Northstar1989

Yeah, but it's an awfully expensive test flight. Probably more along these lines: Politicians are stupid. They will think Mars is impossible, no matter how impressive SpaceX's portfolio becomes (and they still haven't even demonstrated upper stsge recovery yet- they definitely need to do that before politicians will trust them with Mars). Going to the Moon, on the other hand, most politicians KNOW has been done before. And there are still plenty of tourists who'd be willing to pay for it...

Looks like Elon is bending to practicality again. And I don't mean that testing on the Moon first is NECESSARY (although it certainly is helpful- and cheaper than testing equipment on Mars), but that some people THINK it is needed. And sonetimes, perception is all that matters...

Well, a nuclear-powered Propulsive Fluid Accumulator would probably only orbit at 120-150 km, if one were ever built- and I'd call something that caould provide unlimited LOX for orbital refueling until the nuclear reactor ceases functioning pretty darn important... (Solar-powered PFA's would have to orbit at a higher altitude, in order to have enough electricity to have a high enough ISP to counteract drag...) Of course they would operate at such low altitudes BECAUSE of all the residual atmosphere there...

The Merlin 1D Vac doesn't have a TWR < 1. What do you think it is, an ion engine? The STAGE has a TWR <1 at ignition. Give it less fuel and payload, more Merlin 1D Vac engines, or just look at the TWR closer to engine cutoff, and TWR will be >1.

That's *exactly* what I was going to say about how the SSME's achieved it. So why can't they just give the Merlin Vac a new nozzle that does the same thing?

Haven't you ever heard of diminishing returns? There simply aren't nearly as many ways left a fighter design CAN improve vs. in 1967. 50 years ago would be 1967, NOT 1957- and only 5 years prior to the first flight of the F-16 (it was already in development by then). Compare the F-16 and Joint Strike Fighter (50 years apart) vs. The F-16 and a fighter from 1917. The improvement is MUCH less noticeable from F-16 to F-35, and that's with a MUCH greater fraction of the US GDP dedicated to fighter plane R&D between 1967 and 2017 than between 1917 and 1967... Similarly the improvement from F-22/F-35 to whatever we have in 50 years will be EVEN LESS noticeable. 45-50 year development cycles are *just right* to replace current designs just as they are becoming obsolete (and the F-16 is NOT obsolete even today...)

Nobody said anything about living miserably. We just have to learn to.live with LESS than we do now. Americans in particular are MASSIVELY inefficient with resources. The United States needs to: - Embrace public transportation. Particularly rail-based transit such as subways, commuter rail, and streetcars. In practice this means taxing the heck out of cars such that automobile owners actually have to pay for the road construction and maintenance budgets without burdening commuters who take the train/streetcar with any of the expenses. Also, ride-sharing and carpooling. - Relax zoning restrictions on building height and mixed-use residential/commercial development, with the goal of creating more compact, walkable communities. Goes along with the whole mass transit thing- denser cities and town with less fossil fuel and land usage. - Implement pollution and Carbon Taxes. Force polluters to pay for the damage they cause and you'll end up with a lot less of it. - Abandon the concept of grass lawns and switch to edible landscaping. Embracing gardening will help put wasted suburban space to good use and reduce people's ecological footprint. Also, bicycling to work anyone? - Invest BIG money in sustainable materials, such as the recent research at RPI's business park into using fungal mycelia as a building material... (Also, have you heard of their groundbreaking anti-reflective coating research for solar panels? Guess where I spent the first year of my college education before transferring to an even better school?) All this, and some research into solar power satellites (basically Microwave Beamed Power down TO EARTH instead of to spacecraft trying to get to orbit and beyond...), optical rectennas, and improved genetically-engineered crops and humanity don't be living in misery even with 12 Billion people (and maybe 1 billion in the United Statea)- just with substantially more careful resource utilization than we have now... The things that really make life worth living- art, culture, science; they have VERY small material inputs. A world of 12 billion people need not be misery- with the right socioeconomic systems it could be a utopia, with the large population actually ENABLING happiness rather than detracting from it... Similarly on Mars, population will be a valuable resource if used properly, not a detriment. More people means more Einsteins (with good public education at least). Also, if you didn't guess, I'm an Extrovert. I like crowds (most of the time). People don't bother me by sheer virtue of numbers.

Carrying Capacity Mathematicians love to argue this question, but they don't really seem to understand the concept of Carrying Capacity- it is not a matter of the maximum population an ecosystem can COMFORTABLY accommodate- it is a matter of the maximum population an environment can sustain, period. Keeping that caveat in mind, HowStuffWorks gives a decent introduction to the concept for the non-scientist: http://science.howstuffworks.com/environmental/green-science/earth-carrying-capacity.htm The strict definition of Carrying Capacity would say as many as 40 Billion people might be the number- but based on my knowledge of Virology, I suspect infectious diseases will limit the human population well below that point... (hence my estimate of 12-24 billion)

That's insulting, and based on nothing but your disliking what I have to say. *I* am a published biologist with a graduate degree, like most biologists intimately familiar with ideas like "Carrying Capacity" and ecological niches. My estimate was based partly in part on estimates by other biologists when technology was less advanced. Most estimated the planet could only sustain 10 billion people. Since we're already at 7 billion with no signs of the majority of humanity being on the edge of starvation (and most famines in the developing world being due to lack of access to modern agricultural technology and electricity, rather than any hard limits of the land), rapidly rising death-rates (in fact even in the midst of those famines, they generally aren't so severe that the population doesn't continue to rise), or any of the other telltale signs if a population hitting its carrying-capacity, I decided those estimates were probably a little too conservative. Your credentials to argue Biology with a Biologist are, what, exactly?

If you're referring to the Bio-Dome experiments, the later more advanced one (Biosphere 2) failed because an oil company backed investment firm wanted to make some kind of weird point about Global Warming or something. I never really understood what point they wanted to prove- but they DID mis-manage the projects in attempting to do so, because they understood zilch about Biology. Steve Bannon, interestingly, was the man the oil-backed investment firm sent in to manage the project once they took it over. There's no solid proof he tried to sabotage it, but 2 scientists certainly believed so firmly enough to BREAK THE GLASS and ruin the whole experiment... P.S. NOT a conspiracy-theory. VICE News even did a special (on TV) and a written article on it: https://motherboard.vice.com/en_us/article/qkjn87/the-strange-history-of-steve-bannon-and-the-biosphere-2-experiment

The United States doesn't have to give up most of its force-projection capability, just its obsession with having the most advanced weapons out there. I.E. let our rate of weapons-development slow to the point other nations catch up (weapons-development has LONG passed the point of cost-effectiveness in the manner the USA does it. We would be better off restructuring our defense-industry to cut out as much fat as possible and control costs- even if doing so slows research down significantly...) and build a larger fleet of less sophisticated aircraft optimized for cost-effectiveness rather than having the most absolutely dominant capabilities out there. Letting the carrier-fleet age from 11 cutting-edge carriers to maybe 14 much less advanced and more cost-effective ones only as capable as 8 newer designs. Reduce the emphasis on dominance and having the absolute best weapons and increase the emphasis on cost-effectiveness. Cutting-edge weapons cost a LOT more to develop than than they do to build, maintain, and slightly upgrade over time. Most of the "acquisitions" costs of new aircraft actually go to pay back their R&D costs andbthe costs of initially tooling the factories and figuring out how to build them. If, for instance, instead of making the next-generation fighter we're already working on to replace the Joint Strike Fighter a limited-run deal where we just made a couple hundred (or less) and then stop, we declared it the last major fighter design we develop for the next 50 years and just kept the assembly-lines for making it open indefinitely, focusing on automation and figuring out ways to make it cheaper rather than moving on to the next new thing, we could bring down the cost of aircraft by a LOT. Similarly, if we cut back on R&D speed for new ships, and just focused on making more of each design for longer, we could anortize R&D costs over more ships- and make each one effectively cheaper. In the end, this would require a tradeoff of quality for quantity as our weapons systems started to lose their edge over our rivals- but it's the ONLY way the US can hope to survive economically in the 21st century. The cost of the U.S. military budget is ENORMOUS, and slowly bankrupting the country. Just imagine all the economic development we could stimulate if we cut the military budget in half, and invested all the money in Science, Healthcare, Education, and colonizing Mars, for instance... The only OTHER option to avoid the inevitible complete and total economic collapse would be for the U.S. to start annexing other countries without significantly increasing its military budget, to divide up its costs over a larger GDP. Nobody else could really stop us, except by a nuclear strike (which is why such annexations would have to go nowhere near other nuclear powers). But I don't think that would go over too well with the international community, or the populace back at home...

That comment, when taken literally (ignoring the quotes) sums up the entire spirit of your post. No, just so much no. Science on Earth coats land, food, and various other resources to sustain. When Mars is self-sufficienct, it will be able to feed and house its own scientists- which means, for all perpetuity, humanity will be able to support a larger scientist population. Colonizing Mars is a one-time cost, and once it's done it's done- for no additional cost from Earth. Meanwhile, humanity on Earth won't be as to develop forever- and certainly not without destroying the ecosystem. Eventually we are going to hit a hard population-cap (my knowledge of Bioligy leads me to guesstimate somewhere between 12 and 24 billion people, depending on how much of the environment we are willing to sacrifice). At that point, colonizing Mars and the Moon will be the ONLY way to increase the humssn population sooner. We might as well get a head-start on that, since we will reach Earth's population-limit long before Mars does. And Mars, unlike the Americas, has no native population of sentient lifeforms we need to worry about commuting genocide against.

I don't know what gives you the idea that an over-expanded thrust column is never controllable, but that's simply not true. NASA has even tested over-expanded nozzles, and in fact the SSME nozzles were slightly over-expanded (that is, they expanded the thrust column to less than 1 atm of pressure- about 0.9 atm I believe). The result from significant over-expansion (to much less pressure than about 0.9 atm) is greatly reduced Thrust and ISP at sea-level, but NOT the thrust stream becoming uncontrollable. Such engines DO require a slightly different shape to operate over-expanded though, you ARE right that a nozzle with the shape of the Merlin would be uncontrollable at sea-level. But a slightly different shape (more bell-shaped if I recall correctly) and the same engine and expansion-ratio WOULD be controllable, albeit with greatly reduced ISP and Thrust in-atmo, if flow-seperation and atmospheric-compression of the thrust column are the only concerns...

You *ABSOLUTELY DO* lose progress. Think of the history of a human Mars colony like a chart of human progresd vs. time. If you have two lines- one charting the advancement of Mars with the first base built in 2038, and the other with the first base built in 2040, they would probably have more or less the same positive slope over a long time, indicating the same approximate rate of development. However the one with the base built in 2038 would have an X-intercept two years earlier and a greater Y-intercept, meaning that at ANY point along the graph, the older Mats colony would be more advanced. The total progress "lost" by a certain year can then be considered the area between the two lines, starting at the X-axis and ending at that time point for comparison. In reality the slopes won't be straight lines- but they WILL have approximately the same slope at most two points the same time after the bases were established (except where affected by specific outside events that occurred at a specific year- a natural disaster, disease outbreak, etc.), meaning the scenario with the earlier base will always have more human advancement than the one with the later base, though by randomly varying amounts at any given time. You can measure the progress lost in a variety of ways- scientific advancement produced by the Mars colony (by any of a variety of measures of scientific contribution- papers published by Martian scientists, grant money awarded on Mars, etc.), annual crop yield, population, annual electricity production, life expectancy. But my favorite is GDP. The economic value in DOLLARS lost over time is after all the clearest argument as to why colonizing Mars as soon as possible should be preferred, provided the cost of doing so remains the same... The situation with the cumulative scientific advancement for the human species AS A WHOLE looks a little different. Comparing the lines for the two scenarios (base established in 2038 vs. 2040) they will both remain identical in slope up until 2038, after which that line's slope will start to increase more rapidly than the other due to scientific breakthroughs resulting from the colonization process. 2 years later the other line's slope will start to do the same. However as technological progress tends to beget technological progress- every answer produces new questions, and technology provides more people withbthe free time to ask more questions- you'll end up with the first line gaining more and more ground ahead of the second, in a rubaway effect as humanity pulls comparatively further and further ahead in a snowball-effect... As for this point, I actually partially agree. I even have highlighted specific technologies that could reduce the cost of getting to Mars that SpaceX should work to develop before trying to go to Mars. The key word is WORK, though- SpaceX and NASA shouldn't just sit idly by, waiting for these technologies to develop whenever their scientists feel like getting around to them- they should develop strategic initiatives to identify key technologies and PUSH to develop them as quickly as possible, much like NASA did in the Apollo Era. Technically NADA already *HAS* such strategic initiatives in place- but they work to pursue them with no real sense of urgency. What they, and you, need to understand is that they should be applying maximum pressure to develop Mars-enabling technologies as quickly as possible, and then *GO* to Mars as soon as they are ready, because colonizing Mars will eventually increase humanity's annual scientific output by at least 33-50%. THAT is a MUCH better investment of NASA and the government's time and resources right now than almost anything else (except Education spending, biomedical research aimed at CURING or PREVENTING the diseases that are busy bankrupting the US economy and costing millions of lives, and scientific literacy initiatives)-including planetary science, which there is really no rush to do and they can always get around to later, AFTER humanity has a stable colony established on M ars...

No NOT the same thing. Not the same thing at all. My POINT here is that the Interceptor *IS* the Lander in a bare-bones no-frills Cycler mission architecture. Thus it's important to use the same name for both to make clear that one is in fact talking about the same craft. And KSK wasn't- he in fact believed that a Cycler mission architecture would require a "whole flotilla" of seperate ship-designs, including a Cycler, an Interceptor, a seperate Lander, and God knows what else... In reality, it would require only TWO designs- a Cycler and an Interceptor that is capable of also landing on Mars. Anything beyond this is added complexity that may serve to generate some cost-savings with enough flights, but is wholly unnecessary to create an effective mission architecture that beats the standard ITS/Tanker pairing Musk has been sticking with on both a cost basis, while adding little to the development tine- which are ultimately the only two things that matter (time, and money). Those examples might be urban legends (you'll notice you brought them up not me), but the pattern is not. Most of the advances generated by the space program haven't been in consumer goods- they've been in fields like materials science, computer engineering, and precision-manufacturing techniques: fields the average American knows next-to-nothing about. So urban legends like Tang and Velcro being the advancements that came from, and paid for, the space program have arisen as proxies for the REAL advances that space-spending actually HAS generated instead...

It will give them more time to grow their business even further for one- making ITS seem more plausible to investors. And Falcon Heavy is a larger and more complex rocket than Falcon 9, and upper stage re-use is a more difficult and complex goal than launch stage re-use. Not to mention achieving it will likely increase their market-share even further, as it makes the Falcon Heavy more cost-efgicient. And as has been pointed out before, it gives Falcon Heavy more potential customers- launching payloads that could be launched on a Falcon 9 with first-stage recovery, but are FAR too heavy to recover all stages on a Falcon 9 with (like I've said before, I'm guessing they would have to slash the Falcon 9's payload down to just a few tons to be able to recover their upper stage). By the way, a tangent, but Falcon Heavy is actually BETTER suited to upper stage recovery than the Falcon 9, as it releases its upper stage later and at a higher altitude- meaning less Delta-V is required of the final stage, and the payload makes up proportionally more of the final stage mass. This means reducing the payload and adding an equal mass of fuel tankage will do a lot more to increase the fuel mass-fraction of the final stage, purchasing more Delta-V that can be used for upper-stage recovery per ton of payload capacity sacrificed (a specialized upper stage designed for recovery, with larger fuel tanks, landing-legs, etc. will of course have to be developed...) Anyways, showing mastery over something as complex as 100% reusability with the Falcon Heavy will be EVEN MORE impressive to investors, while growing SpaceX's profit-margins even further. Which is important, as many people consider the ITS (and probably also the ITSy) to be impossible to succeed in- meaning the more other supposedly-impossible tasks SpaceX can accomplish the better they can try to assuage those fears. SpaceX needs to build an unshakeable reputation as the doer's of the impossible if they are to hope to succeed in getting funding for the ITSy- as unfortunately many peoole still don't quite see them that way yet... They could reinforce the nozzle if the stresses on it are the only conceen. Maybe shorten it a bit (and slightly enlarge the fuel-tanks) if the structural reinforcement makes the extra expansion no longer worth the extra mass...

Raptor should be able to improve over multiple versions too. *Particularly* given what a novel technology Full Flow Staged Combustion is, there should be even more room for optimization than with the Merlin... As for the fuel-density: let's do some math on that, just to see how extreme the difference is... Kerosene has a density of 0.81 g/cm^3, while Liquid CH4 may only have a density of 0.422 g/cm^3. But Meth/LOX also burns with a higher fraction of LOX, which has a density of 1.141 g/cm^3... CH4/LOX burns with a mass-fraction of 80.0% Oxygen, whereas RP-1/LOX (majority C12H26) burns 77.7% Oxygen. This means that RP-1/LOX at stochiometric ratio has an average density of 1.2762 g/cm^3 whereas CH4/LOX is 0.5658 g/cm^3. However the Raptor gets an ISP of 361 seconds, whereas the Merlin gets only 311 seconds. Plugging those into the Rocket Equation, you can see that with a 7:1 mass-fraction the Merlin gets 5935 m/s, whereas with a 3.66 mass-fraction (what you get if you assume only 44.3% as much fuel due to the lower fuel-density in the same-sized tanks) the Raptor gets 4591.6 m/s of Delta-V... Interesting. So a Meth/LOX upper stage only gets 77.4% of the Delta-V as an RP-1/LOX upper stage of the same dimensions if the Kero/LOX upper stage has a 7:1 mass-ratio... Up that to a 6.32:1 mass-ratio for the Meth/LOX upper stage (by a little more than doubling the fuel tank volume) though, and its Delta-V rises to 6528 m/s, already exceeding the Delta-V of the Kero/LOX stage despite having a lower (only 88.7% as much) propellant-mass at that volume... So, the Raptor certainly seems to have a lot more potential, but you're right- it's a very different design that is required to convert the upper stage to Meth/LOX... Why do you believe that to be true?

(Emphasis added). I missed this earlier, in reading that list a little too quickly, but as a Biologist with specialties in disease-research (both infectious and genetic) in real life, I just *HAD* to comment on it when I noticed it... You DO realize that the early days of Mars colonization will be incredibly harsh, and under unusual conditions, right? Large numbers of colonists will become sick living under such conditions, and the colonies will become a literal GOLD MINE for human disease-researchers from Earth (because it's not ethical to intentionally inflict diseases on people just so you can study the pathology. But if a large number of people in one place all become naturally ill with the same sorts of diseases...) Not only that, but native Martians who were born and raised on the planet will have a MASSIVE incentive to invest in disease-research themselves. Eventually, such trends will lead to cures perhaps CENTURIES ahead of when they might have otherwise been discovered on Earth... That alone is worth every dollar we spend on colonizing Mars or developing the technology to get there...

All great reasons to colonize Mars. Sadly, because of the low gravity, lack of atmosphere, month-long day-night cycle, and scarcity of H2O (unlike Mars, the Moon can NEVER be terraformed), the Moon is an extremely poor candidate for colonization. Mars vs. the Moon are like Iceland vs. Svalbard as candidates for Norse (Norwegian, Danish, or Swedish) colonization. Svalbard is closer, but Iceland had a MUCH more promising climate, and thus developed FAR more rapidly... The day-night cycle of the Moon alone is enough to make almost any colony location except on the poles non-viable. 14 days of night is simply NOT survivable with any technology we have today (except nuclear reactors- and those are... controversial to put on the Moon). A Martian Day, on the other hand, is only 40 minutes longer than our own...

Military *Power* is a Prisoner's Dilemma. You don't want to be too much weaker than your rivals. But it's a tool best never used- not wastefully depleted invading developing countries. And there are plenty of more cost-effective ways of maintaining a reasonable military deterrent without having all the (expensive!) fanciest new toys anyways. Maintaining a large Guard/Reserve force, for instance (that is why many countries mandate 1-2 years of military service from military-aged-males, with a mych longer period of mandatory participation in an active or inactive Reserve force after that...) and having lots of small, localized Guard/Reserve posts so those reservists don't have to change where they live to fulfill their service obligation, and can live wherever the best jobs are... (interestingly the US military has been CLOSING Guard/Reserve bases- which should make the world *very* anxious, economically and militarily, as it means our generals are moving us towards a more offensive and less cost-effective military footing...)

Actually, it has been shown time and time again that NASA spending returns MASSIVE economic dividends from technology commercialization (one study I saw said that technology from the space program generates as much as $10 in activity in the private sectors of the economy for every dollar spent on NASA). This myth that somehow the space program doesn't provide anything worthwhile is just that- a myth. One repeated again and again by the same sort of people who deny Global Warming (often LITERALLY the same people, as it serves their intetests to reduce NASA funding so they can't produce more Climate Change data) until it has soaked into the public consciousness...

See? You accounted for the Interceptor Ship and THEN started talking about additional ships. You were clearly unaware that the Interceptor Ship can also serve as your Lander... It seems to be about saving time and money by not needing to build a new manufacturing facility, and being able to utilize the NASA VAB... I think it's Musk's wisest move so far. Like I said a while ago, now I just wish he would consider making OTHER changes to his mission architecture...

Separate from the Cycler and the Interceptor, which you already accounted for elsewhere:

Funny you should mention that. Turns out a planet doesn't need a ferrous core to be protected from the solar wind. You heard about the recent proposals to use a small heliocentric satellite positioned between Mars and the Sun to generate an artificial magnetic field and divert the solar wind away from Mars, right? https://phys.org/news/2017-03-nasa-magnetic-shield-mars-atmosphere.html http://www.popularmechanics.com/space/moon-mars/a25493/magnetic-shield-mars-atmosphere/ It would be positioned at the Mars-Sun L1 Lagrangian Point, so it would require almost no thrust to maintain its position. A large (compared to the soacecraft) Solar Sail should do the job of station-keeping there quite nicely... https://en.m.wikipedia.org/wiki/Lagrangian_point

It's precisely BECAUSE of those problems we should go to Mars. The answers to those problems can be found in Science, Technology, Engineering, and Mathematics (the "STEM" fields for short). You know- the careers we can never get enough people to go into anymore. Going to Mars could inspire MILLIONS of people to go into STEM fields (just lime did the Apollo program), ESPECIALLY if we accompany the Mars push with a major effort to expand the number of slots at graduate and professional schools worldwide (the Apollo Program was accompanied by a more than TRIPLING of the number of PhD students in America- inspired by the space program and enticed by major government funding-efforts to get more people into the sciences...) Raw Materials aren't just going to magically appear because we wish them to, by the way. The way you discover natural resources is through LOOKING FOR THEM, with the appropriate scientific knowledge to back up your search. Advances in Geology from looking for metals and other mineral resources on Mars should prove MASSIVELY useful for discovering new mineral deposits here on Earth... And on the recycling side of things- early Martians will need to learn how to recycle ALMOST EVERYTHING (right down to their own fecal matter). That knowledge should prove MASSIVELY useful here on Earth...