Let's Design a Settlement for Mars!

[smradoch]

Thanx Tap_sa for link<br /><br />http://www.dunnspace.com/cryogen_space_storage.htm<br /><br />but there are several notes. Actually the Hydrogen tank is very well insulated. Heat losses are 0.056 kW only. I think that they omit any source of heat in the structure. The only losses are from space radiation. It's clear that smaler tank than those 125 m3 and 8.5t LH2 or real one with equipment would have higher % boil off. Also regenerative cooling is quite big source of heat and big consument of electricity. I don't know how much kW of electricity or how much of heat you need to reject regenerating 0.5 kg/h (0.056 kW heat) of hydrogen. But when you account for real conditions I wouldn't be surprised to need few tens kW of electricity and some cooling loops (producers of heat) with radiators (heat sink). Actually I think that allowing boil off would be better possibility.

 

[tap_sa]

<font color="yellow">"I think that they omit any source of heat in the structure. The only losses are from space radiation."</font><br /><br />From the article:<br /><br /><i>"Heat leakage includes that through the insulation, as well as through tank/shell struts and fill, feed and vent lines. "</i><br /><br />And another important thing:<br /><br /><i>"Boiloff rates in the Boeing study were estimated for tank sets in low earth orbit. Lower boiloff rates would be expected for tanks at a further distance from the sun. Lower boiloff rates can also be expected if tanks can be maintained at an angle which minimizes their cross-sectional area exposed to the sun, or tanks protected by a sunshade. The boiloff rates in low earth orbit thus most probably represent a worst case scenario, with better results to be expected for spacecraft on Mars trajectories etc."</i><br /><br /><font color="yellow">"I don't know how much kW of electricity or how much of heat you need to reject regenerating 0.5 kg/h (0.056 kW heat) of hydrogen. But when you account for real conditions I wouldn't be surprised to need few tens kW of electricity and some cooling loops (producers of heat) with radiators (heat sink)."</font><br /><br />Well, you already calculated yourself the first part, 56 watts <img src="/images/icons/wink.gif" /> That's the heat we have to remove from the boil-off to turn it back to liquid. What's the efficiency of cooling equipment, I don't know but tens of kilowatts sounds awful lot, 56kW would mean abysmal 0,1% efficiency. I'd say one kilowatt <i>tops</i>. Naturally we have to radiate that kilowatt to somewhere else than the tank or the whole process is moot.<br /><br />But I agree with you that allowing the boil-off would be no problem, because we'd probably use the hydrogen at least that rate in a fuelcell or something like VASIMR anyway.

 

[smradoch]

All losees through insulation, struts and vent lines are through radiation from space, but I meant other heat sources like batteries, struts to orbital module, electric equipment etc.<br />You need to reject 0.056 kW of heat, but as we talk about that elsewhere, it's not easy to reject heat when the temperature is few kelvins.<br />The problem at LEO is probably with radiation from Earth.

 

[smradoch]

radiating 56W @ 20.3 K you would need 5700 m2 of radiators (according to S-B eq.) with black body and without back radiation from space. Using some cryo plant things get pretty complicated and heat losses will be higher.

 

[grooble]

Can someone write up a summary for this mission? The discussion is 6 weeks old, has anything been decided on how the mission would be made up?<br /><br />Thanks

 

[dan_casale]

I'll start working on the summary. Give me a couple of days. In the mean time here is an interesting link on an advancement in space solar power.<br /><br />http://www.renewableenergyaccess.com/rea/news/story?id=25166

 

[grooble]

27% efficient. That's good. I'm so excited right now at the prospects, these new solar panels could power my space taxis.

 

[tap_sa]

I bet multijunction cells will be production ready for your taxi.

 

[grooble]

Excellent.

 

[arobie]

Again, another post on the water as propellant (and energy) issue.<br /><br />First of all, I'de like to thank those of you who set me straight on the availability of water. I stand corrected.<img src="/images/icons/smile.gif" /><br /><br />Ok, now to the post:<br /><br />I'de like to bring up some long term points. These are future considerations, not just the future of how our settlement will work, not short term considerations, but the long-term future of human settlement of Mars and activities in the asteroids. I feel it is important to take these considerations in when planning how the start of it will pan out. <br /><br />First, since we are settling Mars for the long-term, we don't want to settle it on policies of wasteful use of water. <br /><br />How long would Mars' planetary water supply last if we used it as propellant? <br /><br />How long would it take before we squander Mars' water resources until there is none left for future generations? <br /><br />We need to make this water last as long as we possibly can, centuries, millenia if possible. We should not use it up over a few decades for a settlement's propulsion (and electricity) needs. I just don't want us to fall into our our own trap again and squander priceless resources like we have on Earth. I think it is our duty to our progeny to keep Mars' water on Mars.<br /><br />Another consideration in planning our Mars settlement is whether or not <b>we</b> eventually want to utilize asteroids as resources. A major resource we can get (<i>I think</i>) is water. If that is so, and we plan on (after the settlement is established) sending missions to the asteroids to utilize some of these resources, then we might want to use LH2/LOX as our planned propellant, as long as we replace the water we use from Mars. I just don't like the idea of using needed resources and having no plan to restore them. I don't like squandering resources and then dropping the problem on other people's laps. <br /><br />We should preserve water an Ma

 

[quasar2]

i wonder if equatorial launches on mars make much difference. probably not as much as Earth, but if one is wishing to be fuel-wise. also by that time, one would think maglev launcher or equivalent would be built too. isn`t olympus mons somewhere near the equator? <div class="Discussion_UserSignature"> </div>

 

[grooble]

Where is spacester these days?

 

[arobie]

If everything that we are looking for that makes a great settlement location is found at the equator, then we should go there. Although I don't know how likely that is.<br /><br />Olympus Mons looks to be a little ways north of the equator. Here is a map.<br /><br />Cool Mars Site

 

[quasar2]

i`m certain there will be nomads constantly wandering the martian surface. i know that`s what i`d do. so i don`t think we`d hafta worry bout it all in one place. actually, having things spreadout encourages exploration. <div class="Discussion_UserSignature"> </div>

 

[dan_casale]

Here is a first pass at the pre-launch activities.<br /><br />Assumptions:<br />6 week launch window every two years.<br />200 day one-way journey.<br />960 day minimum mission time.<br />?are lunar resources available?<br /><br />On Earth - Preparation Steps:<br />1) Mars Site Selection process<br />-----A) Best site for water.<br />-----B) Best site for minerals/resources.<br />-----C) Best site for exploration.<br />-----D) Best site for agriculture.<br />-----E) Best site for return launches.<br />-----F) Best overall site.<br /><br />2) Subsystem design & Earth testing<br />-----A) Air handling/management system<br />----------a) Air Circulation<br />----------b) Air pressure<br />----------c) Gas mix<br />---------------I) gas mix sensing<br />---------------II) gas mix adjustments<br />---------------III) storage of excess gases<br />----------d) Particulate/odor removal<br /><br />-----B) Communication <br />----------a) directional/omni-directional <br />----------b) high/low gain<br />----------c) command encryption methods<br />----------d) interface type/style<br />----------e) what telemetry, from what systems is returned?<br />----------f) blackout windows<br /><br />-----C) Electrical<br />----------a) primary system<br />----------b) backup system<br />----------c) battery capacity<br /><br />-----D) Food<br />----------a) menu diversity<br />----------b) storage issues<br />---------------I) How long can each storage method keep food safe?<br />---------------II) How to supply “fresh” food?<br /><br />-----E) Temperature control<br />----------a) What methods of heating/cooling are available?<br /><br />-----F) Waste management/recycling<br />----------a) What different types of waste will be produced?<br />---------------I) Paper<br />---------------II) Plastic<br />---------------III) Metal<br />---------------IV) CO2<br />---------------V) H2O (sweating/respiration/cleaning)<br />---------------VI) Urine<br />---------------VII) Fecal<br />---------------VIII) Methane<br />---------------IX) Other ou

 

[arobie]

Ok Wow! Thanks Dan! <img src="/images/icons/cool.gif" /><br /><br />Looks great and shows what we have and have not decided. We have much to fill in.<br /><br />The best way to use this "checklist/ongoing summary" is to try to systematically fill it out, but first we have an issue to resolve. As said before, it's time for a management decision on our propellant and electricity source. There has been alot put out on this topic over the past few pages, and I think it's time for a definitive decision...so I hope Spacester will drop by some time soon to help us out.<br /><br />We need to finish working out our Interplanetary Spaceship, both the manned and the unmanned. It's the workhorse of our plan. We need to have it fleshed out. We have decided and calculated much about it, but we're not done. Along that line, there are two things I would like to comment on about what you have for it. <br /><br />The first this has to do with the amount of water needed for drinking, hygine, etc. In your calculations, you don't account for water recycling. We should figure that. What did we give it, a 90% efficiency in recycling water?<br /><br />With 90% efficiency, we would have to bring 67,900 kg of water instead of 672,000 kg of water.<br /><br />The other thing, I'm sorry to point out, is a simple mistake. For personal items, the total mass is 2,800 kg instead of 28,000 kg.<br /><br />About the habitats in the manned version, Bigelow's Space Habitats look very promising. For some numbers to play with, one of their habitats weighs 25 tonnes and has an area of 330 cubic meters. How many people could live in that area? Can seven people live comfortably in that space? <br /><br />That would be four habitats attached to the trusses coming out from the hub attached to the booster. <br /><br />On top of the hub, there is a storage/cargo compartment. Do we want to store our water, food, and oxygen there?

 

[dan_casale]

>>The other thing, I'm sorry to point out, is a simple mistake. For personal items, the total mass is 2,800 kg instead of 28,000 kg.<<<br />Actually the error is that the amount per person should be 1000Kg. (after all we are asking them to leave home for at least three years.) I'll make the correction.

 

[spacester]

Well done, my friends! I'm back.<br /><br />Golly, Dan, I had to go pretty deep into your outline just to find the first thing to quibble with! What a fun read for me. <img src="/images/icons/laugh.gif" /> I have a few edits for the outline but that will have to wait. Nothing mission critical, so no prob with waiting on that. I invite others to look over the outline and offer proposed corrections. But that latest outline post is the de facto standard, I can sign off on it it a general sense. Agains, edits to follow, hopefully soon. For now, to address Arobie's questions . . . <br /><br />Great work, Dan!<br /> <div class="Discussion_UserSignature"> </div>

 

[spacester]

<font color="yellow">As said before, it's time for a management decision on our propellant and electricity source.</font><br /><br />The decision has been made, but we have a vociferous dissenter. He makes a valid point. But it comes down to, in this qualitative judgment, the fact that we need to bind something to the Hydrogen to store it efficiently, and the fact that Mars’ atmosphere is mostly CO2. There’s a reason Zubrin picked CO2/CH4 – it’s doable and shouldn’t be all that challenging.<br /><br />As I’ve said twice before, until someone shows me some <i>numbers</i> – a quantitative analysis - we’re going with the same choice as Mars Direct.<br /><br />A major question in my mind is the ease, or lack thereof, of constructing a rocket engine for our propellants of choice. AFAIK no one has ever built such an engine. Can someone start a thread on this question?<br /><br />So it’s CO2/CH4 until I see numbers demonstrating the superiority of LH2/LOX, assuming we can build such an engine.<br /><br />Now that doesn’t mean I’m against the use of lots and lots of water as the foundation of our ‘survival robustness’. It just means that we’re going to have separate fluids for the propulsion system versus the power system.<br /><br />I’m not going to take for granted any more than 10% water recycling efficiency. Yes, I know that it is easily achievable, much higher than ten percent, but that’s not the point. The point is that a single system failure of the main recycling system isn’t going to ruin your whole year. I say, bring all that water, use it as shielding, be wet and cozy and shielded and take hot showers and spas and saunas and be in the picture of health when you arrive with the rest of your small army of 28. Turn all that fresh water into greywater, process the black water as much as possible, and after you depart the orbital craft for the surface, the systems can begin turning that grey water into freshwater for a return journey.<br /><br />Which means I want a lot <div class="Discussion_UserSignature"> </div>

 

[arobie]

Good to see ya Spacester! Welcome back out of the real world.<br /><br /><font color="yellow">IOW, if you budget for low consumption but low recycling, how does that match up with the consumption rate assuming water-rich and efficient recycling?</font><br /><br />Ok.<br /><br />Assumptions:<br />12 kg of water per person per day is bare minimum.<br />50kg of water per person per day is luxurious.<br /><br />For our bare minimum water consumption at the low (10%) recycling efficiency rate for a 200 day trip, we would need 2172 kg of water for one person. 60816 kg for 28 people.<br /><br />For luxurious consumption with a high (90%) recycling efficiency rate for a 200 day trip, we would need 1050 kg of water for one person. 29400 kg for 28 people.<br /><br />Now in an emergency, we would go by the bare minimum/low efficiency amount of water. As you said, we plan on bringing that amount of water as a safe quard. Since we are bringing that, the amount of water one person could consume with a 90% water recycling efficiency is 103.4 kg per day.<br /><br /><font color="yellow">How much room do seven people need? How much room do 28 people need? How about 14?</font><br /><br />I don't know. I'll pass this question along. Does anyone know?<br /><br /><font color="orange">On top of the hub, there is a storage/cargo compartment. Do we want to store our water, food, and oxygen there?</font><br /><br /><font color="yellow">Yes. That would be primary storage, I envision a robot on a rail to access food stores.</font><br /><br />I imagine access would be fairly easy. If the habitat is in anyway connected to the hub, we could just let the food, water, or whatever 'fall' to the habitats. Let our spin-gee gravity do the work for us. We would just have to disconnect the food containers from whatever is securing it down there and let them fall up to us.<br /><br />Everything else in your post, I have no quibbles with or can't add anything to. It sounds good to me. <i></i>

 

[arobie]

<font color="orange">Everything else in your post, I have no quibbles with or can't add anything to.</font><br /><br />Oh, wait. Nevermind. I've got a question.<br /><br />You said that spin-gee is easier with only 2 habitats instead of 4. <br /><br />How much easier?

 

[spacester]

It's a qualitative judgment, just an engineer's best guess at this point. To decide how much more trouble 4 habs are than 2, we'll have to get into more detailed design descriptions. Basically, we need to know how big the volumes need to be for 14 crew and for 7 crew, and then we can start to evaluate the difference between 4 and 2 habs.<br /><br />Two habs means we're spinning a baton with 3 big cans in the middle, 4 habs means we're spinning a cross with 3 big cans in the middle. Four trusses, not just two. More complicated hub design, double a lot of other stuff.<br /><br />It's perhaps more than twice as expensive to do 4 habs than 2 habs, all else being equal. Just a guess. <div class="Discussion_UserSignature"> </div>

 

[dan_casale]

here's an article about NASA having high schools design some hardware. This looks like an easy way to get lots of cheep hardware.<br /><br />----------------------------------------------------------------------<br /><br />Date: Tue, 26 Apr 2005 11:43:31 -0500<br />From: info@JSC.NASA.GOV<br />Subject: HOUSTON HIGH SCHOOLERS CREATE ASTRONAUT TRAINING TOOLS<br /><br />April 26, 2005<br /><br />Debbie V. Nguyen<br />Johnson Space Center, Houston<br />281/483-5111<br /><br /><br /><br />Report #J05-019<br /><br />HOUSTON HIGH SCHOOLERS CREATE ASTRONAUT TRAINING TOOLS<br /><br />Houston area high school students will present to NASA training equipment they built for International Space Station astronauts in a 10 a.m. Monday, May 2, ceremony at Clear Creek High School.<br /><br />Media are invited. The ceremony will be in the high school's auditorium, 2305 East Main St. in League City. Media planning to attend should contact the Clear Creek Independent School District Office of Public Information, 281/338-5803, no later than 9 a.m. May 2.<br /><br />The student-built equipment has been constructed under a unique program offered by NASA to high school students across the nation called High school students United with NASA to Create Hardware (HUNCH). The partnership gives students hands-on experience designing and constructing training hardware for Station and provides NASA a significant reduction in the cost of the training gear.<br /><br />The students' products include replicas of Station audio terminal units, panels aboard the Station that control communications among parts of the spacecraft and with Earth. Other hardware fashioned by the students includes Station stowage lockers, medicine cabinets and caution and warning panels that alert the crew of abnormal conditions.<br /><br />Last year, the program began with one Texas school and two Alabama schools. This year, it has grown to include a school in Montana, two schools in Alabama and seven schoo

 

[spacester]

Well,, I'll be hornswoggled! Looks like NASA stole my idea!<br /><br />Just Kidding, I can't be sure but I think I remember reading about that before, so maybe I stole the idea from them. We might of came up with it independently, I'm really not sure. Whatever, who cares, just for the record.<br /><br />Great program, NASA! Very encouraging. Of course, they'll never be able to grow the thing into the vast network needed for a PSA to work, if for no other reason than that they only have so many people available for public outreach.<br /><br />Which would be an issue for PSA as well actually. You need a lot of coordination and communication (and if we can provide the personal touch, even better) and that takes a lot of people. It's an organizational challenge to say the least, but we'll figure it out together. Affiliates will help (see the finance thread, my most recent post before this).<br /><br />But it's a great gimmick - you have the students make all your mock-ups and a lot of the test specimens. It's not like we're going to run out of projects for the vast network to work on.<br /> <div class="Discussion_UserSignature"> </div>

 

[north_star_rising]

Any effort, of any scale, Luna or Mars, aside, will require an advanced RLV / SSTO / ALT system and infrastructure.<br /><br />No such infrastructure is presently planned or in development!<br /><br />Expendable launch vehicles are not the way to go, and will never provided the needed launch capacity for any space program of scale! Dr. Werner Von Braun - Rocket Systems Genius - knew this, and proposed that NASA focus on this as its primary mission for post Apollo! We all know that never happened!<br /><br />See this web site, as it is a good reference on this issue.<br />http://www.skyramp.org<br /><br />Another good site of a developing effort in parallel with this is.<br />http://www.international-spaceplane-program.org<br /><br />If we are to get into space in any meaningful way, or to Luna or Mars to STAY! We must put the horse before the cart. ie: Focus our efforts and development of an advanced RLV / SSTO / ALT system and infrastructure and philosophy.<br /><br />Burt Rutan of Scaled Composites is one person who is struggling in this direction, and needs to be supported by the Space Community more than he presently is.<br /><br />Others like Kenneth House at NASA MEGLEV Space Launch Research Center is another person who needs to be supported more by the Space Community.<br />