Lunar In Situ Resource Utilization of Regolith with Considering Advancements in Rapid Prototyping Technologies (Part 2)

Last time on Obie's blog:  Space spaccee SPAACCEEE, I love space.
 let's make a moon base.
Why?
Helium 3 is awesome, super fusion magic fun time
Let's try something with more immediate use.

And now part 2 of Mining the Moon.

The characteristics of lunar regolith make it an engineering challenge to work with and a tremendous boon of natural resources.  The chemical make up of Lunar regolith makes it extremely useful with regards to the needs of expanding humanity's frontiers.  (I miss-labeled the link that properly breaks down the individual chemical elements and their actual percentages. until I find aforementioned link, I am going to put in the graph that I am grabbing from wikipedia(ok actually I am taking it from lunarpedia as the wikipedia entry is a png and blogger seems to only allow jpgs to be taken from URLs)

The moon comes with a healthy supply of oxygen, silicon, iron, aluminum and magnesium.  Future explorers and manufacturers will have an excellent set of building blocks to develop a range of useful components for lunar facilities and space, including radiation and particulate shielding, radio receivers  solar reflectors for concentrated PV arrays, structural supports for space stations, etc...
The range of potential applications from this recipe list is tremendous.

Lunar regolith is not with out its challenges whatever mining operation develops in future mining scenarios will need to be able to survive a source material that is both extremely abrasive and has a tendency to adhere itself to most surfaces that humans have sent to the Moon.  NASA, ESA, and Roscosmos (not really sure if the Russians have done research into regolith mining right now so I am giving them the benefit of the doubt) have invested tremendous resources into developing various techniques to extract different elements from Lunar soil.

++
Sorry about this kind of stopping suddenly, I got distracted by pre-Thanksgiving fatness and TV I will update over the next few days and make this more complete. (so I cheated everything after URLs has been changed a little bit or appended)

Lunar In Situ Resource Utilization of Regolith with Considering Advancements in Rapid Prototyping Technologies (Part 1)

Thank you to the Half-Life Wiki
( http://half-life.wikia.com/wiki/Aperture_Science_Personality_Construct ) 

Can I just open with I love space? I mean, not as much as the personality core in Portal 2 but you konw, I do think its really cool.  The whole metaphor of looking outward upon the frontiers of the human experience to discover what is within, amazing image.  Anyways I'm trying to look slightly more professional in this series of posts so I'm not sure what tone I should put forth in a blog post/pseudo white paper beginnings, well see what evolves. (it's not like I have an official editor to give me grief)

Two of the largest costs associated with space exploration lie in the limited re-usability of rocket launch systems and the direct energy requirements of transferring mass between the gravity wells of our solar system, safely.  Developing material resources on celestial bodies other than the Earth is one of requirements for reducing the capability bottleneck that hinders a greater human presence in space.  In late April of 2012 Planetary Resources made the bold announcement that a for-profit business would be developing the technologies necessary to mine the  asteroids that whip through our solar system.  Resources closer to home did not receive the same level of attention, at least in a serious light, when, then Presidential candidate, Newt Gingrich made his proposal for United States to build a long term Lunar Colony.  (I'm just going to say, I didn't really agree with the Gingrich campaign on much, except for the fact that I really think it would be awesome to have a Lunar base).

Establishing mining operations on the Moon have been the theme of speculative and science fiction for many decades now, with NASA providing a good number of financial and intellectual resources to developing preliminary technologies that might be used by such a facility.  In the 2009 Hugo Award winning film "Moon"  Sam Rockwell's character, Sam Bell (we've got some original names going on here people), spends his days overseeing a massive lunar mining operation, in the process of extracting large volumes of Helium 3 embedded in the regolith, an isotope believed to be the Holy Grail of nuclear fusion energy production.  (please don't take my name remark to indicate that I disliked Moon, it was a brilliant film).  While the implications of fusion technology are extremely appealing as a "one day this will happen" reason for establishing a base or colony on the Lunar surface, there are far more immediate benefits from establishing a mining and manufacturing footprint on the Dark Side of the Moon.

More to follow I just want to head out to the gym and get some dinner Nov 20

Make My Browser Better

Ok, so I haven't slept yet, and I still haven't posted my article on 4-dimensional radiators and their applications in various sci-fi series so I'm going to go quick and dirty for something I want for internet browsers.  A frustration I have while surfing the tubes, is that I will open 20+ different tabs, while listening to Pandora or some other audio source, and said additional tabs will start playing random soundbites from flash games or stupid commercials.  What would be a wonderful update to browsers, either as an extension or as a default feature, is to have a small icon displayed within a tab showing whether or not it is playing audio.  Ideally you could pin audio sources, much like you can pin apps in your browser already, you would be able to pin an audio source as your primary and reduce or eliminate sound coming from the other tabs.  All I can say is that it would be magical.

Making Satellites in SPACE!!

Building in space is an expensive task left to only the wealthiest and ... who cares? I want to make LEGOs for space.  A range of innovative individuals and groups are putting forth various ideas on how to reduce the cost developing the resource we know and love called space (terrible phrasing, what do you want, its not like I have an editor here)  Swarm satellites, zombie space probes, and 3-D printed applications.  Personally the approach that I would be interested to see in action (mostly because I think it is kind of a unique idea and I haven't spent 10 minutes on the Googles to shatter my belief that I'm original) is creating an open platform of space certified low primary components that can be assembled by robot in LEO (low Earth orbit) and then have their orbit adjusted according to mission requirements.

Figure 1) Traditional Satellite Launch

Unlike mass produced products like cars or cellphones, satellites are far less common with roughly 4000 listed payload launches and of that number roughly 1000 active platforms in Earth orbit these devices are of limited production runs.  Obviously aerospace manufacturers do not reinvent the wheel with every launch, much of the satellites basic functionality is well defined and roughly replicated throughout a technologies generation.
In Figure 1 you see a rather crude approximation of a launching an orbital system.  The fully assembled platform is launched from the Earth's surface.  Once in orbit the platform will unfold into its optimal configuration from the small volume footprint that was required for launch.  Another requirement of this approach is that the frame of the space craft must be built to survive the rigors of launch, adding to the launch mass.  Part of this additional structural support will remain with the spacecraft through out its operational life, increasing the quantity of maneuvering propellant required over the system's deployment.

Figure 2) Building in Space

What I would propose is that some the more commonly required components should be made into construction elements that can be added to the space craft in Earth Orbit. Step 0) Long before the mission critical elements of our system goes into orbit an established construction platform/system constellation is assembled in either Low or Mid Earth Orbit.  Step 1)  The assembled construction platform takes on supplies for its mission of satellite production.  Propellants (a) and electronic and mechanical components (b) are stored as part of the construction constellation.  To aid in the potential cost savings of this approach the aim of this methodology is to emulate cube satellite launches, parts piggy back into orbit on other missions.  The material stockpile can be built up in a piecemeal fashion in addition to the more traditional supply runs that are seen on the ISS.  Step 2)  An open platform components satellite is launched into an orbit that will allow it to dock with the construction constellation.  Step 3) After docking with the construction constellation, components are added to the satellite, for earlier generations of this technology the augmentations will most likely be limited to adding solar panels, providing additional propellant for maneuvering thrusters, and a radio/microwave dish.  As the capabilities of the construction platform improve and engineers learn how to best utilize this production paradigm the complexity what is built in orbit will incrase, eventually leading to a point where only base components are sent into orbit and all major assembly occurs in space.  In Figure 2) (d) is being used to indicate that a radio dish is being added to the base satellite (e).  Step 4) the fully assembled satellite has is moved into whatever its operational orbit might be.

Satellites will end their operational life for any number of reasons, colliding with orbiting space debris, becoming obsolete, the owners of the satellite lose control, exhaustion of maneuvering propellant supplies etc..  Under optimal conditions a satellite can be placed in either a decaying orbit, where it will burn up in the Earth's atmosphere, or moved into a graveyard orbit.  Additionally DARPA's proposed Pheonix program would attempt to breathe new life into systems once thought dead, by having a maintenance robot repair a selected satellite.  By designing satellites to  be compatible with an open standard for hardware and critical mounting elements, we open the door for a larger range of options for recycling mass in orbit.

Figure 3) 

In Figure 3) you can see a repair robot replacing a broken component with a rather happy working part that will allow the satellite to continue operation.  This approach effectively mirrors what is intended by the Pheonix Program but adds one major feature, a design meant to be reworked while in space.  Current proposals suggest that the system would require a wide number of tools to allow for reworking the satellite, standardized components for future satellites would drastically reduce what the repair robot would need to bring with itself.

Figure 4)  Returning to its spawning grounds the mature satellite
will now give its life for the next generation

For systems totally beyond their useful life span Figure 4) reverses the assembly process.  The old satellite is brought from its operational orbit, back to the construction constellation and broken down into its base components, where they can be used by future satellites.  The owners of the satellite can now resell components to others who may not have the same budget for space development.  In theory the Pheonix Program approach could also follow a similar business plan, but there would be greater capital costs for Pheonix (assuming the construction constellation exists, obviously)

As someone who does not have either the academic or industry experience to lean on in modeling the economics of satellite life cycles, I cannot claim there would be any actual costs savings, nor am I able to model what the ROI would look like over a given time span.  That being said, my gut says this could end up saving the space industry money. Other benefits from this approach could include, increased flexibility in mission planning, integrating more countries into developing space based technologies, and decreasing the quantity of space debris in Earth orbit.  

Follow Up (ok not really I just found out some final details near the end of writing and didn't know where to properly insert them):  While I still haven't exactly found the "LEGOs in space" approach, DARPA's System F6 initiative highlights a solution that is probably more reasonable, swarm satellites collaborating around a pseudo mother ship or as an emergent system. (the latest article on System F6 is here) That being said I think that my approach or other in orbit manufacturing systems will still serve as necessary component for expanding humanities capabilities in the heavens
Follow Up #2 (this time I actually hit publish before I added it)  While reading an article on space debris I learned that under the current approach to the Pheonix Program the repair robot must be manually operated, and deal with a rather long communication delay.  In theory a more standardized satellite design paradigm could help mitigate these issues.
Follow Up #3 (Jan 20 2013, I am so smart S, M, R, T ) so it turns out there is a full on lego approach to satellite design, although  the assembly appears to be more terrestrial at this juncture 

Survival Flashlight

No survival kit is complete without some kind of emergency lighting kit, usually a generic LED flashlight.  While that's fine and dandy for most real world applications I decided to put forth my own pseudo idealized flashlight (the ideal model would have infinite battery life and cook me breakfast).  The general design is fairly straight-forward, 6 LED's, preferably clean white, an on off switch, a settings dial to allow for lower or higher lighting intensities.

To avoid being doomed by dead batteries the flashlight would be wrapped in solar cells, as the surface area of a cylinder does not exactly lend itself to a large exposed surface area for gathering sunlight, the solar panels on the grip of the flashlight, would be able to unroll as a sheet to maximize solar gain.  Many camping kits now come with any number of devices for charging USB devices and consequently I thought it would be prudent to add a USB port to the design.  Said port would be protected by the solar panels, when not being used for charging.  As so wonderfully shown in the cutaway drawing of the design, you will see both Li-Ion batteries in the frame as well as ultracapacitors.  The purpose of the ultracapacitors is to help regulate the energy demands on the standard batteries.  During the recharge cycle the ultracapacitors will aid in leveling out the characteristics of energy coming in, either from the USB port or the solar cells.  The ability for rapid discharge also aids in the most distinctive trait of this concept, the "LASER".  Starting a fire in survival situations can be a mind wrecking experience, especially if you cannot find your lighter or supply of matches.  The high intensity laser is intended to integrate your ignition source with your illumination source.  Rated at ????? mili-Watts (I need to do the math on what the energy transfer requirements) this laser can be pointed at a collection of kindling and cause it to ignite in under 10 seconds.  The triangular shape of the front of the flashlight is meant to aid in the ignition process, users can place the flash light on the ground next to the fire pit and be confident it won't roll around or move from shaking hands, ensuring the laser's energy remains targeted on the proper section of kindling.  Depending on the characteristics of available laser technologies, it might be possible to have far lower intensity settings for more pleasurable uses, such as identifying constellations while stargazing.

How does the Death Star Deal with all of its Surplus Heat?

While I can't say why I'm on his bent of posting about thermally related posts something that has bounced around in my brain for a while, is how can the death star manage to not liquefy itself when it fires its super laser.
For background, according to some calculations done by individuals far more skilled than I have calculated that it takes roughly 10^32 Joules of energy to destroy an Earth sized planet, it is also estimated that all of this energy is expended in roughly one second, meaning the Death Star expends 10^32 watts.  According to Wookiepedia it takes roughly 24 hours to recharge this supremely powerful weapon.  The underlying question I have as an engineering geek is this, how efficient is the Death Star's heat management system to allow for it to operate while allowing for a living and breathing crew of over one million Storm Troopers, fighter pilots, bar tenders, bureaucrats, etc...
While I unfortunately don't have a data base of materials that are available to engineers in the Star Wars universe we can provide ourselves with some critical data necessary for calculations.
First we have a minimum power output of the Death Star's primary reactor system(s) I say minimum power output as it is not unreasonable to assume that the Death Star's other systems could be powered by these primary generator array (hard core Star Wars fanboys, please tell me about any incorrect assumptions that I might have made, long ago I erred from the true path and some details are still a bit too hazy)
This can be relatively simply calculated from the known recharge time, 24 hours, and the energy output calculated by Michael Wong of Stardestroyer.net, For personal ease I am only making the calculations necessary for the Death Star seen in Star Wars a New Hope, that being said the only a few variables would require changing to accommodate the second Death Star, the original prototype or any other number of super-laser based weapons of the Star Wars universe.
Minimum Power Output of Generator = (Energy output of Super Laser Array)(unit of Joules)/(Total Recharge time)(Seconds)
(10^32)Joules/(24(Hour)*(3600 (Seconds/Hour)= (10^32 Joules ) / (8.64*10^4 Seconds)=Min Pout
1.15741*10^27 Watts=Minimum Power Output of Generator

Right now I  will do a really quick and dirty calculation and estimate the minimum temperature of tpoint and just go off the trench run briefing scene, where they explain that all of the Death Star's waste heat is dumped through a thermal exhaust port 2 meters wide and circular in shape.  Using the equations for black body radiation we can calculate the theoretical  temperature at said exhaust port.,  Pnet=1.15741*10^27 watts : A= π*(Diameter/2)^2=π*(2m/2)^2=3.141592653 m^2 :  σ=Boltzmann Constant=1.3806503 × 10^-23 w/[(m^2)*(K^4)]: ε= is the emissivity of a given material, for ease of calculation we will assume that the value is 1: To is the temperature of space and we will assume that it is 10 degrees Kelvin
 substituting the variables with the above numbers
1.15741*10^27 watts=3.141592653 (m^2)*1.3806503 × 10^-23 w/[(m^2)*(K^4)]*1*[(Tport)^4-(10K)^4]
this reduces to 
(1.15741*10^27 watts)/{3.141592653 (m^2)*1.3806503 × 10^-23 w/[(m^2)*(K^4)]}=[(Tport)^4-(10K)^4]
becomes
[2.668410821*(10^49)*(K^4)]-[10*(10^3)*(K^4)]=(Tport)^4
Taking the fourth root of both sides of the equation
we are left with the Temperature of the Death Star's Exhaust Port

T port = 2.273*(10^12)K or two trillion two hundred seventy three billion degrees Kelvin.  For comparison most Earthly materials break down well before 6*(10^3)K or 6000 degrees for those who dislike using scientific notation.  At temperatures like those, the photon torpedoes launched by Luke Skywalker are unlikely to have even gotten within several hundred meters of the exhaust port, let alone close enough to explode within the structure of the Death Star.

What follows below will evolve into some follow up calculations as how the Death Star might work if it didn't rely on that one exhaust port to maintain system stability.


Follow Up Math (Nov 17, 2012)
After posting this article on Reddit one reader pointed out that I was treating the entire generator as a straight heat source, which is bad modelling on my part. As I said on Reddit I was tired the day I made this post originally that being said I should attach a range of corrections and modeling options..
The first is simply considering the system efficiency in making calculations.
To make the math easier, and because I have no way of even remotely accurately modeling the Death Star Super Laser System's (this includes the net efficiency of the firing mechanism, the generators, and the energy storage facilities within the Death Star) we are treating system efficiency as a single variable.
The general Form
System Efficiency=X
System Power Production Requirements= (Theoretical Minimum Power Output of Generator)/(System Efficiency)
Waste Heat Produced =(System Power Production Requirements)-(Theoretical Minimum Power Output of Generator)
Waste Heat Produced is now fed back into the black body radiation calculations

For Different Efficiencies and Radiator Surface Areas
X=50%                Area of the Radiator=3.14 square meters

The radiator temperature will be as originally calculated 2.27*10^12 degrees Kelvin

X=90%                Area of the Radiator=3.14 square meters

The radiator temperature will be as originally calculated 1.31*10^12 degrees Kelvin

X=99%                Area of the Radiator=3.14 square meters

The radiator temperature will be as originally calculated 7.21*10^11 degrees Kelvin

X=99.9%                Area of the Radiator=3.14 square meters

The radiator temperature will be as originally calculated 4.04*10^11 degrees Kelvin

X=99.999 999 999%                Area of the Radiator=3.14 square meters

The radiator temperature will be as originally calculated 4.04*10^9 degrees Kelvin


X=99.999 999 999 999%                Area of the Radiator=3.14 square meters

The radiator temperature will be as originally calculated 7.18*10^8 degrees Kelvin (Still really damn hot)


X=99.999 999 999 999 999%                Area of the Radiator=3.14 square meters

The radiator temperature will be as originally calculated 3.99*10^8 degrees Kelvin (Still really damn hot and Microsoft Excel won't let me look at anything more efficient)

Ok, so what would it look like if we said that the Death Star had the the entirety of its surface area (as a smooth sphere) turned into a black-body radiator

The Death Star is 160 km in diameter, so its surface area is roughly
(80,000m)^2*3.14159265= 80,424,771,917 m^2 : so pretty darn big

X=50%                Area of the Radiator=80.4*10^9 square meters

The radiator temperature will be as originally calculated 5.68*10^9 degrees Kelvin


X=90%                Area of the Radiator=80.4*10^9 square meters

The radiator temperature will be 3.28*10^9degrees Kelvin

X=99.9%                Area of the Radiator=80.4*10^9 square meters
The radiator temperature will be 1.01*10^9 degrees Kelvin

X=99.999 999 999%                Area of the Radiator=80.4*10^9  square meters

The radiator temperature will be 1.01*10^7 degrees Kelvin


X=99.999 999 999 999%                Area of the Radiator=80.4*10^9 square meters

The radiator temperature will be 1.8*10^6 degrees Kelvin (Still really damn hot and microsoft Excel won't let me look at anything more efficient)

And now for the final random calculations.  A friend of mine put  forth the question
Lets assume Vader has some super material for his exhaust, that can take temps of 20k° K.
How big would the exhaust have to be in order to not melt, and how does that size relate to the Death Stars size?

Now we are approaching the calculations from a different perspective, where the surface area of the object is unbound, but the temperature of the system is now restricted

in the rough form we see

Qwaste heat=Aradiator system*Boltzman Constant*(Tradiator^4-Tvacuum^4)

Ok I'm going to take a breather for a bit updates later

Cooling with Hot Water Heaters

Solar hot water heaters are considered one of the most cost effective ways to add a renewable energy source to a home or business. Another way to decrease your energy bill is to take advantage of technologies that consider the cost of energy as a factor of the time of day, one approach that does this very effectively is the production of ice at night to aid in cooling during the day.   (wow this is feeling like I'm writing a report for 9th grade science, but darn it I have no better intro coming to mind)  Several months ago I asked myself if it might be possible to find some kind of synergy between these two technologies.  

For engineers and people who understand my ADD I will provide the quick and dirty thusly immediately below.  As I have time I will add explanations at the bottom, or as requests for clarification come in.

Figure 1

The concept I am presenting here is based on the fact that optimal cooling systems are as close to black body ideal bodies as possible.  The collectors in a solar hot water heater have a relatively large surface area and are painted to behave as a black body.  Traditionally this trait goes unused for half of the day, what I am curious to see, is would it be possible to utilize the black body characteristics for night time cooling, most critically would it be cost effective to utilize the configuration I propose or something similar to it?
To minimize cost, the design shown Figure 1 utilizes a single hydraulic pump and a flow switch that alternates between the two heat exchangers.

Figure 2

  As day turns the night the characteristics of the system will change in a few critical ways.  First and most obviously the flow switch will alternate from having the working fluid move past the Water Heater to the Refrigeration Radiator Augment (yeah I know the name isn't sexy, I'm an engineering geek not a marketing guru, whaddya want from me?) The altered configuration is shown in Figure 2.  For the system to be used as an effective additional convection and black body radiation cooling surface, to augment the standard radiator found on refrigeration systems, the body design will need to under a range of potential configuration changes.  With respect to radiative cooling, the insulation layer that is so critical for day time operation must have the ability to either dynamically alter its thermal resistivity or physically rearrange itself to allow for maximum exposed surface area to the ambient environment.  To increase the overall efficiency of the system convective cooling should also be considered and a design that promotes both active and passive air flow, at night, could drastically alter thermal performance.  One potential approach is roughly shown in Figure 3

Figure 3

 What Figure 3 attempts to convey is that, warm working fluid is piped up through the base of the cooling system, which has expanded itself to aid in nighttime reverse energy transfer.  The glass covers which kept heat in during the day are now open to the night and letting infrared radiation and warm air escape into the night, additionally fan(s) might possibly be used to promote forced convection to aid in the cooling process.  One way to power the fan system might be to utilize some kind of thermal electric generator to minimize the system's energy demands.

Overall I am really curious to see whether or not a design like this would actually be more energy efficient than using the two technologies separately.  The solar hot water characteristics are rather known and the financial models for the technology are readily available and the cost analysis of implementing an HVAC system that utilizes night time cooling can be done by any number of contracting agencies.
       
               The real questions for the system's theoretical synergy stems from the fact that heat syncs experience diminishing returns on their ability to transfer thermal energy. Would this system only be considered beneficial if it was manufactured as a single platform, reducing the amount of radiator surface area built into the actual AC unit?  Could it be utilized as a way to augment existing systems as a way to lower energy costs?  While I can put together the basic equations I unfortunately don't have the resources to do an in-depth analysis on the potential ROI if there is any.  Realistically I  have my own doubts about this concept, no matter how cool I think it is, simply put there are too many moving parts that need to be factored in to the system's design and sadly moving parts/having more parts generally = greater overall cost.  Anyways I hope this at least gave you something to think about, please feel free to provide your own input.

The basic concept of a solar hot water heater is relatively straight forward, a number of pipes are coated in as dark a material as possible, the closer to true black the better.  As sunlight is absorbed by the pipes the energy of the light is converted into heat energy.  This heat energy is transferred to some kind of carrier liquid, with respect to what I will be describing this liquid will be any material that will not freeze or boil within the temperatures normally seen on the Earth's surface (-70 F-250 F).  The carrier liquid will move from the heating pipes through a pump until it reaches the heat exchanger, at the heat exchanger the warmth from the carrier liquid will be used to pre-heat a water source, before that water goes into a hot water heater.  After the heat exchanger the carrier liquid is cool enough to be cycled back towards the hot water heater.

Power for the Zombie Bunker

After making the mistake of deciding that I could watch "just one or two episodes" of the second season of the Walking Dead on Netflix, I am now totally caught up on the plight of post outbreak humanity and have spent a little too much time trying to design a flexible energy supply for my dream hold out facility, although the concept could work equally well for making a home that is energy resilient and self sufficient.  In the sketch below I have sketched out what would be a pretty ideal situation to be in.

In the sketch to the side you will see a large black bar, this indicates the height difference between the bottom of the reservoir and the primary hydro electric generators outlet.  A facility like this should be optimized to provide as much head (height of the water column) as possible.  In addition to the hydro electric generator you see some rather crudely drawn wind turbines and solar panels, the black and white boxy things with the red lines drawn towards them.  These generators, in my opinion, should not be directly connected to the facilities energy grid, instead their power is used to pump water up hill to keep the reservoir as full as possible, creating a pumped storage Hydroelectricity facility.  The overall logic behind this approach deals with the indeterminacy of wind and solar production and human energy demand.  While many homes that use renewable energy utilize battery technologies to allow for load leveling, there is a finite lifetime that traditional battery technologies provide additionally if civilization collapses, it will be easier to scrounge parts to make a new turbine than it will be to make an efficient battery.  Additionally the pumps that are connected to the wind turbines and solar panels can be optimized to utilize the voltages and current characteristics of their respective sources.  The electricity produced by the hydroelectric generators can be optimized to produce true 120 Volt 60 Hz electricity, allowing for any traditional electrically powered appliance to be used. 

Oxygen High Pressure Space Engine

As part of a larger personal project to develop a white paper on in-situ manufacturing on the Lunar surface for deep space exploration, I have been trying to create as flexible a list as possible of potential engine designs that would take maximum advantage of the available resources of the moon.  One engine design that I am considering is based on the concept of super heating a liquid to increase the specific impulse of the selected fuel.  The proposals I have found online all list some kind of oxidation reaction occurring while being heated by some additional thermal source, in most cases the source is a nuclear fuel stack.  I am curious to see whether or not it would be considered worthwhile to simply super heat liquid oxygen and use that to propel your spacecraft forward.  Such a system could be very mechanically simple and would utilize the most common chemical component of lunar regolith, as oxygen is 60.9% of the atoms (table 6.3 pg 238) found in lunar regolith.
Below are some sketches of what the system might look like (yes they are crummy white board drawings, but I am between computers that can run my copy of Autodesk, and I wanted to get away from my addiction to using MS paint in engineering documentation)

In the first image you see a large Liquid Oxygen tank used to supply the entirety of the systems reaction mass.  As thrust is required Liquid Oxygen is pumped back to the reaction chamber, before arriving at the primary heating chamber the liquid oxygen is pre-heated via piping wrapped around the exhaust system ( from my limited knowledge of liquid propellant engines this is done to prevent the exhaust from breaking, so I do't know if its necessary but it looks cool so I'm going with it.)  The now, most likely gaseous oxygen continues on into the primary heating chamber, where solar energy is concentrated by the tracking solar reflectors, in a similar approach to solar thermal generators here on Earth.  The now super heated oxygen will vent out through the rear exhaust providing thrust to the overall system.

In the second configuration the overall premise is the same, the critical difference is that the reaction tank is not directly heated by solar flux, instead energy produced by a collection of tracking Photo-voltaic panels is pumped into a laser system to heat the oxygen.  While the system would not be as efficient as directly reflecting the sunlight onto the reaction chamber, it would allow for energy production to be used for other purposes when thrust is not needed.  Additionally the laser could be placed on a turret for flexible applications, including wirelessly charging the primary spacecraft, allowing the crew compartment to be, relatively, physically independent from the propulsion system in case of mechanical failure

Follow Up Dec 10 2012
While doing research for my general mining the moon/manufacturing in space research project I found an article that listed a healthy selection of propulsion technologies available for space exploration and one methodology is referred to as a Cold gas propulsion solution.  The table there presented it as having an impulse of 780 N*s/kg for comparison Hydrogen and Oxygen (the fuel generally used for launching spacecraft) rates in at 4500 N*s/kg.  Source "Mission and Transportation Applications of In-Situ Propellant Production in the Mars System" (pg 905)  by Benton C Clark Martin Marietta Civil Space and Communications.  So while the liquid oxygen technology is approach is a potential solution, unless you were making the entire system from materials manufactured in space and in relatively large volumes, it is likely that shipping hydrogen from Earth or some other cost effective source, would make more sense.

Too Many Thoughts

Hello random reader (hopefully you exist),

I am establishing this blog to put various thoughts out in the æther, hopefully what is found here finds fertile soil in someone's mind and something actually valuable can come from that, or at least amuse me and keep me from spending too much time trying to watch bad sci-fi series on Netflix.  Please enjoy all materials put forth and understand that I am producing this under a non-commercial Creative Commons Share license.  

All the Best,
Obie