Martian Resources

May 2004

AIR AND SOIL

Martian atmosphere: 0.095 psi (6.518 millibar)

Carbon Dioxide   95.32
Nitrogen          2.7
Argon             1.6
Oxygen            0.13
Carbon monoxide   0.07
Water vapour       0.03
Neon              0.00025
Krypton           0.00003
Xenon             0.000008
Ozone             0.000004

Source - http://www.marsacademy.com/intro/intro1_2.htm

Composition of Martian soil:

SiO2    44  %
Al2O3    7  %
Fe2O3   17  %
MgO      6  %
CaO      6  %
K2O      0  %
TiO2     0.7%
SO3      6  %
Cl       0.8%

Clearly, although there are a wide range of elements available, many of the concentrations are too low to consider them as more than contaminants. Thus, to a first approximation, the atmosphere is carbon dioxide and the soil primarily silicon dioxide and iron oxide with a little corundum.

One great advantage of atmospheric mining is that there is no need for any great deployment. The raw materials arrive most convieniently of their own accord. For a first landing, this is an immense advantage in terms of reliability. Of course, this limits us to but two elements, but it is surprising just how much can be made from carbon and oxygen:

CHEMICAL	USES	NOTES
Carbon black	Reducing agent, fuel	can be stored in pits
Acheson graphite	Lythergolic rocket fuel, electrodes, refractory	will not burn in CO2
Oxygen	Breathing gas, rocket oxidiser
Ozone	Oxidising agent, water purification
Carbon monoxide	Fuel, reducing agent, Mond process
Carbon suboxide	Plastics: tanks, pipes, seals, insulation(?)

These may actually be enough to build almost an entire cargo rocket (some control equipment would have to be imported, at least at first). Some iron (produced by reducing soil with carbon monoxide or lampblack) would be usefull for structural members and combustion chambers.

The presence of silicon dioxide may bring to mind integrated circuits, thyristors, etc, but the production of such items would require a huge amount of specialised equipment. Such items will probably be imported for many years. However, the extraction of aluminium would be extremely usefull, as it is comparetivly simple to produce wire, chokes, condensers, resistors, relays, transformers, alternators and suchlike from iron, aluminium and plastic. These would be quite sufficient for building auto sequencers, small telephone networks, telegraph networks, rudimentary radio equipment, etc. Perhaps a few thermionic valves will be built - 0.095 psi of CO2 isn`t all that bad a substitute for a vacuum and they can`t leak if left outside. A fully Martian cargo lifter would be a notable achievement.

One element which is conspicuous by its absence is hydrogen. That Mars has water is not in question, but the conundrum is how much and where. A polar cap is probably water and there is likely to be permafrost. A little may even be extracted from the atmosphere. However, without a guaranteed source of hydrogen, its presence cannot be relied upon. The only options are to do without or to take our own.

It would be prudent to allow for the possibility of no hydrogen at all being available, but take some nonetheless. Hydrogen is inconvenient to work with, so ammonia would make sense as an alternative. The nitrogen would be welcome as well. Perhaps the landers could burn ammonia and hydrogen peroxide. Residual propellants in cargo landers would be available as feedstocks. Indeed, if carbon monoxide and liquid oxygen can be produced and the landers are able to burn them, then the return fuel could be appropriated as well!

ENERGY

Three prime energy sources spring to mind for Mars: solar, wind and atomic.

Solar furnaces of burnished aluminium are usefull, in that they can provide direct process heat or run thermal cycle engines, but have the disadvantage of failing during dust storms. Particularly bad storms can last for weeks and so solar power can only be relyied upon in the long term or if backed by a large ammount of energy storage.

Wind turbines require no specific materials for their construction, but are, ironically, also probably susseptable to dust storms. Further, they have never been tested in the Martian environment.

Atomic power is immune to external problems and can provide very large power outputs (uranium reactor) or small outputs at high reliability (radioisotope thermoelectric generator). Its problems are safety and environmental dammage.

The problem, then, is this. The preferable power sources (solar furnaces and wind turbines) both fail during a dust storm, but the dust storm resistant source (atomics) cannot be built localy (yet) and cannot be imported due to international restrictions on flying atomic reactors.

Mixed bags are usually best from the point of view of reliability. Thus, we should use solar furnaces for direct heating, solar heat engines and wind turbines for electricity and atomics (in the form of a few RTGs) for life support backup during storms. Personell comfort during storms would be resonable, but fuel production, etc. would be stopped.

What would be ideal, then, would be something which could provide power during a storm (or perhaps even only during a storm). With this power source available, industrial output would drop, but not to zero. Perhaps some arrangement of electrostatic plates could draw energy from airborne dust. Perhaps the dust carries a charge which could be utilised directly? Drawing power from the very dust which shuts down primary power would be an interesting experiment to indeed. Perhaps the dust could be charged by coronal discharge and passed between conductive plates in a magnetic field?

Energy storage will also be required. Not only in the form of rocket fuel, but also to cover for temporary plant outage and unexpected demand.

Electrical supply to the barracks, etc. and essential lighting will have to be maintained during the night during normal operation. If wind power drops, it will be necessary to draw on stored energy. Possibly the simplest way would be to use solar heated sorbtion pumps to pressurise burried CO2 tanks. Air motors would then be used to run alternators.

For long term storage, carbon black could be stored in pits dug in the ground, perhaps with a sheet of corrugated iron or a tarpaulin over the top. They would keep for a very long time and storage capacity is essentially unlimited. Storing something to burn it in is another matter.