly use a similar design to a wheat/corn harvester (http://www.patrawlings.com/detail.cfm?id=964). As the machine rolls on it scoops up the top-most layer of regolith. Passing the loose powder over magnetic drums(beneficiation), we can sort the material into its major compounds.

The sorted compounds are either passed to a furnace(a second bot/equipment), for the compounds and elements we want, or piled for later use.

Using the hydrogen reduction process we can draw off the oxygen that makes up 44% of lunar regolith. The compounds are heated in an hydrogen rich atmosphere. The oxygen bonds with the hydrogen forming water. The water is cracked, hydrogen returned to the furnace for reuse. The oxygen is then pressurized, cooled, and liquefied then stored in containers (http://www.patrawlings.com/detail.cfm?id=1037).

The anoxic material is then smelted. The aluminum is drawn off and pressurized through an atomizer. The tiny droplets cool and become the powdered aluminum portion of the mono-propellant. Mixed with the LO2 and stored.

So we need machines that can tackle this first part of our lunar plan.

All comments and further ideas are welcome.

I am going to attempt to use Google Sketch Up (http://sketchup.google.com/product/gsu.html) to make models of our OTV/Lander and bots.

[Rhyshaelkan]

Here is a link to a nice article comprising many of the tasks that we are aiming at for our first launch or two.

http://www.spaceref.com/news/viewnews.html?id=1290

An excellent study in .pdf form that Joe pointed out to me. Regarding many of the factors involved with what we would like to do.

http://www.niac.usra.edu/files/studies/final_report/341Rice.pdf

Another article dealing with the options of lunar landers. Pointed out to me by Joe.

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?db_key=AST&bibcode=1992lbsa.conf..119S&letter=0&classic=YES&defaultprint=YES&whole_paper=YES&page=119&epage=119&send=Send+PDF&filetype=.pdf

[Rhyshaelkan]

While knowing little about chemistry. The wiki for water electrolysis states that pure water is a poor conductor. However if an electrolyte was used, the process would consume less power and react faster. Things to keep in mind when designing a lunar or asteroidal hydrox fuel plant. Time is the stuff life is made of. So anything that would quicken the process would be helpful.

An example:

If we had an OTV used to transport 30mT(rough cargo of a F9H) of goods from LEO to Luna. We should plan for fuel production that would meet our shipping demands.

Whether we are supplying a service of transporting cargo from LEO to another orbit for others, selling fuel to others, or moving our own supplies. More fuel that can be produced means more revenue. All bots break down in time. However, selling of fuel, or transit would have no direct cost other than the mission control people. The bots will happily crank out fuel till they break down. With a descent enough design, that could be several months to years of work, thus being quite profitable.

I have not ran the numbers for X fuel will deliver Y fuel to LEO with Z fuel necessary to return to Luna for refill. Or D fuel will allow our OTV to move E cargo to F orbit with Z fuel necessary to return to Luna for refill. So do not ask for the numbers =)

Edit:
The making of hydrox fuel is a two step process; first harvesting the ice and storing it as water, then cracking the water into hydrogen and oxygen. As cryogenic fuels slowly boil off with time. The speed that we can crack, liquefy, and use the fuel will be another factor to consider.

Once we know the relative temp of those shadowed craters. We could use them for LH2 and LOx2 storage, producing all the time, with little boil-off due to the extreme cold of the craters.

I might have posted it elsewhere. However there was a nice study by NASA on the storing of Cryogenic fuels in space. http://www.dunnspace.com/cryogen_space_storage.htm

[stevend]

Here's a blog post and video from Astrobotic about their plans to use a bucket-wheel for their lunar excavator:
http://astrobotic.net/2011/08/30/lunar-excavator-development/

Their main reason with going for a bucket-wheel seems to be that as the container being filled up fills up it doesn't require accumulative forward force.

Since the trench their bucket-wheel will make is in the middle of the path they're driving, they'll have to make sure they don't dig so deep that when they turn they won't be able to drive into and out of the trench.

Also, if they want to do open pit mining that means they'll have to dig trenches adjacent to each other so when digging a trench next to a previous one, the wheels on one side of the excavator will be in the previous trench and the other at a higher height. I think there's going to have to be some flexibility in the position of the bucket-wheel and maybe the container being filled with respect to the excavator body proper.
-Steve

[Rhyshaelkan]

Very interesting though as you could almost "mill" the regolith to be a flat area with that bucket. Removing even small amounts of regolith at a time. By sweeping the bucket head from side to side, you could slowly level an area. Precursor to paving with microwave sintering perhaps.

[joertexas]

I have not ran the numbers for X fuel will deliver Y fuel to LEO with Z fuel necessary to return to Luna for refill. Or D fuel will allow our OTV to move E cargo to F orbit with Z fuel necessary to return to Luna for refill. So do not ask for the numbers =)

I have - it's included in my OTV spreadsheet :D

JR