<i>> Those adobe domes look like something right off of Tatooine. I wonder about ability to withstand earthquakes. </i><br /><br />They also resemble various desert habitats here on Earth, most notably Dr. Khalili's native Iran. Superadobe domes are the only structure known that rates a '10' on California's earthquake scale. <br /><br />He has built temporary domes with just sand in the bags. Permanent structures use a high-sand ratio concrete, then are fired from the interior. They are ceramic houses. After firing, the interior is dressed out in stucco or other material. <br /><br />With tough enough bags (probably with integrated barbs) structures could be built on Mars like this using loose-packed regolith. My suggestion for frozen-mud sandbags is not original. If the builders have enough water, they can replenish it from interior and exterior losses. Plastic barriers help with this. Don't discount the strength of hard-packed dirt, too. These domes self-compact the material. The two requirements on Mars are that the bags hold together until cured and the structure can be fired or frozen into a permanent form.<br /><br />The beauty of superadobe, once it works on Mars, is that we already know how to build all sorts of things with them. All the arches, barrel vaults and aquaducts of old can become the template for a true 21st Century architecture.<br /><br />If any chemists want to weigh in on this - what would be a calcium-substitute on Mars for making MarsCrete? Sulfates or hematite powder?<br /><br />Sandbag structures are the leading contender, IMHO, for the first constructed Mars buildings. It's easier mechanically and labor-wise than mud-bricks. It's much more near-term than steel/glass-curtain buildings or metal pressure structures. <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>
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Ok, I'm convinced. The reason I wanted below ground was for better thermal and radiation shielding. It sounds like you could dig a shallow trench, erect these adobe things inside, then after they are cured backfill to an appropriate depth on top, maybe only 1m at the top depending on the insulating properties of the dirt.
For any kind of native material-built structure, holding the atmosphere in is a challenge. Building underground and burying vaults can provide strategic weight to hold it all together. KSR and Zubrin have both explored this area, usually assuming bricks/blocks instead of superadobe. The techniques are the same, and come out looking Romanesque.<br /><br />Here's some art I made for an "aquaduct colony". It would be superadobe and mylar-wrapped pykrete blocks, with most of it buried. Fiber optics running through the dome would provide daylight. <br /><br />http://www.projectsanbao.com/habitats.html<br /><br />Superadobe is something that might be ideal for small-unit Mars. The materials out-bound are minimal: sandbags, barbed wire (or purpose-made bags), and an attachment for the Dozer than can bag them. The dozer might only be able to lay a foundation for starters, but it could make setting up a plastic dome much easier. A central arm and converyor belt could build full domes, if it could be kept supplied. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>
I wouldn't worry at this stage about how to make martian concrete. Earth concrete is, to put it simply, just a form of artificial stone after all. Set some materials science students on the subject and we should have a viable martian concrete way before the mission launches. I would just assume it is possible at this stage.<br /><br />17'600 lbs to TMI is 8 metric tons as you pointed out earlier, therefore unfortunately not 9...<br /><br />If we consider the latest NASA Mars Reference Mission Design by Borowski we find the following data for a 6-person Mars lander:<br /><br />crew and suits: 1.44 tons<br />surface payload: 26.54 tons (includes life sup + consumables)<br />descent stage: 4.2 tons<br />aerodescent shell: 7.94 tons<br />parachutes: 0.7 tons<br />propellant: 7.92 tons<br /><br />total: 48.74 tons<br /><br />If we divide by 6 we get an 8-ton lander. That means with current technology you can probably get one man to Mars with an 8-ton vehicle...<br /><br />Concerning C3, as jimfromnsf pointed out, this is velocity squared. Therefore a C3 of 10 km2/s2 is an actual velocity of 3.16 km/s after having escaped Earth's gravity. Ie just enough to engage on a Hohmann, 258-day long transfer to mars... therefore the 26-ton "surface payload" in Borowski's scheme necessarily includes all the life support and facilities necessary for a 9-month trip. Maybe that can be reduced to accomodate 2 or even 3 in our 8-ton capsule but at what cost to comfort?<br /> <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>
Send the "surface payload" on ahead (in multiple copies in case of failure). That way the manned vehicles only carry what they need on the way out.
Right Thereiwas, so we need to work out the minimum life support payload to carry. According to this study a man needs per day:<br /><br />1 kg O2<br />30 kg water<br />1.5 kg food<br /><br />Ie: 32.5 kg.<br /><br />If this was all transported it would anount to 8.4 tons for a 258-day trip. If we were to develope more robust and less failure-prone water and air recyclers than we have today (but with the same efficiency) we should be able to have the following mass break-down for a 258-day trip (still from the same study):<br /><br />Air recycler 365.00 kg<br />O2 cache 51.60 kg<br />Water recycler 558.83 kg<br />Water cache 154.80 kg<br />Food cache 387.00 kg<br /> <br />Total 1'517.23 kg<br /><br />So the 26 tons of "surface payload" divided by six gives 4.42 tons, of which 1.52 should be used by life support for a single person. Therefore at most we should be able to squeeze 2 persons aboard the 8-ton ship with nothing much else apart from their life support 
<br /><br /> <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>
<br /><br /> <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>Laundry? Showers every 2 days?! The people on ISS get by with <font color="yellow">no</font>showers for six months! They don't like it, but it doesn't hurt them. Their <font color="yellow">sweat</font>gets recycled into drinking water!<br /><br />Plenty of water for showers once they get to Mars.
OK lets assume no showers and no laundry. So water requirements drop from 30 to 2 kg per day, which is only drinking water. Assuming alinear mass to productivity ratio for the water recycler, it is now 15 times lighter, and so is the water cache:<br /><br />Air recycler 365.00 kg<br />O2 cache 51.60 kg<br />Water recycler 37.26 kg<br />Water cache 10.32 kg<br />Food cache 387.00 kg<br /> <br />Total 851.18 kg<br /><br />Note I do believe the guys on ISS get new clothes every so often and simply dispose of the old, this won't be possible on a TMI. Our 4.42 tons of "surface payload" must include everything that is necessary for life during 9 months. <br /><br />According to the June 1998 addendum to the NASA Design Reference Mission 3, crew accomodations for 6 amount to 10.5-12 tons excluding life support. That is a minimum of 1.75 tons per person. So 2 persons would need 2x(0.85+1.75)=5.2 tons for life support and accomodations, assuming only 2 kg water consumption per day. A finalised and highly optimised design may squeeze two persons aboard our 8-ton ship but certainly not more. <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>
You are going to need to do laundry on Mars. Either that or take a whole lot of spare clothing. Not washing becomes a health hazard. You also need to use water to clean the hab in what will be a dusty environment. Twenty five-30 L of water per day per person is not a lot of water for all this use. Don't skimp it.<br /><br />You also need to allow for inefficiencies in recycling, typically about 10%. Plus loss of gas and water through leaks. <br /><br />Remember too that recycling costs power, which has to come from somewhere. The more power the more mass.<br /><br />Then there is the issue of minimum volume. people need a minimum volume to live and work effectively. For a Mars mission that comes to 10-20 m3 of free voilume, maybe 30-60 m3 of presurised volume per person.<br /><br />Last of all you need a safety margin on almost all of these numbers. Your crew is going to be well beyond any material aid. You don't want to lose them because some measily mass accounting. I would allow 10% on top of everything. Note that standard space design pratice is 20%, which hurts.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>
<blockquote><font class="small">In reply to:</font><hr /><p>..on Mars.<p><hr /></p></p></blockquote><br /><br />But there is water on Mars. No need to drag it all with us as was previously thought. Lots of recycling in transit, much less required once there. To me this is a big benefit of Mars surface over Phobos for long term occupation.
The amount of water on Mars in various forms is very promising for long term stations. But, you need to be careful how you factor this into your mission planning for the first few visits.<br /><br />The water isn't on tap. It has to be located, extracted, purified and the waste disposed of. All this requires power and equipment, which equals mass. Plus it requires a certainty that you can do all of this at the selected landing site. The bottom line is you can't assume water availability, you have to plan for it.<br /><br />Jon<br /><br /> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>
<i>Assuming alinear mass to productivity ratio for the water recycler, it is now 15 times lighter, and so is the water cache:<br /><br />Air recycler 365.00 kg<br />O2 cache 51.60 kg<br />Water recycler 37.26 kg<br />Water cache 10.32 kg<br />Food cache 387.00 kg<br /><br />Total 851.18 kg </i><br /><br />I just love how engineering types can calculate masses for technology that doesn't exist down to the nearest 10g.
Water recycling has been available for space missions for more than a decade. There has been a lot of work on O2 recyling as well.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>
<blockquote><font class="small">In reply to:</font><hr /><p>The bottom line is you can't assume water availability, you have to plan for it.<p><hr /></p></p></blockquote><br /><br />I would not send the manned vehicle first; I would send it <i>last</i>, after the water had been located and the necessary life support equipment had been sent to that spot, turned on, and been working long enough to store up inventory of fresh water, etc. <br />
Certainly, but you still have to allow for the equipment in the mass budget. <br /><br />Each of the different potential water resources requires very different types of equipment. So are you going to extract water from the atmosphere, hydrates, permafrost, or surface ice?<br /><br />Are you going to have an open or closed water circuit? if open, how will dispose of the waste? <br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>
Pick the best spot first, based on orbital or lander missions. Then send appropriate equipment for that spot.<br /><br />The equipment to mine water on Mars does not go in the mass budget for the trip that carries people 2 or 4 years later. <br /><br />As for waste there is another discussion somewhere here about "lunar poop processing engineering" and much of that would apply on Mars, though not the parts requiring intense sunlight.<br /><br />Closed cycle for sure. Don't throw anything away. Greenhouses.
You still have to budget that mass into the cargo that is sent ahead.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>
How many 8 tonne chunks do you think will be required?<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>
<blockquote><font class="small">In reply to:</font><hr /><p>I just love how engineering types can calculate masses for technology that doesn't exist down to the nearest 10g. <p><hr /></p></p></blockquote><br /><br />Dude, I gave the source of these numbers earlier on. As for the weight calculated to the nearest 10g, you can see that it is the result of an equation which I did not bother to round off, as I expect you to be smart enough to do that yourself. <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>
<How many 8 tonne chunks do you think will be required?><br /><br />And I still suspect 8 tonnes of cargo to the surface of Mars is wildly optimistic for the Delta IVH.<br /><br />
I agree, I was trying to see if he had thought though these issues. I suspect that the landed mass is more likely to be 5 tonnes with 7 as an outside stretch.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>
Jon and Guns - Any suggestions on how to maximize surface payload from such "small" chunks? My single favorite leverage is multi-pass aerobraking - using a limited heatshield instead of just solar panels should allow a compressed (2-6 pass) session instead of months of dipping. I doubt airbags (pathfinder-style) would be usable. What about the "skycrane" they've talked about for MSL? Also, what about using the third stage or even a redesigned aeroshell from launch as the main aerobrake at Mars? <br /><br />Another option, but I'd like Jon's permission to discuss, would be a 2-stage landing solution. The lander/ascender flies minimally provisioned to Mars were it is met by crew and cargo in orbit. The lander masses 9t empty and about 90 full for ascent. It docks with a common-sized module (crew or cargo) that is 9t minus aerobraking hardware. This can be any configuration, but I'd favor something like Jon's lander (if he'll talk about it) or a smaller of my "spider" concept lander - the lander should enable easy ground access and reuse. The craft is dedicated to Mars orbit and landing, swapping modules up and down. This also has implications for "flotilla" flights to Mars, with new lander hardware. <br /><br />We've discussed having separate "pallet" landers for heavy equipment, a setup with a dedicated lander would help with this. The pallet version for a common module would be a protective unpressurized tube that holds the surface hardware and is the same shape as the crew/cargo module. Designed right, the pallet could double as a low-pressure greenhouse or incubator.<br /><br />A flight profile using dual-launch (18t TMI) would be a lander and methane plant/ solar field or a crew module and docked resource/Service module (also used for Earth return, has aerobrake). This allows a full Delta launch for the common cargo modules, maximizing useful payload. Everything that goes to the surface except the lander/ascender, is recycled somehow. <br /><br />This might be the best <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>
<i>> And I still suspect 8 tonnes of cargo to the surface of Mars is wildly optimistic for the Delta IVH. </i><br /><br />The original premise was 9t (really 8+t) to TMI. Any suggestions for maximizing useful payload to the surface? Would you go with an architecture that puts each individual payload on the surface or stage from orbit after aerobraking? What about separate Landers and common-shaped cargo/crew/pallet modules? (See my re: to Jon) This is a simple, understood way to move cargo on Earth, except that we don't normally house passengers in 40' containers, but you get the idea? <br /><br />Another thing that came to mind is that both Dragon and SunDancer are projected to mass close to DeltaIVH limits TMI. It'd make a sweet dual or triple-launch scenario for crew or pressurized-cargo shipment. With triple launch the crew docks with both SunDancer and a lander or cargo pod, aerobrakes on Dragon heatshield. This is about $500M-1G for 4-6 people to get to Mars once developed, baring improvements and available perhaps in 2012-15 range (second-Gen SD and Drg). It fairly neatly solves the getting to Mars orbit and could build substantial orbital hardware there. There are already several companies working on VTOL landing rockets. DIV-H could easily throw a Fregat upper stage to Mars as well. In a "cargo container" scenario, eventually you want to figure out how to aerobrake containers without a capsule or tug attached. Once aerobraked in Mars orbit, the container is collected by a tug and docked to a lander or used in space.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>
OK, * tonnes TMI ~5 tonnes on the surface.<br /><br />On areobraking You got have have a aeroshell good enough to descend to the surface (5 kms) from orbit, anyway, you could aerocapture in the first pass (3 km/s) and land on the second.<br /><br />With lots of 5 tonne modules landing on the surface you need very accurate navigation so as not to land too far away or too close. You would also need each module to be on wheels, so that it can be moved round on the surface. this calls for advanced field robotics to do this sort of assembly on the surface of Mars. So more landing sequence might be:<br /><br />1 - Dual control rover 1<br /><br />2 - ISRU power system and plant.<br /><br />3 - Dual control rover 2<br /><br />4 - Mars ascent vehicle (unfueled)<br /><br />5 - Hab power<br /><br />6 - 1st hab module<br /><br />6 - 2nd hab module<br /><br />7 - Crew descent vehicle<br /><br />The spacecraft to carry people to and from Mars would have to be larger than 8 tonnes, and require some orbital assembly.<br /><br />For final landing a skycrane with legs would be good. The not bouncing airbags of the type being considered for the CEV might be an alternative as well.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>
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