Moonguy

For the MOTS, we want an orbit that is exposed to the Sun full time. The MOTS is put in a near-polar orbit because the pole is where the base is to be. At least within 5 degrees of the pole. The polar orbit of the MOTS allows its photovoltaics to be exposed to the Sun 24/7 while the majority of the MOTS’ surface area (ie, radiators) is facing out to black space. Also, With a polar orbit that is at a very slight angle to the terminator, the MOTS can be flying over al-dark terrain for half the orbit, reducing reflected heat load even further. In a polar orbit, the orbit can be circular. If an equatorial orbit is used, the MOTS will have to be in a very elliptical orbit with the apoherm well above the daylit side to minimize reflected heating. A major headache with an equatorial orbit like this is the line ups for descent to the surface base are complicated by the need to begin descent at the point of periherm, but the base site is not always positioned right for the most efficient descent path. Designing the Cycler’s orbit to pass above or below Mercury would seem to be the way to resolve the plane change problem. The only issue would then be if the Crew Vehicle has to do a plane change between two polar orbits. Bizarre to think about, but functionally the same problem as going from an equatorial to a polar orbit. My guess is this would be a minimal propulsive maneuver because we would inject into a polar orbit over the terminator. Since the MOTS is kept orbiting over the terminator (or nearly so) the difference might only be two or three degrees. Very much better than an 87-degree plane change from the equator! Regarding sail testing. . . I’m not sure any test done on Earth’s surface can really be conclusive. Even if a ‘large’ (hectare or better) sail could be tested in a vacuum chamber, the effects of gravity would still leave questions. Since sails are designed to operate under microgravity conditions, it makes sense to test them under such conditions. IMHO, that was IKAROS was all about and it proved the concept in its basic terms. Why not just test a full-sized sail, in space? Even large sails are light enough to be injected directly into interplanetary transfer trajectories. That is an ideal test because the real issue is handling a sail over interplanetary distances. The launcher would only need to be able to get the payload to a high Earth orbit with a perigee well above Earth’s atmosphere. If the test works, we have an operational sail that can bring payloads to Mercury on a repetitive basis. Since Mercury is so much like the Moon, I originally considered base designs that were much like the LESA program for the Moon. Basically big tin cans connected together over several years to make a complete base. Self-landing modular shelters are ideal for early, short-term habitats. The problem is they have no real future because you get diminishing returns by deploying module after module designed cookie-cutter style. At some point you want larger volume or more specialized layouts not accommodated by modules confined to the dimensions of an Earth-launch vehicle payload shroud. There is more than one reason for burying the base. Ionizing radiation is just the biggest one. Deliberately burying to ten meters allows the shielding dead-load to equal the pressurization load of a full atmosphere in the habitat. The pressure structure (a fabric in the current plan) would have almost no differential stress across its surface and so could be very simple in construction. I have been looking into the properties and formulae for Beta-Cloth that could be made from Mercury’s own resources. If that works out the possibilities for structures on Mercury are staggering!

I am interested in the 90-day Mars mission issue but I need to look into their reasoning before I comment further on it. Might be a good subject for a later thread here. . . As far back as the mid-1970’s JPL researchers were confidently talking about 2μ/m2 sail material in time to build a probe to Haley’s Comet in the mid-80’s. That would be 2000 kg/km2 of sail material. Doubling that with the booms and mast brings that to 4000 kg. The sails used for the Mercury project are 820 m per side square sails with CFRP masts and booms. Total load for the sail is 3 gm/m2 (~2017 kg) for the sail material alone. Assume a similar mass for the spacecraft control systems, docking unit etc. and related structure and you get 4034 kg. I do know that the radiation threat is very real and will not be resolved by even the fastest trip times we can do for either Mars or Mercury. Shielding of some sort will be needed. Prior to looking into the Cycler concept for Mercury, I had the idea of inserting the crew module into an upper stage tank so that a couple meters of LH2 protected the crew during the coast phase of the mission. Clever, I guess, but not practical. The Cycler protects the crew with four meters of plain ol' water. The MOTS is in a near-polar orbit to minimize heating. The rendezvous between the Cycler and Mercury takes place after an in-plane transfer, so the crew vehicle will need to make a plane-change maneuver to go into the same orbit as the MOTS. The Cycler continues on it's in-plane orbit. There is a penalty for the plane change, but it does not seem ruinous. Alternately, the first base could be positioned nearer the equator with a subsidiary operation at the pole limited to producing water and regional exploration. The MOTS would have to be in a very elliptical orbit where the apoherm is several thousand kilometers above the daytime hemisphere. This would lessen heating, but still allow access to an equatorial base. Once the crew lands, they have 88 days of darkness where the surface temps will be cold enough to make you forget what warm is. After sunrise, the surface takes up to six weeks to heat up to the boiling point of water. Ionizing radiation after sunrise concerns me, but the crew could have a total of 18 weeks to build and bury a shelter before it gets too hot. By 'shelter' I include facilities for protecting spacecraft and equipment form surface conditions as well.

Thanks for the clarification regarding the orbits. As for the plan being ‘. . . based on finding water on Mercury’ Later, yes. Initially, though, the MOTS would have enough water on board to support several flights of manned or unmanned landers to Mercury’s surface and back. For the Cycler’s water supply, water would be obtained from Mercury and transported by sail to the Cyclers. These deliveries would be faster because of the 8-fold increase in photon flux at Mercury allowing a greater rate of acceleration for a given payload mass. For those who have not heard, the MESSENGER team has confirmed the presence of massive amounts of water ice at both poles on Mercury – and the presence of a mysterious ‘hydrocarbon’ material, likely comet-derived. The total amount of water ice is at least equal to that on the Moon, likely greater. It’s still under study. . . I am desperately hoping they go for a sail-propelled Mercury landing mission next. The ice has been characterized as solid ice with dust mixed in. ‘Snow’ is not quite the same thing. Figures of hundreds of billions of tons have dominated these findings. I will get updated on that before I say more. I do not contemplate the use of solar sails for manned flights. They are the most economical way to go for cargo, but they take too long for crews. At these distances from the Sun we want to seriously decrease the amount of time the crews are in transit. There is an exception: If a crew module limited to five tons mass were carried by a large sail (1,000,000 m2 or more) it might be delivered to Mercury after several months, but with zero propellant used foir departure or MOI. I have not yet worked that out and want to give it quality attention. I’m open to comments on it, though. . . On the Cyclers, crews are protected by 4 meters depth of water all around them or masses of equipment where there is no water mass. Also, the interior of the habitat is insulated with radiation absorbing materials such as hydrogenated polyethylene. As for NASA’s 90-day ‘requirement’, every study NASA has ever done was predicated on providing sufficient radiation protection within the payload mass limit of the transportation system used. I suspect the 90-day figure was politically motivated to justify development of fast nuclear powered systems on the ground of safety. I don’t buy it. You are essentially correct about the Sun’s magfield protecting Mercury from cosmic rays. Radiation from the Sun itself is another matter. When the first crew arrives they will have a turnkey habitat waiting for them to inhabit while they build the first permanent base facilities. They will land just before sunset, set up some lights, and have over 88-days of protected EVA time to do the construction of the base. Mercury itself protects them from solar radiations during the night. The 17 months (~520 days) refers to Earth’s synodic period with Venus. Nominal mission stays on Mercury are multiples of Mercury’s year if the Cycler is used. With the Cycler, there is no variation in the transfer times (176 days each way) between Earth and Mercury. However, since the Cycler relieves the propellant mass issue by such a great amount, missions are no longer needing to be defined by delta-V. The Cycler enables much longer stay times at Mercury as long as they come in increments of 88 days. Generally, a basic mission plan would have the crew on Mercury for two Mercury years, or 176 days.

Thanks for the very helpful responses.

Yes, that is a good basic description. Add the function of storing propellant water and producing LO2 and LH2 for Mercury Orbit Insertion (MOI) and the Earth Return burn and you have it. Mercury’s orbit has an eccentricity of .2056. The Cycler would also have an eccentric orbit. The precession of Mercury’s nodes complicates things long term. Part of the answer to these issues is to keep the sail that delivers the Cycler to its operational orbit attached to the Cycler to perform corrections over long periods of time. Alternately, a high-impulse system could be designed into the Cycler for the occasional adjustments required, similar to mid-course correction maneuvers. The J2-X was baselined here for standard Hohmann transfer using the larger payload required for the traditional approach. It would take everything the SLS Block II has to get even a small manned payload to Mercury orbit. In the Cycler concept, the manned crew vehicle and its single-stage system only needs something like the RL-10-B-2. In any case, I really do not want to use SLS components for anything if I can help it. Not at $2 Billion a pop. I am considering your STE. Given the flux potential available at Mercury, it would be a very economical boosting system for manned flights back to Earth. I also like its simplicity and supportability. Another point about an STE: it can be a bi-modal system to generate substantial electrical power – possibly in a powersat application. Not a healthy situation at all. The Cycler resolves this problem be enabling a returning crew vehicle to fuel up for an insertion burn into Earth orbit instead of an all atmospheric return. Or, alternately, some combination of the two. The point is the propellant is on board the Cycler to allow this. Other scenarios, providing any kind of high-impulse return to Earth is a logistical nightmare. We have enough of those already. I would be happy to utilize Venus Gravity Assists, if only they were more frequent and did not require the crew to be en-route so much longer. Venus and Earth line up for transfer every 17 months. So this option would only be available for maybe a third of the potential flight opportunities. The Cycler routinely gets crews to Mercury’s orbit in 176 days. Flight times for the VGA flights to Mercury range between 145 days and 305 days, with most being well over the 176 days for the Cycler. You correctly define the function of the Mercury Orbiting Transfer Station, or MOTS. This unit is also delivered to a 1000 km circular, near-polar orbit over Mercury by a solar sail. As in the case of the Cycler, the sail remains attached to the MOTS to serve as a sunshade and to provide station-keeping propulsion. The MOTS carries two manned landers with it. It also carries two unmanned landers that deliver key equipment to the surface. Like the Cycler, the MOTS carries a mass of water to provide propellant for the first few landings. Eventually, water from Mercury itself is used to replenish the MOTS on a continuous basis. Both the MOTS and the Cycler(s) are developed from propellant tanks salvaged commercial launchers. Any tanks would do as they are only containing water at any given time. For my claculations, I use a LO2 taken from expended single-stage orbiters. These tanks are 4 m in diameter, 8.4 m long with a volume of 88 cubic meters and a dry mass of just over a metric ton each. There are six on the MOTS (though some are empty when it is deployed to Mercury orbit) and on each of the Cyclers. All together, a fuluy loaded Cycler would suppoirt ten one-way missions or five round trip missions.

How would crews get to Mercury? Is there any way we can beat the high delta-V penalties for classic style ballistic flights? Yes, there is: Cyclers. Mercurys orbital period is 87.97 days. Earths is 365.25 days, or 4.15 Mercury years. A cycler deployed to a 351.5 day orbit, with Earths orbit as the aphelion and Mercurys orbit as the perihelion, will encounter Mercury every time it (the cycler) reaches perihelion. Crews departing Earth would still have to generate a high delta-V. In fact, cycler missions would require a delta-V around 9.5 km/sec. while some standard (Hohmann) transfers can be done for 6-7 km/sec. The difference is that a cycler mission puts most of the payload mass required for the 176 day transfer time on the cycler. This drastically lowers the payload mass injected into the transfer. In a classic Hohmann transfer scheme, a manned payload would be injected with an upper stage able to effect the Mercury rendezvous and orbit insertion. For a 10 ton payload and a stage using a J2-X engine, a mass ratio of at least 4.1 would be needed for even the most favorable MOI delta-V, which is about 6.3 km/sec. The resulting stage would be about 60 tons. Pushing this into a transfer orbit from Earth would require a stage which also has a 4.0 mass ratio and hence masses over 100 tons by itself. The cycler reduces the requirement to launching the crew in their Earth-return capsule. This could be an Orion, A DragonRider derivative or something similar. If it had the same 10-ton mass as the first example, it would not need to be boosted with a second stage. Instead, propellant for the maneuvers at Mercury would be derived from water stored on the cycler. Food and living accommodations would also be on the cycler as well. A 15 ton cycler could easily store enough food and consumables for several mission cycles. These supplies would be replenished to the cycler periodically by the same solar sail that deploys the cycler to the 351 orbit. The water used for propellant would also be supplied using solar sails. Initially this would be from Earth, but it would eventually come from Mercury. With an orbit of 351 days, the cycler would encounter Earth every third orbit of the cycler. This is due to the synodic period of Earth and Mercury is 115.9 days. Multiplied by three yields 347.7 days. There is just over a 4 days discrepancy between an exact encounter., However, launch windows to Mercury are open for about 20 days, so it could be assumed a delta-V penalty would be incurred to make up for the 4-day difference. The cycler mission requires much less propellant be available in Earth orbit. Only one stage is used. This is refueled at the cycler for the MOI burns and again for the return to the cycler for the return trip. If the Earth-entry interface velocity is too great for the return modules heat shield, the crewed stage could refuel a third time to execute a burn into Earth orbit. This architecture enables a crew to launch to Mercury every 347 days. Twice as frequently as flights to Mars. 0 . Quote MultiQuote

How would crews get to Mercury? Is there any way we can beat the high delta-V penalties for classic style ballistic flights? Yes, there is: Cyclers. Mercury’s orbital period is 87.97 days. Earth’s is 365.25 days, or 4.15 Mercury ‘years’. A cycler deployed to a 351.5 day orbit, with Earth’s orbit as the aphelion and Mercury’s orbit as the perihelion, will encounter Mercury every time it (the cycler) reaches perihelion. Crews departing Earth would still have to generate a high delta-V. In fact, cycler missions would require a delta-V around 9.5 km/sec. while some standard (‘Hohmann’) transfers can be done for 6-7 km/sec. The difference is that a cycler mission puts most of th payload mass required for the ~176 day transfer time on the cycler. This drastically lowers the payload mass injected into the transfer. In a classic Hohmann transfer scheme, a manned payload would be injected with an upper stage able to effect the Mercury rendezvous and orbit insertion. For a 10 ton payload and a stage using a J2-X engine, a mass ratio of at least 4.1 would be needed for even the most favorable MOI delta-V, which is about 6.3 km/sec. The resulting stage would be about 60 tons. Pushing this into a transfer orbit from Earth would require a stage which also has a 4.0 mass ratio – and hence masses over 100 tons by itself. The cycler reduces the requirement to launching the crew in their Earth-return capsule. This could be an Orion, A DragonRider derivative or something similar. If it had the same 10-ton mass as the first example, it would not need to be boosted with a second stage. Instead, propellant for the maneuvers at Mercury would be derived from water stored on the cycler. Food and living accommodations would also be on the cycler as well. A 15 ton cycler could easily store enough food and consumables for several mission cycles. These supplies would be replenished to the cycler periodically by the same solar sail that deploys the cycler to the 351 orbit. The water used for propellant would also be supplied using solar sails. Initially this would be from Earth, but it would eventually come from Mercury. With an orbit of 351 days, the cycler would encounter Earth every third orbit of the cycler. This is due to the synodic period of Earth and Mercury is 115.9 days. Multiplied by three yields 347.7 days. There is just over a 4 days discrepancy between an exact encounter., However, launch windows to Mercury are open for about 20 days, so it could be assumed a delta-V penalty would be incurred to make up for the 4-day difference. The cycler mission requires much less propellant be available in Earth orbit. Only one stage is used. This is refueled at the cycler for the MOI burns and again for the return to the cycler for the return trip. If the Earth-entry interface velocity is too great for the return module’s heat shield, the crewed stage could refuel a third time to execute a burn into Earth orbit. This architecture enables a crew to launch to Mercury every 347 days. Twice as frequently as flights to Mars.

If we can get past our preoccupation with Faster Than Light travel we could leave for the stars any time. A much more urgent matter is to learn how to live on alien planets of all types. Our thinking has been constrained to 'Earthlike' planets and so we presuppose people cannot have gratifying lives elsewhere - including life on board a generation ship. As long as we continue to insist on planets like Earth or Mars as targets for interstellar settlers, we very likely will have no real incentive to go.

What it seems you are trying to create is a very fast interplanetary transfer vehicle. Since you say you are 'looking for help' with the math and science, I would recommend you check out the 'Project Rho' website called 'Atomic Rockets'. It is loaded with valid, real-world information about actual technologies but it is presented in a very light, easy-to-read way. I think you will enjoy it. As for the technology you are seeking to power your concept, you might want to specifically check out 'VASIMIR'. What you describe seems to be very similar. Regards, Moonguy

I would be interested in knowing more about it. Could you send me a personal message here?

Dude, every time I read one of your posts I get at least 100 ideas to chew on. I'm starting to mutter things like "Inverse square rule at Saturn would yield. . ." at the dinner table. My family is starting to worry. STOP!! Get out of my head!!!

Arc, We are not acquainted but, being a cancer survivor myself, your wife's story resonated with me. The great thing here is she has a husband who truly appreciates her and is with her in the struggle. I'm sure she is as proud of you as you are of her. .

Picture aluminum foil that is very shiny (reflective) on one side but somewhat dull on the other. . . Solar sails also have two sides. One is a reflector which can routinely be upwards of 90% reflective. A good mirror by any standard. The other side is an 'emitter' surface that allows the sail to re-radiate most of the 10% of sunlight absorbed. In between stars, the sail need only turn its reflector side towards a destination star and use its light to maneuver into the distant system. If it fails to do this, and the emitter side remains turned to the distant star, the sail will not be able to slow down as the emitter side is usually much less reflective. Solar sails cannot just stop at some balance point between stars as their excess velocity (as relates to the Sun) would keep them moving.

My point was the we don't have any SSO's developed. You are asking me to document evidence that we don't have SSO's. . . ? As for documenting WHY we don't, I strongly encourage you to read G. Harry Stine's 'Halfway To Anywhere'. It is a 1996 publication so it is a bit dated, but it is an excellent read on the history of all SSO efforts in this country up to that time. Stine was an insider to the NASA/Industry system. He had both the technical and experiential knowledge to speak on the subject He was not an outside reporter-wannabe. If you can't find a library copy or one on eBay message me and I'll see what I can do. . . As for Musk's plans, I don't think he will achieve the 100:1 cost reduction stated, but he doesn't have to. Any significant fraction below the competition's cost (actually price) will get him the sales he needs to keep going. Were it up to me, I would not bother man-rating any of the Falcons. I would develop a small shuttle vehicle for a half-dozen passengers, not including pilots, and mount it on a large solid booster. If it is a ballistic up and down thing it would be very inexpensive to both develop and operate.

I completely agree, but with one caveat: it doesn't have to cost ten times. It just does because NASA prefers to keep transport costs artificially high. We could have had economical, Single-Stage Orbiters several times over the past 50 years. What happened? I suspect it will be very soon that some other country will develop something that looks suspiciously like concepts presented over the years here. I wonder if anyone here will notice. . .

What people want, what people can afford and what is healthy for people are often at odds with each other. You are right: People will always want to go into space. Perhaps the one-tenth of one percent who would actually be 'space-worthy' and useful there will make that their reality. Right now, I suspect they are too busy just trying to pay off student loans with their sub-level salaries.

Much of this discussion has to do with the number of people needed to mine an asteroid (for profit) versus the number of people needed to staff a fully developed colony. If I understand the concept in the link posted to start the thread, the investors do not plan to build a colony right off. They also do not plan to move the asteroid, intact, to an orbit around Earth. They do plan to use robotics. I submit this means they studied the matter from a profit-making point of view, Knowing they would be spending other people's money, they opted for the least cost/highest gain option. I think those who (still) see themselves as visionary space advocates should observe their example and learn from it. . .

I'm just trying to understand how an asteroid in L4/L5 is a better situation than the Moon's surface. Particularly for astronomy. An asteroid small enough to be moveable with anything we could have is not going to be large enough to provide a stable platform for the sensitive instruments being deployed even now. What would induce an astronomer to choose an asteroid over either the Moon or a much closer (more accessible) orbital location?

You can. If it is orbiting Venus it will likely become locked in a synchronous rotation eventually, but its totally feasible to maintain a specific rotation rate with periodic thrusting. For a low Venus orbit, the asteroid will get a lot of reflected heat from Venus itself. For that matter, since Venus reflects about 60% of the sunlight and is .73 AU from the Sun, a solar panel pointed at the planet would yield about 290 watts per square meter. That could be useful. . . Moving asteroids around is a major task. A 'small' asteroid 100 meters in diameter would have a volume of 523,600 cubic meters. If it is a solid body with, say, 2.7 g/cm3 the mass is 1.43 million tons. Aircraft carriers are only 100,000 tons and we use eight nuclear reactors to move just one of those around. Suppose there is an unforeseen situation where the entry trajectory at interface is off. . . Just exactly how do you plan to stop the mass of 14 aircraft carriers travelling at better than 10 km/sec. with maybe a day or two to act? This is not the kind of thing you can afford to be wrong about. Better to try it at Venus first. . . Sorry about your mood. . . Asteroids do not 'heat through' at the distances that make them easily accessible to Earth. They rotate. Usually with a rapid enough rotation to dissipate surface heat captured on the day side.

Why Venus? Mars already has two moons. Hardly seems sensible to add a third. . . Chances are any asteroid we can put into orbit around either Earth or Venus is already a 'hot rock'. . .on the surface. Dig down a meter or two and temperatures stabilize and are cooler. Dig deeper and you have a volume that can be made habitable with an inflatable module. A station installed inside an asteroid would not notice even the worst CME events. With a mass of rock on all sides tens of meters thick, the only temperature issue would be rejecting excess heat away from the station. That would only require an array radiators out on the surface. Of course I assume here that the asteroid is a coherent rock and not a 'rock pile' like Itokawa. . .

Just an additional thought: A truly meaningful asteroid mission would be one that involves re-orbiting an asteroid to serve as a future space station orbiting Venus. It would be interesting to see what candidates there are. . .

Do you want proposals that make sense to the people you expect to pay for them? Or do you want to just recycle ideas that were trashed years ago because people would not buy into them for their excessive expense? Mining asteroids to build colonies so that the colonies could. . .mine more asteroids for. . . what? No real hint of what the colonies would do to justify their initial expense much less pay their daily bills. And there will be bills. Asteroid mining is all about seeming to get something (asteroid minerals) for nothing (very low launch delta-V) and that is not the entire reality. You pay for the lower delta-V with time. Asteroids are interplanetary objects and doing interplanetary flights usually involves long flights and long waits for a return. Asteroids small enough to move around with current technology are probably to small to yield enough of the elements we would be looking for (Rare Earth's? Iron? Carbon?) to pay off by very much. If you do cost analysis - and I have - you will find that time, not delta-V, is what makes the difference between financial success or failure. This is why I initiated the Mercury Project. Your comments about China are well taken. As long ago as 2001 Chinese officials were claiming they would have taikonauts on the Moon by 2010. . . now its was 2020. They were also saying they would consider the Moon a part of their economic development plan Translation: they would consider it theirs. China does not have room in their economic situation to make the kind of major blunders that are routine for us. If they do a Chinese Apollo program, they will remain committed where we didn't. As for my being 'argumentive', what is the point of open forum discussion if not to engage in a spirited way? I have no personal issues with anyone here, so none of my comments should be taken on that level. But I'm not here to just tell people what they want to hear either. . .

You are starting to see my point. The modular concept you describe here is exactly what Aquarius could give us. Without having to spend unknown billions to get to an asteroid. I can tell you the launch program for Aquarius Colony would be very much less than half a billion dollars. Less than the cost of a single Space Shuttle launch. This colony would not be glamorous, but it could be built with today's dollars and be occupied by today's people. Sure, we want to build colonies in space for the future. The difference - and the reason I left the advocacy - is the future promoted by would-be space colonists was high-debt, low return. It was doomed. I appreciate that you have this vision. I would only say that you should not colonize tomorrow what you can colonize today!

Space colonies is a huge expense. Whenever you send people into space the costs skyrocket. That is why I agree with Michio Kaku, that robotic probes is the way to go in the near future. Gradually we will develop the technology to put people, a few at a time, on the Moon or Mars. This will take at least a hundred years. Space colonies, that are independent from the Earth, Moon or Mars, with artificial gravity and radiation shielding, and everything recycled and raw materials taken from nearby asteroids, however, will take MUCH longer to develope. We were ready to put six people on the Moon in a program called LESA in 1970. We had the technology ready to go. Taken solely as a technology issue we were already there. The problem was maintaining public support for the program over time. You can get one or two consecutive Presidents to fight Congress for the funds. But sooner or later you get some short-sighted clod who thinks that is a waste or just has other ideas. As for 'space colonies', I refer you to the Aquarius Rocket concept Space Systems/Loral was working on a few years ago. This could have gotten you a rotating colony in orbit in only one year's worth of launches. And it had a payload of only one ton. The resulting colony would have been roomy, self sustaining and cost less than half a billion dollars. It would not have been the glamorous thing you see in the Don Davis paintings. There is a Wikipedia article on the Aquarius launch vehicle and at least two YouTube videos that I know of. I apologize for not having a link.

I agree about 'not having the capabilities long enough'. Recent attempts at things like inflatable orbital habitats are encouraging, but we are way off from what most would call a 'colony'. Space colonization as a public issue is what has failed. I often hear the joke about how all they need to do is find oil on Mars and we would colonize it in a heartbeat. Well, in the 1960s we 'discovered' how we could provide Earth with clean, unlimited energy. All we had to do was build colonies to build powersats to provide the energy. Energy is universal to every society and so basic to everyone. . . Yet the advocacy could not sell it to a world that was in the middle of an energy crisis. Why? My guess: The cost of building colonies was 'prohibitive' because the emphasis of their design was to make them 'Earthlike'. They were not 'valid statements of what it is to live in space' (quoted from T.A. Heppenheimer, Colonies In Space ') Instead, they were expressions of the abandonment psychology I mentioned. Had the advocates concentrated on solving problems people cared about (at the time it was providing cheap energy) instead of constantly pitching massively impractical engineering feats they might have been taken more seriously more often. Of course, I'm just guessing. . . I don't think this is what's been presented at all. Who assumed any guarantee? We've always had pioneer mentalities as well as homestead mentalities, and darned near everything in between. Unless there was some imminent danger that threatened everyone, I don't see how anyone would feel abandoned just because some humans wanted to explore the system, building facilities using their own resources to help them continue to explore. Space advocates, that's who. Myself among them. For years advocates have been making claims about how space settlements, including those on the Moon, Mars etc. could do such great things for humanity. Usually the one's doing most talking were experts in physics as if all we had to do is rearrange enough molecules or direct enough watts in the right direction. Rarely did they even try to convey a sense of costs in a meaningful way. When they did, they usually got their ears knocked off. Remember mass drivers on the Moon? That way exceeded the costs for Apollo and yet it had to be built before a space colony could be built. . .And a space colony had to be built before powersats could be built. . . There are STILL space advocates who think this was a reasonable proposition and are trying to pitch it to a world that is running out of time.