PB666

Yes and I am not reviewing papers anymore or assisting the manuscript production . . . .thank god. Wikipedia is knowledge enough for the masses.

28 tons 28,000*9.8 274400. 110000/274400 = 0.404. u = 398600441800000. Lets see what the laws of physics say. 6371000 + 200000 = 6571000. Vorb = 7788 m/s and g = 9.23 1125 sec x 110000 = 12375000/(462*9.8) = 27332 kg of fuel, empty mass is 3042 kg =30710. If the payload is 28 tons then 58710 at the beginning of the burn would have a TWR of 0.198. if r = 6571000 and a = 1.98 m/s then our ship is only capable of fighting gravity when 9.23 - 1.9404 < centripedal acceleration = 7.29 ac SQRT(ar) = V . V = 6291 So in terms of burning to orbit, its could only burn for the last 1500 horizontal dV and do so rather inefficiently because of a huge vertical component. Which . . . .is what I was saying. I have a working model of the RL10b-2, I generally have 3 or 4 of these on the backside when I need to push, the problem is that the rocket has a fairly wide nozzle. On a 5 meter diameter rocket they get packed close together and its difficult to put fairings around them. 3 engine mount is on a F4 fuel tank (5 meters) and there is a modified 38 stack decoupler that goes under. I generally give it the roscosmos treatment with structs and no shroud (swinging in the breeze all the way up).

Peale, S. J.; et al. (1979). "Melting of Io by Tidal Dissipation". Science. 203 (4383): 892–894. Bibcode:1979Sci...203..892P. doi:10.1126/science.203.4383.892. PMID 17771724 The vertical differences in Io's tidal bulge, between the times Io is at periapsis and apoapsis in its orbit, could be as much as 100 m. Its Laplace resonance with Europa and Ganymede maintains Io's eccentricity and prevents tidal dissipation within Io from circularizing its orbit. The resonant orbit also helps to maintain Io's distance from Jupiter; otherwise tides raised on Jupiter would cause Io to slowly spiral outward from its parent planet. "Io: The Volcanic Moon". In Lucy-Ann McFadden; Paul R. Weissman; Torrence V. Johnson. Encyclopedia of the Solar System. Academic Press. pp. 419–431. ISBN 978-0-12-088589-3. Moore, W. B.; et al. (2007). "The Interior of Io.". In R. M. C. Lopes; J. R. Spencer. Io after Galileo. Springer-Praxis. pp. 89–108. ISBN 3-540-34681-3. -Good ole wikipedia.

Do-do birds as I recall could not fly, what are the flight dynamics on this?

If you had the capability of doing a dyson sphere why not just create hydrogen bombs, create a large sphere, pull a vacuum on it, blow up a hydrogen bomb at the center, remove all the heat compress the remaining gas, repeat. Alas someone has come up with a viable source of nuclear energy in space, lol. You could put your steam transformer on the inside and the secondary radiators around the shell, and overtime you will have all the deuterium and tritium you need. IN fact you could just surround the bomb with about 100 meters of water, it would vaporize the water and you could just gate the steam through a tubine and collect the condensate on the other side of the radiator. In fact you could just use all the nuclear bombs left over from the cold war take the war heads into space, detonate for a few months.

The reason for that is in KSP the atmosphere height is 70 km and you can power up your burn to horizontal about 24km which means the burn to horizontal meaning you have 46 km to burn out about 1700 dV and to add to that your gravity falls off quickly 0.5 g is 240 km above surface, and on top of that you are approaching w2r more quickly. Once you establish a suborbital trajectory you have plenty of thrust*time to circularize before you reach the apex and in general this is going to push the apo higher. If we go by the equation d = 0.5 a t2 and a = 6.0 on average then you have 118 seconds to burn at 13+ a and that gives 1534 dV that with the spin of the planet and 400 or so horizontal V before the turn the 2295 you need to orbit. On earth your orbit is 140 and you can start really powering up the burn to horizontal about 40 km, meaning you have 100 km to traverse but 6950 dV to burn. Since the average gravity is nearly 9.8 and w2r is not realized as countering gravity until relatively much later the typical downward acclearatoin is around 8.0 a. 100,000 = 0.5 * 8 t2 meaning that you have 158 seconds to burn the 6950 dV and thus using 1.3 TWR you would not achieve that speed (only 2054) with a lateral burn in the required time. Either you have to turn later getting a higher apogee or burn harder. Burning harder is very difficult to do and 140,000 m is rather low anyway, so a combination of both suffices. If you have a 400 Vtan, Earth rotates at 450 m/s surface, and you have TWR of 2.0 during the burn. Total orbital velocity at the apex is 4010, which does not seem bad until your realize that at the end it only reduces effective gravity by about a quarter son instead of 9.8 effective gravity is a = 7.3. If the rocket has a TWR of 2.0 and you want to hold altitude you need a pitch of 21' which is not too bad because 93% of your thrust goes into horizontal acceleration and that increases to saturation quickly as the pitch falls. Are there ways to improve on this: 1. Increase the amount of thrust in your upper stages, this decreases the time and decreases the cosine losses. 2. Burn high quickly after launch and turn and burn as quickly as possible keeping the pitch about 10' above the prograde bug until omega-based waste reductions take effect. Note this is why I was complaining about the RD-150's thrust a while back, as an upper stage engine it really was not up to the task of burning to orbit. RL10b-2 is not a final burn to orbit engine either. On many of my rockets I just use the RL68-A to get to orbit.

If you are really on top of things you can do this, but the problem is that if you pitch over too fast, what happens you end up losing all your dV to drag and may end up stressing parts or overheating solar panels. I pitched over too quickly awhile ago and lost my McJeb controller. There is no uniform thrust situation, so its best to control things. If you have MechJeb you can look at drag force, this will tell you when the rockets form drag my be so high as to tilt the rocket or break something. Theoretically on lift off the best acceleration gives you a drag that equals effective gravity, this however is not generally a good thing in rocket science. The reason is that once a rocket takes off its already got 1g of of force, as it climbs the a increases the force on the upper parts increases while those on the engines only increase with ISP as you approach 273 m/s your drag force is no longer the square of speed but increases quite rapidly. Thus the force at the top of the rocket increases with acceleration and with drag creating an ephemeral quantity known as Q. At a certain Q the rocket is at risk of damage or flipping. Thats why its a good idea to go 'up' until Q goes down and then go 'sideways.' since pressure ~ 1/alt2 rougly to be precise below Mach speed. At exactly Mach speed is 3 times as great, and then it falls. q = P0 * e(-g*M*h/R*T) * V2 /2 If you apply increasing acceleration (as a result of fuel loss) to a rocket going strait up, q will increase but because dp/dh has a dependency of v [ p is ~ e(-h)] as h get large quickly pressure drops quickly and q follows. For this reason you want q to fall away because of the increase in h before attempting to break Mach Speed in many rocket designs (especially using KSP parts because they have a tendency to be bulky). The problem with this that the rate at which the AoW (surface pitch bug) drops is both a function of pitch and speed, so that if your pitch is too high slow down and it will fall over more quickly, if your pitch is falling too low, speed up and it will fall less quickly. If your pitch is way too low (e.g 30' at 10,000) and your altitude is too low and you speed up, you burn all your dV fighting drag. So if your space craft is draggy, then travel up and turn later. If its very sleek turn sooner and power up to 2g. The other reason you want to control the pitch is this: For your heaviest rockets you will be staging. Heed this warning, stage separation always works better when the wind bug and pitch are identical; however, this is particularly true for radial separation. The problem is for instance, you don't want to dump alot of used rocket parts on your space center, it costs money. So you lift turn down course a few degrees maybe seperate then turn back to 90 and then turn again to match the bug and separate, then maybe let the rocket turn and separate more boosters. In my biggest rocket designs (32,000 tons) I want to hold back the turn of the rocket and 3 seconds before stage separation let it tilt over until exactly on the bug separation while still under full power. Following this I might separate structural parts offsetting the stage from the core (The hydrolic separator just does not provide the spatial clearance for huge boosters). IOW you don't want to be correcting pitch because of drag while you are trying to separate a 1kt boosters. You may see a ball of fire and some control part appears on its way back to the planet.

OK, how about your house? Please, lets dispense with the hand-waving stuff, everything takes energy, either M = E/c2 and/or E.

How about horses and horse flies, lol. This thread is supposed to be a joke right, telekinetic pulses? For a biological organism to evolve you only need one thing, mutations, thats all its called random drift . . remember the Ne I referred to in the other thread.

First off if you don't have Mech Jeb, or Flight engineer get one of these. Here are some targets. This is done with a sleek rocket and a powerful engine (TWR = 7) If you launch strait up with a fairly large fuel mass and alllow the apoapsis at 70k, then a powerful burn 10s of second before hitting apo you can achieve orbit for 3122 m/s dV with a very streamline rocket waste is 750 dV) If you launch strait up and gain a apoapsis of say 40k, then close to 40k turn to 20' pitch and fire until Apo is 70 k. and then circularize. Dv required is 2688 (waste is 304 dV) If you launch to 60' and then turn to 45' gain a apoapsis of say 72k, Apo is 70 k. and then circularize. Dv required is 2592 (waste is 210 dV) Using standard KSP equipment. Launching and turning slowly to 45' by 15,000 then to 30' by 25' then zero by 56' and circularizing at 70k. dV = 3406 (waste is 1022 m/s) [Aerodynamic rocket saved about 700 dV] Launching strait up and circularizing at to achieve 70k (i.e burn along 0'pitch starting 30 or so seconds before reaching 70k). dV = 4043 (waste is 1658 m/s) most lost through the slow burn at 1.4g. In these scenarios we can see the loss, some of the losses are from having a not so streamlined rocket, some are from not being so powerful. To achieve a good launch , launch strait up start with TWR = 1.4g until you have a good build strategy. At about 100m m/s tilt ' to 89' From there tilt about 1' per 1000 meters, until you get close to 9,000 meters then start tilting faster. Between 10 and 15 k meters if you have more power use it but once you get to 310 m/s hold speed past 18 k feet, at this point you should be around 45 to 60' pitch Here is the formula I use from that point on. By the way trubngin your rocket fast will flip your rocket if it does not have AV-R8 winglets to keep it close to the true. The way a control a rocket between 0 and 24k has alot to do with its shape and with other flight characteristics, if the rocket is sleek and powerful I turn it more quickly, If im hauling up a bulky payload I use less TWR and turn later. The strategy for slow rockets is basically to peel off boosters until it safe to burn at a higher speed. When the apo passes 26k then pitch is 40', when apo passes 36k pitch is 30', when apo passes 46k pitch is 20', AV when apo passes 56 k pitch is 10'. Adjust apo and burn speed from that altitude to control the circularization process, highly dependent on the thrust of the space craft. Although you can make orbit with nth-stage TWR below 1 on kerbin (not on earth) it is much easier if your vacuum engine has a TWR about 1.5 and you will waste. So that once you are over 45k meters and your speed is below 1600 m/s (orbital) TWR should be close to 2.

They have to have some kind of plan up their sleeve, they must already have a solution on the table, they are probably hashing out the details. We know for sure, though 2020 will not bring the return vehicle, it will require 4 more years. They don't even have to get it into a transfer, just get it high enough for a fly-by to pick up and carry back..

Well, I tell you if we can get fusion to work we could also make a black hole, theoretically If you had fusion in space, you manage to deplete neutrons of energy, spin them and then hold them by spin until you have enough to form exotic matter. If you had fusion you could make iron in carbon (except those are made in the last dying moments of a star during core collapse) If and if and if and if and if and if . . . . . . If you took hydrogen from the Sun just exactly where would you keep it? don't answer.

Well at least when a heavy wind storms breaks out in Africa we notice a spike a month later over here in microbial allergies (namely molds).

The minimum orbital velocity required is =SQRT(2*(70,0000*8.5 + 1/2(2295-175)^2)) = 2384m however because it takes two burns to orbit a body some of the first burn must include gravity losses. So lets say 2500. The additional 1000+ dV required can be lowered by making parts with higher density and lower coefficient of drag. Modding alllows you to make these and I have a number of fuel tanks with much lower drag. For drag modding to work properly in KSP you need the drag mods to occupy the entire stack (IOW a stack of fuel tanks becomes one aerodynamic fuel tank. The other thing is you need thrusters that can fight gravity at very low angles. If we were to make a hohman transfer from the surface of kerbin the launch pitch would nearly be zero, unfortunately we would have no lift. To compensate if you launch at 10' pitch the the rise would be 0.173 so that to remain up you would need to produce 60 m/sec2. To launch at 45' requires 12 m/Sec^2 but the rate of horizontal acceleration falls. If we imagine a launch where you travel up to 10 K then turn at 45' and travel to 30K and turn to 30' pitch. At 30K plus are climb is 86.8% efficient, at 10 to 30k our climb is 70% efficient, at 0 to 10K our launch is 3% efficient compared. So now the problem is time, time x inefficiency = loss. If it takes 2 minutes at 1.6 g to reach 10k, it means you spend 320 dV to get 1/7th the needed altitude and 1/12th the needed velocity, most of the other 1/12th is wasted because the direction vector is off by 90' and although it has value at a displacement theta, you still loose most. In turning to 45' the next loss is from gravity and drag as speed increases the force squares as altitude increases the force drops as a function of scale. The more aerodynamic the space craft the more rapidly it can turn, the more rapidly it converts dV into horizontal thrust and the higher thrust requirment the spacecraft can have, that means a smaller proportion of the thrust goes into keeping the craft up. So for a craft of standard KSP design about 1.4 TWR is a good launch 65% is wasted. With improved parts 2.0 TWR 50% is wasted until turn to 45 in which 40% is wasted. With greatly improved parts 3.0 TwR 33% is wasted at launch and turn to 45 30% is waste< turn to 30' and 14% is wasted. The problem is that drag is the square of speed, that affords 50% drop in drag = 41% higher speed or that speed about 3000 meters below. So that if we cut drag by 3/4ths it really only means we can turn about 3000 meters lower and have 50% higher speed. One earth it does not make that much of difference but on Kerbin it does. Gravity decreases faster on kerbin, getting into lower gravity faster saves up to 10%. The atmosphere is thinner which means you pay a cost in drag for a shorter period of time if you hammer your speed as long as you are moving up by 100s of meters per second.

A fusion reactor by itself does not have the power to start its reaction. Fusion power exists but there are costs to harnassing it, the cost of harnassing it is often not considered, For example it may cost 90% of a reactors output to initiate the next reaction. First off at the turn of the last century we did not have the base of phycisicist we have now, no did anyone, in fact the whole world dump a considerable amount of GDP into a rocket to go to the moon. All-things-being held equal it like comparing airplane concepts, BUT all things are not equal, the scientific base is much better now than then. I can point out a few other flaws with Daedelus, the fuel for the reaction comes in pellets, you would not store them in spherical tanks, the would be dispensed from a hopper (like a grain silo). Project Longshot evolved, the BIS basically has not. The tank structure is nothing more than targets for granule strikes. Once upon a time people believed they could make gold from lead and mercury. That has never happened. Once upon a time people believed that comet dust would kill them. Myth is a wonderful thing as long as your realize that its value is in the story, not in its factuality. Yes, but we are not talking about Nuclear bombs are we, we are talking about controlled reactions that require a continuous power input to be sustained, the drive essentially assumes that this power comes from their drive (handwaving). The power input per cycle could be a high percentage of the power generated. You cannot wave this problem away, no amount of trust in the British Interplanetary society solves the problem. I detest hand-waving arguments, they deserve to be picked to pieces. Because its not a chemical rocket, when you talk about ISP in the -3 to -1 c magnitude(10) you are talking about an extremely erosive and destructive particle velocities. In essence you are creating cosmic rays, something to be carefully disposed of in the opposite direction in which your are moving. You keep changing the argument to suit your opinion. We are not talking about a larger object, we are talking about the probability of crossing a grains of sand to grain of silt sized particle. Let me convert the argument to facts at least an object person would find useful. Size of a speck of silt or medium sand 0.0003 meter, area 27E-12 cubic meters at 1000 kg per meter^2 = 2.7E-8 kg. a grain of silt is about 1/1000 the weight or 2.7E-13 Here are the impact energies at various speeds: silt, sand, gravel. 0.001c = 0.012, 12 J, 12000 J 0.01c = 1.2 J, 1200 J, 12000000 J 0.1c = 120 J, 120,000 J, 120,000,000 J 0.8c = 12000J, 12,000,000 J, 12,000,000,000 J Here is the energy of a 50 calibre mounted. it can basically penetrate 1 cm of solid titanium. Assuming a muzzle velocity of 2000 feet/sec (860 m/sec) and a grain size of .1174grams < 43,400 J So if we assume are vessel walls are on the same order as a titanium version of the ISS, then here is what would kill that craft at the given speeds (maximally, without including the melting for caused by a higher velocity object hitting over a much smaller area. No possible survivals are not included. 0.001c - would survive a silt sized impact, probably survive a sand sized impact, probably would not survive a gravel sized impact. 0.01c - would probably survive a silt sized impace, might survive a sand size impact. 0.1c - might survive a silt sized impact 0.8c - improbably survive a silt sized impact. Particle densities in space. Of the gas in the ISM, by number 91% of atoms are hydrogen and 9% are helium, with 0.1% being atoms of elements heavier than hydrogen or helium,[3] known as "metals" in astronomical parlance. By mass this amounts to 70% hydrogen, 28% helium, and 1.5% heavier elements. Assuming hydrogen and helium will not solidify we can eliminate these. However we might want to know what the mass is, since along the journey we will have to move this out of the way, the force exherted is the square of the velocity. of the 1.5% 66% is in the form of dust. I will take the value of 35E6 hydrogen masses per cubic meter. This corresponds 4.98 x 10E-23 kg of gas per meter. Its about what we expect 5E-25 kg of dust. So how much dust will we collide with in our trip to a nearby star. 1021x 5x10-25, about 0.0005 kg of dust or larger particles. That is to say the weight of 18,518 grains of sand, 18,000,000 grains of silt. In addition images of certain interstellar events have lead scientist to believe there are aromatice carbon compounds in space, these compounds are known to autoattract into ring-on-ring structures. Therefore we also have potent nuclei formers in interstellar space.

2295 at 70 km, and this does not belong in this group.

There is no impetus for them to finish as long as 50 countries are willing to dump billions into it. The way to do it is to set it up like a grant, you reach this hall mark by this date or we fund the other guy.

It is extremely difficult to watch these videos, really, Im not making fun of the guys accents but: He is treating non-physical concepts as if they are real physics, I can give a couple of points. I can see how people in this group are getting confused, this is a grand discussion of science-fiction and fantasy. 1. Habitation. You cannot place habitats anywhere without paying the 'anywhere costs'. I'm not trying to be nitpicky but I reach a limit when the habitation stuff is not plausible physics or just waves off the cost. a. Example as before - a materials strength does not afford the highest plausible spin rate, that plausibe rate does not afford engineering tolerance of payload costs in determining the height of high. b. Example colonizing rogue planets - yes its possible, but its not a generation ship because you cannot control its destination, most of the rogue planets we will encounter are those that are and will always be tied to the Sun and very close proximity to our system, which means they will take the age of human species to reach the proximity to another system. A rogue planet is a planet in which the gas on the planet is either in frozen or liquid form. Entering such a world and colonizing it requires the payment of a huge energy cost. Rogue planets have all but zero breaking atmosphere, and where your energy is almost certainly fusion, how do you drop a 1 kt reactor onto the surface of a rogue planet???? Yes rogue planets have a huge level of resources, they might as well be in the Polaris system. The dV required to get to a Rogue planet and the time required is beyond even the capability of roboticized fusion driven ion drive systems. ION drives canot land, which means they need to carry a lander on board. c. Example. Any number of the rings. Seriously high walls to hold in the gas, your spinning at 9.8 g centripedal force and you intend to build a wall 300,000 meters in height????? d. A central cyclinder with LED lights to similate a blue sky? PLants don't need blue light, they generally like red and a trace of blue an no green, your lights are purple. Human can have place the LED screens on the windows of their houses to simulate. 2. Everything evolves some type of matter that is eitehr hard to get in space or does not exist. Carbon fiber planet sized structures . . .there is not even that much carbon on Earth. Where in the solar system do we find planet sized loads of carbon, in the middle of the sun? Nuetronium fibers? OK lets say it does exist, who would want to live in a structure made of mesostable neutrons. 3. With all the really bad physics what is the obsession with night time, you can't spend on day-night cycle before it flys apart into space and there is no nighttime. 4. Gravity is not a space occupation killer, humans may do just fine at 0.5 g, there is no reason to spin a ship to SQRT(9.8/r) before one even things about spinning a ship at that angular velocity they should first consider the added weight for doubling gravity and the added thickness of materials. if you are thinking about Nuetronium structures, artificial gravity should not be your major health concern. If I watch more of the videos I will only find more problems, its the reason I don't watch Star-Wars movies, all I see is bad physics modelling.

Wait, curiosity had problem with its wheels, they fall apart, weren't they going to redesign them?

Yes but the structure began to erode. First because New Spain tried to control Spanish holdings from Africa to the Philippines. Second political instability in Europe undermined their control. Third, while New Spain was an Iberian holding, the church was an Italian holding, and basically during the second revolt the church to the side of the colonist and Spain lost. You throw in a megalomaniac like Santa Ana and you have an independent colony. This will always be a problem in colonies. Similar processes took place in the Americas between England and the Colonist. If we talk about where the middle east problem came from, people in the west tend to think of it as a Palestinian problem in origin, but that is not true, the problem started with the Mandates (which was in a sense a deflating colonialism) which then broke down because of purely European events (the rise of nationalism in Europe). The irony of the palestinian problem is that palestine never existed, the Ottoman empire broke down, it became a mandate as part of transJordon, which then crumbled in 1948 despite the intervention of the United Nations. In effect the west so messed up transjordon that will of the entire world could not fix it. We talk about Hamas and the PLO as the 'enemy', the enemy can be found in Wilson, Rothchilds, a variety of British Prime Ministers. This brings up at least one important Sci-Fi context, the prime directive, if you find intelligence you either prepare to exterminate because you think its a threat or you leave it alone until its prepared to meet you on some sort of level playing field. exactly

Then you don't apply ecological models to humans, which makes archaeology a soft science.

Why are they showing the curiosity rover?

I see you are looking to pick a fight so I will deal with your aversion to facts one step at a time. Have you never heard of effective breeding ratios? Ne Is this the first time? because its been used in the Molecular anthropology literature since Brown et al. 1979, and after that in 1988 by Vigilante et al and so on. Go look up effective breeding populations, after you have spent a few days researching it we can talk about it. When you talk about breeding ratios you are not talking about birth ratios, thats a different thing. You seem to have no familiarity at all with molecular phylogenetics. While you are at it look at climate conditions in Europe during the Younger Dryas. "The Younger Dryas is a climatic event from c. 12,900 to c. 11,700 years ago (BP). It is named after an indicator genus, the alpine-tundra wildflower Dryas octopetala, as its leaves are occasionally abundant in the Late Glacial, often minerogenic-rich, like the lake sediments of Scandinavian lakes. Physical evidence of a sharp decline in temperature over most of the Northern Hemisphere, discovered by geological research, has been the key physical evidence found for the Younger Dryas. This temperature change occurred at the end of what the earth sciences refer to as the Pleistocene epoch and immediately before the current, warmer Holocene epoch. In the social sciences, this time frame coincides with the final stages of the Upper Paleolithic." The global optimum occurred about 9000 years before present, however the stand rate did not inflect until after the optimum and continental glaciers were still melting in the Irish Sea, Scandinavia and other parts of Europe. While the climate of the entire world generally stabilized after the Younger Dryas, in Europe the climate was not particularly stable until almost the onset of the C.European Neolithic ~7800 years ago. To be fair it was nearly stable about 8500 years ago but then again there is evidence of bovid culture in England about the same time. There are a couple of reasons, before and following the Younger Dryas Europe is characterized by dense pine forest, its not a particularly good place to support humans, and most of the populations subsist on sea-food. (you can look up the literature), within the period that follows the conifers slowly give way to deciduous trees such as Hazelnut, Oak . . . . . . ) As for sources, I am preoccupied going through the on-topic video collection of Isaac Arthur so you will have to wait until I vacuum my papers so I can breath long enough to quote them. Plus it will give you a chance to control your emotions.

The guy does a fairly good job of burying the logical flaws in his arguments but over time they begin to pop out, I watched many of his videos. 1. The strength of a metal makes no assumption that an object can built of that length and size. For example if you are building a ring structure, that length limit may assume all of the the structure is made of the construction material, not just some. 2. There is no such thing as a reactionless system. This argument creeps into many of his arguments. The surface of the Earth has momentum and a direction vector, due to friction between the surface and the gases the gases that surround the earth also have momentum. This is why 1000 dV or so is wasted getting into orbit. Without getting rid of the gas (which turns out to be bad for the ecosystem) you cannot get rid of the friction. a. launching a ship in a tube filled with plasma to create a vacuum is a really bad idea. b. launching any ship in a tube from any mountain top in the world at near - orbital velocity is a very bad idea. The only way a tube launch system will work is via strait up and lasers to repel the atmosphere around the tubes exit long enough for the rocket to acquire the momentum and altitude needed to completely avoid the lower atmosphere, which by the way can almost completely avoided by launching from a launch pad on a tall mountain (much cheaper just build a tractor way that goes up the side of a mountain). 3. This is actually 2b. but its so big. There is the basic opinion, for example raising an object from the Surface of the Earth to GSO or LEO cost much less than a rocket. NO!!!!!, it costs in energy nearly as much, the only difference is that a rocket launches loses about 10% of its energy due to gravity effects and drag. It takes 85% of the energy used to get a rocket into GSO as a magic hand-waving space elevator, but you also have to move the counter mass to keep it up. OK its not that bad, it could be worse!!!! Here your object is traveling over an Earth with a non-uniform field, its mass is horrendous, the station keeping cost are horrendous. What you save is the mass of some rocket fuel that amounts to 1500 dV over 10000 dV total. how does that equal a cost to orbit in cents per kilogram?????????? (we forget here on Earth capital equipment has a cost, what that money spent on equipment could have earned say in interest, if it was not sitting in space). Trillions of dollars in infrastructure, the cost would not be zero maintenance. 4. Energy. OK so lets talk about energy. Suppose you want to put 1kg into space 1000km up, the energy require to place an object into orbit is this -(u/r1 - u/r2) + 1/2(7824-460)^2 = ~9,800,000 + 27,113,200 = 36914000 J/ kg lets assume that the process is 60% electrical efficient (very optimistic given the distances that need to be covered) and you pay 0.05$ per kilowatt hour. A kilowatt hour is 3,600,000 J. Thats 10 Kwh per kg, we are not talking about cents per kilogram, we are talking dollar per kilogram (this is ideal). The capitalization cost for solar panels on a ring floating in space or other energy producing devices would likely have a cost 5 times that high. RIght now SpaceX charges 60,000,000 for 20,000 to LEO, but that cost is expected to fall. But there is another thing, while you are lifting something into space, there is a gravity cost and friction cost to be paid, for example an elevator does not conserve all or even most of its energy. The other disclamer that is buried in there is that it cannot be used to life humans . . .whats the point then. Before you would ever have enough free capital to invest in a space ring, space X will have the cost down so far it would never be competitive. 4b. This generally applies to any handwaving means of getting an EP PL into space except the rotating space bar (I will not deal with a completely insane proposal) Even if fusion power does not become a thing, these projects are still doable! Even if you have fusion power its not going to be a thing, If you cannot take humans into space via elevator, neither are you going to be able to lift a fusion reactor. The other problem see above, the cost of the infrastructure outweighs the benefit of infrastructure once complete. To transmit power from point A to point B requires either increasingly larger conductor (and field losses, leakage losses) or increasingly higher voltage. The PL that is being moved around is not where the power source is, either it power is on the ground or in space and you have to transmit power 100s of km (two wires) which means you are carrying conductor with payload or more likely the PL has to provide its own power. If you are going solar and you want to carry a kilogram of material into space OK so lets say you want to move the payload at 10 m/s. This would take 100,000 sec to go a million meters. So lets consider this: A solar powered PL would not be able to reach its destination in a day, it would stop, wait for sunrise, continue, stop, etc. So that 10 m/s averages out at 5 m/s. If the infrastructure is at its load limit then the transfer times are 2 days in length 180 PL/year. 10m/s is 980 watt per kg, solar panels at 1 kg/sq.meter produces optimally 400 watt per kg. So you are not going to travel 10 m/s on a tether. So lets put the ascent rate at 2 m/s we could have 190 watt per kg 19 watt for PL-carriage, 190 watt for solar panel. This gives us a transfer time to say 1000 km of 15 days. The power required increased from $1,00 per kilogram to what . . a meter of solar panel cost $500? OK so we reuse the solar panel it needs to be removed and reinstalled in space, lets say we generously give the PL buyer 450$ credit on the cost of the panel he is still at ~55$ per PL not considering the cost of depreciation of the infrastructure. He said the PL cost is a few cents, he's only off by a factor of 1000. He's very good at tucking very difficult problems under the rug, but they are still under the rug. 5. The very basic problem in some of these is that they were proposed by an author 50 years ago or some handwaving physicist. If the proposal does not have a credible source, its probably not credible. There are lots of people who designed space rockets for movies or books, none of them where the Saturn V. Its the folks at JPL and NASA that made the moon landing thing, not the folks in Hollywood. None of these guys are experts in cost analysis.

Not always the truth, some of them became nomadic (e.g. the pueblo revolt - Apaches - they wanted the horses) because of European culture not in-spite of it. There are several sites of continuous NA settlement in New Mexico. Europeans were arrogant and abusive and often failed to recognize the contribution of NA culture, some groups took offense and went back into the jungles (Lacodan Maya, Achue as examples). Many settled native American farming groups don't exist any more, that is because they are American (waves hand). Compatible cultures do that sort of thing. If Mexico was purely a colonial state, when New Spain was forced to severe ties with Spain during the Napoleanic period, they would have rejoin Spain afterwards, but that is not what happened. If you look at Mexico per say, its 5 or 6 million NA population dropped to 100,000 individuals, but now Mexico (about 2/3rds native American by gene weight) is 100s of millions. At some point after Cortez 'broke' the population it did rebound in great numbers. This gets into a basic problem with colonials, not all . . .For example the Basque were extremely well suited for pastoral agriculture and fishing in Northern Mexico, but colonial settlements north of the Rio grande faired poorly for 200 years, people were given huge land grants . . and left back to Spain. If you are going to settle in someone else's territory (planet) you better make sure you have studied the culture well or you might end up on the menu. The Comanche had a bad habit of allowing the settlers to recover gain livestock, breed horses . . . .and then they would attack steal women, cows and horses take off and not be seen again for 20 years. The utes were a fairly quite culture that occupied the high plains area of western US until the colonials came, then their splinter groups blossomed or less like Atilla the Hun. BTW. Its not just NA groups. Slaves sent to Caribbean Islands revolted and resettled in Honduras, slave groups in South America revolted and resettled in the jungles.