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*I'm not so well versed in this regard. We've discussed various modes of transportation, and perhaps this particular has been discussed before (it's been years, and perhaps I've forgotten)...
Okay, so it's cold on Mars. What about nuclear materials to heat and run the engines of trains, other land vehicles, etc.?
Maybe I'm way off, but thought I'd ask. ::shrugs::
--Cindy
We all know [i]those[/i] Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...
--John Sladek (The New Apocrypha)
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You would need something like this if you wanted to explore any great distance from the base.
Dig into the [url=http://child-civilization.blogspot.com/2006/12/political-grab-bag.html]political grab bag[/url] at [url=http://child-civilization.blogspot.com/]Child Civilization[/url]
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We have to look at the different ways to generate power to power all the transportation to get Mars and power everything on Mars that we want to do.
There this idea called energy density. Basically what it is, is the amount of power that can be generated by a particular energy conversion process. The best way to show it will be to use a graft. I can't put any picture of one up, so I will make a home made graft of energy density.
Amount Wood Coal Gas Fission Fusion Antimatter
of
energy *
Produced *
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This thing not totally accurate and not a really good graft either, but it illustrates what we are talking about. When dealing chemical process, which are the first three, you can see they produce less energy than the last three which are nuclear. Wood produces about half the energy than coal does and produces waist to that burned for coal to energy produced. Gas produces more energy per pound than coal does and generates less waist. Fission potential energy density is several hundred time to over thousand times the energy density of these chemical process and it produces less waist to the amount of energy it produces. Fusion potential energy two or three that of fission with virtually no nuclear waist to the amount of energy produced. Now Antimatter potential process would produce over a thousand times the energy of a fusion process and waist would be nil in comparison too.
Looking this over, you should be able to answer your own question: Why nuclear power? And why is it importune?
It should be self-evident, it the only power source that could power a self-sustaining colony on Mars and power development and terraformation of the planet Mars. Without this power and development to a higher levels of the nuclear power above fission, we won't be doing much more than having temporary camp sight on Mars and having great science project, but not a whole lot more. As we move to these higher levels of energy that can be produced, we can do more things, because we have power to do it. We are also solving technological problems old boundaries fall and we are doing things that we could not do before. That why we should always be pushing to the high of developing technologies and generating power and means nuclear power too.
Larry,
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Antimatter does not occur naturally; it can't because it would annihilate instantly upon contact with normal matter. Contrary to some science fiction shows, any anti-neutron will instantly annihilate upon contact with any normal neutron. Both are converted into energy; 100% mass to energy conversion, but the energy density is sufficient that some energy may spontaneously convert into matter. The same thing happens when an anti-proton contacts any normal proton, or a positron contacts an electron. Positrons and electrons don't have much mass so they don't release much energy, and spontaneous energy to matter conversion doesn't happen often because there isn't much energy. But this means a hunk of antimatter will not be lying around.
Controlled synthesis of anti-matter is a very inefficient process. I saw an interview with one researcher who said when the Fermilab nuclear accelerator is used to make antimatter it uses enough power to supply a town, but only generates enough antimatter to power a single 40 watt light bulb. Antimatter has to be considered energy storage, not an energy source. To generate power look at fission, fusion, or natural power sources like solar, wind mills, tidal harness, or on a global scale capturing solar wind with a planetary magnetosphere.
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Energy density is important and all, but its not just about the energy per mass of fuel, its the total mass of the reactor and its associated systems too. For transportation, the total weight of the system is very important, and no fusion or antimatter system will likly be possible for a mobile power plant because of their very large minimum reactor size. A Fission reactor can be built that is pretty compact, but its problem is the associated shielding and cooling systems, which make a really mobile reactor impractical. A Fusion reactor needs big coils for plasma confinement and so will an Antimatter containment bottle, and both will still need radiation shielding (neutron and gamma respectivly). Another problem for mobile Fission is decay heat, that even if you turn the reactor off, it will continue making heat for weeks or months.
For mobile applications, chemical energy storage is clearly a much easier proposition, with a light weight "reactor" (a turbine, fuel cell, or even a piston engine) that doesn't need shielding, that can turn on and off basicly at will (Fission decay heat, Fusion startup time), is easy to refuel (Methane, Methanol, Hydrogen, LOX, Peroxide, etc) and requires no thermal-to-mechanical/electrical conversion or massive radiators.
As for stationary applications, sure Fusion would be nice, but Fission really hasn't been given a shot beyond running scaled-up submarine reactors for electricity here on Earth. A pebble bed reactor small enough to fit on a truck could crank out 200-300MW continuously without much trouble, and building those in number could provide terraforming-class power supplies. A "farm" of them could power a fairly modest Martian city too.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I agree with GCNRevenger on this issue. We know how to make fission reactors, not a practical fusion reactor, but fission has two problems: radiation and a heat sink. Efficiency of a heat based power plant is highly dependant on some place to dump the heat. Air on Mars is cold, but it's very thin; difficult to cool something. A power plant as a building can have cooling coils buried in the ground. How deep, how long the coils need to be, what heat sink fins if any are necessary, are details for a nuclear engineer. This means a fission power plant is just a matter of engineering, but a nuclear vehicle is much more difficult. In the late 1950s the US military designed a plutonium RAMjet cruise missile to carry fusion bombs, but that used an unshielded reactor because no one was onboard and a deployment system for a multi-megaton thermonuclear bomb didn't have to worry about radioactive waste in its exhaust. In fact, after deploying all its bombs they planned to send the missile over another Russian city and fly back-and-forth spewing radioactive waste until the nuclear material ran out. A vehicle for civilian use can't do that. A nuclear rocket works because it operates in space where radioactive exhaust is so much less than radiation from our Sun that it's like adding a teaspoon of water to the ocean. Crew on the rocket don't have to worry because nuclear thermal rocket (solid core or vapour core) uses liquid hydrogen as propellant, and a tank of that is the best possible radiation shield. But it's too large for a ground vehicle. Ground vehicles can be easily powered by traditional chemical fuel produced at a refinery powered by an advanced power plant.
There is one exotic fuel for Mars: magnesium powder blow into the jet engine with nitrogen gas will burn in a CO2 atmosphere. Which means this fuel will power a RAMjet engine on Mars.
One comment about fusion power: magnetic containment of a Tokomak reactor will always consume more energy than the reactor produces. A commercial fusion power plant will require an entirely different design. I have suggested a form of inertial confinement. Use deuterium gas that's normally too cool and too low density for fusion, but direct it through a wind tunnel with a constrictor that creates a supersonic shock wave. Engineer the shock wave to focus at a point within the gas in such a way that the temperature and pressure is sufficient for fusion. This will permit fusion combustion at that point within the gas flow. Exhaust gasses will quickly expand so that downstream from the constrictor it won't combust, and hot gas will expand and cool. Ensure that it cools sufficiently that it won't melt a super-alloy such as inconell or a high-temperature ceramic, and make the downstream tunnel walls out of that. This permits solid walls to contain the stream, not magnetic containment. Once you have fusion within solid walls, it's just a matter of heat exchangers, turbines and/or Peltier effect devices to convert that heat into power.
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Anyway as far is vehicles go, obviously there are nuclear power ships and submarines. Of course those vehicles are a little bigger then a transfer truck.
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*Another ignorant question: Can nuclear material be stored in (searching for descriptives :hm: ) small, removable (insertable and extractable) compartments/containers? Like a car's battery, for instance? Can it be recharged? I mean for use on Mars, of course.
Don't know why this suddenly has me curious, but whatev...I'm going with it. Thanks for the responses so far.
Feel free to laugh...I probably sound like a loon (unintentionally of course).
--Cindy
P.S.: If there's one thing I've learned about antimatter, it's this: If it's about to blow up your spaceship, climb up the red ladder in the Jeffries Tube with a silver wrench and bang on the pipes until it switches back over to normal. It worked for Scotty. -laugh-
We all know [i]those[/i] Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...
--John Sladek (The New Apocrypha)
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Travel on Mars is going to be fundimentally different then it is on Earth; air travel, by and large, simply is not going to exsist. A jet engine powerd by burning magnesium powder with nitrogen and carbon dioxide would be a horrible waste of precious nitrogen, and could very well be unworkable because of the solid fuel and combustion products... But that is not that important, because the air on Mars is so thin, wings, rotors, and turbines don't work. The only flying going to be done on Mars is by small balloons, ultralight unmanned airplanes, and rockets. Probobly methane/LOX powerd ones.
For large-scale travel on Mars, airplanes and rockets are out of the question for everyday movement, but with the thin air comes one advantage over Earth, that maglev trains can go faster. Much faster. Just as fast or even faster than airliners on Earth today in theory, or lower speeds more easily. If you are going beyond the Martian domes and burrows, probobly getting around town on subway trains, you'll be doubtless taking a train.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Uranium is easy to store. I keep talking about a video from Ontario Hydro of nuclear workers loading uranium into fuel rods. They wore white lab coats, a plastic shower cap over their hair, a paper filter mask over nose and mouth with a thin elastic around their head, and the same loose plastic gloves that come with oven cleaner. They stuffed uranium oxide powder into steel tubes to form fuel rods. Uranium is not chemically toxic, it's just a metal. However, it is a low-level radioactive material. As long as your exposure is short, it's quite safe. The filter mask, shower cap, and gloves ensured uranium didn't get into workers bodies. This demonstrates that anything that contains the uranium is good enough. You could enclose it an a plastic box like a battery, or stainless steel tubes like a CanDU reactor. If your intent is to stick it into a reactor, then the container has to endure the inside of the reactor. That means it can't be something that'll melt in the reactor; stainless steel sheet metal will do.
The big "however" is getting the stuff out. Uranium occurs naturally in a mineral called pitchblend. But when it comes out the atoms have been split into isotopes that break down rapidly. Those isotopes have a short life, most of the radiation lasts a couple months, but that same short life means they emit a lot of radiation quickly. Those isotopes are called "fast and hot". Reactor rods are removed by robots with several feet of lead or concrete between the rods and any workers. Spent rods are stored at the bottom of a pool of water, several feet deep. Pools are typically 40 feet deep, but rods are stacked 14 feet above the bottom. Studies have reported that a minimum of 8 feet of water is needed to keep radiation below acceptable levels. So removing spent fuel from a nuclear car, or operating the reactor with people on-board, is difficult.
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the air on Mars is so thin, wings, rotors, and turbines don't work.
NASA has already built an unmanned airplane that can fly so high on Earth that the air is as thin as Mars. On Earth it's a lot higher than it would be on Mars, but the thin air is enough to support wings. A manned aircraft would have huge wings, so it may be impractical, but I wouldn't call it impossible.
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Uranium metal is fairly chemically toxic, which is why it is converted to Uranium Oxide before being used in nuclear reactors, like the CanDU. Normally today, it is used in the form of ceramic pellets about half the size of a AAA battery, placed in long metal tubes many feet long, and bundled into an array for easy handling. For a small semi-portable space reactor, the fuel will be in fatter pellets and will probobly be weapons grade pure Uranium metal, and the reactor cooled by liquid alkalli metals.
Future reactors may very well be of a type called a pebble bed reactor, where the fuel is in tiny pin-heard sized granuals that are wrapped in Silicon Carbide, grouped in another Carbide sphere a bit bigger then a golf ball, and that wrapped again in Graphite to yeild a sphere about the size of a tennis ball.
Yes yes NASA did build a super-ultra-mega-light plane that could work in Martian air, but it is so slow, the payload so small, and takeoff/landing/handling so hard that it isn't useful for air travel. No vehicle that derives its lift entirely from wings is going to be much good for getting across Mars.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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So we'd need special facilites near, but not too near, to base camp to house the stuff.
"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane
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Helios wasn't that slow; potentially, about 150 miles per hour. It moves us into the pre-turbojet era on Mars, basically. I've never seen anything about the length of runway; have you? If so, I'd like to see. The payload was 1/7 of the vehicle's total takeoff weight; 150 kgs out of 1050.
In twenty years, we may be in the position to build lighter, faster, more reliable solar-powered planes on Mars. Higher efficiency solar cells will reduce total vehicle mass. New materials will make the structure lighter. A berylium thermal storage tank and liquid carbon dioxide could provide vertical take off and landing ability, or at least supplemental power to shorten the runway needed. I wouldn't write off solar-powered airplanes yet. In *Mars on Earth,* Zubrin briefly describes Twin Otters as "the workhorses of high Arctic travel"; "they have a crew of two, and seat seven people, or alternatively, can carry a cargo of up to 1000 kilograms." Based on the Helios, such a vehicle would have a mass of 7 to 8 tonnes.
--RobS
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Only 150mph? Actually yeah, that is pretty slow, less then double what what a ground vehicle could do on roads, and a quarter (or less) of a maglev train. Also, there isn't going to BE a turbojet era on Mars, since there are no practical fuels in the nearly inert Martian atmosphere.
The fact of the matter is that Helios was flimsy. It is a fragile aircraft, and making a big one for everyday air travel is a very bad idea. Helios is already using pretty advanced solar cells, light weight composits, etc... with advanced technology you might be able to make it carry a useful payload or be sturdy enough for day-in/day-out travel, but not both.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Antimatter does not occur naturally...
Neither does free hydrogen gas on Mars, but you can run an engine on the stuff.
Chemical propellants really are the best fuel for a mobile vehicle, but they have to be made from something unless you just find them lying around. That takes power - more than can be released from the stored chemical fuel. So, unless someone strikes oil on Mars, all those chemical fuels the settlers need are going to have to be made using another power source.
Nuclear seems as likely a source as any. For example, the Mars Direct mission profile proposed a rover powered by fuel that was made using a nuclear reactor (essentially stored energy from the reactor).
I think we'll be seeing a lot of "nuclear powered" vehicles on Mars. The reactors will just be on either end of the trip instead of on the vehicles.
"We go big, or we don't go." - GCNRevenger
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I think the key to long range ground travel on mars will be convoys of chemicaly powered vehicles towing nuclear reactors and propellant plants. This should help to solve the problem of neutron radiation. When a nuclear reactor is shut down, the neutron flux is MUCH lower, pretty much negligable, so it could be towed a short distance from a vehicle. When the convoy starts to reach the limits of there fuel endurance they can stop, setup the reactor and propelent plant, fill it with their surpluse water, and move a safe distance away and carry out scientific activities. They activate the reactor remotely, and in a short period of time, it will have produced more than enough fuel to fill up there tanks. At which point, they can remotely shut down the reactor, approach it, fill up there vehicles, and move out. Oxygen could be produced at the same time as well.
The only remaining problems I see would be how to deal with the reactor waste heat (probably bulky and heavy radiator fins), and having a rover buff enough to tow the assembly which will probably mass several tons (just bigger rovers). Neither of these seem insolvable.
This would permit a convoy of methane/methanol powered ground vehicles to travel as long as there supplies of hydrogen/water (which should be recycled) and consumables last. Another limiter would be human endurance, both in the rather cramped quaters of a rover, and existing on an atmosphere of pure Oxygen, which is probably a bad idea for long periods of time.
Failing this, there is no reason why a chemicaly powered vehicle could not simply tow a large fuel tank behind it to help increase endurance.
The only problem with ground transport on mars is that some large sections of the terrain are probably dowright impassible, such as the Marineris canyons. Many obsticals can probably be avoided, or bypassed, but Mars also has some extream surface features that are contental in extent, and getting around them is bound to be very difficult.
He who refuses to do arithmetic is doomed to talk nonsense.
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A nuclear powered exploration vehicle is possible but not efficient when compared to a combined fuel cell and solar powered one.
Where does the crew move out to when the reactor is running?
Oxygen can be produced. How so? The carbon dioxide to oxygen conversion machines produce such a small amount that it would take 144 of them to produce enough oxygen for one sleeping human.
Also the weight of the smallest reactor is one ton at least. This means that you have less than a ton to build the rest of the vehicle out of or it won't be within the Mars Direct weight limit.
Methane powered? I thought you were promoting nuclear power?
Also mars vehicle design has been debated extensively in the following posts: Simple Mars Vehicle, Simplest Mars Vehicle, and Combustion Engines on Mars posts.
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A nuclear powered exploration vehicle is possible but not efficient when compared to a combined fuel cell and solar powered one.
I don't know about that. It's probably not possible to power both propulsion and life support systems off of solar power alone. It is difficult enough to manage propulsion alone of a system on Earth, let alone on Mars, where the sunlight is weaker. Adding the power requirments of life support, and it is pretty much impossible, especialy when you need a high performance engine to move a realitivly heavy rover over rough Martian terrain. I mean look at the Solar Racers, those things use every weight saving trick in the book and still have some difficulty a single rider over smooth roads.
But fuel cells augments with solar power are propably far more efficent when it comes to being an energy store than a nuclear reactor, since the reactor has to carries all the fuel necessary for its entire life in addition to a heavy reactor. So in the short run, fuel cells (and chemical stores) are supperior. But nuclear power offers potential unlimited range, which other sources cannot match for any amount of mass. So in the long run, nuclear power is more efficent by default. The question is, will rover excursions be long enough to make nuclear reactors worth it. I think initaly no, but eventualy yes, you will want rovers that can traverse the entire planet if necessary.
Where does the crew move out to when the reactor is running?
Under my proposal the reactor is carried on a detachable trailer which is depositied a safe distance from the manned rovers (behind a hill or something) and then activate remotely. After the reactors buisness is done, they deactivate it, go back, hitch up the trailer, fuel up and move out. The rovers themselves are chemicaly powered, with the reactor producing the necessary fuel for them.
Failing that, a reactor would have to carry some neutron shielding to protect the crew. This is probably do-able (vehicles on Earth do it) but it would adds mass, and would best be avoided.
Oxygen can be produced. How so? The carbon dioxide to oxygen conversion machines produce such a small amount that it would take 144 of them to produce enough oxygen for one sleeping human.
With the several kW of power that a nuclear reactor would provide, you can utilise much more industrial methods of oxygen generationg. Such as the sabatier process and electrolisis or carbon dioxide electrolisis. The sabatier process will be necessary to produce fuel in any case.
Also the weight of the smallest reactor is one ton at least. This means that you have less than a ton to build the rest of the vehicle out of or it won't be within the Mars Direct weight limit.
This is very true. I figure the reactor and propelent plant would probably mass as much as 5 tons as more. The probably could not be brought on an inital mission, but they would be ideal items to bring on a later mission or a cargo mission.
Methane powered? I thought you were promoting nuclear power?
Chemicaly powered rovers, that tow a nuclear reactor that the utilise to produce fuel when necessary.
However, another idea is a larger "expedition class" rover that would be powered by nuclear power alone. It would trail either a cargo trailer with water and supplys or a drilling rig to get some more water. A pair of such rovers could probably traverse the entire planet safely.
He who refuses to do arithmetic is doomed to talk nonsense.
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You obviously haven't read any of the posts I referred you to. A combined fuel cell/solar vehicle can have almost unlimited range on mars. Food, oxygen supply, and crew comfort are the main limiting factors on range.
As I said nuclear power is too heavy meaning YOU CAN'T TAKE IT on mars direct so by default it's not more efficient.
You repeat your idea about starting the reactor and the crew moves out but you left out one very important thing. WHERE DO THEY GO? It's mars. Are they supposed to walk to a crater 100 yards away and wait in the pressure suits while the reactor works?
More industrial methods of oxygen production? Too much weight. You can't take it, plus it's totally not needed. A few pressurized oxygen bottles provide plenty of air.
So you want to take a nuclear powered vehicle, use the nuclear power to make methane (I suppose from a tank of stored hydrogen), then use the methane to drive the vehicle? That is absolutely crazy. Why not just power the vehicle by batteries and use the nuclear power to recharge batteries when needed? We've already discussed combustion engine's use on mars and it is not possible. They use too much air which you would have to carry in a very large LOX tank.
If it's too heavy for early missions then it's too heavy for any mission. We want to explore the planet from the very beginning.
Now it is obvious that you still have not looked at any of the posts I referred you to. It's all there if you would just go back and read. You will learn a great deal.
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Chill Dook, I think he understood you just fine...
-A solar powerd anything is going to be of limited usefulness on Mars, because Mars recieves a fraction of the light as Earth does, you have to orient the arrays for efficency, and they won't work if it gets dusty. You simply can't produce much energy this way, maybe enough to drive the vehicle a little, or enough to keep the crew warm and alive, but probobly not both.
-A SMALL nuclear reactor is very much possible, about the size of a trash can, and MarsDirect even calls for placing the reactor on a small robot truck to drive it away from the ERV. The size of reactor needed to drive a large rover for a few hours a day is not unreasonably large if you can store the energy when it is not in use.
-Energy storage with batteries may get very heavy, since batteries aren't very light for the amount of energy stored. A Methane or Methanol driven fuel cell system can pack WAY more energy per pound. The water from the reaction can be recycled to make hydrogen for the next batch.
-The whole idea is to stop the convoy, unhook the reactor/ISRU trailer and drive the rover away from it. Thats "where they go." You turn the reactor off by remote, drive back to the trailer and load the day's fuel, hook it up and go to the next site.
-"If it's too heavy for early missions then it's too heavy for any mission."
Really? Why?
The only problem with this scheme is that the reactor will still produce boku radiation and heat even when shut off thanks to nuclear decay, so signifigant shielding will be needed to tow a reactor that has been used in the recent few months. That might make the thing kinda heavy, but it may not be a show-stopper.
I like a slightly modified scheme myself, make a series of small nuclear ISRU fuel "gas stations" small enough to tow, and drop them off at various places distant from the landing site. The chemical fuel cell powerd rover will do its thing and recapture the water made during its 1-4 month trip, then return to the gas station. There, it will refuel with Methane and Oxygen produced by the little reactor a month or two ago, drop off the water for the next batch of Methane, and head back out. The reactor extracts the Hydrogen from the waste water, makes more Methane/Oxygen, and the process repeats.
The reactor could be very small and well shielded to permit you to refuel even though it was recently operating, or a slightly bigger reactor that could do the conversion quickly and shut down a month or so before the next scheduled fueling. The latter would have a small solar array to operate the cooling system to remove decay heat, and both models could serve as weather & communications stations.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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As for Storage of energy other than batteries and or shutting down the reactor maybe Under the compressed air (atmosphere) vehicle topic we have a partial solution. Much like your thought I too put forth simular thoughts for the refueling stations for a compressed air motor. Maybe somehow we can marry the two systems together.
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Compressed air as a storage medium isn't going to be practical for a large long-range rover even with refueling stations, simply because making a big compressed air tank is hard, and it still doesn't hold enough energy for anything except short range trips in small vehicles, or perhaps maybe for high-output portable machinery, but that is about it.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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The equipment has some things going for it though usually smaller and lighter than a nuclear reactor, Probably less hazardous to crew, easy to setup, multiple use freindly and so on... Large scale rover activity probably will not happen even within the first 10 missions unless each mission lands at the same site forcing longer drives to those places of interest....
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GCNRevenger covered most of what I was going to say, I'll just extend it a little bit.
- I think you have misunderstood me on the whole fuel cell/solar power bit. What I am saying is that there is no way you could power a long range rover with solar power alone. Fuel cells work fine as a energy store, and you could surely power a long range rover off of them, but no way are you going to gather enough energy with solar cells to charge them up for continuous opperation.
I perfer chemical energy to fuel cells as energy store due to their greater energy density, and the easy with which they can power a high-performance engine. However fuel cells do have some things in their favor, for one, recharging them via hydrolisis is much simpler then the sabatier process necessary to produce more chemical fuel. Either could readily be charge up by the nuclear power system I proposed.
- The point of the system is to produce great quantities of fuel, which is the biggest limiter, to allow unlimited range. The sabatier process does not produce enough oxygen for optimal combustion in any case, so an additional means of producing oxygen will probably be necessary. The fact that the crew can breath the excess is just gravy.
- As I said above, the reason I favor a chemical power store (such a Methanol and O2) is it's greater energy density. Despite the need to carry both the fuel and the oxygen, chemical energy is still signifigantly more energy dense than either fuel cells or simple batteries. But either is certianly do-able. Both would eliminate the need for a ISRP, but I'm not sure this would make up for the loss in efficency. Also, the hydrogen for the sabatier process would probably be stored as water (reclaimed from the engines after combustion), and broken into hydrogen only when necessary, to avoid having to carry hydrogen tankage.
- While this system is probably to heavy for an inital mission, there is no reason at all it could not be sent on a latter mission, or to an established base camp. Idealy the trailers could be hitched right up to one of rovers already sent to Mars, making it an easy expansion of mission capabilities.
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GCNRevenger, I like your "gas-station" idea. Kind of like how you can cross a desert, or climb a mountain by setting up a chain of supply stations along the way. It would be even more ideal if the stations were set up next to a convient source of H2O, so that hydrogen losses could be made up for. These gas-stations would be natural steping stones to full-fledged bases in the future, an ideal way to expand.
He who refuses to do arithmetic is doomed to talk nonsense.
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