And if you mix the water with other ingrediants to form a slurry that freezes as it is applied such that the ice itself is both reinforced and in part self insulated.........Like the Mars Ice House
Quote from: Aussie_Space_Nut on 06/25/2016 05:33 amAnd if you mix the water with other ingrediants to form a slurry that freezes as it is applied such that the ice itself is both reinforced and in part self insulated.........Like the Mars Ice House The Mars Ice House is supposed to be 3D printed with like little robots and also applying like an ETFE film to keep the ice from sublimating. I was talking about something different, where you can skip the 3D printing altogether just by using an inflatable design. A lot simpler. You can pack up the inflatable plastic in a very small, lightweight volume, then simply pump in water and wait for it to freeze.
Quote from: Robotbeat on 06/25/2016 05:55 pmQuote from: Aussie_Space_Nut on 06/25/2016 05:33 amAnd if you mix the water with other ingrediants to form a slurry that freezes as it is applied such that the ice itself is both reinforced and in part self insulated.........Like the Mars Ice House The Mars Ice House is supposed to be 3D printed with like little robots and also applying like an ETFE film to keep the ice from sublimating. I was talking about something different, where you can skip the 3D printing altogether just by using an inflatable design. A lot simpler. You can pack up the inflatable plastic in a very small, lightweight volume, then simply pump in water and wait for it to freeze.I'm fond of inflatables for the simplicity - the first time I saw a inflatable shelter that has a concrete mix in the wall that hardens into a permanent building I fell in love with them. I like 3d printing for buildings but the more i'd have to depend on machines not breaking down the better.
Suppose a cylinder 6 m long and 7 m in diameter, internal volume is 230 m^3, covered in 30 cm of polyethylene and the dosage would be 1 mili sev/day in space at a mass 70 tons of shielding. Yes that is a lot of shielding mass but it's not prohibitive considering the expected payload masses involved and if it is left in orbit to use during the return transit. A 5 month transit time each way would thus yield an acceptable radiation dose without cranking up speed to things like 3 months which is likely to require a lot more then 70 tons of additional propellant to do.
Because both increasing propellant mass to shorten duration and adding shielding mass experience strong diminishing marginal utility the optimum solution for any desired radiation level is to mix speed and shielding strategies rather then relying on one exclusively. The sweet spot between them always moves towards more shielding mass as the vehicle size and payload increase because the surface area to volume ratio makes shielding more efficient while propellant requirements scale linearly with total vehicle mass for any given DeltaV. Hibernation makes the protected volume much smaller and likewise amplifies the efficiency of shielding, note that only the actual people in transit need to be shielded, life-support equipment and consumables can be outside the shielded zone.
Simplicity.Ice is nice but digging a hole is so much simpler. I'd prefer using an inflatable structure with inflatable internal bracing (inflatable in the sense that blowers would hold the structure upright while the majority of the 'walls and ceiling' are filled with earth - inflate the 'braces'). The structure would be inflatable so that you can access it from above to pour in scooped up dirt into he walls and braces. A dome with braces from ceiling to floor in the form of coned pillars would push out and into the ground. The thickness required at the roof apex would inform how thick the base and walls need to be. Once you fill it with native dirt you can turn off the carnival air blower (whatever kind of blower you need) and work on the next building. Access could be via cargo and suitback ports built into the inflatable so martian soils don't intrude on living/working areas.The simplest solution is using a lot of dirt. Preserve your water where an accident can't deprive you of it. Resources required: 1 Dome infaltable with suit and cargo ports, inflator, shovels, Martian Dirt. Duct tape for rip repairs.Even simpler is digging into the ground but we don't know whats there just yet and might need above ground habitats to start.The material of the dome, though we could use some hotshot radiation proof plastics, should be durable more than anything else.
...A shorter transit time is always a good idea (fewer consumables, less exposure to GCR and CME, lower MTBF for the ECLSS target etc) but the question is how good an idea compared to simply adding more shielding?
Quote from: gospacex on 06/22/2016 12:10 pm"Assemble a 10 meter thick masonry dome" would be a VERY stupid plan.Why not "put a ~0.5 meter thick airtight ceiling made of basalt slabs and bulldoze several meters of regolith over it" plan instead? Even easier than water/ice plan - you do not need to produce water. And when done, you never need to worry that your ceiling can melt, leak or sublimate. I see that as important features of my ceilings.Using regolith as radiation shielding instead of water is, using thicknesses earlier in this thread much heavier. 10 meters vs 3, and much denser. Ice still needs a cover layer but 1/2-1 meter is probably enough to cut down sublimation. The roof ends up around a quarter the weight
"Assemble a 10 meter thick masonry dome" would be a VERY stupid plan.Why not "put a ~0.5 meter thick airtight ceiling made of basalt slabs and bulldoze several meters of regolith over it" plan instead? Even easier than water/ice plan - you do not need to produce water. And when done, you never need to worry that your ceiling can melt, leak or sublimate. I see that as important features of my ceilings.
It might end up needing to be anyways to support enough weight that the roof doesn't blow off, But I haven't gotten to working that out yet.
It is necessary not just to rethink material availability in the early stages but also equipment availability. What needs to be built must be built using 95% locally-sourced materials but also using small equipment.
No backhoes or bulldozers will be going to Mars in the first long while.
People need to specify what phase of development they thing their solutions are good for.Were not going to have water available in that kind of quantity on an initial human landing, any water that you can make will be going into fuel so you can actually return. Building with water is a mid to long term concept usable only after a super abundance of water is available, and I'm very doubtful any such super abundance will ever be available.
First I don't believe that BFS will hold the propellant you imagine or that it will need to volumes of water your anticipating and the cost and slow speed of acquiring water will preclude it from being used for anything but propellant and life-support topping off....
The volume of water needed to build a single igloo shelter is likely to be greater then or equal too that needed to make the propellant to return a single BFS, so the trade off to making an ice shelter is to forfeit an entire BFS delivery due to not having the propellant to return the vehicle to Earth. The additional payload will always be preferable because it can contain regolith moving equipment that can trench and cover more habitats and keep doing so for years on to come.