You are not logged in.
Subliming ice directly leaves a surface coated in contaminants, eg dust, which would reduce the rate of sublimation. In addition, you would need a liquid condensate to remove the product from the chilled surface. If the still can have its internal temperature and pressure raised above the triple point of water it would work, albeit slowly.
If we have a process with a large amount of waste heat available this could be used in an evaporation process, as can be done on Earth.
If Mars has already done the separation for us, we might be able to dig up ice and use it with little further purification.
Small inflatable, plastic, solar stills are supplied for use in marine liferafts to provide drinking water distilled from the sea water. I'm not sure they would work satisfactorily on Mars due to the very low vapour pressure of water that could be achieved there, but this could be tested in a polar station on earth.
It is (almost ) always my intention to focus on early exploration and installation of permanent bases. I will be long dead before any thing else by way of human activity happens on Mars. Hence anything said about the future beyond these first steps is going to be overtaken by new knowledge and other circumstances. I think it was Macmillan who was asked what he thought was the main threat to his plans and responded with "Events, dear boy".
I would like to be able to see proven resources which could be used to support a base and exploration activities, The first of which is water for consumption, crops and electrolysis. I envisage mining of water in large lumps and removing unwanted contaminants. Water will almost certainly be required in construction as well.
you need two units, each able to accommodate both crews so that rescues could be effected should one of them fail or be irreversibly damaged in an accident.
I considered explosives, but not an Alkali metal. I thought that the extremely strong signal from an explosive would mask any small signals from any organics that might be at the impact site, so I abandoned that idea. I think the same would apply to use of an alkali metal in obliterating some of the signals from the spectra given out by the ejecta- you would get something like high pressure sodium lighting.
Consequently I went for an iron impactor as we would, for sure, get an iron signal at almost any point on Mars regardless of the impactor. It's rusty! Also Iron would be likely to withstand atmospheric entry- provided it is sufficiently massive.
Any designs for human support systems (and for some industrial ones) need to avoid closed loops. These allow build up of undesirable substances/bacteria etc within the loop. So there must always be some discard and fresh make up.
Here's a thought for a Mars mission not involving a lander. Purpose would be to assess the shallow subsurface geology at numerous points of interest, including, I would hope, locations for early landings.
As was done with a spent satellite of the moon and deliberately with one device on a comet, a series of objects (cannon balls?) could be impacted on Mars surface from orbit and the impact ejecta observed from an orbiter. This would enable us to examine potential ice masses or lava flows for example, without landing. Much cheaper!
Depth of penetration would vary depending on the mass and velocity at impact. Different size impactors would give access to different layers in the same area.
The data could be checked by impacting a well examined area, or by moving one of the surviving rovers to an impact site.
I would propose pure iron for the impactors as it wont affect the results. We already know that Mars is covered in it.
You are right, Robert, it isn't absolute, but it is effective, especially with a wash step. If not sufficient in one stage, repeat. It would use less energy than evaporation. Recrystallisation is widely used to purify materials is the chemical industries.
It seems to have been established recently that water is pretty common on Mars. If it proves to have the same isotopic composition as that reported so far, deuterium will be abundant and can be separated by electrolysis, which I expect is going to be done anyway, to generate oxygen and hydrogen. This by product heavy water is just what is needed for a Candu or similar reactor. A heavy water moderated reactor can burn Uranium or Thorium fuel with a much lower degree of enrichment than other reactor types. They are not so popular on earth due to the expense of the heavy water that they require and due to their production of tritium which can be used in Hydrogen weapons (and is toxic because of its short half life). With abundant heavy water and the ability to freeze the tritiated waste this should not be a problem on Mars and the risks of shipping fuel from earth would be much reduced by reason of its low enrichment.
Desalination on Earth generally involves reverse osmosis or distillation and recondensation. it is, however, possible to exclude most contaminants from a dilute brine by partial freezing, producing fresh ice which can be crushed, washed to remove residual salts and then melted again. This happens to old sea ice in the arctic on earth which can be used as a potable water source, despite being formed from sea water. On Mars water is all frozen but brine would have been expelled during the freezing process so the ice may be available for mining with fairly low levels of contamination.
Shame. I don't suppose any other government would either- unless the Chinese do. Missed opportunity Canada.
If there is water ice in large quantities it could be mined to provide feed for an electrolysis plant generating Hydrogen and Oxygen. These are rocket fuel and oxidiser. With a bit of basic chemistry you can make peroxide also, which doesn't require cryogenic storage and is a suitable transportation fuel (it has been used in torpedoes and rocket packs). The equipment and seed chemicals required would have to be imported from earth, as would a nuclear reactor to power it. I doubt that the required power could be practically generated using hectares of solar panels without having a large crew to clean it.
First we need to prove that the water is there and find out what, if any, purification will be needed. so we need a drill rig capable of drilling say 5 metres deep and extracting cores for an analyser.
We also need to find a location with many interesting targets in a small area, or send a rig with a hopper to transport it.
Because Silane will burn to Silicon Dioxide it will not be useable in internal combustion engines, including gas turbines. The Silica will be deposited on the relatively cool parts and either wear the engine away or coke it up, or both. It could be used in external combustion equipment such as Rankine or Sterling cycle engines. These would be easier to decoke and there need be no moving parts in the exhaust stream.
Another easily portable energy source is peroxide. If the concentration is sufficient its breakdown produces steam and oxygen. The higher the concentration the higher the temperature of the breakdown products (=superheat in the steam fraction), the more oxygen you get and the more power you can extract in your expansion turbine. On the downside the higher the concentration the less stable the stuff becomes and (above about 60% H2O2) the higher the boiling point, which translates into heavier tanks). Stabilizers are available which would help, here.
SHOULD HAVE BEEN ABOVE 60% THE HIGHER THE FREEZING POINT. sorry!
There is one imported resource that hasn't been considered yet. Parachute "silk". This could easily withstand the pressure needed inside a greenhouse and if proofed or lined with film, would enable a very low leakage rate. Processing it into a translucent skirt for an agriculture enclosure should need only sticky tape, thread and a sewing machine. You would need a double wall, I should think, for safety and reduction of heat loss. Mirror film deployed on light frames could reflect sunlight through the translucent wall into a regolith covered masonry structure
You need to provide a lot of energy in the form of pressure drop to make a vortex tube work.
If you do rail transport on Mars in the manner that we do it here, there's the rails, and there's the ties, and there's the roadbed.
You don't lay track on unprepared ground (I know they did for the transcontinental railroad, but it didn't last). Roadbed is appropriately-graded gravel mix of the correct stone shapes, and it must be available in truly mass quantities. Without it you bend or break your tracks. This is not something you just scrape up with a bulldozer.
Ties here are most often wooden, but on the faster lines, can be cast reinforced concrete. We would need a concrete substitute on Mars, in mass quantities, to make the ties. And we need steel for its reinforcing. About the only other useful material strong enough to do the job as a tie would be steel itself.
The rails are not plain low-carbon steel. They are a low-carbon alloy steel using some other metals that confer enormous strength and resilience. Plain carbon steel wears out way too quickly, and is far too easily destroyed in a derail incident.
There's a lot of manufacturing infrastructure needed to support building such a thing on Mars.
GW
Plain carbon steel rails would undergo brittle fracture in Mars temperatures. You would need to find a lot of alloying elements to make the steel usable- eg Manganese and Nickel.
I was thinking in terms of use of bamboo for structures (like Chinese scaffolding for instance), when I introduced its lack of durability. It would be an issue if it were used inside a habitat, but not if used outside.
Some tests would be needed to establish the effects of the cold dry ultra low pressure environment on cut and seasoned bamboo before it could be considered for structures outside.
Some varieties of bamboo produce edible shoots as well. Strong fibers can be extracted from it and it has great merit for structures. Its Achille's heel is its lack of durability on earth and this would prevent its permanent, structural use inside a habit, but that may not be an issue when exposed to martian (or moon etc) conditions.
There will need to be a system for recycling organic waste. This might include anaerobic digestion which would generate methane. There would then need to be some aerobic treatment of sludge and liquids, after which they could be diluted and transferred to aquaculture ponds which would also need addition of Oxygen. In these ponds Settlers might grow shellfish, crustaceans, marine snails and even fish which would clean the water ready for reuse and the settled mud could be added to rinsed regolith to make soil. At some point there must be a discard percentage to avoid build up of unwanted substances (heavy metals from regolith, for example).
I should point out that few to none of the reactors previously launched into space (the numbers are skewed by varying degrees of secrecy) have been capable of more than 10kW, and none exceeding 2kW are known to have lasted more than 6 months.
Check out a rough list of known reactors in orbit here:
http://www.globenet.free-online.co.uk/ianus/npsm1.htm
Solar arrays can be built with these outputs, and with better reliability.
CME
I believe these were isotope generators, rather than critical nuclear reactors. The output of the latter would be measured in megawatts.
Only problem with the train track conducting electricity from solar cells is the fact that Mars is made of Iron... which conducts electricity granted not as good as copper or gold or other metals. One would need to insulate the tracks from the planet to make it work.
Insulation will be necesarry although I personally doubt that the natural conductivity of the Mars soil is so great to represent electricity leakage or short-cut problem. Mars soil has comperativelly big percent of iron oxides not pure iron. Regarding the direct maglev road-construction option and hence the need for superconductors, we could do the opposite: put the natural iron magnets as an armature in the glass-amorphic silicon road, include the superconductors with the criogenic equipment onboard the vehicles and power them by induction from the road...
The solution to integrate the electricity grid lines with the roads and railways and the bands of photovoltaic cells is just a way to arrange the hardware in spatial aspect.
Please, tell me exactly in what it differs to the way it is done the last hundred years here on earth?
In the UK one of the old railway companies installed a third rail when they electrified the lines. This rail is mounted on ceramic insulators. The system works, although not so well as overhead conductors which can run at a higher voltage.
The problem with railways is not that they wouldn't work but that of smelting sufficient iron, rolling rails from it then grading and installing track and ties. This is a large industrial operation so will not happen any time soon on another planet.
For the sake of a discussion, suppose there was a Martian crater containing a lake, in the distant past. The lake would freeze from the surface downwards, but would not necessarily freeze right to the bottom owing to the possible presence of concentrated brine expelled from the ice as it froze. The surface of the ice would be covered by wind blown dust which would be bound by subliming and recondensing interstial ice, due to temperature changes. This dust blanket would slowly increase in depth and might allow the ice to persist over very long periods in favourable locations. There may still be some craters like this.
Now, if the crater wall were breached so that the underlying brine could flow out, the ice would be left as a grounded mass.
Crater floors are not generally flat, but frequently have internal peaks. These may have formed islands in the putative frozen lakes , with ice already grounded around them. In this case if the brine were to escape the floating part of the ice would settle and break off from the already grounded part, forming grounded bergs.
I quite like the crater at 3deg North, 92deg East as a possible candidate for this process. There are others.
Landslips are widespread on Mars eg in Canyons and in craters, and I suppose that many slopes are at the limit of stability and their fall could be triggered by activities involved in construction or exploration. The base may be destroyed or just buried and rendered inaccessible. It's just a consideration when selecting base sites and targets for examination.
Reading back, I should have been clearer. I was proposing stirling engines for surface use (stationary or rover mounted), not for flight.
If Mars meteorites can arrive on earth and potentially carry Mars life, as has been theorised, then earth meteorites should arrive on Mars carrying life. So life should be around on Mars if it is possible for life to exist there, whether or not it originated there. The possibility can not be eliminated, but the probability will reduce as we examine more and more possible habitats without finding life. How to examine lots of possible habitats? Go and have a look.