| The Inner Solar System by Dave Dietzler with special thanks to Peter Kokh for his creative contribution Hot Property Most space travel advocates these days have just about written off Mercury and Venus while focusing on the Moon, Mars and orbital space. The blazing hot Sun on Mercury and the corrosive atmosphere and heat of Venus make these two planets seem like worthless territory. Actually, they offer much to mankind in the future. First of all, they have unique positions in the solar system. Solar energy is 6.7 times more intense at Mercury, therefore a silicon solar panel or foil solar thermal collector can gather almost seven times as much energy from a given area as would a solar panel at Earth's distance from the Sun or on the Moon. About 9000 watts of energy falls on a square meter at Mercury. If the solar panel is 15% efficient it will generate 1350 watts. A 100% efficient solar panel would be needed to do that on the Moon or in Earth orbit. Foil collectors will reflect about 95% of the light falling on them. On airless Mercury or in solar orbit at that distance robotic factories will be rich in electricity and solar energy for direct application to smelting and melting of metals for casting or alloying. Moreover, Mercury seems to be 60-70% iron and 30% silicates. The planet is a storehouse of heavy metals waiting to be mined and launched into space with electromagnetic mass drivers. Venus Venus is enshrouded by a thick atmosphere of CO2 that contains far more carbon than is available in Earth's fossil fuels. At Venus, solar energy is twice as intense. Many schemes for terraforming Venus have been devised. We could also build balloon borne robotic factories floating at high altitude where the pressure is only one atmosphere and the temperatures reasonable. Chemical processing equipment could be used to extract carbon and nitrogen from the Venusian atmosphere as well as some hydrogen and sulfur from sulfuric acid in the Venusian mists. Oxygen could also be extracted. A simple 19th century chemical process involving catalysts to spur the reaction of CO2 with hydrogen to form methane and water which are then easily decomposed to hydrogen which will be recycled, carbon and oxygen is all that's needed. Rockets using nuclear thermal engines and liquefied CO2 could orbit those payloads. Carbon dioxide is easily liquefied by expansion and pressurization, thus it is easy to separate from nitrogen which must be much colder to liquefy. Water vapor which composes about 1% of the Veneran atmosphere will also liquefy out but this precious substance will be reserved for making plastics in the floating island Aerostat Xities of Venus (the biggest industry on Venus will be tourism!). Carbon dioxide is essentially inert and will not corrode nuclear thermal engines or their cooling jackets since it doesn't decompose to carbon monoxide and oxygen until about 3000 degrees C. The rockets could also have jet-atomic engines. Nobody is going to be harmed by power from uranium, plutonium and thorium on Venus! Even so, Venus has a deep gravity well, and even with nuclear rockets the cost of exporting things from Venus is likely to be high. There isn't much hydrogen or sulfur in the Veneran atmosphere, so it will be more economical for Mercury and the Moon to get these from other worlds like the ice moons of Jupiter or Mars. Since the silicates that compose so many bodies in the solar system are mostly oxygen there won't be much use shipping oxygen from Venus to anywhere; however, the use of LANTR (Liquid oxygen Augmented Nuclear Thermal Rockets) for manned ships exiting Veneran orbit will extend hydrogen supplies imported from elsewhere. The high value of carbon on planets like Mercury or the Moon may offset the costs of orbiting Veneran CO2. And despite the fact that Venus has a gravity well 91% as deep as Earth's, single stage to orbit atomic rockets will work much cheaper than two or three stage chemical rockets launched from Earth's surface, so I'd be willing to invest in a Veneran carbon export scheme. Nitrogen has many uses including the manufacture of graphite fibers. Since nitrogen composes 3% of the air de Venus it may be worthwhile to upport some of this too. Transportation of metals from Mercury and carbon plus nitrogen from Venus to other places in the inner solar system ( Mercury, the Moon and Space Oases. Mars and Earth have plenty of carbon and nitrogen) will not require vast amounts of rocket fuel. Slow "interplanetary barges" using a combination of mag-sails with solar sails affixed to the mag-sail staying lines could use the free and intense solar wind and light of the Sun to ride out to other places in the inner solar system where space colonies were being built in solar orbit (interplanetary communication stations, solar observatories, etc.), and the Moon. The AI robots that do the work will originally be built of lunar materials ( Si, O, Mg, Al, etc.) and martian materials (H, C, N, S) and sailed down to Mercury and Venus. Once mining and transportation between Mercury and Venus is established metals from Mercury could be used to build more replicating robots and rockets for Venus and Venusian carbon, nitrogen and perhaps hydrogen and sulfur can be used by robots on Mercury to make chemicals and synthetic materials like silicones. The metals exported from Mercury to Venus are likely to be specialty metals required in small amounts. The balloon borne factories, Aerostat-Xities and even atomic rockets of Venus will be built primarily of Veneran plastics and carbon fiber composites. Mercury Mercury will be more than a big chunk of iron. When iron is combined with carbon we have steel. It gets better than that. The iron core of Mercury is bound to be rich in nickel also. Like iron meteorites, it will be rich in siderophile or "iron loving" elements like sodium, zinc, germanium, arsenic, selenium, bromine, silver, cadmium, indium, antimony, tellurium, rhenium, osmium, iridium, gold, thallium, bismuth and tin. The crust will contain more silicates and the mantle magnesium-silicates, but the mantle of Mercury is thin, the core huge, thereby enabling extremely deep mining by the AI robots that work tirelessly. There will certainly be places where core material upwelled volcanically in the past. If we must, we can use nuclear explosives to bore deep shafts into Mercury. Metals like silver, indium and even tin will be required in small amounts, unlike iron which is used in great quantity for construction, but they have high value. Rhenium has a very high melting point and may find use in rocket and jet engines. Sodium ( along with chlorine which is present on Venus and may be exported) is used in the synthesis of many plastics including polycarbonate. Veneran carbon may be as expensive as any precious metal, but it will come in handy when we go to mine precious metals on Mercury. It may be presumptious on my part to claim the presence of mineable precious metals on Mercury, but prospecting is largely a matter of speculation. It may be argued that iron asteroids are easier targets for metal mining, but these don't have the strategic locations that Venus and Mercury have. Even so-called "near Earth asteroids" are not near Earth most of the time and they travel on wildly elliptical orbits that take them back to the Main Belt and far from the Sun. The advantages of Mercury and Venus's locations are indicated in the tables below. To and From Mercury Planet Launch Windows T.O.F. By Hohmanns Venus Every 144 days 75 days Earth 116 105 Mars 110 170 Jupiter 90 855 Saturn 89 1965 Uranus, 88 ------ Neptune, Pluto To and From Venus Planet Launch Windows T.O.F. Mercury 144 75 Earth 593 150 Mars 337 217 Jupiter 238 931 Saturn 230 2015 Uranus, 227 ----- Neptune, Pluto It takes more energy to travel between Mercury, Venus, Earth and Mars but time of flight is low and launch windows frequent. Launch windows between Earth and Mars are 778 days apart and a Hohmann takes 260 days! And while you might think that Mars is a "springboard" to the outer solar system, launch windows from Mars to the outer planets are 800 to 700 days apart. Mars doesn't have the intense solar winds and light pressure to drive sails on their way without any fuel. Ice Moons What do the outer planets have that would be of interest to inhabitants of the inner solar system? Mostly hydrogen. Ice could be mined on Callisto, Ganymede and Europa. Hydrogen extracted and launched in tanks to orbit around the Jovian moon could be loaded on freighters that use nuclear powered electrodynamic tethers to move around amongst the Jovian moons since Jupiter has a powerful magnetic field and even spiral out to escape velocity. A VASIMR drive using hydrogen could also help the freighter. The "interplanetary barges" loaded with liquid hydrogen would use foil shaded radiators exposed only to the depths of space to reliquefy boil off from the massive LH2 load with out much energy at all. They would not need to drag along retro rocket fuel and the higher initial fuel load that that would require. Upon entry into the inner system the barges would just unfurl their rolled up solar sails and energize their mag-sails and brake for free into orbit around Mercury or Venus or space colonies in solar orbit and unload their hydrogen cargo. Since they would head back out to Jupiter with tanks empty the sails won't have to acquire too much thrust from the Sun's light and charged particle streams to get up to speed. If they travel by capture orbits they will not need retro rockets upon return to Jupiter. Once captured into orbit by Jupiter's gravity they would use their electrodynamic tethers to get around and rendezvous with space stations for more hydrogen. Pipelines of slow interplanetary barges would emerge between Mercury, Venus and Jupiter's moons. We won't get enough hydrogen to douse Venus with water but we will have enough to supply miners on Mercury and Venus as well as space colonists in giant toruses with thousands of inhabitants orbiting within the orbit of Earth or Mars. Lunans might enjoy hydrogen imports from Jupiter also for rocket propulsion, although the Moon can use aluminum-oxygen rockets, mass drivers and perhaps space elevators in the future. With Jovian hydrogen, Venusian carbon and abundant lunar silicon and oxygen it may be possible to build huge silicone "eco-spheres" on the Moon shielded with water or transparent silicone oil that isn't effected by the temperature extremes of the Moon. Affording the Future How much would all this cost? I can only believe that these things will be possible in a world that has controlled its population growth rate and planted colonies in space and on other worlds for the excitement of doing so. Artificially intelligent robots would do most of the mining and factory work on Earth and in space. The robots would produce such a vast wealth of material goods that poverty is abolished and humans are freed to pursue the arts, sciences, and even sports. Many people will have information technology jobs and do the fine handiwork the robots cannot do. If a man builds a robot and the robot goes to work night and day producing metals and finished products, that man will be highly productive. People would still work but the work they do would be far more valuable than planting rows and picking cotton or slaving away on an assembly line. I don't suggest androids that climb ladders and build skyscrapers, but I do suggest robots that can crank out steel beams, building materials and modules so fast that the price of these things becomes negligible and robot assisted human construction workers become more productive than ever. Imagine human crane operators assembling a pre-fab modular skyscraper. The cost of high rises would plummet and the supply would be enormous. Anybody who wants an office on the 100th floor or a penthouse could have one. Technology designed for space could be applied on Earth. We envision modular habitations on the Moon made of steel and glass-glass fiber composites assembled by robots with humans moving in later. What if we did that on Earth? We could have more mansions than people to fill them! Population growth will not be limited by housing but by food production which will be increased with GMOs. |
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