Northstar1989

Electric engines are smaller, lighter, and easier to miniaturize- which means you can more easily have one engine for each direction of propeller rotation- reducing the mrchanical complexity of contra-rotating propeller designs (with just one engine, complex gear arrangements are necessary). Otherwise, you're right, there's nothing new about contra-rotating propellers- they're just infinitely more practical with electric propulsion systems...

Apparently, use of electric motors allows you to design aircraft with contra-rotating propellers- as is demonstrated in these electric racing aircraft designs: I had no idea this was possible, and this massively changes the game in terms of electric vs. internal combustion aircraft. For one, with contra-rotating electric propellers it's easily possible to pack twice as much Thrust into a given airframe as with an ICE design, allowing for higher speeds (in racing designs) ot larger wings and more space/weight for batteries (in actual utilitarian planes). It's also possible to achieve a much higher ratio of propeller-area to Thrust with the same Thrust- allowing for better performance at higher altitudes (electric engines also operate better than ICE ones at higher altitudes, due to not requiring Oxygen..) I could easily imagine an Electric passenger aircraft being designed someday with 5 sets of contra-rating propellers (1 on the nose and 2 on each wing), each with 3-4 blades rotating in each direction with a rather large propeller diameter, being used to support very high-altitude flight with electric aircraft for the inherent advantages this provides (lower drag for a given speed, less turbulence, more glide time/distance in case of engine-failure). At high altitudes electric propellers eventually reach their maximum torque and rotation-speed, and start to consume less and less electrical power as the Thrust produced and air resistance to rotation starts to fall off with even greater gains in altitude. So, if you climbed high enough you could eventually reach the point where 10 contra-rotating propellers (5 sets of 2) with large diameter blades spans and 3-4 blades on each propeller only draws as much electrical power, and produces as much Thrust, as a single propeller at sea level. However at this altitude, Drag would be greatly reduced- meaning you could (and would need to in order to generate adequate Lift to maintain altitude) fly substantially faster than that amount of Thrust would allow you to fly at sea-level. Even accounting for decreasing Lift/Drag at higher speeds, you could still cover far more miles of distance per kilowatt-hour of electrical power consumed with a design optimized for high-altitude flight and cruising at high altitude... This would lead to substantially extended max range compared to electric planes with lower cruising-altitudes, and might (just barely) allow for practical electric Transatlantic flights on a large plane (larger planes encounter less parasitic drag relative to their volume, and have less mass dedicated to cockpit computers, landing gear, and pilots compared to their payload) with a substantial portion of volume (maybe 50% of the plane's internal space) dedicated to batteries, for instance... Other videos worth watching on the topics of electric aircraft and high-altitude flight: (Above: a general overview of efforts at small electric aircraft...) (Above: a video on the development of "Alice", a proposed 800 km range passenger aircraft by Eviation...) (Above: Airbus and Rolls Royce' efforts at developing Distributed Electric Propulsion for large passenger jetliners- with company estimates putting a rollout date of about 2030-2050, target of 2042)

Ok, so I'm not sure exactly what the rules are regarding topics like this in the Lounge section, so any moderators please forgive me if I'm breaking a form rule by bringing this up here, and just wuietly kill this topicand let me know why it was inappropriate... Anyways, I've been thinking for a while the US should have a Sovereign Wealth Fund to take advantage of the extremely low interest rates available for government borrowing right now, as well as a way to force reinvestment in the economy (raise taxes, invest the revenues in the SWF- that way the money is being invested in growing the private sector rather than in buying luxuries...) And this got my to thinking- perhaps such a Sovereign Wealth Fund could also be used as a method to stimulate exploitation of outer space... Sovereign Wealth Funds have the potential to become VERY large, as they invest the surplus resources of an entire nation into generating economic growth. And as such, they have the potential to be used to build entire industries from the ground up by investing in multiple synergistic enterprises that increase each other's value... (this is known as co-investment) So what if the US started a Sovereign Wealth Fund and used it to build space-inindustries like asteroid-mining and space-tourism from scratch? The advantage of doing this with a Sovereign Wealth Fund, rather than direct government funding, is that it ensures that the government collects more of the profit from its investment- in the form of capital gains of seed money invested in startups and dividends from public corporations, as WELL as taxes on the executive salaries and profits of those corporations... Space Tourism is a potentially very lucrative industry if SpaceX can realize fully-reusable launch vehicles, for instance. If the government were to invest in developing a space-tourism industry it could not only push the development of reusable launch vehicles along, but also realize considerable profits that could be reinvested here on Earth in things like education and healthcare. Similarly, if the US invested in the enterprises of asteroid-mining startups, it could not only help to provide cheaper fuel in Low Earth Orbit for purposes like Mars missions and upper stage reusability- it could also provide a Return On Investment for the government in growth of valuation of its stock shares in such companies- which could be held onto for the dividends or sold to private investors for a profit... In short, if space is such an untapped market, maybe the government should take an approach to ensure it gathers a larger share of the profits from exploiting it than what can be achieved merely by taxing the profits...

Landing is a different problem, with different challenges than getting to Mars in the first place. So if your mission costs are at all sensitive to the mass you need to launch to Low Earth Orbit, you DON'T use the same spacecraft to reach Mars as to land on it. The BFR only gets away with thos because Musk thinks rapid reusability will make costs to launch a bigger rocket to LEO a joke compared to the R&D of designing multiple spacecraft for different roles, but under ANY other set of conditions (or even with Musk's miracle launch-costs if you want to bring down marginal mission-costs even further, at the expense of large additional R&D costs you have to amortize and pay interest on over future missions) you go for the specialized approach. Certainly if it costs you $10,000/kg to get payload to Low Earth Orbit... Really, you only have one practical option if you're going to specialize to bring down overall launch-mass: you must design a capsule to reach LEO (and act as your ship for reaching the main vessel in a Cycler Orbit under that kind of plan), an orbit-to-orbit specialized vessel to reach Mars (if It's a Cycler, you definitely want to give it electric thrusters, as they help with extremely small/efficient course-corrections, but otherwise the minimum design requirements are much the same), and a specialized lander/ascent vehicle to carry your crew to the Martian surface and back... It's possible to combine your capsule/interceptor and lander into one vessel, but you don't perform either role quite as efficiently then, as the requirements for EDL (Entry, Descent, and Landing) on Earth and Mars are quite different (you face much more re-entry heating on Earth, but a higher terminal velocity and a more difficult propulsive landing on Mars) Some missions even call for SEPARATE landers and ascent vehicles- but this isn't as mass-efficient, unless you have no ISRU or reusability and need to carry ALL your propellant with you in single-use spacecraft... Even refueling a 1-man lander (remote-controlled by one of the mission's pilots) 5 times in orbit from propellant brought from Earth, for 6 trips to carry a 6-man crew to the surface of Mars and back is many times more mass-efficient than a pair of disposable 6-man ascent/descent vehicles... Anyways, Capsule, OTOTV (Orbit-To-Orbit Transfer Vehicle), and lander- basically you have the mission architecture the Mars branch of Constellation was going to use before it was cancelled. Also, the inspiration for one of the raddest KSP videos ever made based on that mission architecture: https://youtu.be/Tp6yj2k0Fpc Simply put, unless your launch-costs to Low Earth Orbit are obscenely low (like Elon Musk hopes for with the fully-reusable BFR) having a specialized lander simply makes sense for the mass-savings provided by not having to carry your Mars return-fuel all the way to the Martian surface with you. Also, It's actually much less aerodynamically and structurally challenging than an all-in-one rocket like the BFR, and enables more specialized OTOTV designs- like those relying on an inflatable rotating habitat or a counterweight-and-tether system to create certipetal force based "artificial gravity" on the way to Mars... So, given the need to design a separate lander anyways, using chemical propulsion for landing, and electric thrusters and atmospheric drag for orbital maneuvers (including your Mars transfer and aerocapture) really isn't that big a deal. Each vessel ends up specialized for a different type of propulsion- neither needs to be capable of BOTH propulsion methods (even propulsive Earth or Mars capture can be managed with electric thrusters, at higher Delta-V cost, if you start your maneuver 3-4 weeks ahead of reaching the planet and design your transfer trajectory with this type of capture in mind to begin with...)

You need to adjust your thinking. 0.000327 g's equates to 1 m/s of velocity change ever 312 seconds (a little more than 5 minutes), and the capability to accelerate 6 km/s in a little more than 21.67 days of acceleration. That's not bad at all, when you're talking about a journey that already takes 6-9 months! (for that Delta-V cost) Not to mention you don't have to perform all that acceleration with crew onboard. It's entirely possible to place your mission vehicle into a Mars free-return trajectory and just accelerate the crew in a smaller and more lightweight vessel to meet up with the main spacecraft on its next journey by Earth... If what I just described sounds familiar, That's because what I just described is a Mars Cycler, with the most practical free-return trajectory being an Aldrin (named after Buzz Aldrin, who postulated its existence) Cycler Orbit. Place your spacecraft in that trajectory (the Delta-V requirements for which are nearly IDENTICAL to a normal 4-5 month "fast" transfer to Mars) with electric thrusters and gravity-assists over YEARS if you want- it doesn't matter, as long as you eventually get it into an orbit that makes a cycle between Earth and Mars. Then just take your crew capsule you already needed to get people to Low Earth Orbit, stick an oversized upper stage on the back (the requirements for Cycler intercept are highly similar to those for the upper stage of a rocket going to GTO), and intercept with the main mission vehicle in a Cycler Orbit instead of in LEO (time from leaving LEO to intercept should only be a week tops- so similar space and life support requirements to the Apollo Command Module are all that is needed). Ta Da! You now have a practical way to use electric thrusters to get to Mars without having to worry about how many weeks, months, or years it takes to accelerate to Mars with electric thrusters...

That entire history was one of cancelled half-finished projects, political interference in the R&D process, and skimping on upfront R&D costs and paying for it in much higher flight costs. When you constantly get partway through projects and the cancel them, those sunk costs don't go away. They may not be important to future decision-making on how to finish the overall program, but they are inevitably tallied up by bean-counters who then claim them as part of the final cost of the program. In truth the Shuttle Program was not one continuous set of projects but 16-20 *DIFFERENT* projects, most of which were cancelled after some money had already been sunk into them.a more honest accounting of the Shuttle's R&D costs for the purpose of appetizing them over the flight schedule would only look at the line of development that was followed and not cancelled- all the other costs were not really the cost of developing the Shuttles, but of political contractor nepotism and interference in tbe design process by power-mad politicians who don't know the limits of their own scientific knowledge... So, the Shuttle wasn't really as expensive as most people give it credit for being- It's not really fair to plough all the projects thst were cancelled for reasons having nothing to do with technical feasibility into the program costs... And the actual Shuttle flight costs, ignoring amortized R&D, were MUCH higher than they could have been- because the politicians, in all their power-plays over whose favorite contractors would or would not get rich off the Shuttle's sweetheart contracts, forgot that NASA was supposed to be trying to design an actual feasible, affordable spacecraft- and thus they did not allow many critical projects (such as the improved boosters) to become a reality. Shortsightedness also played a major role- politicians often only think ahead to the next election, and were unwilling to suffer some pain now for a substantially larger payoff down the line (most likely after they had already left office). So R&D into design improvements and better designs thst could have paid for themselves many times over were never funded through to completion, because politicians couldn't bear to raise taxes a little (or rather not LOWER taxes) in the short term on their wealthy constituents for large cost-savings down the limr... The Shuttle was a political (and consequently, economic) cluster I-won't-say-what, and a lesson in why politicians should keep their grubby paws out of certain matters and just let the scientists and engineers do their bloody jobs. But SpaceX doesn't have to deal with nearly as much political interference, and will instead hopefully prove a lesson in the strengths and weaknesses of a more independent private space industry (technically the Shuttle was built by private firms as well- but on government contract and under NASA leadership) that proves a SUCCESS rather than miserable failure like did the Shuttle Program and ultimately could the Space Launch System...

Internal prices and the price SpaceX charges consumers are two entirely different things. By most accounts, SpaceX makes a very considerable (more than $10 million) profit on each launch. A lot of that is plowed back into the company to make further upgrades to the design and work on future projects, which is why company profits don't well reflect this. But make no mistake, SpaceX *is* inching towards the cost/kg that $10 million price would represent (capacity upgrades mean the Falcon 9 is now a larger rocket with higher payload capacity than it had when that promise was made- so $10 million wouldn't be a fair bar to set) and could have eventually achieved it if they didn't decide to discontinue the Falcon 9 to rededicate resources to the Big Falcon Rocket... As for timelines- yes, Musk does tend to give very optimistic timelines (which is why I think SpaceX won't send humans to Mars until 2032, not 2024), but his company does achieve remarkably well. You've clearly got a chip on your shoulder against SpaceX and Musk though- I've never seen you give this kind of treatment to companies like Boeing or people lime Jeff Bezos, no matter how obscenely unrealistic their projected timelines are (if the established players made accurate projections, Constellation and the Area program would have been a roaring success and not deemed "financially infeasible" with NASA's budget and cancelled by Congress after numerous development delays... Mind you I think that was a bad idea- but my point is made.)

Yes, you absolutely can. However the SpaceX Raptor is not designed for CO/O2 combustion, nor is any other rocket engine that I know of. Doing this just to avoid the need for ice-drilling would require an entirely new class of engine, which is a lot of work. The key technology really is orbital propellant transfer, though. If they get that down, that opens up the door to a lot of alternative mission architectures. Like slow-boating Liquid H2 to Mars (preferably with some kind of electric thrusters- which could even operate on the H2 itself with the right thruster technology...) and landing a portion of it for Surface ISRU, with a Propulsive Fluid Accumulator collecting CO2 for making CH4 and LOX for the return burn home right there in orbit. Or slow-boating a mostly full fuel tanker to Mars for refuelung the BFR, if all else should fail... ISRU is all about mass-leveraging, but if you perfect orbital refueling tech and cheap/rapid reusability of your stages, there are few practical constraints that prevent you from just launching more mass from Earth in the first place... (and many possible mission architecture optimizations that reduce your mass-requirements and have nothing to do with ISRU, like dedicated landers and reusable orbit-to-orbit transfer vehicles, or an Aldrin Cycler mission architecture...)

Polynesian were skilled navigators, but their BOATS could never have survived something like an Atlantic Crossing. They were only able to spread like they did because the islands tgey reached were relatively close together (there's a reason Easter Island, for instance, was isolated from the rest of the Pacific islands- it was much too far for boats built without nails to travel. There is evidence the first settlers were shipwrecked there or blown off-course by a storm, and unable to return home due to the distance...) That's a grossly inaccurate characterisation of everything I said, and nothing but a straw-man argument. A resupply ship every 6 years for 60 years is NOT "totally self-suffclient from day one", and the numbers I provided were not totally make-up, they were calculated based on the known laws of Compound Interest and the predicted price of a SpaceX ticket to Mars. Mathematics is a hard science, you CANNOT argue with it, as much as you might like to- only with my (very conservative) assumptions...

I'm.pretty sure most people attempting that would end up dead, and certainly at least losing all the cargo that they were *supposed* to be transporting between islands. No. Surviving on an island requires timber, metal, and high ground to protect against storms- none of which are present in sufficient quantities to sustain a permanent settlement on your average desert island. By contrast, Mars has all the minerals needed to eventually sustain a self-sufficient civilization. It might take 100, even 200 years (building advanced societies took longer in the past- but they had less sophisticated technology available to them than we do today, and certainly a much less educated/motivated/intelligent citizenry than your average Mars colonist...) And, as I've pointed out in my previous post, if colonists, governments, and corporations put aside enough money at the beginning (about $882,000 per colonist including the cost of the initial ticket) it would be possible to send colonists a re-supply mission every 6 years for the first 60 years, assuming a price of $25 million per BFR launch (Cargo OR Crew version) and 100 colonists per passenger variant. More often, or for less money, if colonists sold media back to Earth, SpaceX provided re-supply missions at closer to cost, or SpaceX made improvements to their mission architecture and technology over time...

Why not? Assuming food, clothing and oxygen/water are easily produced in-situ from plants grown in greenhouses, 60 years of supplies wouldn't actually be that hard to send. Assuming colonists were upper-middle class or wealthy, and tickets sold for $250,000 each, most colonists could probably scrounge together an extra $720,000 with some government subsidies/grants on their initial ticket, corporate sponsorships, help from family, etc. That would be enough money, assuming they invested their money at 6% ROI in index funds (which average 6-10% ROI a year in the long run) to send a cargo mission every 6 years for FOREVER for each ship-load of colonists. I'm pretty sure any Mars colony could relatively quickly attain sufficient self-reliance to get by with an average of just 1 cargo shipment per 100 colonists every 6 years... (that's 1.5 metric tons of cargo per colonist every 6 years- a little less than the mass of a midsize car!) $720,000 invested at 6% ROI is worth $1,021,333.76 after 6 years with all dividends re-invested so as to avoid paying Capital Gains Taxes until the stocks are sold. Compound Interest really is the most powerful force in the Universe! http://www.moneychimp.com/calculator/compound_interest_calculator.htm They wouldn't have to actually scrounge together this much, of course, as they could afford to slowly draw down the balance so it is depleted after 60 years (much longer than most colonists would live on Mars). $632,000 invested at a 6% ROI with a 1.2% average annual inflation rate would be enough for that purpose... Colonists might also be able to deposit additional money into this fund over time, by producing media (such as movies, books, and reality TV) and occasionally, scientific discoveries, they could sell back to Earth. So really, they wouldn't have to put together as much in savings as I listed here... SpaceX could also sell package-deals to future colonists, where they get future resupply shipments for themselves or any selected friend/spouse/successor/descendant at closer to cost. It would be worth ot if it tempted more people to become Mars colonists in the first place... And, of course, ALL of this assumes that SpaceX doesn't develop technologoes/improvements that bring down the cost of re-supply even further in the future, such as refueling outbound cargo BFR's in highly elliptical orbits (like they plan to do with Lunar missions) so they can carry more than 150 tons of payload to Mars onboard with each trip, capturing into Mars orbit before final re-entry so they can partially refuel before landing (and thus reach Mars without any landing-fuel onboard), making use of Lunar gravity-assists to increase the cargo per trip, or developing ion-engines they can use to slowboat cargo shipments to Mars for lower cost than a 4-5 month journey on the BFR... (a 12-18 month journey requires less Delta-V)

Seems cheat-y to me. Besides, my rig already chokes on lag with relatively small, low part-count rockets. Adding an ISRU rig to the picture (and probably a refueling rover- since refueling reusable rickets that way is impossible, and taxiing spaceplanes is a pain) would probably cause it to melt... Clearly, you don't know much about ship-building. Large ships (the kind that are capable of crossing the Atlantic, and not just short, risky voyages between Polynesian islands) REQUIRE metal to build. You simply can't hold a large ship together without lots of metal nails, at a minimum... Everyone knows you can't land on Jupiter either. Obviously it's a joke...

If everyone adopted that philosophy (let someone else jump on the train first), nothing would ever get accomplished. You have to dare bravely, and sometimes fail miserably, to ever succeed amazingly. Put another way, you miss 100% if the shots you don't take. There ARE no physical reasons a rocket can't be built this large (the Saturn V was actually both taller AND wider than the current BFR design, with only a slightly smaller payload). There are only political and possibly economic reasons holding us back. You're saying something can't be done that waa already accomplished BEFORE, in the Apollo Program. I can only imagine what you'd be saying if they stick with the original ITS design, which was *slightly* larger than the Saturn V instead of slightly smaller... Built habitats require mineral inputs to maintain. Recycling is not to the point yet where we can survive without constant metal inputs. Mars has plenty of metals to sustain a built habitat, desert islands do not (and, as I just explained, would not be long-term survivable even WITHOUT a built habitat. No metals means no agriculture or fishing ships on a desert island, which means eventual starvation...)

You're mixing up cause and effect (correlation does not equal causation- at least not in the direction one assumes). It's the set of problems such as inadequate funding and support that lead to delays, and the delays are only used as a proximate excuse to cancel a project that politicians and wealthy donors/investors were never willing to fund adequately in the first place, often when it really was possible all along. It's not the delays that lead to problems, but the problems that lead to delays.

Like France, Britain, Germany, The Netherlands, and Italy. And yes, Spain and Portugal are actually MORE prosperous than they would have been if not for their colonial history. Their decline was inevitable- whereas their Golden Ages were brought on by colonizing the New World... Earth is, similarly, rapidly approaching a socioeconomic peak- a Golden Age after which will follow a long period of decline before any hope of another worldwide Rennaisance similar to what we are experiencing today. The planet as a whole has maybe only a couple hundred years of improvement left. Some countries, such as the United Ststes, have arguably already reached their peak [snip] No amount of money invested back here on Earth is going to prevent the inevitable orgy of war and violence that will destroy much of what has been achieved recently. THAT is why colonizing Mars is a great investment- because anything we achieve in Earth now is doomed to be undone in Workd War III. By contrast, any investments we make in colonizing Mars will continue to benefit Earth long after the current world order is nothing but ash and dust... TANGENT: Which talk of a nuclear-irradiated future reminds me of this song, by the way... If you send 1 million colonists (breaking the islanders up among several thousand such islands- if that many existed) and give the Martian colonists all the equipment and supplies they need to survive for 60 years, and don't allow the islanders or Martians to trade with anywhere else or leave, it's the islanders who die first due to lack of many critical metals. Mars has all the metals humanity needs for a technological civilization, regardless of the inability to breath the atmosphere. Most desert islands do not- and contrary to your belief, it is NOT possible to survive on a desert island just by fishing (and you NEED metal just to fish effectively enough to feed a large population). You NEED agriculture- and on a desert island that's simply not possible without metals (unlike somewhere much more fertile like in Polynesia or the Fertile Crescent). The islanders will mostly all eventually starve or die of severe inbreeding (without metals, you can't build long-distance sailing ships for their populations to trade and intermarry with each other... The Age of Sail, was enabled by metal nails).

The flight and landing is fully automated- so it really doesn't matter when in the flight you fall unconscious. And, for the record, peak g-forces are usually *higher* in stock KSP. Earth has a MUCH larger scale height (5.6 vs 8 km) for its atmosphere than Kerbin, which means you have more vertical distance to bleed off a given amount of speed. I'm not sure at what point in the flight you're saying your ship would experience 10 g's (if it's during the flip- the real maneuver would be performed at much lower g's than anything possible in KSP), but if it's it the landing-burn, by which point all a spacecraft has left after re-entry is vertical (downwards) momentum, you'd actually be moving *slower*, at closer to terminal velocity on Earth, due to the planet's larger scale height...

Mars will eventually pay off- just not less than a couple hundred years down the line... (stop trying to imply I said you would start reaping returns QUICKLY) Asteroid-mining pays for itself much more quickly, but has a lower long-term potential (because once you glut the Earth markets with things like Platinum, there's no reason to go hunt down more asteroids with it). Still a nice one-shot way to make money, though... When you eliminate the need for a lot of jobs in an industry, like Platinum mining, you free up labor for other purposes. Not only can you now use Platinum in a lot more technology, you also free up lots of technically skilled people who can re-train and move on to other things- like designing bridges and office buildings and discovering new pharmaceuticals. As long as the labor required to obtain that asteroid was a lot less than the labor that would have been needed to mine an equivalent mass of Platinum here on Earth, society benefits in the end.

You're starting to sound like one of the Aurorans from Isaac Asimov's Robot Series. There's a great deal to be said for the pioneer spirit. If we never go anywhere until it's comfortable, we lose something of humanity. That's not the kind of world I want to live in, without that vital energy- and neither does Elon Musk...

Governments who want to see the Mars effort succeed, or just see greater representation of their cultural values in the new society, could incentivize people to go by paying for part/all of their ticket, and even providing cash transfers to relatives they leave behind on Earth. Corporations might pay for employees to go so they can start up enterprises on Mars to sell certain products to the colonists at a lower price than importing them from Earth. And, of course, there's the whole pioneer-spirit thing you mentioned before.

I was never implying that all of this IP would actually be SOLD. So e would. Some would simply be shared, or stolen/ripped-off. What I was saying is that the IP, even if not monetized, would contribute to the betterment of humanity, and that some small PORTION would be commercialized- which would provide governments and corporations at least some incentive to invest in Mars... The most easily-commercialized IP just happens to be straight out of my fields of biology and medicine- pharmaceuticals, patents on medical devices, cures for diseases, and GMO's. There's no reason a new drug developed to treat Cancer (likely a high-priority research topic there, due to all the radiation) on Mars couldn't also be licensed out to a pharmaceutical company on Earth. Similarly, a new strain of genetically-engineered soybean designed to grow with 10% less water than existing varieties could sell just as well on Earth has on Mars. Once Mars' economy becomes sufficiently advanced to make such products, there is PLENTY of return governments will see on their investment. Until that time, Mars colonists will probably embark out of a sense of adventure and a search for new frontiers- not because they're in it to make money (although, governments could incentivize select groups of people with certain critical skills yo go with cash-transfers, to help subsidize their tickets or provife a bdtter living for loved ones they leave behind on Earth...)

You completely fail to grasp my argument. Early on, almost NONE of the colonists would be doing intellectual labor. They would be scrabbling just to survive. What I'm talking about is what a fraction of the original colonists' great-great-grandchildren would be doing 160 years down the line. If you start with 1 million colonists, then in 160 years you could easily have 15 million colonists, just by natural population-growth, and a million of them might be doing work that produces some kind of intellectual property (these are the artists, scientists, engineers, authors, and professors all put together). THAT is the eventual return on investment in Mars, and no corporation would need to invest in it specifically. People would pay to go to Mars out of their own personal finances, and then corporations would follow to start industries there providing them goods and services in exchange for whatever residual savings they had left. These budding industries would grow with tine, and the whole thing would likely receive additional help from governments. But the prinary drivef of geowtg woukd be the colonists themselves- learning to exploit Mars' many mineral resources and building an industrial base to provide a better future for themselves and their children...

Colonies on Mars would be heavily dependent on mining and exploitation of natural resources, just like on Earth. They would also almost assuredly produce emissions. The difference is, on Mars there are no other cities around to be polluted by those emissions and that mining activity, whereas on Earth there are already plenty... Even if none of that were a concern and closed-loop communities were possible (they're not, and Mars colonies will produce their share of waste and garbage, just like Earth cities do- although recycling will likely be much more extensive due to the relative difficulty in obtaining new resources), on Earth it will always be CHEAPER to burn fossil fuels than to avoid doing so, when you can offload the Economic Externalities of all the pollution you produce on every one else. This means so long as no laws (such as a Carbon Tax) are in place to prevent this, communities here on Earth will always pump out tons of pollution when given the option. The only way to prevent this is to force them to pay for the damage that pollution causes to all the other people on the planet. On Mars, there are no naturally-occurring fossil fuels, and no freely-available Oxygen to burn them with, so none of this is even a concern...

You've heard of the concept of Minimum Viable Population haven't you? Mostly, the term is used in a genetic sense- what's the smallest population you can have without tons of inbreeding-related problems quickly appearing (although as many backwater communities on Earth have demonstrated, these problems are rarely ever sufficient to actually wipe out a community, or even stop its population from growing naturally...) but it can also be thought of to exist in an economic sense- what's the smallest number of people you need to establish a Mars colony that can eventually survive without support from Earth? Musk (and myself) seems to think this is around a million people, spread out in a half-dozen or more small cities. Any smaller and one catastrophe could easily cripple the colony's ability to survive, and you wouldn't be able to develop the kinds of Economies of Scale and specialized industries thst are needed for a truly self-sufficient colony. Obviously, to get to that point you have to have some support from Earth. But Musk's plan, and one I agree with, is to try and get to that point relatively quickly- because the period in between is when living on Mars will actually be at its most dangerous and difficult... Small communities are inherently vulnerable to the vagaries of fate. Most of your criticisms could be leveled against nearly ANY tiny colonial community here on Earth. Most small isolated communities are only ever a single crop-failure away from starvation. That is why Economies of Scale, trade and mutual interdependence between communities is so important...

You'd have to show me the research on that- I don't believe it would be cheaper in direct costs. Colonizing the oceans or living underwater is a lot more expensive than you might think (the pressure-differences are GREATER than 1 atmosphere, and there is water you have to pump OUT in the event of a breach rather than just air you have to pump in. Plus, there is native sea life to contend with...) However, even if living on/undrr Earth's oceans WERE cheaper than colonizing Mars in direct do annual costs, it's MUCH more expensive in REAL costs. Why? Economic Externalities. An ocean colony on Earth would generate pollution and CO2 that would interfere with the rest of Earth's biosphere. This would leverage massive unaccounted-for (at least in your accounting) costs on the rest of humanity, making ocean colonization far more expensive than colonizing Mars. Thos is not to mention the direct economic disruption ocean colonies could create by shifting the world patterns of trade to their benefit. By contrast, Mars HAS no biosphere to disrupt, and there are no pre-existing cities on Mars to disrupt either climatically or economically. Mars has a totally separate atmosphere from Earth, and is too far away for large-scale trade in material goods to be viable except for by necessity. What happens on Mars STAYS on Mars. The very isolation from Earth that so many critics have pointed out is actually a massive blessing in disguise. Mars is too isolated from Earth to cause any real damage or disruption to it with today's technology except for in the intellectual property sectors of the economy... Similarly, Mars is isolated from any event that might disrupt life on Earth once it a Mars colony is self-sufficient, which is why it serves as a useful lifeboat for humanity in the case of an extinction-level event... (massive volcanic eruptions, anyone? Wars due to Climate Change?)

America trades because it has the OPTION to, and trade enables a better standard of living than would be possible without trading Similarly, a Mars colony will likely trade with Earth because it will have the OPTION to, and that trade will enable a better standard if living on Mars. However, what will CONSTITUTE the items of trade will most likely not be material goods, but intellectual property and knowledge. Almost anything that can be made on Earth will eventually be able to be manufactured on Mars, and vise-versa. With the enormously-high transport costs between Earth and Mars, it will almost never be beneficial to ship material goods from Earth when there is much more money to be made by a bootstrapping an industry and figuring out how to make it on Mars. Why would anybody on Mars ever choose to run an import-export business between Earth and Mars (except in rare goods like artwork) when there will be much more money to be made by starting up a factory to make a good on Mars that would otherwise have to be imported from Earth? The only trade in physical goods that is ever likely to occur will be in the early days, when it will be a physical impossibility to manufacture certain goods in Mars' early colonial economy, and the colonists will have no choice but to import them from Earth. Once the colonies there have sufficiently matured, they will make all necessary goods on-planet, trading between various cities specialized in different industries just like on Earth.