| Cargo Transport to the Moon Rockets to LEO Success of the lunar industrialization program for SPS construction and eventual helium 3 mining when he3 fusion is realized does not depend on high performance rockets but on economical rockets and reliability. Presently, we baseline the Boeing Delta 4 heavy as the launch vehicle of choice that can put 25 tons in LEO with a five meter diameter payload faring. If the Space X Corp. Falcon 9, comparable to the Delta 4 is ever built and operates for a much lower cost as predicted, the Falcon 9 may become the launcher of choice. Ares V rockets that can orbit 80 tons of more might also be useful if they are cost effective. Manned vehicle development may take the form of the NASA CEV or a privately built vehicle like Space Ship One. The future will tell. Rockets to LLO Propulsion from LEO to the Moon may take the form of a hypergolic upper stage, a more powerful hydrogen/oxygen burning upper stage, ion drives; or tethers, electrodynamic/momentumn transfer types may do the job. Tethers are certainly simpler, more reliable and less costly than ion drives. Solar powered electrodynamic tethers use a charged cable and the Lorentz force to accelerate back to an elliptical orbit with high apogee after tossing a payload to the Moon.. If tether propulsion is perfected it will be an excellent way to propell cargos to the Moon cost effectively without need for any propellant at all. Another advantage over ion drives. High thrust chemical propulsion for trans lunar injection does have its advantages as far as time savings are concerned. Ion drives can be slow, and time is money. For a privately financed project time is of the essence. Investors are impatient. Tethers can toss payloads onto 5 day orbits to the Moon or 90 day WSB orbits just as chemical rockets can. Tethers look best. This technology holds great promise and must be developed further. Cost Cutting Launch vehicle costs could be reduced by bulk purchasing. For two hundred Delta 4 rockets the price tag per rocket might be reduced. Launch operations will still be expensive. Perhaps launching for Korou in French Guyana will be wise, as perhaps 10% more payload can be orbited from that location and major orbital plane changes for TLI are not necessary. Barging D4s from the US to Korou at ten cents per ton mile, the average ocean shipping cost these days, may lead to payload increases that greatly offset barging costs. The possibility of parachute down zero stage boosters for the D4 or Falcon 9 to reduce costs must not be discounted. The RS-68 engines have been considered as replacement reusable engines for the Space Shuttle. Even modified Soyuz re-entry capsules and Artemis Project habitat and manned lander systems must be considered for low cost manned transit to and from the Moon. Making use of existing hardware and development of existing designs rather than designing and building a manned lunar transportation system from scratch would be a wiser strategy. An overpriced "All-American" taxpayer funded "flags and footprints" is not the goal of free enterprise in this age of global trading. Without tether systems or ion drives, we would have to consider a hydrogen/oxygen upper stage that could send the most payload mass Moonward from LEO and is thus preferable to a UDMH and N2O4 fueled TLI stage. However, UDMH and N2O4 will be used for landers because they are space storable for days and even months, unless some kind of solid rocket of equal performance is developed. There is also the possbility of a lunar rotovator to land payloads without fuel. If we can make that stretch, cargo space elevators made of fullerene nano-fiber might be the way to get cargos to GEO and then the Moon. A conservative/optimistic prediction would be the use of tether systems to toss payloads on 90 day WSB orbits that allow gravitational capture into LLO without retro rockets and a mass produced low cost lunar lander. Eventually reusable landers fueled by propellants produced on the Moon will go into action. To be really optimistic, a space elevator from L1 or the lunar surface or a rotavator will be built to land cargo without any rocket fuel at all. However, we must refrain from wild optimism about rotavators and space elevators. Mascons might cause rotavator orbits to be unstable and rotavators can only land payload in one location. Rocket powered landers will not remain in orbit long enough to encounter instability and they can land cargos in more than one place. Cargo Landers It has been shown using sophisticated computer programs that ice could be crash landed on the Moon with very little being lost at impact. I propose inexpensive one-way cargo landers to reduce costs. HARD LANDER: Theoretically, and in want of experimental verification, a shell of lithium metal could absorb the heat of impact at 2.4 kps on the lunar surface. The specific heat of lithium is highest of metals, H2 highest of all, with lithium at 3.56 kj/kg K So if 2000 kg hits at 2.4 kps the KE is 5.76 million kj If the delta Temp is 1342 (Li vaporizes at 1342 C) then 1200 kg. vaporizes and 800 kg would survive, maybe more if the heat of vaporization is allowed for also. So 800 kg of cargo could be surrounded by 1200 kg. of lithium, maybe the lithium would be in the nose like a bullet. Q= m*c* dT 5.76E6kj = 1200 kg * 3.56 kj/deg. kg. * 1342 C If we use a WSB orbit and impact at 1.6 kps then 2.56E6 kj and 536 kg vaporizes and almost 1.5 metric tons survives!! Also there will be phenomena like regolith shock absorbtion, evaporative cooling, and the increase in specific heat capacity at high temps. As the lithium metal jacket heats up-it can absorb more heat. Hard to beleive anything that decels from 2.4 kps to zero in a fraction of a second won't be flattened! Have to wonder what happens to a high speed bullet at 900 m/s shot into sand... Inert bulk cargos and industrial metals rare on the Moon could be delivered to the lunar surface by hard landing. A shell of cheap lithium would be cheaper than any lander with exotic tech of all sorts. A lander on hydrazine and N2O4 would need MR of 2:1 to land on the Moon-equal mass of fuel and lander+ payload. Since we'd cannibalize the lander it's all payload, so 50% is fuel and 50% is cargo, but at 2.4 kps with a hard landing lithium shell 60% of the mass sent Moonwards vaporizes on impact and 40% survives as payload. Comparable and the cost has to be much, much less. Say the lithium shell consists of layers with pressurized hydrogen in between and that gives it more "bounce" and the shells "pop" and the hydrogen spews out. H2 has the highest specific heat capacity of all elements. If you let some LH2 evaporate into the vacuum it cools the LH2 to a slush...so the expansion of H2 gas might add a cooling effect. For a rocket from LEO to V esc dV is 3.2 kps with LH2/LOX ex.V is 4.4 kps e^(3.2/4.4) = mass ratio 2:1 Delta 4 heavy puts 25 tons in LEO, so 25 tons (fuel, cargo, upper stage structure)/ 12.5 tons ( cargo+upper stage) Since a rocket's structure is about 20% fuel mass we have 10 tons cargo, 2.5 tons upper stage and 12.5 tons LH2/LOX. So we shoot 10 tons Moon bound. 6 tons lithium impact absorber, 4 tons cargo. Inert cargos only: copper (Al alloying), zinc (Mg alloys), lead (red glass tinting), tin (Ti alloys), vanadium (Ti alloys and tool steels), Teflon, plastics, V2O5(H2SO4 catalyst), platinium (catalyst, fuel cells), fused solid LiCl and LiF salts (for lithium,chlorine and flourine), oxysilicon nitride (for ALCOA process electrolystic Al making cells), gallium arsenide (for making 30% eff. solar panels, gallium indium nitride (for making 70% eff. solar panels), other metals, even freeze dried compacted food stuffs. Ice? We can mine volatiles and get ice at the poles, I am confident, but some ice might help. If we take WSB orbits we could land even more stuff because these encounter Moon at orbital speeds of about 1.6 kps. Also, I am certain regolith will absorb some energy like a cushion. The stuff is soft and powdery. And shock waves will be absorbed by regolith, so maybe 50% cargo and 50% lithium energy absorber. What if there is a lithium alloy with higher specfic heat that is "spongier" and has higher vaporization point and can absorb more energy???? Lithium costs about $100 per kilogram. Perhaps slightly impure lithium would suffice and be cheaper. Or there might be a lot of scrap lithium around in a couple of decades given the increasing use of lithium-aluminum alloys for aircraft construction. If 100 hard landers are fired at the Moon then 400 tons of cargo is deposited and 600 tons of lithium destroyed. That's $60 million worth of lithium. Less than half of one Delta 4 launch. And probably far less than the price for 100 soft landers! Lithium is very soft, moh's hardness 0.6, melts at only 180 C but doesn't boil until 1342 C When it impacts and heats up will it form a liquid cushion?? Heat of fusion 661 kj/kg (158 cal/gram) so when it melts 1200 kg would absorb 793,000 kj and I calculated (2000 kg.)(2400 m/s squared)/2 = 5,760,000 kj and that would induce a dT of 1342 C with a specific heat of 3.57 kj/ deg. kg. So if it was at zero C. it would boil. But another 793,000 kj is absorbed when it melts, more when it vaporizes (heat of vaporization), and its spec. heat must increase with an increase in temp. So maybe more than 800 kg. can be spared on impact if 2000 kg. total impacts. As for the G forces, cannons shoot projectiles at 10,000 G shocks or more. Super guns have fired projectiles to sub-orbital velocities. And so what if spheres of metal flatten out on impact? Or do they? If the soft lithium soaks up all the energy on impact, melts at a low temp then boils into a vapor or even a plasma...almost instantly. You may argue that the lithium goes splat and vaporizes but the sphere of metal keeps going, but it would crush into the lithium and the lithium would soak up all the energy when the mechanical energy transforms into heat. Think of lithium as an "energy sponge." It can absorb more than its own kinetic energy due to its mass at hi V and boil away. Hi spec heat cap and hi m.p. Carbon has a hi b.p. but a lower spec. heat. so it can't do it. It takes about 2300 kg carbon to absorb the energy of 2000 kg. at 2.4 kps. The heat of vaporization for lithium is a whopping 147 kj/mol Since a mol of Li is 7 grams this is 21,000 kj/kg. If the 2000 kg. projectile hits at 2.4 kps that's 5,760,000 kj but if 1200 kg of lithium vaporizes it can absorb 25,000,000 kj!!!! I am convinced that a jacket of lithium can protect metals and other solid cargos , and the configuration is a sort of projectile with the lithium up front. Maybe some kind of system that traps the vaporized lithium upon impact in a honeycomb could exist so the lithium vapor doesn't just expand and escape when the cargo projectile impacts but fills the honeycomb with lithium vapor and absorbs even more energy allowing an even better payload to lithium impact energy absorber mass ratio. Experimentation is called for. SOFT LANDERS: For inanimate cargos not consisting of sensitive instruments or inert cargos of materials a semi-soft lander could work. This could be a very simple machine with a solid fuel motor similar to the lunar Surveyor's using aluminum and ammonium perchlorate in a polymer binder with a spherical steel or titanium casing because the sphere can contain the most pressure and a highly expanded vacuum nozzle. Verniers for velocity and attitude adjustment could use simple pressure fed hydrazine monopropellant. This lander would be simple, robust, reliable and low cost. It would contain very few moving parts. Guidance and control could be done with a miniature electronic system using solid state miniature gyros and accelerometers and a radar altimeter that amasses no more than ten pounds. Instead of landing legs simple cheap gas bags would be used and these would allow a damage free touch down at significant speed on uneven terrain. Soft landed cargos would consist of machinery, tools, fuel cells, mining robots, magma electrolysis units, solar panels, a small nuclear powerplant, 3D additive sintering devices, etc. Lower performance for the solid fueled retro with monopropellant verniers might be outweighed by cost reductions and reliability, simplicity of manufacturing the landers, etc. See the discussion below. If the landers have 280 second motors, then at 2.4 kps they would each land about 4.17 tons of cargo (if we count the lander itself as cargo too since we will cannibalize it) given ten tons to TLI by a LH2/LOX upper stage with an initial mass of 25 tons in LEO. One hundred D4 launches could send 417 tons of cargo soft landed to the Moon. All parts of the lander would be "cannibalized." So 200 D4 launches for about $30 billion could result in 834 tons on the Moon at about $17,900 a pound. If tethers are used to propell payloads to excape velocity payloads could be more than doubled and prices per pound to the Moon more than halved. If WSB orbits are followed then of ten tons Moonward 5.6 would be cargo (if you count the lander itself as cargo). Now 200 Delta 4 launches results in 1120 tons on the Moon at a cost of $13,390 a pound. Once again tethers could more than double the payload and cut the price per pound by more than half but the cost of constructing the tether system would have to be figured in to the cost of the whole project. If we don't count landers as payload mass then only 3.2 tons is cargo if we launch directly to the Moon from LEO on a 3 to 5 day trajectory and 4.9 tons is actual cargo if we use a 90 day WSB orbit. So the WSB orbit increases the "actual cargo" to the Moon by 50% and the total cargo by 34%. The most efficient way to land things on the Moon without a rotavator or space elevator would be to use reusable landers fueled by polar ice, but can we land anything on the Moon this way without a substantial system of mining robots, power supplies, water electrolysis and fuel production systems, storage tanks and pumps, plumbing, costly reusable lunar "shuttles" and even a small manned presence? This may be impractical. Now, if we could use a comparatively simple nuclear lander using water for reaction mass, that would be best. See: http://www.neofuel.com/space98/ We have to land on the Moon and tap its resources before we can use those resources to land things on the Moon. Simple logic. Once an industrial presence is established on the Moon it should be less expensive to expand by shipping cargo from the Earth and utilizing lunar resources to build metal smelters and more mining machines, construction equipment, manfacturing devices, products of all sorts as well as rocket refueling facilities for reusable soft landers that haul down humans and cargo and rockets for Earth return. Naturally we will manfacture everything on the Moon that we can. |
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| Lithium projectiles could be spin stabilized. No guidance or control systems. Very inexpensive. Trans-lunar injection upper stages would need precise navigation ability to pin point targets on the Moon. |
| Discussion If a moonbound lander plus payload amassing a total of 50 tons is tossed into a WSB orbit by a tether system and needs a delta V of 1.6 kps to land, then a solid fueled lander with a 2.7 kps exhaust velocity will need a mass ratio of 1.8. Let's say the solid fueled lander has a mass 10% of fuel mass, as opposed to 20% for a liquid rocket, then: 1.8= 50/x x = 27.78 Propellant mass = 22.22 Lander mass = 2.22 Payload mass = 20 If a liquid rocket with 3.5 kps ex. V is used it will need a MR of 1.6 1.6= 50/x x = 31.25 Propellant mass = 18.75 Lander mass = 3.75 Payload mass = 27.5 The solid lander can only deliver 73% as much payload. The liquid 137.5% more. In other words, if it cost $100 million ton launch 50 tons of liquid lander, propellant and payload then ten launches would cost $1 billion. To get the same payload to the lunar surface with a solid lander, we would need 14 launches at a total of $1.4 billion. If the liquid lander costs $5 million and the solid lander only $1 million then we spend $50 million + $1 billion versus $1.4 billion + $14 million. Or $1.05 billion versus $1.414 billion. The more expensive lander is much cheaper! An aluminum burning rocket has about 7,000 BTU per lb. of exhaust products while hydrazine has only 4,180 BTU/lb. of ex prods but the hydrazine burning rocket has much lighter exhaust products that move faster and create a more efficient rocket, so an Al burning rocket gets about 280 seconds and a hydrazine burning rocket about 350 seconds. Lithium has 8,570 BTU/lb ex prods and much lighter ex particles than an Al burning rocket. Beryllium also has light ex particles and 10,450 BTU/lb. ex prods. Conceivably, a simple, robust and highly reliable solid rocket burning Li or Be could approach the specific impulse of a hydrazine burning rocket. I have no data on Li or Be solid rockets. Lithium costs about $100/kg. and could be more expensive now due to demand for Li/Al alloys while Al is just a couple of bucks/kilo. Beryllium is even more expensive. Lithium and beryllium are two very interesting and useful metals. Beryllium alloys can be as light as magnesium and as strong as mild steel. They can be hazardous to one's health but robotic machining and handling of these metals can prevent illness in workers. We wouldn't want beryllium spewed into the environment because it is toxic. In space or on the lunar surface beryllium rocket exhaust would not be anything to worry about. If the supply of these metals is ever increased and the price drops low enough, we might use them for one way landers to the Moon someday, barring the success of a lunar rotavator or lunar space elevator. Hydrazine is also hazardous to health. Maybe I am like a kid who remembers the Ranger lunar probes even with an attachment to the lunar Surveyors. I just think a real simple, cheap, robust and highly reliable cargo soft lander with a solid rocket main motor loaded with lithium or beryllium so it can compete with hydrazine and nitrogen tetroxide would be a cool thing to build and launch to the Moon. Given the usefulness of Li and Be I don't doubt that some corporation will figure out how to produce them in large amounts someday at a low price. There was once a time when aluminum cost more than platinum and Pt is more valuable than gold!!! So it's possible there is a future for Li and Be and even solid rockets that burn them. Perhaps the best way to burn Li or Be is in a fluorocarbon binder or a binder with a high percentage weight of oxygen with a super oxidizer like lithium perchlorate. See: |