The problem isn't temperature, per se. I'm presenting my argument based on a mass balance. If we assume that all the hydrogen on Mars is bound in water, then we can get a feel for how much water vapor would be in the atmosphere at any point. In the upper atmosphere, solar protons and gamma rays ionize water vapor into H2 and O2. The hydrogen is so light it is lost into space, while the oxygen remains. This mechanism accounts for the high relative abundance of deuterium on Mars, as well as the highly oxidized state of the surface.
So, even if the temperature of Mars was stabilized in the liquid water range, hydrogen would continue to be lost and oxygen accumulated in the atmosphere. On Earth, volcanic activity serves to replenish the hydrogen lost through photo ionization, and plate tectonics recycle the oxidized crust into the mantle. Mars has no tectonic movement or volcanism anymore. Heating the planet to allow liquid water to form would actually accelerate the loss of hydrogen from the planet.
What this means for colonization/terraforming efforts is that no equilibrium can be reached between hydrogen loss and replenishment. If the rate of ice cap melting and release of water from permafrost were very carefully controlled, it would be possible for human-habitable conditions to prevail for perhaps as long as ten thousand years.
Ultimately, the Earth and Mars share the same fate: to become dry, cold desert planets that will be burned to cinders in a few billion years. Hopefully, by then the human race will have established itself across the galaxy.
By melting the ice caps and driving water out of the soil, it would be possible to create a shirt-sleeve environment for humans and many other terrestrial species. I won't go into specifics, but I'm sure most/. readers are familiar with the concept: big orbiting mirrors focused on the ice caps, black dust spread on the ground to raise the temperature, artificial greenhouse gases, etc.
The point of all this effort would not be to create a stable system - that is probably impossible, due to the weak gravity and solar radiation environment. However, for a few tens of thousands of years, Mars would be habitable by almost every species on Earth.
I agree that the reality of making Mars habitable is not like the fantasies of most Mars Society members (I'm not one, though I link to them in my.sig). We can't turn Mars into another Eden, but we don't have to in order to learn a great many things & create a biological reservoir in case a truly astronomical disaster befalls our current ecosystem.
Mars is valuable in the minds of many for the opportunity it offers - truly global projects can be done that would be impossible on Earth for reasons of safety. Some of these are silly (melting the ice caps with thermonuclear weapons), others serious (building giant cables that stretch from orbit to the surface). The problem comes when, for whatever reasons, the delusions of some people crash headlong into reality.
Percival Lowell thought he saw a network of canals built by a Martian civilization, and Burroughs wrote books chronicling the end of that noble race. Neither the canals or the civilization existed.
If we approach the unknown with an open mind and a sense of wonder, then we learn much more about the way things really are. If we keep pinning our hopes and dreams on phantoms, we will forever be disappointed.
The article states that the evidence of hydrogen was found in the soil near the polar caps - not unexpected, but nonetheless interesting.
There is overwhelming evidence that water flowed on Mars in the geologically recent past. The main question for those studying Mars is, Where did that water go?
We've known since the Mariner probes that there is a large reserve of water in the ice caps at either pole, but this reserve is not large enough to account for all of the erosion features of Mars. If, as has been suggested recently, there was once a giant ocean covering the northern hemisphere of Mars, then there is a LOT of water missing from Mars.
If, as has been suggested, there is a significant amount of water adsorbed into the soil of Mars, and as these results seem to indicate, this could account for the missing water.
Other theories suggest that the absence of a Martian magnetosphere may explain the lack of water on Mars - without a shield from a planetary magnetic field, the solar wind would dissociate large amounts of water vapor in the atmosphere - raising the amount of free oxygen. The hydrogen would be lost into space, especially on a planet as small as Mars.
Why is this important? Because some of the smae processes are going on here on Earth - water is lost through photo-ionization and conversion to crustal rocks. The amount of water vapor in our atmosphere is a very important factor in global warming and weather patterns. So, by studying another planet, we can learn about our own. Very neat stuff.
Re:This is a weapon of massless destruction
on
Lunar Lasers
·
· Score: 5, Informative
Answers to safety questions -
1. Focus - the beam will most likely be a maser, or microwave laser. Given a reasonable size emitter in geosynch or elliptic earth orbit, the footprint on the surface of the planet is only a few kilometers wide, and has an energy density of perhaps ten to a hundred watts per square meter.
2. Guidance - the same way they keep aircraft away from anything else - tell them not to go there. Note that this isn't really a problem, as the metal skin of an aircraft would deflect the beam.
3. Of course they will coordinate with other satellite operators. Although, if some satellite DID accidentally cross the beam path, it wouldn't necessarily be harmed, for the same reasons as 2.
The proposals I've seen for this (including a gov't study in the Sixties), all addressed the safety question. The REAL question is whether or not this can be done ECONOMICALLY - it's no use if the power so produced is ten times more expensive than fossil fuels (though note that such a scheme becomes more attractive as fossil fuels become more expensive...). The most attractive source of building materials for the solar cells and support hardware is not the Earth, but asteriods that cross or come near the orbit of the Earth - they contain all the necessary elements (silicon, iron, hydrogen, carbon, etc.) to make a solar power satellite in orbit, instead of having to haul every component up from the planet.
Re:are artillery shells that delicate?
on
Battlefield Lasers
·
· Score: 1
The laser doesn't really have to destroy the artillery shell - think of high school physics and the conservation of momentum - the laser pulse heats a small area of the shell's case to a few thousand Celcius. The heated gases fly off, and in doing so, push the shell off course - so instead of hitting it target, the shell chews up empty ground (hopefully!). If the shell DOES explode, it's a bonus.
... not with only a 10gig drive! Plus, remember that the XBox is currently a "loss leader" - MS loses money on each box sold until sales are in the millions (Sony JUST started making money on PSones). MS hopes to make money on the GAMES, not the HARDWARE. There's no incentive for them to bring out a competing product (Call it XBox Converge, or something else silly), for YEARS.
It doesn't matter how much any random asteriod is worth if you can't get to it.
The cost of launching a payload is the bottleneck for all forms of space exploration, manned or unmanned. Check here for an interesting read about launch costs. I don't agree with everything the author says, but he raises some salient points.
Asteriod mining, missions to Mars and the outer planets, a return to the Moon - all these are wonderful ideas, but until the cost of a ride to orbit comes down, it's all academic.
NASA's "budget black hole" is less than one percent of the amount your government spends. We taxpayers spend more money on farm subsidies than space exploration.
The point is that it doesn't matter if it's $1.5 billion per launch, $400 million per launch, or $100 million per launch - no commercial operator could make money using the Shuttle to launch payloads, and they know it.
Until the politics of space gets cleaned up, NASA has to make do with what it can do and what its told to do.
That is exactly right - but NASA's bureacrats *are* the problem! We need to get the vested interests of middle managers out of the space program.
Damn. Real life doesn't meet unreal expectations. Too bad. Deal with it.
All great things in human history were accomplished by people who made unreal expectations into concrete realities, people who refused to "deal with it". Once, it was an "unrealistic expectation" to consider going to the Moon, but we did it in less than ten years!
No, what I said was it depends on whose numbers you use - the official NASA estimate has hovered around $400-$500 million since the beginning of the program. But other estimates vary if you include the costs of the payloads, or spread the R&D costs over a different timeline, for example.
The point is, any way you look at it, it's not economical.
Read "Halfway to Anywhere" by G. Harry Stine for a description of the politicking that got Lockheed the X-33 contract instead of Douglas. Douglas wanted to build a scaled-up DC-X, but Lockheed's lifting body was sexier, so they got the contract.
It costs more to develop something which can be used multiple times, and then it costs more to individually produce components, then it costs more to do the recovery & restoration.
Not true for all situations - yes, as NASA and the majority of the aerospace industry does it, developing a resuable launch vehicle takes years and costs billions. But there are counter-examples. Take the DC-X (or Delta Clipper or Clipper Graham, whatever). It cost $60 million to build, and was finished on time.
The technology already exists to build a fully reusable LV, with long-life thermal tiles and engines. Such an LV could reduce launch costs by an order of magnitude or more.
Just because NASA can't operate a reusable LV doesn't mean it's "proven to be a mistake".
If I remember correctly, NASA tried to find a buyer for the Shuttles in the 1980s....
The reason no one bought them then, and the reason no one will buy them now, is the horrid expense of launching & reusing them - for example, on return to Earth, the Space Shuttle Main Engines are pulled, shipped to California, rebuilt to spec, and tested for ~75% of their design lifetime - any deviation during this test period results in the engine being scrapped. The Shuttle is an old design, and it wasn't efficient when it was new. Or consider the Solid Rocket Boosters, which actually cost more to retrieve and reuse than disposable boosters would.
The BBC quotes a figure of US$400 million, but the total development cost of the Shuttle program is *much* higher - some figures I've seen give a total cost per launch of over US$1.5 billion.
I think the solution to bringing down launch costs is to "open" the space program - let private companies build new launch vehicles, and have NASA test and certify them. This would allow NASA to perform more basic research, much like its predecessor the National Advisory Commitee for Aeronautics did from 1915 to 1958. This research, in turn, would lead to a new generation of launch vehicles.
I'm not a rabid NASA-hater like some out there, but I do think the agency has too much to do, with too many people, and too small of a budget.
Heinlein said "Get to orbit and you're halfway to anywhere."
The Moon is a heap of dessicated slag. The only good reasons to go there are national pride (done that) and astronomy - can you imagine the resolution telescopes would have with a baseline that long?!? We'd be able to read newspapers on Alpha Centauri!
I'm still amazed at the successes of our space exploration program - Galileo is still working, even after exposure to Jupiter's radiation belts, Pioneer 10 is still sending signals, and the Viking landers (designed for a six-month mission) functioned for more than two years (four in the case of the second lander)!
I could go on and on about the good things NASA has done - the Deep Space mission, NEAR, etc. But of course these don't get as much press as when a mission goes wrong. The media has created in the mind of the public the irrational desire for perfection - we want it to work 100% the first time. But when pusing the frontiers of science, sometimes things break.
Methanol might not be the best way to store hydrogen...
A properly designed hydrogen=powered engine would be able to burn slightly "dirty" fuel - such as hydrogen containing a few percent methane.
Adding methane "gels" the hydrogen at low temperature, making it easier to liquefy, store and transport.
This mixture woud still have the advantage of having vapors that are lighter than air, and thus rise in the event of a spill, rather than pooling in low spots and creating an explosion hazard.
Most leaks in a tank come from the seals and joints of the tank, but hydrogen leaks mainly by diffuing throught the tank walls. At high temperatures, this is significant, but at low (~50K) temps, it's hardly a show-stopper.
I'm not bashing carbon-based fuels, just pointing out that there are many alternatives we should pursue in the quest for clean energy.
Going to Mars is not necessary or sufficient to become an interplanetary sociey.
This statement could not be more wrong. Mars is the only other place in the solar system that can support a truly interplanetary society. Why? Simple: We can live on Mars much more easily than any NEO or asteriod.
Mars is more like the moon than earth. The atmosphere is less than 1% of the earths, that's practically a vacuum.
Not true. Mars does indeed have a tenuous atmosphere, but that's not anything like a vacuum. The Martian atmosphere is composed mostly of carbon dixoide, with a little nitrogen and argon. Why are these important? Life as we know it is based on carbon chemistry, which uses all of the above, plus water. Now, water on Mars isn't easy to come by - but it's a bit easier to find than on a Near Earth Object. Systems have been designed that can extract water from the Martian atmosphere fairly easily - but it's extremely likely that we'd find liquid water in the form of brines or geothermal pools within reach of a drilling rig.
The radiation levels on the surface are high, the problems of growing stuff under domes are extreme.
The radiation levels on Mars are far lower than those on any Near Earth Object. Additionally, constructing underground vaults on Mars would filter radiation down to terrestrial levels. We have grown crops on Earth under domes for years - transporting the dome to Mars is the hardest part.
Mars has a quite large escape velocity (about 3km/s). Mars lacks continuous solar energy available off-planet.
Large compared to what? Earth (at 11.2km/s)? Remember also that the escape velocity of an object does not by itself determine the delta-v than a spacecraft must perform to match orbits. The Martian atmosphere is more than sufficient for aerocapture maneuvers, which reduces propulsion requirements, and thus spacecraft mass. Your argument for solar energy is specious, because for any sort of industrial operation, a power source more compact than solar is needed. Nuclear reactors in the form of radiothermal isotope generators are far better.
We should go to Mars, but we need to go to NEAs first to get the materials we need to do that.
No, we don't. In fact, we could go to Mars with nothing better than the technology that took us to the Moon. We need to go to NEOs for various reasons, including mining, but we will not stay there for a long while. In fact, Mars makes a much more attractive location for launching missions to the Belt and beyond, due to it's lower gravity.
NEOs represent a source of raw materials beyond count, but only on Mars will it be possible to have a growing society. If I seem a bit fanatical, it's because I am: I once thought as you do, but for the reasons above and a few others, I have become convinced otherwise.
It's nice to see research in this area go forward, but it's really not needed. A quick look at some numbers tells us why:
A Martian greenhouse gets only half as much light as one on sunny Earth. Does this mean we get half as much yield per acre? Not quite
On Earth, carbon dioxide levels are typically well below 1% (usually around 350 parts per million). Raising the level of CO2 in a closed greenhouse is possible, but not economical. On Mars, however, the atmosphere is hardly anything but CO2 - and any greenhouse there must be tightly sealed already, so we can alter the CO2 level without additional construction.
What this means is that, although plants on Mars would get less light, they would actually produce higher yields per acre than plants on Earth, by virtue of the fact that they are growing in an atmosphere containg about 3% carbon dioxide! Now, this means astronauts would have to wear scuba masks to work in the greenhouse, but not spacesuits, since the greenhouse would be pressurized.
The point is, we can go to Mars with technology that exists today, right now, with no investment in R&D, and, more importantly, without waiting years for new technology. Yes, we should vigoursly pursue new technologies that lower the cost of space missions, but we don't have to.
Interesting thing is, the carbon's not primal - it had to be made by other processes later on. The only primal elements are hydrogen (75%), helium (25%), and a very small amount of litium (0.001%, if that). All the other elements were made from reactions between these three.
So somehow these clouds had to form from hydrogen, carbon, and oxygen, then be blown into interstellar space, but not hard enough to break them down. I wonder if anyone has done an analysis of these to determine the isotope ratios.... ---------------
Liquid "water" is possible on Mars, in the form of brines - essentially, salts dissolved in water. Mix a bunch of table salt into a glass of water and put in in the freezer - some may freeze, but as it does, it concentrates the salt in the liquid portion until equilibrium is reached. Remember that pure water is rare, it is much more likely to have salt in it (Earth's oceans).
So, instead of looking only at the phase diagram of water, take a look at the binary or ternary phases diagram of water and various salts - some brines are liquids at -53C.
And there are other ways of making water on Mars - the atmosphere contains a few parts per million of water vapor. Yes, vapor, not ice. Run that past a zeolite bed, an extreme dessicant, and the level drops to a few parts per billion. Eventually, the zeolite absorbs about 20% of its mass in water. You then close the container, heat it up, and the water vapor is driven off to be collected and liquified. We don't have to go to the poles for water. The energy balance on this scheme works out to around 10 kWh per kilogram of water produced, quite doable with a few radioisotope thermal generators.
I recommend to every one Robert Zubrin's excellent book, The Case for Mars. You can buy it from the Mars Society, linked below. ---------------
Slashdot Mirror
Not to nitpick, but....
The problem isn't temperature, per se. I'm presenting my argument based on a mass balance. If we assume that all the hydrogen on Mars is bound in water, then we can get a feel for how much water vapor would be in the atmosphere at any point. In the upper atmosphere, solar protons and gamma rays ionize water vapor into H2 and O2. The hydrogen is so light it is lost into space, while the oxygen remains. This mechanism accounts for the high relative abundance of deuterium on Mars, as well as the highly oxidized state of the surface.
So, even if the temperature of Mars was stabilized in the liquid water range, hydrogen would continue to be lost and oxygen accumulated in the atmosphere. On Earth, volcanic activity serves to replenish the hydrogen lost through photo ionization, and plate tectonics recycle the oxidized crust into the mantle. Mars has no tectonic movement or volcanism anymore. Heating the planet to allow liquid water to form would actually accelerate the loss of hydrogen from the planet.
What this means for colonization/terraforming efforts is that no equilibrium can be reached between hydrogen loss and replenishment. If the rate of ice cap melting and release of water from permafrost were very carefully controlled, it would be possible for human-habitable conditions to prevail for perhaps as long as ten thousand years.
Ultimately, the Earth and Mars share the same fate: to become dry, cold desert planets that will be burned to cinders in a few billion years. Hopefully, by then the human race will have established itself across the galaxy.
Well, not necessarily.
/. readers are familiar with the concept: big orbiting mirrors focused on the ice caps, black dust spread on the ground to raise the temperature, artificial greenhouse gases, etc.
.sig). We can't turn Mars into another Eden, but we don't have to in order to learn a great many things & create a biological reservoir in case a truly astronomical disaster befalls our current ecosystem.
By melting the ice caps and driving water out of the soil, it would be possible to create a shirt-sleeve environment for humans and many other terrestrial species. I won't go into specifics, but I'm sure most
The point of all this effort would not be to create a stable system - that is probably impossible, due to the weak gravity and solar radiation environment. However, for a few tens of thousands of years, Mars would be habitable by almost every species on Earth.
I agree that the reality of making Mars habitable is not like the fantasies of most Mars Society members (I'm not one, though I link to them in my
Mars is valuable in the minds of many for the opportunity it offers - truly global projects can be done that would be impossible on Earth for reasons of safety. Some of these are silly (melting the ice caps with thermonuclear weapons), others serious (building giant cables that stretch from orbit to the surface). The problem comes when, for whatever reasons, the delusions of some people crash headlong into reality.
Percival Lowell thought he saw a network of canals built by a Martian civilization, and Burroughs wrote books chronicling the end of that noble race. Neither the canals or the civilization existed.
If we approach the unknown with an open mind and a sense of wonder, then we learn much more about the way things really are. If we keep pinning our hopes and dreams on phantoms, we will forever be disappointed.
What the heck. It's only Karma.
The article states that the evidence of hydrogen was found in the soil near the polar caps - not unexpected, but nonetheless interesting.
There is overwhelming evidence that water flowed on Mars in the geologically recent past. The main question for those studying Mars is, Where did that water go?
We've known since the Mariner probes that there is a large reserve of water in the ice caps at either pole, but this reserve is not large enough to account for all of the erosion features of Mars. If, as has been suggested recently, there was once a giant ocean covering the northern hemisphere of Mars, then there is a LOT of water missing from Mars.
If, as has been suggested, there is a significant amount of water adsorbed into the soil of Mars, and as these results seem to indicate, this could account for the missing water.
Other theories suggest that the absence of a Martian magnetosphere may explain the lack of water on Mars - without a shield from a planetary magnetic field, the solar wind would dissociate large amounts of water vapor in the atmosphere - raising the amount of free oxygen. The hydrogen would be lost into space, especially on a planet as small as Mars.
Why is this important? Because some of the smae processes are going on here on Earth - water is lost through photo-ionization and conversion to crustal rocks. The amount of water vapor in our atmosphere is a very important factor in global warming and weather patterns. So, by studying another planet, we can learn about our own. Very neat stuff.
1. Focus - the beam will most likely be a maser, or microwave laser. Given a reasonable size emitter in geosynch or elliptic earth orbit, the footprint on the surface of the planet is only a few kilometers wide, and has an energy density of perhaps ten to a hundred watts per square meter.
2. Guidance - the same way they keep aircraft away from anything else - tell them not to go there. Note that this isn't really a problem, as the metal skin of an aircraft would deflect the beam.
3. Of course they will coordinate with other satellite operators. Although, if some satellite DID accidentally cross the beam path, it wouldn't necessarily be harmed, for the same reasons as 2.
The proposals I've seen for this (including a gov't study in the Sixties), all addressed the safety question. The REAL question is whether or not this can be done ECONOMICALLY - it's no use if the power so produced is ten times more expensive than fossil fuels (though note that such a scheme becomes more attractive as fossil fuels become more expensive...). The most attractive source of building materials for the solar cells and support hardware is not the Earth, but asteriods that cross or come near the orbit of the Earth - they contain all the necessary elements (silicon, iron, hydrogen, carbon, etc.) to make a solar power satellite in orbit, instead of having to haul every component up from the planet.
The laser doesn't really have to destroy the artillery shell - think of high school physics and the conservation of momentum - the laser pulse heats a small area of the shell's case to a few thousand Celcius. The heated gases fly off, and in doing so, push the shell off course - so instead of hitting it target, the shell chews up empty ground (hopefully!). If the shell DOES explode, it's a bonus.
... not with only a 10gig drive! Plus, remember that the XBox is currently a "loss leader" - MS loses money on each box sold until sales are in the millions (Sony JUST started making money on PSones). MS hopes to make money on the GAMES, not the HARDWARE. There's no incentive for them to bring out a competing product (Call it XBox Converge, or something else silly), for YEARS.
What the heck - it's only Karma.
It doesn't matter how much any random asteriod is worth if you can't get to it.
The cost of launching a payload is the bottleneck for all forms of space exploration, manned or unmanned. Check here for an interesting read about launch costs. I don't agree with everything the author says, but he raises some salient points.
Asteriod mining, missions to Mars and the outer planets, a return to the Moon - all these are wonderful ideas, but until the cost of a ride to orbit comes down, it's all academic.
Please, I'm tired of hearing this same BS every time
NASA's "budget black hole" is less than one percent of the amount your government spends. We taxpayers spend more money on farm subsidies than space exploration.
I'd love to continue this conversation - but not in this forum. E-mail fenris@nmt.edu instead.
That is exactly right - but NASA's bureacrats *are* the problem! We need to get the vested interests of middle managers out of the space program.
All great things in human history were accomplished by people who made unreal expectations into concrete realities, people who refused to "deal with it". Once, it was an "unrealistic expectation" to consider going to the Moon, but we did it in less than ten years!
Not in the case of commerical carriers, but if the payload was developed by NASA (i.e. Chandra or Hubble), then it does.
Converting game programmers to oranges would be even more impressive.....
No, what I said was it depends on whose numbers you use - the official NASA estimate has hovered around $400-$500 million since the beginning of the program. But other estimates vary if you include the costs of the payloads, or spread the R&D costs over a different timeline, for example.
The point is, any way you look at it, it's not economical.
Read "Halfway to Anywhere" by G. Harry Stine for a description of the politicking that got Lockheed the X-33 contract instead of Douglas. Douglas wanted to build a scaled-up DC-X, but Lockheed's lifting body was sexier, so they got the contract.
Had one, but it moved - I'll try to find it again.
Not true for all situations - yes, as NASA and the majority of the aerospace industry does it, developing a resuable launch vehicle takes years and costs billions. But there are counter-examples. Take the DC-X (or Delta Clipper or Clipper Graham, whatever). It cost $60 million to build, and was finished on time.
The technology already exists to build a fully reusable LV, with long-life thermal tiles and engines. Such an LV could reduce launch costs by an order of magnitude or more.
Just because NASA can't operate a reusable LV doesn't mean it's "proven to be a mistake".
If I remember correctly, NASA tried to find a buyer for the Shuttles in the 1980s....
The reason no one bought them then, and the reason no one will buy them now, is the horrid expense of launching & reusing them - for example, on return to Earth, the Space Shuttle Main Engines are pulled, shipped to California, rebuilt to spec, and tested for ~75% of their design lifetime - any deviation during this test period results in the engine being scrapped. The Shuttle is an old design, and it wasn't efficient when it was new. Or consider the Solid Rocket Boosters, which actually cost more to retrieve and reuse than disposable boosters would.
The BBC quotes a figure of US$400 million, but the total development cost of the Shuttle program is *much* higher - some figures I've seen give a total cost per launch of over US$1.5 billion.
I think the solution to bringing down launch costs is to "open" the space program - let private companies build new launch vehicles, and have NASA test and certify them. This would allow NASA to perform more basic research, much like its predecessor the National Advisory Commitee for Aeronautics did from 1915 to 1958. This research, in turn, would lead to a new generation of launch vehicles.
I'm not a rabid NASA-hater like some out there, but I do think the agency has too much to do, with too many people, and too small of a budget.
Not quite....
Heinlein said "Get to orbit and you're halfway to anywhere."
The Moon is a heap of dessicated slag. The only good reasons to go there are national pride (done that) and astronomy - can you imagine the resolution telescopes would have with a baseline that long?!? We'd be able to read newspapers on Alpha Centauri!
I'm still amazed at the successes of our space exploration program - Galileo is still working, even after exposure to Jupiter's radiation belts, Pioneer 10 is still sending signals, and the Viking landers (designed for a six-month mission) functioned for more than two years (four in the case of the second lander)!
I could go on and on about the good things NASA has done - the Deep Space mission, NEAR, etc. But of course these don't get as much press as when a mission goes wrong. The media has created in the mind of the public the irrational desire for perfection - we want it to work 100% the first time. But when pusing the frontiers of science, sometimes things break.
Methanol might not be the best way to store hydrogen...
A properly designed hydrogen=powered engine would be able to burn slightly "dirty" fuel - such as hydrogen containing a few percent methane.
Adding methane "gels" the hydrogen at low temperature, making it easier to liquefy, store and transport.
This mixture woud still have the advantage of having vapors that are lighter than air, and thus rise in the event of a spill, rather than pooling in low spots and creating an explosion hazard.
Most leaks in a tank come from the seals and joints of the tank, but hydrogen leaks mainly by diffuing throught the tank walls. At high temperatures, this is significant, but at low (~50K) temps, it's hardly a show-stopper.
I'm not bashing carbon-based fuels, just pointing out that there are many alternatives we should pursue in the quest for clean energy.
This statement could not be more wrong. Mars is the only other place in the solar system that can support a truly interplanetary society. Why? Simple: We can live on Mars much more easily than any NEO or asteriod.
Not true. Mars does indeed have a tenuous atmosphere, but that's not anything like a vacuum. The Martian atmosphere is composed mostly of carbon dixoide, with a little nitrogen and argon. Why are these important? Life as we know it is based on carbon chemistry, which uses all of the above, plus water. Now, water on Mars isn't easy to come by - but it's a bit easier to find than on a Near Earth Object. Systems have been designed that can extract water from the Martian atmosphere fairly easily - but it's extremely likely that we'd find liquid water in the form of brines or geothermal pools within reach of a drilling rig.
The radiation levels on Mars are far lower than those on any Near Earth Object. Additionally, constructing underground vaults on Mars would filter radiation down to terrestrial levels. We have grown crops on Earth under domes for years - transporting the dome to Mars is the hardest part.
Large compared to what? Earth (at 11.2km/s)? Remember also that the escape velocity of an object does not by itself determine the delta-v than a spacecraft must perform to match orbits. The Martian atmosphere is more than sufficient for aerocapture maneuvers, which reduces propulsion requirements, and thus spacecraft mass. Your argument for solar energy is specious, because for any sort of industrial operation, a power source more compact than solar is needed. Nuclear reactors in the form of radiothermal isotope generators are far better.
No, we don't. In fact, we could go to Mars with nothing better than the technology that took us to the Moon. We need to go to NEOs for various reasons, including mining, but we will not stay there for a long while. In fact, Mars makes a much more attractive location for launching missions to the Belt and beyond, due to it's lower gravity.
NEOs represent a source of raw materials beyond count, but only on Mars will it be possible to have a growing society. If I seem a bit fanatical, it's because I am: I once thought as you do, but for the reasons above and a few others, I have become convinced otherwise.
It's nice to see research in this area go forward, but it's really not needed. A quick look at some numbers tells us why:
A Martian greenhouse gets only half as much light as one on sunny Earth. Does this mean we get half as much yield per acre? Not quite
On Earth, carbon dioxide levels are typically well below 1% (usually around 350 parts per million). Raising the level of CO2 in a closed greenhouse is possible, but not economical. On Mars, however, the atmosphere is hardly anything but CO2 - and any greenhouse there must be tightly sealed already, so we can alter the CO2 level without additional construction.
What this means is that, although plants on Mars would get less light, they would actually produce higher yields per acre than plants on Earth, by virtue of the fact that they are growing in an atmosphere containg about 3% carbon dioxide! Now, this means astronauts would have to wear scuba masks to work in the greenhouse, but not spacesuits, since the greenhouse would be pressurized.
The point is, we can go to Mars with technology that exists today, right now, with no investment in R&D, and, more importantly, without waiting years for new technology. Yes, we should vigoursly pursue new technologies that lower the cost of space missions, but we don't have to.
Interesting thing is, the carbon's not primal - it had to be made by other processes later on. The only primal elements are hydrogen (75%), helium (25%), and a very small amount of litium (0.001%, if that). All the other elements were made from reactions between these three.
So somehow these clouds had to form from hydrogen, carbon, and oxygen, then be blown into interstellar space, but not hard enough to break them down. I wonder if anyone has done an analysis of these to determine the isotope ratios....
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Not quite.
Liquid "water" is possible on Mars, in the form of brines - essentially, salts dissolved in water. Mix a bunch of table salt into a glass of water and put in in the freezer - some may freeze, but as it does, it concentrates the salt in the liquid portion until equilibrium is reached. Remember that pure water is rare, it is much more likely to have salt in it (Earth's oceans).
So, instead of looking only at the phase diagram of water, take a look at the binary or ternary phases diagram of water and various salts - some brines are liquids at -53C.
And there are other ways of making water on Mars - the atmosphere contains a few parts per million of water vapor. Yes, vapor, not ice. Run that past a zeolite bed, an extreme dessicant, and the level drops to a few parts per billion. Eventually, the zeolite absorbs about 20% of its mass in water. You then close the container, heat it up, and the water vapor is driven off to be collected and liquified. We don't have to go to the poles for water. The energy balance on this scheme works out to around 10 kWh per kilogram of water produced, quite doable with a few radioisotope thermal generators.
I recommend to every one Robert Zubrin's excellent book, The Case for Mars. You can buy it from the Mars Society, linked below.
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