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This is basically my original concept for the MH12500 Heavy Lift Launch Vehicle standardised module. The baseline stats (basicly the mass budget allowances) are essentially identical to those I noted for the MH12500A module (the more advanced version). Although the mass budget is in the same range, the actual mass and capacity of the MH12500 are somewhat lower than the advanced version (this should be self evident, since the advanced version has the same dimensions, but "squares out" the structure toward the exterior). I have made a few revisions to the design. Instead of a lateral triple tank, I have pulled-in the walls of the first (innermost) pressure vessel to 10m diameter. This is now a single tank, intended to store LH propellant for Earth launch. The second vessel has been brought in to the original 12m diameter, but now serves as an outer wall for a concentric LOX propellant tank. This means that the inner tank now functions as a common wall for both LH and LOX tanks. The benefit of this is that less insulation is required for the LH tank, as there is less temperature differential. Likewise, as the cross-sectional proportions of the two tanks happen to be just about the optimal burn mix ratio (so the propellants will be consumed at the same rate, linearly), the LH tank can be much lighter, as the mass differential is also greatly reduced. The two propellant tanks share common "endcap" bulkheads.
This is a 12.5m x 25m "wet-workshop" module currently under development. It is a derivative of an older, purely cylindrical design (an updated version of which I expect to post in the near future... once I have solved a problem that I am having with my CAD programme). As a "wet-workshop" design, the module is intended for conversion to a habitat module following initial service as a propellant tank for a Heavy Lift Launch Vehicle. Given the intended eventual use, it is intentionally rather heavy for a propellant tank, with much greater mass than would otherwise be necessary or desirable. The MH12500A (The "MH" is obviously my initials, but it could also be interpreted as "Module-Heavy"; the number denotes the radius in mm; and, the "A" distinguishes this as a more advanced design) has a mass budget in the range of 80 to 100 tonnes, although it could prove to be much lighter in terms of actual structural mass (the remaining mass would be water added to the voids -I'll explain shortly- to provide extra radiation protection, as well as increased service water reserves). The much of this mass is intended to provide additional insulation / thermal protection, as well as micro-meteoroid and radiation protection. The design is intended to permit up to five of these modules to be stacked in an HLLV configuration, although four modules would be the standard load-out. There would also be a propulsion assembly with at least four independently ejectable thrust assembly modules (to be staged when the added thrust is no longer needed), together with a fifth integral module that places the HLLV in orbit; and a nose-cone fairing... all of which are intended for recovery and reuse. A single module stack is possible, with an estimated 10 tonne useful load capacity (in addition to the converted structure and propulsion mass). The mass allowances assume a mass distribution of 90% propellant (required for an SSTO to achieve LEO with an average Isp of about 400s), 7% structural mass (the STS ET actually achieved a structural mass of just over 3%), 2% propulsion systems (assuming a thrust/mass ratio of 50... normal ratios are closer to 75), and 1% payload. Among some of the more interesting features: * Each module actually has five shell layers, spaced by four 5cm void sections. This layering provides added low-mass insulation (incorporating the voids); as well as a "whipple shield" protection mechanism, enhancing the actual mass/material shielding. * The inner shell is actually composed of three distinct "tanks", incorporating common bulkhead techniques and technologies. The common bulkheads allow for decreased overall insulation requirements (since the common area has a much reduced temperature gradiant), as well as reduced containment mass (since the common area has a much reduced pressure gradiant). The integrated design provides greater mass protection against radiation and micro-meteoroids for the central volume. * The linear (vs stacked) common bulhead tank arrangement greatly reduces the length of plumbing necessary to distribute propellants, which actually reduces added mass considerably. * The modules are designed to "dock" with one another, with multiple docking ports, allowing for propellants to flow directly from tank to tank. Again, this reduces required piping mass. * Intertank modules will be designed to: support the mass of "strap-on" boosters; permit continuous flow-through for the outermost void (which may serve as an added or alternative propellant flow channel, if necessary); serve as load space, directly serving the adjacent modules; and accomodate eventual repurposing as tunnel wall support (etc). Modified intertanks could serve as an alternative propellant configuration (incorporating the flow-through capabilities of the outermost void spaces. The CAD drawings attached (converted to JPEGs) show the general arrangement of the voids, the three tanks of the interior shell, general boundary outlines for the remaining shells, one panel of the exterior end-cap bulkhead, and various construction lines. The parallel construction lines inside the tank space denote centrelines and boundary lines denoting compartment divisions. These latter consist of four lateral decks, themselves divided into a central corridor, two primary living space channels, and two supporting space channels. The outer decks and supporting space channels provide additional radiation shielding for living space areas.
Energy is a critical limiting factor in plans to develop a base on Mars into a manufacturing facility that can expand into a self-sufficient colony. It limits how much subsurface ice can be melted and processed, how many structural bricks can be baked, how much iron and glass can be smelted, and critically, how much CO2 and water can be processed into rocket fuel, plastics, and lubricants. The extreme cold also means that many types of equipment left outside will need to be heated to keep them operational. Importing power generation systems from earth would be costly for the organization sponsoring the base, and would limit what the colonists could do in terms of growing their industry during the 18 month periods between launch windows. Additionally, unexpected failure of power generation systems that cannot be replaced on-site would put the colony in danger, or at least drastically slow down its industrial growth. Using resources that are relatively simple to refine and readily available on Mars, like iron, glass, and polyethylene, what energy generation systems could be mass-produced by martian colonists with minimal use of materials imported from earth? The book “Mars: Prospective Energy and Material Resources” by Vlorel Badescu, which I read a year or so ago, gives several options, some more realistic than others. Two that stand out from a simplicity of manufacturing perspective are wind turbines and solar-thermal generators. (Yes, wind power is possible on mars, it’s because of the higher density of CO2 and the higher wind speeds) How would you go about designing and manufacturing these systems, or can you think of an alternative? I’m thinking that this could turn into a project that someone could build in their backyard at fairly low cost, which would demonstrate a piece of space technology that would be very useful to base designers and mission planners.