| Moving the Masses Through Space Beyond Lunar Tourism I have envisioned moving tens of millions of people to the Moon yearly, a task on the level of air travel in the USA alone, but how do we move billions of people through space? If 30 million people fly to LEO yearly in rockets that can haul 200 passengers then about 420 rockets must lift off every day. Just one big metro airport handles over a thousand flights a day, so this is not too farfetched. But the population of Earth will grow and the standard of living will rise, and everybody will want space travel in coming centuries. How do we get all those rockets to orbit? Enter the Space Elevator Perhaps big rockets that can haul 500 people at a time and launch bases all over the world can do it. But then how do we get them beyond LEO? Even taxis for cycling stations are going to hog lots of propellants and I don't know if the Moon miners and asteroid miners can supply it all. Space elevators become the answer. Numerous space elevators based along the equator and bases or terminals inland, on islands and on artificial floating cities that are reached by airplane, train, automoblie and ship seem to be the answer. The space elevators, made of some super strong yet flexible material could then be linked by a ring world at GEO altitude. The counterweights could consist of elevator shafts that extend up another 22,400 miles to 2x altitude of 44,800 miles. When would we have this? My guess-2400 to 2500 A.D. Although the first elevator could be built by 2200 A.D. And simple cables lowered down from GEO for experimental reasons might be seen in the next 50 years. Now things get interesting. We could pump hydrogen and oxygen extracted from sea water with cheap electrictity from fusion reactors and solar panels mounted on the ring world up to the outer edges of the counterweight shafts and fuel up rockets for travel beyond. Also, as Eric Lo has made me realize, you could use centripetal force to launch spaceships with no fuel at all from a ring at the upper end of the shafts. At 44,800 miles altitude the centripetal force is only 4% of one gravity. That's not much; however, the outer ring is moving at 5.7 kps and escape velocity there is 3.18 kps. So ships could be launched into outer space without fuel from the outer ring. A mere 4% of one G should not add much stress to the structure which will be made from super materials of the future from spider silk to fullerenes and materials derived from these by chemists. The inner ring world at GEO will be more massive at the system's center of mass. The thin outer ring at 44,800 miles is just a big spaceship terminal with a few penthouses for the rich and some hotel rooms, so it won't unbalance the system. As for mass being added to and subtracted from the ring thereby changing the angular momentumn, a giant linear motor system in the rings that wraps around the entire circumference will compensate for this like a gyro. Such engineering will be tremendous. Perhaps only genetically enhanced geniuses with long life spans which give them plenty of time to think about these challenges with the help of AI super computers will be able to do the job. The construction would take centuries even with AI robot armies working in space! Billions of Travelers Anyhow, billions of people can travel to or from the Earth every year and billions can live in space in the ring world and others can live in O'Neill colonies at higher altitudes. Of course, rockets and satellites at lower altitudes than the elevator/ring world system will become things of the past for safety reasons and space will be scrutinized in great detail by radars that will spot threatening meteors that will then be zapped by lasers or electron beams or missles. Some kind of shielding will be necessary for the structures. Meteor bumpers composed of layers of C60 perhaps. We still need some rocket fuel. Ships releasing from the outer ring at the right time to go on the right trajectory to the Moon let's say will need fuel for thrusters and fuel for retro maneuvers when rendesvouzing with rings around the Moon or Mars. In all likelihood, small taxi ships similar to airliners will leave the ring and dock with cycling stations on the way to the Moon or Mars, or will the ships be like luxury liners? Either way they still need some fuel to perform maneuvers, and we'll get that by pumping it up from Earth. At the Moon we could refuel with aluminum and oxygen. At Mars we could refuel with methane and oxygen or hydrogen and oxygen. Will nuclear powered ships be permitted at the outer ring? We will need nuclear electric or fusion propulsion to reach distant planets like Saturn. Cycling stations to Mars, which will be the size of ocean liners or bigger, won't always be available so sometimes we will need mighty NEP or fusion ships that can fly to Mars under their own power after a leaving the ring. Antimatter could be used, but so very dangerous and so expensive to produce. Luna and Mars Elevators There is no GEO around the Moon, but there are Lagrange points and there could be 40,000 mile long elevators from the lunar surface to stations at L1 and L2 and a ring system around the Moon. If we push the lower martian moon Phobos up to a higher orbit and mine it to build a ring and elevator system around Mars at 11,000 miles altitude, that planet becomes accessible to the masses of humanity living on Earth, the Moon, in ring worlds, space colonies and elsewhere in the solar system. We will worry about spaceship crashes with our structures as we do airplane crashes, but these will be rare, I hope, or non-existent. Venus Skyhooks If we can do all this, it seems we could build a shield to cool down Venus and terraform that crazy planet, presuming there is no silicon based life there. Mars will be terraformed. Asteroids will be mined and O'Neil colonies built in the solar system. That we can be sure of. A very slow population growth rate of 0.2% or less can be sustained for a long time, but I'm not going into that here. How could be build a space elevator system around Venus which rotates only once very 245 days? A multimillion mile long elevator from a Sun-Venus Lagrange Point? Perhaps. Venus is a tough one. The best thing to do would be to build a ring world system similar to the one around Earth and extend space elevator shafts only down to within 1000 miles of the surface, and use skyhooks that can catch hybrid jet/rocket vehicles that reach a speed of just 1000-2000 mph. If the ringworld-skyhook system has roughly the same dimensions as the one around Earth and it rotates once every 24 hours, then the skyhooks will be moving at about 1300 mph at an altitude of 1000 miles. Vehicles could climb to the upper atmosphere of Venus under nuclear thermal SCRAMJET power then switch on the rockets and arc up to the skyhooks and rendesvouz. This will take only a small fraction of as much fuel as flying all the way to Venus orbital speed of 14,000 mph. Sun-up to sundown takes about 59 days on Venus. If the planet can be cooled down sufficiently with a giant shield at the VS L1 "point", if sulfuric acid clouds react with surface minerals to form sulfates and water, if CO2 forms carbonates, if blue-green algae can live there, multiply and convert the CO2 to oxygen, will anybody want to live there? Could we build world-houses with human and animal freindly air and artifical lights during the 118 day-night cycle? Perhaps Venus could be a big nature preserve for plants where oxygen mask wearing humans can go to find out how puny they really are in the world of the jungle and make them realize how big the solar system really is. That will make them grateful for all our gardens and parks and cities and such!! Something to think about. Another possibility for Venus is the creation of ballon borne floating islands at an altitude of about 30 miles where pressures and temperatures are reasonable. Star Terminals So, in the future we could develop our solar system this way then venture to other solar systems and develop them. The mighty Star Carriers could haul people between solar systems and tens of thousands of people or more could travel to and from the stars every year. Asteroids could serve as Star Terminals where Carriers dock and people transfer to interplanetary ships of all different sizes bound for various destinations. These asteroids would have their rotation stopped or modified and cities would be built on them, orbital stations, space docks etc. Star Terminals are necessary as Carriers have limited maneuverability by riding solar winds. Driver beams at the destination system could help the Carriers maneuver. The best place to locate Star Terminals would be near the Sun or destination star. Powerful Driver beams using solar energy or solar wind gases or even matter harvested directly from the star's 6000 K photosphere by magnetic scoops fed into artificial miniature neutron stars could send interplanetary ships out to other planets in the system. Laser sails and microwave sails would not need matter for their beams and may be preferable. Harvesting matter for mass beams (particle beams) from the atmosphere of an inner planet with skyhooks seems more plausible than mining a star with intense gravity! Fusion propelled interplanetary ships are also good ways to get around fast within a solar system. See: Fusion Revisited Of equal or greater importance than locating in close stellar orbit to tap solar energy, objects orbiting rapidly near a star have the shortest synodic periods in relation to other worlds. In other words, launch windows come more often from Mercury to other worlds of the solar system and vice versa than for any other planet. Mercury would be the best place to base a Star Terminal in the form of a Ringworld with skyhooks perhaps for people who wish to visit that planet. If there are no Mercurys orbiting other stars we could push asteroids into solar orbit around those stars at a similar distance and build the Terminals. There could be hundreds of small asteroids converted to terminals. There would be thouands of interplanetary ships for travel to various worlds in the destination star system. Actually, more. Three thousand interplanetary ships, each carrying 3000 people, would be needed to move nine million people per year ( why nine million? see foot note) assuming that each ship makes only one journey per year. If we want to keep the flight from the Terminal to the destination planet, moon or space colony down to one month, so we could have six flights per year, one month from the Terminal and one month back, then we only need 500 ships. Seems reasonable in 1000 years to me for destination star systems to have 500 too 3000 ships at work after centuries of development in that star system by colonists who went there on one way journeys in beamriders (or fusion pulse and even amat pulse ships) smaller than Rama carrying a few hundred people. The 3000 passenger interplanetary ships might amass 10,000 tons, not including the fusion drive, and that's the mass of the Eiffel tower or a naval destroyer. If the ship is made of graphite, C60, polymers, magnesium, aluminum and beryllium instead of steel it will be much larger than either the tower or a destroyer so it will be very roomy. How will these interplanetary ships be propelled? Fusion is a favorite dream. Mag-sails riding the solar wind up to high speeds, interplanetary cycling stations, and interplanetary propulsion beams may also be used. Mag-sailers and cycling stations don't use any fuel and that simplfies logistical operations and may reduce costs. Some Carriers, with all passengers headed for a single planet, could let them stay on the roomy laid back carrier until it rode the solar wind with its mag-sails to that one planet and transfer its passengers over to the space elevator system and down to the planet and then by planes, trains and automobles to where ever they wanted to go. But with thousands of planets, moons, asteroids and space colonies in a given system, there will be thousands of destinations. We must have Terminals and IP ships galore. I'd Like to Book a Room on... Planning an interstellar voyage will require experts. Since money is no object in this imaginary future of robotically produced abundance when people work only because they want to the price of things is no problem. Reservations must still be made, cabins and hotel rooms allocated to individuals and their families, etc. The speed of light presents a few problems. If a traveler wants to book a room in a hotel on a planet orbiting Tau Ceti he or she has to wait 10 years for the message to get there, 10 years for a reply, and then spend about 15 years getting there at 66% light speed. It would make more sense to book rooms on other worlds from the Terminal a few weeks or months in advance by radio or laser crossing the comparatively short distances of interplanetary space while one waits for a launch window and spaceship to the destination. If money is a thing of the past, resources like passage on an interstellar vessel and hotel rooms or cabins will be provided on a first come first serve basis. With robots producing more than enough for everybody there should be no shortages. The question remains, who builds and programs all these robots? Humans who work will be given larger rewards than other from the pool of wealth everybody taps into. The colonists who populate and industrialize other star systems and terraform worlds will probably make property claims and establish governments and pass laws that they see as righteous. The dangers of tyranny and repression exist if some group of religious fundamentalists decide the world of tomorrow is too wicked and the only thing to do is to go to another solar system and claim a planet to be their own. That could mean a return to war over territory. |
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| ABOVE) Space elevators and ring worlds surround the Earth and Mars. Ring worlds and a system of skyhooks surround Venus. Ships launch from outer rings and apply NEP or fusion drive. They maneuver to cycling stations. Beamrider stations in the L4 and L5 regions and at L1, L2 and L3 for each planet drive ships through interplanetary space and apply thrust to the sails of interplanetary cycling stations to keep their orbits adjusted and in harmony with the positions of the worlds for regularly scheduled space flight. A 16,000 mile wide solar shield exists at Venus-Sun L1 point. Funny to think that in the 1950s we envisioned a lush tropical Venus and a Tibetan Mars that could be reached by nuclear thermal rockets. We had the rocketry right, but the astronomy was wrong and we didn't have the healthy fear of nuclear power we do now. Now we have enormous challenges ahead of us but this gives us more to do, a real challenge to apply our creative enrgies to... |
| END NOTE) Nine million interstellar travelers a year? Why so many? At first I imagined nine billion. Originally I envisoned a system harnessing 10% of the Sun's energy with a 10% efficiency and calculated that this would be enough to propell 900 giant starships amassing 2.5 billion tons each up to 66% c ever year. I imagined ten million passengers in each ship, so that's where the nine bilion comes from. Then I decided to cut this number to a thousandth because that seemed more real. Will there ever by so many people in the solar system that nine million or even nine billion people want to embark on an interstellar voyage every year? I don't know, but it might be possible. I have down sized my vision and dispensed with the giant solar collector system. How many interstellar travelers could be transported yearly on ships propelled by beams generated by artificial minature neutron star power? I have no idea, but somebody will certainly come up with the answer someday. |
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| Pages discussing matters related to those in preceding article: Interplanetary Tourism |
| This index links to several pages of interest. Many thanks to Peter Kokh for his input. Also, see: Advanced Interplanetary Ships |
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