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Tyr's right.
To do what you propose the spacecraft would have to carry twice as much fuel as it would it need to simply go and stop at mars (using it's engines, not aero-breaking) and much more than to simply get there and come back via a free return orbit. When ever you got to the stopping place, it would have spend essentialy the same amount of energy it has spent to get there to stop, and then spend that amount again to get back.
Here's a good in-depth lesson on orbital mechanics.
http://www.marsacademy.com/orbmect/orbles1.htm
Idea:
since Mars is full of silicates, why not to add a layer of Martian clean white sand of top of a hemispherical dome of material and then heat the sand layer layer until fusion occured, then removed the underjacent material to leave a pure bubble of crystal.first point: I think when you are on Mars you should always keep trying to use local materials rather than imported material from earth.
second point: at the beginning at least, some primitive techniques could apply to Mars, such as the egyptian techniques to move and raise big stones into pyramids, but also more generally artisanal techniques that have been replaced on earth by industrial production. I prefer to build myself my small silicate dome/house (like a big igloo) with my own artisanal techniques and with local materials rather than to always depend of the next shipping of titanium/kevlar/nylon ultramodern fabrics send from Earth.
A couple of problems with this idea.
#1. The glass would have to be extreamly thick to support the internal pressure of the dome. Glass does not have alot of tensile strength. There are various way's to augment it, but all make it more complicated to make, and some disrupt it's clarity.
#2. It would be vary hard to make glass in this manner, especialy in the thickness necessary. It would be difficult to cool, would warp in various manners, ect... all this would disrupt it's optical and strength properties, which are highly varriable for glass in any case.
But this idea could work very well for concrete or various plastics (as well as fiberglass which is somplace bettwen glass and plastic). But of course none of these are likely to be transparent either.
I agree with your secound point whole hartedly however, and I'm working on a paper that adress the potential for the production of various materials on mars.
I like this idea, however it strikes me that that the actual construction of the canyon habitat would be a great deal more difficult than that of a similar dome. You would need all kinds of cranes, cables, bridges, ect, ect.. on both sides of the canyon.
One problem however, is that for many breakdowns repair will simple be impossible either on Mars, or in space. A leak in the hab, for example is probably an easy fix. Malfunction of the propulsion or lifesupport maybe impossible to fix. Replacing the subsystem in some cases, such as propulsion may be impossible. Maintance in orbit will obviously be more difficult. While a "maintance hab" is a good idea, at least at one point. I think much of the equipment will probably be prohibtably heavy as would the stocks necessary for the equipment. However, this repair equipment could be used to build new equipment for new stuff which would always be good. Universal componets is of course and excellent and always a good idea.
Due to the low gravity and the very very low friction, you wouldn't want to build anything to heavy or you wouldn't be able to stop or turn.
Well you could if you built it pretty wide, and you went pretty slow, especialy when you turn.
I wonder how well cleted tires would work on Martian soil though...
Drag races on mars, could be very, very fun.
I was thinking, are regular air-inflated ruber tires realy necessary? Since the G is lower, could some other more sturdy material be subsituted, one that couldn't "go flat?"
Also, while certianly the idea of fast speed buggies on Mars is realy cool, I don't see the point. Faster = more dangerous = less fuel efficent = bad. Getting to place to place quickly is important, but getter there safely and cheaply will probably always be more important on mars.
It seems to me that at the start highly accurate navigation is not that necessary. Certianly knowing you possition down to the cm is extream for the start. The rovers don't have to drive themselves, the highly trained astronauts can do that as well.
Also not mentioned, but certianly VITALY important are MAPS! Without a map knowing where you are and where you want to go may be worthless because you may not be able to get there from here (like there's a big canyon bettwen you two). A good map can also help you figure out where you are by identifing the terrian features and landmarks. While Mars is not Earth it still will have prominate landmarks and landformes.
Even while in the boy-scouts my patrol and I had little trouble with 10-12 mile orientation hikes using just our compasses and a map. Certianly highly trained astronauts with good maps, sextants, and internal navigation will be able to do better than I, even on a alien planet over larger distances. Indeed in some ways the sparsness helps. In the woods my "horizon" was only a couple of hundred feet away, and I (and my buddies) could only transmit as far as our voices could carry. Since NASA has so many Eagle Scouts, shurely one of them earned his wilderness survival merit badage and can help find where they are. So only the slimist of GPS systems should realy be needed at the start.
Not to encourage the defacment of an virgin enviroment, but the astronauts could easily mark there trail as they go as well. This would slow them down certianly, but would make getting lost very difficult. It's funny to think of an some one in a space suit with a can of blue paint, marking his trail on a red-rock but such a system could be very effective.
To help facilitate the return to important areas they could carry small radio beacons with them as well. All that would be needed would be a little solar pannel and an antenna it probably wouldn't have to put out that much juice since all it has to do is beep (and not even that frequently, one a half-hour or so would be more than sufficent). Put these on diffrent frequencies, and once the come over the horizon they could tune in the frequency, and easily find the spot with a little simple trig.
Also, for safties sake more than anything else, astronauts shouldn't leave the base or the rover over the horizion anyways. Even on Mars thats more than a short walk, and they shouldn't get that far away from a hab or rover lest there suit rip or something if nothing else. So even if the astronaut does get lost on a walk, all he has to do is climb the nearest hill, he should be able to SEE the rover/hab but if not he should be able to pick it up on radio. And if that fails, he should stay put and the rest of the guys go look for him. Individual GPS units are overkill. You might need one in the rover, but it could have a large reciver so your satilite could be smaller.
Also, just because there's not a strong magnetic field doesn't mean you can't find your berrings. If you know the time of day you can use the sun, and at night you can use the stars.
To sume up, I don't think to much money and space should be wasted on navigation on Mars which realy shouldn't be that difficult. Good maps (important in any case), maybe a satilite or two to help find position, good use of radio transmiters, and some basic stuff in the rovers (sextant, computer, ect...) and any Eagle Scout should be fine.
It seems to me that at the start highly accurate navigation is not that necessary. Certianly knowing you possition down to the cm is extream for the start. The rovers don't have to drive themselves, the highly trained astronauts can do that as well.
Also not mentioned, but certianly VITALY important are MAPS! Without a map knowing where you are and where you want to go may be worthless because you may not be able to get there from here (like there's a big canyon bettwen you two). A good map can also help you figure out where you are by identifing the terrian features and landmarks. While Mars is not Earth it still will have prominate landmarks and landformes.
Even while in the boy-scouts my patrol and I had little trouble with 10-12 mile orientation hikes using just our compasses and a map. Certianly highly trained astronauts with good maps, sextants, and internal navigation will be able to do better than I, even on a alien planet over larger distances. Indeed in some ways the sparsness helps. In the woods my "horizon" was only a couple of hundred feet away, and I (and my buddies) could only transmit as far as our voices could carry. Since NASA has so many Eagle Scouts, shurely one of them earned his wilderness survival merit badage and can help find where they are. So only the slimist of GPS systems should realy be needed at the start.
Not to encourage the defacment of an virgin enviroment, but the astronauts could easily mark there trail as they go as well. This would slow them down certianly, but would make getting lost very difficult. It's funny to think of an some one in a space suit with a can of blue paint, marking his trail on a red-rock but such a system could be very effective.
To help facilitate the return to important areas they could carry small radio beacons with them as well. All that would be needed would be a little solar pannel and an antenna it probably wouldn't have to put out that much juice since all it has to do is beep (and not even that frequently, one a half-hour or so would be more than sufficent). Put these on diffrent frequencies, and once the come over the horizon they could tune in the frequency, and easily find the spot with a little simple trig.
Also, for safties sake more than anything else, astronauts shouldn't leave the base or the rover over the horizion anyways. Even on Mars thats more than a short walk, and they shouldn't get that far away from a hab or rover lest there suit rip or something if nothing else. So even if the astronaut does get lost on a walk, all he has to do is climb the nearest hill, he should be able to SEE the rover/hab but if not he should be able to pick it up on radio. And if that fails, he should stay put and the rest of the guys go look for him. Individual GPS units are overkill. You might need one in the rover, but it could have a large reciver so your satilite could be smaller.
Also, just because there's not a strong magnetic field doesn't mean you can't find your berrings. If you know the time of day you can use the sun, and at night you can use the stars.
To some up, I don't think to much money and space should be wasted on navigation on Mars which realy shouldn't be that difficult. Good maps (important in any case), maybe a satilite or two to help find position, good use of radio transmiters, and some basic stuff in the rovers (sextant, computer, ect...) and any Eagle Scout should be fine.
While far out there anti-matter is also an option. With its obscenely high conversion efficency you could use it to heat your propelent far more than any other other option could possibly begin to. However, producing it difficult (and expensive) and contaning it is next to impossible (and very, very expensive). But heck if you want matter to produce you some energy, anti-matter has by far the highest possible returns. Probably the highest possible, if true total conversion of matter is impossible. Of course cost wise, a fusion rocket would probably beat it pants of unless a (much) cheap method if found of producing it.
Another fundemental issue to consider is this. No matter how efficent you engine is. Lifting and accelerating large amounts of matter into orbit requires a set amount of energy. You can change the timeframe on which this is released but you can't change the amount. Anytime you assemble this amount of energy in one place you must also consider the risk that it might accidently go off in a critical manner (ie. all at once). And when you're dealing with such large amounts of energy, you have to be careful that you don't blow the place your launch pad is in off the map.
Also, anytime your dealing with heating a propelent. You also have to find a way to deal with the wasted heat this will build up on your rocket. Unless you want it to melt, which you probably don't. This tends to be the limiting factor for many types of engines (NTR, ect...). If you find a better way to deal with that wast heat you can generaly heat your propelent faster and thus have a higher ISP.
Regardless of weather or not liquid fission is possible or not, I bet the key limiting issue for these types of enginges will be heat. Whatever you intend to push these very hot gasses agianst is also going to get very hot. And there are limits to what amount of heat any substance can take. As I understand it you could use a nuclear reaction (be it controled as in a reactor or runnaway as in a bomb) to heat your propelent up practicly as much as you could desire (well maybe not but you could make it realy, realy hot). But you have to find a way to hold onto this hot gas long enough for it to give you some thrust. You can refrigerate you plate (like they do on most modern chemical engines), make it realy thick (like with car engines), give it a high melting point (jet engines), let it radiate is some how, or whatever. But you've got to deal with that waste heat somehow. Or do I misunderstand things entirely?
Unrelated and even contradictory to what I just said. It ocurs to me that you could heat up chemical propelents before you combust them (although combustion maybe more difficult at high temperatures). Modern engines already do this, but not on a very large scale. You might be able to, for example, heat you LOX/LH up with a nuclear reactor and then combust them. Assuming combustion is possible, I don't see any theoretical reason why the temperature (and thus velocity) wouldn't add up. Practicly there might, of course, be some difficulties (like what I mentioned above). What do you think?
While I would certianly be cautious about landing on the Poles due to the difficulties of terrian there. From my experince here on Earth, Glaciers (or for that matter larger bodies of ice anywere on earth), would make terrible landing sights due to large crevasis, hidden caves, and generaly unstable terrian (not to mention it's inherint slipperyness). The yearly sublimination of CO2 ice from the poles doesn't make me any more comfortable either. However, Mars is a diffrent planet than Earth and so the glacial landforms may be very diffrent.
Also on such a mission you douldn't cout on just hanging around on the surface until another assent/return vehicle could be sent to you if yours malfunctioned. Winter and night would come and you would be up the proverbiale creek. It might be wise to send two such vehicles at the start.
I also tend to think that the potential for scientific investigation might not be as great on the poles as it would be elsewhere. The terrain might limit your travel options. However, such a mission would certianly have unique scientific oportunities as well.
It cannot be forgoten that it is well, colder on the poles, then it is elsewhere on the planet. Which may cause some additional hardships. As well as the fact that all that ice will make footing more dangerous for the explorers (even with crampons and the like).
What about weather on the poles? on Earth the weather on the poles is generaly much more sevear (in many ways) than elsewhere on the planet. Even with Mar's less-dense atmosphere this should be considered. Maybe wind-power would be more attractive on the poles?
Finaly a perminate facility while difficult is not necessarily impossible. While the weather and CO2 situation makes putting something on the surface next to impossible. The situation may not be the same beneath the surface! Like in Kim Stanley Robertsons Green Mars, book a habitat under the ice might be possible. Construction would be relativily simple, and insulation would be great. Shifting of the ice might be a problem though (don't know if that is a factor on the Martian poles).
One problem that occured to me is that the reliability of these components can probably not be counted on over a very long period without regular maintance and replacment which may be difficult to impossible for some of these craft. You shouldn't count on a object you launched 14 years ago to be highly reliable today. In fact, it will probably have already failed. Habs will spring leaks, engines will break, life-support and other systems will all breakdown in various ways. The craft and habs used in this program will all have to undergo maintance and more than likely replacment, which should be counted for.
Also, since this program extends over a long period of time. I think it would be realistic to assume that over this period of time technological advancments will make various upgrades possible. Any program extending over such a long period of time should hopefully have some hand in directing that technological advance would occur (especialy since this would be by far the most expensive program NASA would be undertaking at the time).
Third I feel strongly that utilising nuclear power can add so much to a martian mission that it should be included in the cards at some point, at least at some point. A nuclear reactor on the surface, and NTR to deliver crew to mars as well as to lift objects once there to orbit (and back perhaps).
Another problem that cannot be ignored in both Mars exploration and colonization is food.
Generaly speaking, food cannot be kept "fresh", or in a ready-to-eat fashion for long periods of time. Even food kept safe from bacterial and fungal contamination will eventual break down from heat and other sources.
So most food is kept in some in-ediable (or at least un-appitising fashion), and then cooked before it can be consumed. On earth this posses little problem. However, in a zero-G or enclosed hab enviroment, several other factors need to be taken into consideration:
Safety. A fire breaking out in space or in a hab on Mars would be VERY, VERY bad news. Open flames are absolutly forbidden, and ovens, broilers, and friers likely would be as well. Even the beloved microwave could potentialy be a risk.
Efficency. Weight must be kept to a miniumum, both in cooking equipment, and cookware which must be disposed.
Enviroment. Most proposed habitats (both in space and otherwise), would have signifigantly diffrent air-pressures and make-up then is found on earth. This can also effect the cooking process, and must be compenstated for.
So, what do you think, how should food preperation be handled?
Well, Uranium and other fissionable isotopes certianly exists on mars. It certianly would be possible to mine them, and refine them there as well eventualy. A CANDU style reactor (uses heavy water as a moderate) could even be used so that refinment would not be necessary.
A solar power tower, and other solar-mechanical systems are also good alterntives to the various nuclear alternatives. Focus a bunch of sunlight on a fluid to heat it up and turn a turbine. Many of the bulky materials could be refined on the surface, it's simple, and can produce a good amount of power-output on a clear sunny day.
About transporting nuclear fuel into space, the Mars program wouldn't be the first, IIRC the USSR used to have spy-satilites powered by nuclear reactors (not a RTG) as well. One in fact de-orbited (AKA crashed), over Northern Canada, although the actual amount of radioactive polution was negligable.
-off the topic-
Breeding reactors can make use of most of the so called "nuclear waste," only the actual products of Fission deserve to be called waste, and there half-lifes are very short (less than 30 IIRC). Certianly the amount of waste is tiny compared to that of the other options, such as coal.
About transporting nuclear fuel into space, the Mars program wouldn't be the first, IIRC the USSR used to have spy-satilites powered by nuclear reactors (not a RTR) as well. One in fact de-orbited (AKA crashed), over Northern Canada, although the actual amount of radioactive polution was negligable.
-off the topic-
Breeding reactors can make use of most of the so called "nuclear waste," only the actual products of Fission deserve to be called waste, and there half-lifes are very short (less than 30 IIRC). Certianly the amount of waste is tiny compared to that of the other options, such as coal.
Well the refinment of Silicon for the production of solar pannels (as well as the refinment of the dupping materials) would undoubtably take oddles of energy, especialy heat energy. So a nuclear reactor would probably be necessary just to get the party started anyways.
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As an aside, even if a disaterious nuclear accident (Meltdown)was to happen on Mars, the end result probably wouldn't be that bad. There's little risk of people in Space suits growing dome-grown food breathing or eating radioactive materials, and the additional radiation would proably be nothing in comparission to the normal background radiation on Mars anyways. The biggest threat to any growing settlement would probably be loss of power.
Well, I'm certianly not a nuclear engineer or an expert in steel refining, but I'm sure nuclear power could be harnesed directly to help in refining steel.
A nuclear reactor could be used to greatly heat up concentrated martian air, in place of Coke which is typicaly used on Earth. Crushed steel-ore and limstone would be placed into the furnace where it would be heated, then tapped off into Steel beams. Most of the Carbon and other impurities necessary for steel would probably be present in great quantities in the Ore anyways, and would have to be refined out, not added in.
At least this is one semi-convential method (replacing nuclear heat for coke) which might work. I'm sure there are other possible methods (like electro-arc) which also could be engineered to work on the Martian surface.
The steel produced at the start would no doubt be low-quality. But since great amounts of it could potentialy be produced, and even low-quality steel would be MUCH stronger than brick, I think steel production on Mars has lots of potential.
Well with all this manufacture of bricks (and even magnesium beams), underconsideration, the use of other construction materials should also be thought of, specificly steel. Certianly steal-beams could be used more effectivly in many places than bricks.
The real question becomes, how much more difficult would it be to creat steal beams, and compare that to the difficulty of manufacturing large quantities of brick.
A Nuclear Reactor is realy the only way to go. No other option can generate as much power for so little mass. It can do it 24 hours a day, regardless of weather. It also produces large amounts of waste heat which might be utilisable. It is also highly reliable, although the other alternitives certianly are not defficent in this area.
Solar Power is good for a back-up system, but would be much heavier than the comparible nuclear system. A solar pannel system would have good reliablity as well.
Fuel Cells (or other combustibles), are even worse than solar-power in terms of mass. However they are an excelent way to save power generate by other means (Solar or Nuclear), in case of a power-failure.
Wind Power, again are even worse than solar power in-terms of weight, and are not as reliable.
Geo-thermal power cannot be expected to be extracted on the first few missions. And so is not even an option.
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In terms of a existing colony, things change. While nuclear is still VERY attractive (especialy breeding reactors which could produce even more fuel), Solar-mechanical systems and Geo-thermal start to catch up. Where geo-thermal power is avliable it is clearly the choice, if only for the water. Solar-mechanical power performs slightly worse than nuclear power, but is lower-tech and so easier to engineer nativly, rather than having to bring it from earth. Solar pannels and wind power are simply to heavy for there power, and not reliable enough to be adquet.