Saturday, January 3, 2009

Mining the Moons of Mars

by Marcel F. Williams

Moving towards a non carbon dioxide polluting energy economy does face a few problems as far as natural resources are concerned. Without breeder technologies, nuclear power faces the problem of limited terrestrial uranium resources. However, if emerging technologies designed to extract uranium from seawater come into fruition then there could be enough marine uranium resources to power all of human civilization for over 3000 years-- even without the reprocessing of spent fuel or the use of breeding technologies.

The new electric vehicle (EV) and plug-in hybrid vehicle (PHEV) technologies face the problem of limited lithium resources for their electric batteries. Here too, emerging technologies to extract lithium from seawater may be a partial solution. But PHEVs may have to fall back to using nickel-iron batteries in order to deal with the lithium shortage. This would reduce the projected range of these vehicles during electric mode to just 20 or 30 kilometers per charge instead of the 60 kilometer range, if billions of people on Earth are going to have access to these partially electric vehicles. The range for commuters could be doubled if they were able to recharge their vehicles again in cities that have recharging units located at every parking spot or parking lot in a city. That would be a very good infrastructure investment for the new Obama administration.

But its clear that synfuels are going to have to make up the brunt of power for the next generation of ground vehicles. Liquid fuel efficiency could be substantially increased, however, if future ground vehicles used methanol fuel cells. According to the Department of Energy, urban and rural biowaste in the US has the potential to produce up to 30% of our current transportation fuel needs within the next 20 or 30 years. But additional hydrogen is going to have to be added to the process if we are to take full advantage of 80% of the carbon dioxide wasted during synfuel production if we are going to completely replace petroleum for our transportation and industrial chemical needs. CO2 extracted from air could also be an additional source of carbon dioxide for carbon neutral synfuel production.

However, renewable sources of hydrogen could be a problem. The electrodes for the electrolytic production of hydrogen from water and the fuel cells required for high efficiency methanol and hydrogen ground vehicles requires-- platinum.

Platinum is an extremely rare metal that is 30 times rarer than gold. It occurs as only 0.003 ppb (parts per billion) in the Earth's crust. If all of the world's gold reserves were poured into an Olympic-size swimming pool, three such pools would be required to accommodate the total gold supply. But all of the world's platinum reserves would not even fill up one such Olympic-sized pool, only coming up deep enough to reach one's ankles.

Platinum currently sells at approximately $27 per gram. And 239 tonnes of platinum was sold in 2006. 80% of that supply came from South Africa with most of the rest coming from Russia and Canada. Approximately 130 tonnes of platinum was used for automobile catalytic converters, a demand that is likely to increase as rapidly growing economies like China and India begin to conform to Western automobile pollution standards. Another 49 tonnes was used for jewelry. The remaining 60 tonnes was utilized for various applications including electronics, chemical catalyst, electrodes, spark plugs and even anticancer drugs.

But if platinum were required for high efficiency fuel cells for automobiles, only 20% of the world's ground vehicles could be supplied. This of course doesn't even include the substantially higher demand for platinum if electrolysis became the primary means for producing hydrogen for a carbon neutral hydrocarbon fuel and industrial chemical economy.

While alternatives to platinum use in fuel cells and electrodes for electrolysis are currently being intensely pursued by researches, it is interesting to note that while platinum is rare in the regolith of Earth, it is extremely abundant in space-- in the form of asteroids. In fact, the largest sources of platinum on Earth occur in regions that appear to have been hit by large asteroid impacts in the more recent geologic past.

The total mass of the asteroid belt between the planets Mars and Jupiter is estimated to be about 3.0–3.6 quintillion tonnes (3.0 t0 3.6 billion billion tonnes of material). If all of this asteroid material were sprinkled over the entire land area of the Earth, it would be approximately 8 kilometers deep. Asteroids on average contain about 15,000 parts per billion (ppb) of platinum vs an average of only 0.003 ppb of platinum found in the Earth's crust.

Planetary scientist, John Lewis, estimated that if all of the total platinum wealth in the asteroid belt were divided amongst every person on Earth, each-- individual's-- share would come out to be over $30 billion. Furthermore, he estimated that if the total value of resources of the asteroids: iron, nickel, aluminum, titanium, gold, silver, uranium, etc. were divided amongst every individual on Earth then each individual's share would come out to be over $100 billion. So its clear that while we may live on a planet of limited industrial material resources, we also live in a solar system of virtually unlimited industrial material resources.

Interestingly, two additional potential sources of asteroid material may be in orbit around the fourth planet of our solar system. Mars has two moons, Phobos and Deimos. Both of these rocky moons resemble C type asteroids and may have originated elsewhere in the solar system before being permanently captured in orbit around the red planet. The inner moon, Phobos, orbits approximately 9377 kilometers from the center of Mars. The outer moon, Deimos, orbits more than 23,000 kilometers away from Mars. Our own Moon, orbits the Earth more than 384,000 kilometers away. It is interesting that Russia and China are currently planning a joint robotic mission to Phobos to be launched in 2009 to analyze-- and retrieve-- a sample of the material from the surface of Phobos for return to Earth.

The Martian Moon Phobos

The potato shaped Phobos has a maximum diameter of nearly 27 kilometers with surface area of approximately 6100 square kilometers and an estimated mass of more than 10 trillion tonnes. So at possibly 15 parts per million, Phobos could contain 150 million tonnes of platinum, enough to supply the Earth at current levels for about 500,000 years and at ten times current consumption for 50,000 years.

The Martian Moon Deimos

Deimos is the smaller outer moon of Mars. It has a maximum diameter of 15 kilometer and a total mass of approximately 1.5 trillion. So at 15 parts per million, Deimos could contain more than 20 million tonnes of platinum.

Even without platinum mining, the resources of the Martian moons would be extremely valuable for space exploration, space tourism and colonization and perhaps even for the extraterrestrial manufacturing and deployment of satellites in space. Because of the deleterious effects of cosmic and solar radiation, permanently manned facilities in orbit-- even within the Earth's magnetic field, are going to require at least hundreds to thousands of tonnes of shielding material. Phobos and Deimos with their low gravity wells have the potential to supply such shielding much more economically than such resources from the Earth or even the Moon-- if interplanetary lightsails are utilized to transport the material from the orbit of Mars. Approximately 40% of the chemical material of Phobos and Deimos is composed of oxygen, the principal oxidizer for rocket fuel and of course the essential element for breathing aboard space vehicles and orbiting space stations. Phobos and Deimos may also contain significant amounts of chemicals containing hydrogen, and essential rocket fuel and chemical component water (H2O) essential for human life and for growing food. Phobos and Deimos could also contain other valuable chemicals for growing food such as carbon and nitrogen. The metals and silicates from these Martian moons could also be used for manufacturing satellites for eventual deployment in Earth orbit.

Phobos has a tiny escape velocity of only 40 kilometers per hour (11.3 m/s). Deimos has an even tinier escape velocity of only 20 kilometers per hour. The Earth's moon, on the other hand, has an escape velocity of 2380 m/s. So transporting materials off the surfaces of these tiny Martian moons should be very inexpensive. However, Phobos and Deimos are still within the significant orbital influence of Mars which would require a delta v of 8.0 kilometers per second to transport material to low Earth orbit (LEO). So it would actually be cheaper to transport material from the lunar surface to Earth orbit than from the moons of Mars-- if chemical rockets were used.

However, there have been proposals to use lightsails (solar sails) for interplanetary travel. Unmanned lightsail space craft could transport hundreds or perhaps thousands of tonnes of freight practically anywhere within the inner part of the solar system from Mercury to Jupiter without any fuel cost. Lightsails simply use the reflected photons from the sun to provide acceleration for travel between the planets. While the acceleration of light sails is low compared to rockets, it is continuous. While a chemical rocket may fire its powerful engines for several minutes, a light sail can continue accelerating for hours, days, weeks, months and even years with zero cost of fuel. Such sails could be principally made of aluminum film as thin as 0.1 microns (one ten thousandth of a millimeter) and could be several kilometers in diameter while weighing less than 30 tonnes-- if constructed in space. Lightsails, therefore, could be the key towards giving humans affordable access to the vast material resources of the solar system.

Interplanetary light sail

So once material is transported out of the meager gravity well of a Martian moon, the delta v of getting the material out of Martian orbit would cost nothing since the cost of transporting material via light sail would only be determined by the capital cost of the sail plus the operational cost. In 1977, Eric Drexler determined that the cost of transporting material via lightsail could cost only 22 cents per kilogram; in 2009 dollars, that would be approximately 66 cents per kilogram ($66o per tonne, $660,000 per 1000 tonnes). However, if the source of material for light sail construction came from the low gravity wells of the Earth's moon or from the moons of Mars, then capital cost could potentially be even cheaper.

But even if the Earth were annually importing a million tonnes of material from the moons of Mars, and all of the platinum from this material was extracted, it would still only supply the Earth with about 15 tonnes of platinum annually (about 16% of current annual demand). So as far as platinum mining is concerned, it might be substantially more efficient to extract and process the platinum on site, on the surface of the Martian Moons.

If we assume that full fledged mining and processing facilities operated by a few companies on each Martian moon could conservatively process 10,000 tonnes of material daily on each moon, then about 110 tonnes of platinum (46% of annual demand) could be exported to Earth annually. Such large scale mining operations on the Martian Moons would probably require a significant human presence on the surface of Mars which would allow humans to operate such facilities mostly by remote control in the relatively healthier gravitational environment on the surface of Mars. It would also be much more convenient and cheaper for humans to access the Martian moons via rocket from the surface of Mars than from Earth.

Of course it might be possible to extract 10 million tonnes of platinum from Phobos and Deimos every year for the next 1000 years in order to supply all of Earth's current needs for platinum. This would still mean that only 0.1 per cent to 1 per cent of the total mass of the Martian Moons would be commercially exploited. But I consider Phobos and Deimos 'natural wonders' and would be strongly against over exploiting the resources of these Martian moons. The over mining of Phobos and Deimos might be somewhat alleviated by using lightsails to capture and import asteroids ( perhaps 500 to 5000 tonnes in mass) from the asteroid belt and transporting them safely into Mars orbit for processing.

But there are also many other large asteroids in the asteroid belt where platinum could probably be processed on site. And these large asteroids could help contribute to the platinum supplies needed for the Earth currently and in the future. There are nearly 30 large asteroids in the asteroid belt that are larger than 200 kilometers in diameter; and thre are more than 200 asteroids in the asteroid belt larger than 100 kilometers in diameter (all larger than Phobos and Deimos). These large asteroids would be lonely outpost that would probably require orbiting manned rotating facilities capable of producing at least some marginal but significant simulated gravity. Such outpost, however, would probably require thousands to millions of tonnes of radiation shielding that could be cheaply supplied by the host asteroids that they're mining.

The US currently has a 10 to 20 billion dollar a year civilian space program predominantly dedicated towards the 'exploration' of space and an even more expensive military space program. In my opinion, the new Obama administration needs to reprioritize NASA's goals away from space exploration in order to utilize their funds in a manner that would be more economically beneficial to the American people. Exploiting the natural resources of the Martian Moons would be a good start in that direction, in my opinion, which would probably require manned facilities on Phobos and Deimos, in Martian orbit, and on the surface of Mars.

Perhaps in the future when people are off duty after working all day or all week on the Martian surface or in orbit on one of the Martian moons, they could spend at least some of their free time-- exploring-- the exotic places where they're living and working!

New Papyrus 2009

References and Links

1. The Hydrogen Economy and Peak Platinum

2. Platinum (Wikipedia)

3. Highly Efficient Hydrogen Generation via Water Electrolysis Using Nanometal Electrodes

4. Asteroid Composition Table

5. Going (almost) all the way to Mars

6. AsterAnts: A Concept for Large-Scale Meteoroid Return and Processing

7. Why Mars?


9. World Book at NASA (Asteroids)

10. Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets
John S. Lewis

11. Out of the Cradle: Exploring the Frontiers beyond Earth
Williams Hartmann, Ron Miller, and Pamela Lee

12. Lightsails

13. Solar Sailing- Eric Drexler

14. Starsailing: Solar Sails and Interstellar Travel
Louis Friedman


qraal said...

Hi Marcel

Nice discussion. I've read your papers on the Aquatic Ape mailing list and never realised you were a space-nut like me. I think Phobos would be a great anchor for a Mars skyhook, allowing deuterium to be cheaply exported from Mars, which is relatively enriched compared to Earth. Shipped Martian deuterium for all those CANDUs we'll need for a nuclear future. What do you reckon?

Anonymous said...
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Marcel F. Williams said...

Greetings qraal

There's plenty of deuterium in the Earth's oceans and I believe there are laser enrichment techniques that are being developed that could vastly improve the efficiency of extracting deuterium from water. Plus the new generation of CANDUs don't require as much heavy water as they the older versions.

But I think future Lunarians would be extremely thankful if we shipped hydrogen from the Martian moons to the lunar surface. The moon is looking pretty dry these days:-)

I'll probably be posting something on Sir Alister Hardy's hypothesis next month on this blog.

James Tierney said...

Hi Marcel,
I liked your post on 'Free Space' and found it funny that more people commented on your comment than the article (chuckle).
We need to come together and make a plan for the future, but with all the political rabit chasing I'm not sure anything can get done in this environment, but I'm still very optomistic.
First stop; the moon to mine Helium-3 then, off to the moons of Mars for the Platinum and Deuterium. Lets clean this place up!

Marcel F. Williams said...

Thanks for the comment James. I'm not so sure about any extraterrestrial mining of helium 3 or deuterium since there are no commercial fusion reactors in existence.

I think manufacturing and launching satellites from the lunar surface to Earth orbit will probably be the most lucrative lunar enterprise in the long run.

Darrell B. Nelson said...

With your solar sail idea, you might want to look at Buckypaper, carbon nanotubes weaved together and bonded in a polymer. Strong as steel but you can cover a football field with it and it would weigh less than a gram.
Once you have that the place for asteroid mining is Ceres. A dwarf planet inside the asteroid belt. It's as big as Pluto and possibly has a liquid ocean, under the clay and ice. A normal person would weigh 5 lbs so they could work almost normally.

qraal said...

Hi Project Savior

Ceres averages 476 km in radius, while Pluto's is currently estimated at 1161 km. Quite a size difference, but their densities are similar and their bulk composition is probably similar. Surface composition is very different - N2/CH4 ice on Pluto and rock/clay on Ceres.

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