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This scenerio developed by Zubrin uses Chemical and Nuclear Thermal propulsion as the only means for transporting cargo form Earth to Mars or from Mars to Earth. Even then, he shows that ultra-conservative near-term technology can be profitable enough for a Martian Export Colony. But this low-level of technology does result in only high-value materials being suitable economically to trade with Earth. But if a mass-driver was set up on Phobos, the potential cost of sending cargo to Earth would be reduced and the number of potentially profitable materials to send back would increase (as the required value per kg to make a profit falls). Nuclear Electric Propulsion (NEP) although too slow for manned traffic between the Earth and Mars, would reduce the cost of transportation between world significantly. The low-thrust, highly efficient fuel consumption would be superb for cargo shipping between worlds allowing the ship to take as long as it likes to reach it's destination. A NEP cargo ship could launch years ahead of it's intended arrival date and arrive with a significantly lower cost per kg than it's competitor making the entire exersize in the lengthy mission and costly development worthwhile.
If Magnetic Sails or Solar Sails were introduced it would reduce both the cost of both outbound and inbound transit between Earth and Mars singificantly. The reduction in the cost of payload traveling both directs would reduce the required value per kg exported neccessary to make a profit further. And hence, just like the demand of the New World drove trans-atlantic transportation innovations in the 19th and 20th centuries, so will the Martian import/export trade cause a demand for advanced technology.
I can see the change proceeding from Chemical to NTR to NEP to Solar Sails to Magnetic Sails to Fusion and from Expendable HLVs to partially reusable LVs to fully reusable HLVs. NEP and Fusion propulsion are both key for human exploration and colonization of the Outer Solar System (and in the case of Fusion the possiblity of Interstellar colonization opens up).
While I agree Mars will use it's InSitu resources for agriculture, manufacturing, water/oxygen/propellant extraction etc. Unless Mars becomes completely self sufficient (a distant prospect) it will require imports and that means it will require exports to pay for the imports. High value Minerals/Metals and Deuterium seem to fit this category.
"cost per immigrant would be $40 million" really not all that bad as I recall the Space Adventures brokered seven clients rides to the ISS starting with American businessman Dennis Tito for a reported $20 million payment, making him the first space tourist with Five Clients who participated in training only. Space Adventures is offering advance booking for a future lunar mission involving travel to circumnavigate the moon, on a circumlunar trajectory. Pricing has been announced at US$100 million per seat with no possible vehicle at this time from Russia to make use of....
The problem is that $40 million/immigrant, while perfectly acceptable for government sponsored colonization (allowing an average of 100 people/year and a population growth comparable to 17th Century America), it limits the number of creative-driven individuals seeking to reach Mars to a relatively small number selected by a government agency. If Mars One has shown us anything, it's that thousands want to go to Mars now. In Zubrin's own words
"If Mars is ever to benefit from the dynamic energy of large numbers of immigrants motivated by personal choice to seek to make their mark in a new world, the transportation fee will have to drop a lot lower than this." Luckily if sufficiently low cost reusable SSTOs are developed ($100/kg to LEO) along with fully-reusable Cycling habitats, the privatelly-funded model (of individuals saving up and paying their own way) does become workable.
I doubt very many billionaires would spend $40 million for a one-way trip to Mars. Key words, one-way. The people going will be colonists, pioneers, rugged individuals on the frontier (ironically living quite communally), although I could imagine the odd Elon Musk type paying his way even in this scenerio.
The Habcraft honestly reminds me of the Conestoga Wagons from the old Frontier. They transported pioneers and the beginings of families across the frontier and then they were dissassembled upon arrival and used as building material for the first houses. The Habcraft works in a similar way in which 24 colonists fly out to Mars and upon arrival, use the Habcraft as their initial house for the first colonists. The inflatable greenhouse and tools are taken with them aswell. The upper (fifth deck) used for cargo on the way is used as additional living quarters after the cargo is removed upon arrival at the surface. Perhaps the first 6 children born on Mars will move into the uppermost deck before additional housing is built from InSitu materials (Plastic Domes, Brick Vaults etc). The entire proposal is extremely technically conservative colonizing Mars with only a Shuttle Derived HLVs, NTR upper stages, a large habitat module and use of InSitu resources (for oxygen, water, agriculture, manufacturing, transportation, mining etc).
This is Zubrin's writting not mine. But what I think is significant is that even without all the technical improvements he suggested the basic Chemical Methane/Oxygen upper stage, Crew Capsule and Cycling spacecraft may be sufficient for mass immigration to Mars. Zubrin in his book "Entering Space" noted that immigrants coming to America in the 18th and 17th centuries spent seven or eight years salary just to afford the trip over. $320,000 would be equivelant to this in modern terms (the median household income in the US is $50,000) and the high wages from the massive labor shortage on Mars would probabley payback the cost quite quickly. The hardest part of the idea is the $100 per kg to LEO reusable SSTO.
I think Elon Musk's idea of $500,000 for a one-way ticket to Mars on the MTC is completely achievable eventually. In fact it's quite close to (if slightly more conservative) Zubrin's estimates two decades earlier. The value of a Cycler is that you can reuse a billion dollar spacecraft countless times and artomorize the cost accordingly.
The other government sponsored model is also interesting however. According to the estimates made in the Case for Mars, Zubrin estimates that 100 years after such a program of immigration started the population on Mars would reach 80,000 (enough for terraforming?).
Robert Zubrin back in the 1990s proposed two possible means of transporting the vast number of immigrants required to colonize Mars. Of all the proposed methods, these two in my opinion are the most near-term and realistic. The first essentially uses a modified version of the Mars Direct Hab (with five decks instead of two) a Shuttle-Derived HLV and a NTR upper stage. The second uses SSTOs, chemical propulsion and a Cycler. The following quotes directly from his article "The Economic Viability of Mars" but all the information is also available in "The Case for Mars".
"If government sponsorship is available, the technological means required for immigration on a significant scale are essentially available today. In fig. 2 we see one version of such a concept that could be used to transport immigrants to Mars. An Shuttle derived heavy lift launch vehicle lifts 145 tonnes (A Saturn V had about this same capacity) to low Earth orbit, then a nuclear thermal rocket (NTR, such as was demonstrated in the USA in the 1960's) stage with an Isp of 900 s hurls a 70 tonne "habcraft" onto a 7 month trajectory to Mars. Arriving at Mars, the habcraft uses its biconic shell to aerobrake, and then parachutes and lands on its own sets of methane/oxygen engines.
The habcraft is 8 meters in diameter and includes four complete habitation decks, for a total living area of 200 m2, allowing it to adequately house 24 people in space and on Mars. Expansion area is available in the fifth (uppermost) deck after the cargo it contains is unloaded upon arrival. Thus in a single booster launch, 24 people, complete with their housing and tools, can be transported one way from Earth to Mars.
Now let us assume that starting in 2030 AD, an average of four such boosters are launched every year from Earth. If we then make various reasonable demographic assumptions, the population curve for Mars can be computed. The results are shown in fig. 3. Examining the graph, we see that with this level of effort (and the technology frozen at late 20th Century levels forever), the rate of human population growth of Mars in the 21st Century would be about 1/5th that experienced by colonial America in the 17th and 18th Centuries.
This in itself is a very significant result. What it means is that the distance to Mars and the transportation challenge that it implies is not a major obstacle to the initiation of a human civilization on the Red Planet. Rather the key questions become those of resource utilization, growing food, building housing, and manufacturing all sorts of useful goods on the surface of Mars. Moreover the projected population growth rate, 1/5th that of Colonial America, while a bit slow, is significant on a historical scale, and assuming a cost of $1 billion per launch, the $4 billion per year program cost could be sustained for some time by any major power on Earth that cared to plant the seeds of its posterity on Mars.
However, with a cost per launch of about $1 billion, the cost per immigrant would be $40 million. Such a price might be affordable to governments (for a time), but not to individuals or private groups. If Mars is ever to benefit from the dynamic energy of large numbers of immigrants motivated by personal choice to seek to make their mark in a new world, the transportation fee will have to drop a lot lower than this. Let us therefore examine an alternative model to see how low it is likely to drop.
Consider once again out CH4/O2 SSTO vehicles used to transport payloads from the surface of the Earth to low Earth orbit. For every kilogram of payload delivered to orbit, about 70 kilograms of propellant are required. CH4/O2 bipropellant costs about $0.20/kilogram, so $14 of propellant costs will be incurred for every kilogram lifted to orbit. If we then assume total system operation cost is 7 times propellant costs (roughly double the total cost/fuel cost ratio of airlines), then the cost of delivery to low Earth orbit (LEO) could be about $100/kilogram. If we assume that there is operating between Earth and Mars a cycling spacecraft which has the ability to recycle water and oxygen with 95% efficiency, then each passenger (100 kg with personal effects) will have to bring about 400 kg of supplies to provide himself with food, water and oxygen during a 200 day outbound trip to Mars. Thus 500 kg will need to be transported through a DV of about 4.3 km/s to move the immigrant from LEO to a (2 year period) cycling interplanetary spacecraft. The capsule mass, used to transport the immigrant from LEO to the cycler and from the cycler to the Martian surface could be assumed optimistically to have a mass of 500 kg per passenger. Thus for each passenger a total of 1000 kg needs to be delivered to the cycler orbit, which with an Isp of 380 s for the CH4/O2 propulsion system on the transfer capsules translates into 3200 kg in LEO. At a delivery price of $100/kg to LEO, and assuming that the cost of the cycler itself is amortized over a very large number of missions, this in turn translates into a cost of $320,000 per passenger to Mars.
Obviously, there are many assumptions in the above calculation that could be changed that would either raise or lower the calculated ticket price significantly. For example use of air-breathing supersonic ramjet propulsion to perform a significant part of the Earth to orbit DV could cut orbit delivery costs by as much as a factor of 3. Using an electric propulsion LEO to L1 electric propulsion ferry followed by a powered flyby through a LEO perigee using high thrust chemical stage would allow the cycler to be reached with a chemical DV of only 1.3 km/s, thereby doubling payload and reducing costs yet again. If the cycler employs a magnetic sail11 instead of simply using natural ballistic orbits with gravity assists, the hyperbolic velocity departing Earth required to rendezvous with it can be essentially zero, thereby allowing the entire LEO to cycler delivery to be done by electric propulsion, or conceivably even solar or magnetic sails. Increasing the degree of closure of the life support system on the cycler would reduce the consumable delivery requirement for each passenger, thereby reducing passage costs still more. Thus eventually Earth to Mars transportation costs could be expected to drop another order of magnitude, to $30,000 per passenger or so. The costs impacts as each of these innovations is progressively introduced is displayed in Table 3.
Table 3. Possible Cost Reductions of Earth to Mars Transportation System
Baseline Advanced Reduction Fare to Mars
Factor
Baseline Mission ------- ------- 1.0 $320,000
Earth to Orbit Rockets Scramjets 0.3 $96,000
Life Support Closure 95% 99% 0.7 $67,000
LEO Escape Propulsion CH4/O2 NEP 0.6 $40,000
Cycler Propulsion Natural Magsail 0.7 $28,000
"
What's the value of thorium in $ per kg value on Earth. Thorium is potentially a more-near term fuel for Fission power generation. I imagine just as with Deuterium if any Thorium power generation became commercially viable the demand for Thorium would rise and with it it's price. The same would be true with Deuterium when Fusion power generation comes online.
Also, that brings up something else. Fusion propulsion will likely be developed to meet the demands of a growing developing Martian colony/base. This could give the world Fusion electricity generation as a spinoff (the same happened with the Nuclear Bomb and Nuclear Submarine resulting in Nuclear Electricity as a spinoff) as generate a large market for Martian Deuterium. With the reduced cost of shipping to and from Mars thanks to Fusion, this only makes the whole trade more profitable and more practical.
I truely believe that Mars will develop a sizeable export economy (and must to support itself) even as it developes InSitu Mining, Manufacturing and Agriculture.
This is my first post on the thread so I'm kinda new.
Robert Zubrin in 1990 proposed a transportation system that could lift high value minerals/metals from the surface of Mars and return them back to earth for a profit.
"Consider for example a large unmanned NIMF, a cargo NIMF if you will, capable of lifting 45 tonnes to Low Mars Orbit (LMO). If a methane/oxygen stage is used to fire the payload from LMO to Earth (where it aero-enters and is picked up on the ground after a parachute landing), about 40% of this payload in LMO, or 18 tonnes, can be useful cargo sent to Earth. Now the 45-tonne object in LMO weighs about 17 tonnes in Mars gravity, so for a desireable stage thrust/weight of 3.4 or 7.5 klb of engine thrust. The typical T/W of a chemical engine is 40, so this means that for each 18 tonnes of useful cargo transported to Earth an engine weighing 85 kg is required. Let's say that the tanks, propellant and stage structure can all be manufactured on Mars but that the engine must be imported along with another 35 kg of space parts to repace high-tech items expended in the coarse of producing the cargo or launching the NIMF. Thus 18 tonnes of cargo can be transported to Earth at a cost of 120 kg of required imports. 18,000/120= 150 for this example. The Balance of trade ratio or B, which determines whether the Mars colony can produce any income is then given by:
B= UMP
where P is the ratio of the price per kg of the Mars produced cargo on Earth divided by the cost per kg (production plus transportation costs) of the Earth-produced items, and U is the fraction of total Martian imports can be extended to support the export operations (the rest being used to support the colony). To continue with the example, let's say that U=0.1 and that the cost of terrestrial imports is $10,000/kg (which is about what it would be if a 121-tonne to LEO class Ares with an NTR third stage costs $500 million per launch). Then if the Martian produced goods are worth $1,000/kg on Earth, we find: B=UMP=(0.1)(150)(0.1)=1.5, and the Mars colony is producing a 50% profit."
Dr Zubrin then goes on to mention some of the minerals potentially on Mars that would be economical to send back to Earth including Lanthenum, Geranium, Hafnium, Cerium, Rhenium, Gadolinium, Gallium, Samarian, Palladium, Iridium, Gold, Rubidium, Platinum, Rhodium, Europium, and really any metal or mineral as valuable or more so than Silver.
Zubrin mentions in the article that Mars has had ore-forming processes in the past over an extended period of geological time. Hence although such minerals haven't yet been discovered, there's every reason based on geologic science that they should be there and no reason to think they're not there. He also makes the point that Mars hasn't had 4,000 years of human civilization acting to use up all the easiest to discover and richest ore. Finally he makes the important point that this is using ultra-conservative late-twentieth century technology like Methane-Oxygen chemical stages, A Expendable Heavy Lift Vehicle and Nuclear Thermal Rockets (all developed in the 1960s as Chemical stages, the Saturn V and NERVA). If technology were to advance to using Magsails or Solar Sails, then the methane-oxygen stage wouldn't need to be imported and the transportation ratio M would increase from 150 to 514, further increasing profits for the colony and increasing the range of minerals/metals that could be profitably exported. Similar results would occure if low cost transport to LEO such as fully-reusable Scramjets, SSTOs were developed.
Sources:
Mars Direct A Proposal for the Rapid Colonization of the Red Planet
by Robert M. Zubrin and David A. Baker
[chapter 3 of Islands in the Sky]
What do you guys think? Could such a basis of a Martian export economy work? We already know Deuterium (currently valued at $10,000/kg) is five times more common on Mars than it is on Earth and may be a byproduct from the life-support systems. It's the critical fuel neccessary for Nuclear Fusion so when Fusion becomes viable the demand for it will rise and with it the price.
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