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a table top tokamak? You're dreamin' IF such a device was possible it would only crank out out a few hundred watts at most, and that's a flea's sneeze when you're talking about the energies required for space travel. As for nuclear pulse, it is terrible inefficient and hogs alot of uranium as well as releasing enough radiation to kill the crew and damage the payload. And what do you do about those intense square wave thrust pulsations? Shock absorbers? Not good enough. Stick with NEP (vapor core is best), gravity assists, hi-thrust chemical, gas core fission (not to be confused with vapor core reactors) and solid core fission. That's stuff is or will soon be real.
Let's stick with carriers instead of an argument about NEOs vs. the Main Belt. The Nuclear Propulsion thread is nothing but a debate about plasma sails these days. The titanium truss would be the "keel" of the ship. You could bolt different habitat modules to it depending on crew size and even bolt different drives on it depending on mission, to get as many customized configurations as you want. A truss about 100 feet long of 12 inch wide titanium tubes one inch thick would amass about 100 metric tons. Since your in microgravity and you won't be accelerating very fast you could bot massive modules to it. You could go out into the main belt, leave the hab mods out there for a mining base along with other equipment and send the skeleton of the ship to some other asteroid to pick up cargo and go back, etc. Since fusion has not been perfected yet, and it may turn out that fusion reactors are too massive for efficient drives ( look up the ITER-its about 10,000 tons for just 500 MWe), I like the vapor core fission reactor system with a VASIMR or ion drive. If the ship is going to accelerate out of LEO it will pass thru the belts over the course of weeks or months, so it would be unmanned until it got out of the belts then the crew would fly up to it in a small rocket "taxi." If leaving Mars orbit, no problem, Mars doesn't have radiation belts.
For information on vapor core reactors see: http://www.inspi.ufl.edu/index.html and http://www.highway2space.com/ast/presen … _knigh.pdf
Make your carrier ship not much more than a titanium truss with a drive system attached under robotic and radio control. The mass will all be in the form of cargos bolted to the truss. Then when your ship comes back from where ever it went it can drop off all that cargo and go back amassing next to nothing, unless it picks up more cargo. The point is: in the vacuum of space your ship can be 95% cargo. That should be very efficient. Maybe you head out to the asteroid belt with 450,000 tons of refining and smelting equipment, get to work on an asteroid and come back home with 450,000 tons of platinum, irridium, or hydrocarbons, etc. Just leave the refinery out in the belt where it can work until it goes kaput.
If you really like nuclear propulsion, you should be thrilled by this, if not, well maybe you're dead.
Ok, so now we have plenty of water. Then there are those strange superoxides in the soil. How much oxygen would the soil release if we warmed it and hit it with water? Of course, how do you get it warm enough to melt water ice without all the CO2 to greenhouse the planet-I say we need to produce super greenhouse gases like sulfur hexafluoride that have far higher heat trapping ability than CO2, and maybe a giant reflector in orbit. Where there is a will there is a way as long as no physical laws are violated. Have you even seem this: http://www.space.com/science....13.html I think it is kinda stupid to oppose terraforming. I advocate cloning to. Overcoming the poltically correct opposition will be harder than anything.
check out www.spheralsolar.com They have low mass solar panels made of silicon microspheres mounted in foil. They are lighter that ordinary panels and are flexible. A combination of solar, winds (how much will a windmill weigh versus the potential energy return?) and nukes until we can drill for areothermal seems like the right path.
One of the Lagrange points would be the place to locate for various reasons. Eventually, we will tap lunar materials like silicon, oxygen, aluminum, iron, magnesium, titanium, glass, ceramics, etc. We will also import light elements like H,C and N from NEOs or Mars and useful metals like copper that the Moon doesn't have much of. Our factories on the lunar surface and in space will grow and we will manufacture almost everything in space. There will be no more RHLLV launches from Earth, just SSTOs with people and small items like vaccines or microcircuit chips.
Also of interest is the use of mini-rovers and micromachines to bootstrap a lunar base by remote control. The machines self-replicate and even build larger copies of themselves and this seed becomes the giant redwood tree of space industry after several years. That will really cut down on heavy payloads from Earth also.
Soph, you must realize that I was ten years old when Apollo 11 landed on the Moon. The newspapers carried articles about manned missions to Mars by 1981 with about 50 men going there in nuclear ships launched by the Saturn V and assembled in LEO. The Shuttle was supposed to be a two-stage vehicle with a fly-back fully reusable first stage and there were hopes of sending the president up on the shuttle in 1976!! Then, after Apollo 17 they started hacking away at NASA and the shuttle became the thing it is today. Even so, in the late seventies I read articles indicating they planned 50 to 100 shuttle launches every year for ten years beginning in 1980 for satellite delivery and repair, a space station, a Moon base, a space telescope and a Mars mission. Heck, if we did all that by 1990 we'd be exploring the moons of Saturn and have permanent bases on Mars. Well, the shuttle launched in 1981 and you know what really happened. Do you see why I am such a pessimist????
Yes, the tanks would have to be redesigned and the engines modified. More thrust would be needed to lift the rocket off the ground also as the lower energy CH4 will amass more. I am just wondering about launch rates. Fueling up a rocket with LH2 is a big deal. The tanks actually contract due to the cold. Everything is checked out before the rocket is fueled up and checked again after fueling. LCH4 would also be cold. I must wonder if a shuttle burning kerosene and N2O4 or H2O2 would ever work for regular scheduled space flights for tourists let's say.
Yes, the ET would have to be redesigned for the Magnum or Ares. The Energia is designed to haul a 150 tons payload (I've also read 170 and 200 tons) mounted on top of the core with 8 Zenit boosters on the sides of the core. They call this configuration Vulkain. With 4 Zenit boosters 95 tons. Energia exists in reality. Magnum and Ares do not. The Russians need money, but would they offer a fair price? Would they deliver reliably. The only thing that seems to work in Russia these days is the mafia. I'm not cutting down Russians. It's just a sorry situation over there.
500,000 tons ships with fusion drives? I like it. Just wait another 100 to 200 years!!! What about going to Saturn with a ship like that. Send out the smaller ships to explore the moons of Saturn and send helium 3 harvesters into the atmosphere of Saturn. Now the question is-do we build these things with lunar materials in Earth orbit or do we build them with materials mined on Phobos and Diemos in Mars orbit and fly to Saturn and the main belt for Mars??? Visiting some of the Kuiper Belt objects beyond Pluto would also be interesting. Pluto is no longer the edge of the solar system.
A nuclear SSTO would be cool and highly effective, if it was allowed. If it crashed it would probably land in the sea where billions of tons of U and Th are dissolved by nature already, and if it crashed on land it would bury itself 50 feet under ground where it couldn't irradiate anybody, in other words-anybody close enough to the crash site to be irradiated woudl be killed outright by the impact!!! So I am for it, but legal realities stop us. Launch to Mars from the Moon doesn't gain anything, but launch from L1, assuming fuel launched up from the Moon, and Earth fly-by gravity assist are interesting concepts. As for a space hangar, some kind of inflated KEVLAR balloon and flexible sphincters instead of hatches would be interesting, but why can't we just assemble ships i the vacuum??? Granted, our first explorations of Mars can be like Mars Direct, but eventually we will use large ships assembled in space and refueled in space, with nuclear propulsion also. As for space elevators, they seem like far future stuff to me.
I like what you guys have said about the Energia and using Khouro. Seems to me it could be done. Get an assembly line going and maybe we'd have a relatively cheap RHLLV system. The Ares would take a fair amount of development and then there's those SRBs. How about using Zenit boosters on an Ares instead of SRBs?? Here's a good one if you haven't seen it already: http://www.russianspaceweb.com/energia.html
I read Robert Dyk's letters to Russia and translations. Don't remember exactly how I found them, Robert!!! One thing bothers me-LH2 is just fine for launching small numbers of payloads to Mars, but what about routine space flight?? What if we fueled up the Energia core with liquid methane and LOX instead of LH2?? It would cut the payload mass down but it could allow more routine launching. LCH4 might be cheaper than LH2 also. And what about recovery of the four core engines? Is recovery of the core tank possible? I imagine an inflatable heat shield in the nose of the core tank might make it recoverable. If we can just get the main engines back and use the Energia core or ET for the Ares in space for stations, ship hulls, surface hab, storage tank, scrap metal even grind it up for rocket fuel (Al powder+LOX) we might have an excellent system. See http://www.space-rockets.com/Wickmans.html and http://www.spaceislandgroup.com
And besides radioactive elements (about 1 ton of U per million tons coal and an average 1000 MW coal plant burns 3million tons coal/yr.) coal emits heavy metals including lead, sulfuric acid, irritating sulfur dioxide, lung clogging particulates, carcinogenic chemicals like benzpyrene, etc. Millions of tons of sludge are produced every year that has to be dumped. Vast areas have to be strip mined. Transportation via RR trains, barges etc. leads to deadly accidents. Coal is really filthy.
To rendesvouz with the cycler you will still need to reach escape velocity. As the cycler passes Earth it will be moving faster than the Earth is in its orbit around the Sun. You will have to rocket out of orbit at a bit more than escape velocity to match velocities with the cycler. I really wish I knew of a good website about orbital mechanics that would explain this to you.
I think you have missed the point of cycling stations. To rendesouz with the cycler takes just as much energy and rocket fuel as going there, however, the cycling station is big and roomy, has greenhouses aboard, etc. So all we have to do is take a small fuel efficient rocket to the cycler then travel in comfort. When nearing the destination we board another small taxi and enter orbit while the cycler flies on. The only reason this saves us anything is because the large mass of the cycler doesn't have to be accelerated or decelerated. Cycling stations are no good for cargo-no savings. The best thing would be to use ion drives or solar sails to move cargo from orbit to orbit or Lagrange pt. to Lagrange pt.
Regarding the two previous posts, I agree 100% with both of them. If it does turn out that privateers can't make money in space, could a future where robots and perhaps nanotech has made everything so cheap that we don't even worry about money anymore? At the very least, use your caclulator to see what happens at a mere GDP growth rate of 3.5%, which is considered low. In 100 years the economy would be 30x as big-that's alot of goods and services.
A) Such pessimism
B) you guys suggesting space elevators and anti-gravity know you are on the "lunatic" fringes, but so what? If I told an engineer 40 years ago that I would have a computer on my desk like this for under $500, he would have laughed at me!! There's no telling what might come out of high energy particle physics in the future.
C) once again, see http://www.spaceislandgroup.com
D) Lower launch costs=tourism for sure
E) have you read anything about undercooled alloy research in microgravity?? Liquid metals can be cooled in microgravity to temperatures below their freezing point without solidifying and this leads to interesting possibilities. Raw materials might come from Earth or the Moon to be alloyed in huge amounts at LEO factories in the future. I'm keeping my fingers crossed. Of course, the success of such operations depends on low cost access to LEO
F) low cost access to LEO will lead to space observatories operated by consortiums of large universities-building those observatories will be profitable for the builders
G) Inmarsat, Globalstar, Astrolink are doing OK. Sirius and XM radio are going good. DirecTV is no flop. As for Iridium, it was bought up for only $25 million and is now operating mostly with defense contracts. Teledesic is on hold for now, but when the economy picks up again, which it will, Bill Gates and Craig McCaw will build their internet in the sky.
H) protein crystals, pure gallium arsenide,???
I) sub-orbital rocketplanes and mach 7 bombers
J) advanced satellite applications involving the most sophisticated microcircuitry and high powered radios
K) helium 3-when we get fusion beyond D-T
L) low launch costs will make Moon mining and solar power satellites possible and profitable. Future world energy demand will be so great that all forms of energy will be developed-fusion, winds, tides, OTEC, biogas, ground based and space based solar. High temp. superconducting cable, now in production by American Superconductor, will allow efficient transmission of power and all the remaining fossil fuels will be used for chemical and synthetic materials rather than being burnt and causing global warming.
I suggest you go back and read my posts more closely, and give it some thought. What has 40 years of government activity and corporate welfare for Lockheed and Boeing achieved??? If we stay the present course, the most you will ever get is a token Moon base and a tuna-can mission to Mars if your are lucky. A new direction is necessary. Profits-tourism, alloying, energy, comsats, etc. This all depends on the price of a pound orbit coming down to well under $1000. What's your idea??? Some original thought would be appreciated.
And while I am on the soapbox, the creation of fully reusable launch vehicles made of standardized parts, mass produced with automation and even some cheap foreign labor, simplified designs (the RS-68 motors have 90% fewer parts than the SSMEs), in other words building space vehicles the way we build cars and airliners, would make things cheap. When the price to orbit comes down to $20,000 a person, there will be millions of customers in the tourism and industrial sectors of the market. Washington D.C. just has no interest in operating a for profit business. If they did, maybe our taxes would be much lower!!!
Rob, my answer can be found at http://www.spaceislandgroup.com As long as Congress is in control of the space program instead of businesses trying to make a profit off everything from comsats to tourism to SPS or helium 3 (when we get fusion), we will get nothing but political pork projects. The best way to get more done in space is to do away with NASA the way they are doing away with AMTRAK. The defense space operations which are separate from NASA will have to remain intact, and since the DOD uses Titans to launch their spy sats they don't need the Shuttle. As long as Congress sets the objectives which amount to nothing but flags and footprints missions or flags and a space station that's no better than the MIR and not nearly as good as Skylab, instead of entrepeneurs whose objectives are high-volume space tourism and low cost space transportation for industrial operations, we will have $500 million per launch dinosaurs and not much else.
The only problem with asteroids is that the launch windows are years, even decades apart. The velocity increment to get there may be small, but once your there, you are stuck there for years until an opportunity for return comes around. On Mars, the launch windows are 2.13 years apart, there is a reasonable amount of gravity, an atmosphere that although is thin supplies some protection from galactic cosmic rays as does the bulk of the planet itself, subsurface ice probably, and two nice asteroids in orbit. I favor working out the details of asteroid mining on Deimos and Phobos before heading out to some distant 'oid or NEO that comes near Earth every ten years. Mars is the next most freindly place in the solar system, it can be terraformed and we'd have to build 1000 L5 colonies every year for 1000 years to have as much surface area as Mars. As for space solar power-I think it's possible. All we need is a vast reduction in prices by privatizing NASA and mass producing space shuttles. The Moon can be explored and mined with teleoperated robots (Mars is to far away for teleoperation-hence the need for humans) and SPS can be contructed with teleoperated robots. Most Moon miners and SPS builders in the future will work at a computer center in Houston instead of in space!!
Both ideas sound good to me. In his book,"The Millenial Project," M.Savage mentions using a mass driver on Pavonis Mons because it is just about on the equator. That mass driver could tak a while to build. NTR rockets using CO2 or H2O which seems to be very aboundant on Mars based on Mars Odyssey results, would be an excellent way to get exports from Mars going.
If a significantly sized Martian civilization develops I think they'd be far more likely to be spacefarers than people on Earth. Not only does their low gravity make it easier but they'd already be accustomed to living in spacecraft-like environments and there'd be a lot of economic incentives to getting out there in the asteroid belt. Personally I hope it happens. I think such a culture will aid us in our ultimate drive to the stars.
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"To achieve the impossible you must attempt the absurd." --AAA
[I]You can say that again!!
If the moonlets contain no water, they will still certainly be composed of rock that is about 40% oxygen. Since 8x as much oxygen as H is needed for rockets, the moonlets are still useful. Aluminum can also be burned in rockets.
OK, imagine the human race run amok, people breeding like wild, AI machines self replicating and tearing up asteroids and moons to build "space colonies," the whole solar system turned into an artificial habitat for human rabbits...doesn't sound good.