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.
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 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 failureFollow 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.
No comments:
Post a Comment