Northstar1989

Carbon nanotubes attached to an aluminum oxide dielectric and aluminum or calcium as a functional metal...

What about the potential benefits for Mars colonization. Better solar panels would mean less payload required to set up a colony or research outpost. Also, would the raw marerials to make these be more easily acquired on Mars than those needed to make solar panels? Regards, Northstar

You drastically underestimate just how expensive those airport additions you're talking about would be... And how expensive LH2 is to store so it doesn't boil off... Also, LH2 won't sell for $0.05 a gallon. No way. That simply would never happen. The transportation costs alone of getting the stuff from the countryside where the solar farms would be to the city airports would dwarf that... Anyways, I started this thread to talk about Optical Rectennas. Particularly their applications for spacecraft. Maybe we could get the discussion back on-track? Regards, Northstar

Well, more time to dedicate to their analysis of the recent launch-failure, and present their conclusions and the steps they will take to prevent such issues from happening again in the future should only act to help rebuild confidence in their company. People understand that hurricanes mess things up- so I doubt this additional delay will hurt them too much... I'm more concerned about ULA's seemingly unrelenting media campaign to discredit SpaceX (their CEO has been writing letters to the Pentagon, and making media statements, claiming the military should launch all its payloads with them because their rockets are more reliable, even if far more expensive, and claiming the bidding process needs to be revamped to quote "form a level playing field". Says the company that has had a monopoly on defense launches for decades, and still has many powerful allies in DC ...) than I am about a hurricane-induced delay. ULA seems to have a real stick up their butts about SpaceX, probably because it forced them to actually compete on all those lucrative defense satellite contracts... Regards, Northstar

Cite your figures. The estimated value of these asteroids in the trillions per-asteroid was cited by an earlier poster- you will have to cite your claim that Iridium sells for only $20k per kg for it to be believable... However even at that cost the numbers *do* add up, and it *would* it would be profitable... SpaceX *currently* sells payload capacity at $2719/kg, according to Wikipedia, and has announced a 30% reduction in pricing for the first reusable flights. However in time, Musk thinks the cost will come down further, eventually reaching under $300/kg (This is the assumed cost all my earlier arguments hinged on). At $300/kg, you could launch over 64 kg of mass to LEO for each kg of Iridium recovered at a value of $20k/kg price (leaving some margin for refining costs). Further, it's perfectly reasonable to expect at least a 10:1 or 12:1 mass-ratio for capsule mass to recoverable mass if the capsule is unpressurized, contains the sensitive electronics in a seperate compartment from the payload- which is allowed to reach basically any temperature as long as it doesn't melt, and relies on a propulsive-landing with nothing more than drogue chutes at most... So, you could launch a 64 kg capsule that recovers 640 kg of ore for less than $20,000 in launch costs if Musk's predictions prove true (and a 64 kg payload would be in the range of a secondary payload on a Falcon 9- so you might get it to LEO for *even less* than that). If that capsule were reusable, then the construction costs of the capsule itself wouldn't be astronomical once amortized over many uses (let's say at least 40 per capsule- as you can afford for a capsule or two to fail during reentry/landing), and as long as you recovered at least a kg or two of Iridium for each 640 kg of ore, you'd make an operating profit... The key would be to perform operations on a large enough scale to pay back the initial R&D costs and those of getting the asteroid to LEO in the first place... As you can see, there's definitely a slim margin to make a small profit here if the assumptions that I outlined in my earlier post to begin with (that Falcon 9 reusability works and is cheap) pan out. It could be that the Falcon 9 cost estimates Musk has been making don't pan out, but that's not the same as the numbers here not adding up if they *do*. Respectfully I don't appreciate your constant weakly-supported criticisms of anything innovative I argue or suggest Derek, and would love to see a little more open-mindedness from you. Between yourself and Nibb, I get no end to constant (often factually-inaccurate) criticisms and pessimism on a *variety* of posts on this subforum, and haven't for the past two years of posting here... Do what you will, I'm just voicing my feelings about your behavior, and letting you know I'm very unhappy about it. Regards, Northstar EDIT: So Elon thinks his Mars Colonial Transporter will be able to put payload on Mars for $140k/ton (that's IMHO both extremely optimistic, and *still* too high for large-scale colonization without government financial assistance, but that's beyond the point...) That equates to $140/kg to Mars. If the MCT can achieve THAT, then surely Musk should be able to achieve $300/kg to LEO (which is low enough for a scheme that just relies on recovering raw Iridium ore from an asteroid hauled to LEO to be profitable) with at least *one* of his launch vehicles...

I'd suggest not making use of a continuous burn approach, even to a suborbital trajectory. You can get much faster/further by throttling back up to max once you pass the lowest 6-10 km of atmo, cutting engine power to cruise to APO once you have enough vertical speed to clear the atmosphere, and then re-igniting your engines near APO to build up as much horizontal speed as possible. You probably also want to pitch over earlier and more sharply in ascent- so you build up horizontal velocity sooner... If you do this right, you also require little to no heatshielding, as youre-entry will be quite shallow. Finally, more fuel tanks could have gotten you a LOT further on your first liquid fueled launch. Your TWR was far higher than is optimal. Regards, Northstar

Nibb, I must remind you that the Delta-V necessary to reach a given speed and altitude and the speed you travel at that altitude are two entirely different things. It takes well over 2000 m/s to reach Mach 3 and 24 km altitude. You also can efficiently use vacuum-optimized rocket nozzles at 24 km, which drastically increases your ISP... See below: The problem with air-launch really isn't that it doesn't make sense from a physics perspective. It's that to really get the most out of it, you need an expensive-to-develop plane uniquely built for high altitude flight with a very heavy payload... The R&D costs are what get you... Besides, if you're trying to get the most out of a plane, why stop at air-launch? It makes a lot more sense to just build a spaceplane that dolphins out of the atmosphere, and release a heavy upper-stage on a suborbital trajectory at a couple km/s of speed. This way, you eliminate the need for a first stage entirely, while not needing to design a spaceplane that can get all the way to orbit (the difficulties of spaceplane design increase exponentially the more Delta-V it needs to carry- and the wings/ airbreathing engines don't provide any benefit once you're high enough you need to swap to rocket propulsion, they're just deadweight, and at that point Lift/Drag is likely to end up below 1...) Of course, at that point you're probably just better off with a reusable launch stage, ala Falcon 9, unless you're using something like Microwave Beamed Power which is very limited in takeoff-thrust (and since Escape Dynamics went under, MBP probably won't happen for at least 40 years...) Regards, Northstar

My point is that the costs of fetching those resources from LEO down tobthe syrface really aren't that high. It doesn't matter what the concentrations are if the wlements within that ore are valuable enough. With a reusable capsule system (the capsules wouldn't even need to be pressurized), the costs to bring that ore down to the surface would become comparatively very low indeed. We're talking hundreds or thousands of re-uses each year (for a single large asteroid) of a small capsule launched atop a reusable rocket- something no larger than the Falcon 9 at most... With enough launches/re-uses each year, the economies of scale really start to add up... And, as any veteran KSP player is well aware, many Near-Earth Objects would require *very* little Delta-V to bring to an aerocapture trajectory in the first place (less than 100 m/s). So the fuel costs of moving an asteroid to LEO could be very low- less still if you're willing to make shallow aerobraking passes that leave Earth's SOI a few times (possibly with Lunar gravity-braking as well) before finally capturing such an asteroid. Regards, Northstar

At a value of multiple trillions of dollars for a single asteroid (for reference, NASA's annual budget is 18-19 billion $, and $4 trillion is nearly the annual US budget), you wouldn't need to purify the minerals. It would literally be profitable just to cut the asteroid up into chunks that you send down to Earth unrefined. Especially if the recovery capsules were, reusable, and could be re-launched back to orbit on reusable rockets... Cutting an asteroid up into lots of small chunks wouldn't be easy- but it's certainly feasible. Regards, Northstar

Ummm, actually the survivability of US and Western European fighters is excellent. The chances are they will be used in asymmetrical wars, against oppoments who aren't capable of shooting them down. And they make plenty of patrols and teaining flights in peacetime. If we ever started chewing throughhigh-tech fighters like in WWII, by contrast, we'd be *forced* to opt for a cheaper design. Single-use high-tech fighters simply aren't an affordable prospect... So no, fighters really *are* reusable... Regards, Northstar EDIT: My bad- didn't notice how old that post was...

You can't seiously be suggesting the Long Smokestack Theory, can you? That theory has been proven wrong so many times and in so many ways it's not funny. Conventional cars are far less environmentally friendly than battery-electrics, hands down, even when you produce the electricity 100% from coal, simply because of how much more efficient utility-scale power plants are. That's an incredibly off-topic discussion not even tangentially related to SpaceX's goals of space exploration though, so I'm not going to bother to discuss it any further. Regards, Northstar

Gotta fill the wait until the next launch somehow. Seriously, though, this thread has been subject to countless merges. It's not fair to ask me to go off and discuss other SpaceX things in another thread if every time I do the moderators just merge it in here and I get berated by you for going "off-topic" again... I think I've said my piece on the SpaceX plans anyways. There's really not much to say besides this- when I do out the math, it still looks like Musk's Mars plan will end up with costs about an order of magnitude too high, if it even works. None of the ideas I suggested will shave more than 10 or 20% off the costs, in a best-case scenario, and a lot less if R&D costs end up being high for them... So, it's clear to me that Musk will either (a) have to give up on his plan when costs turn out too high for most people to afford a ticket *and* all the cargo they need to syrvivebon Mars (b) Musk will realize before it is too late that his estimates of what people are willing to pay are too high, and come up with new, technological cost-saving measures, (c) he won't, and the colony will fail either due to insufficient colonists or because too many of those who go to Mars die there due to bringing inadequate amounts of cargo, or (d) Musk will seek government funding to make up the difference, like in the "public-private partnerships" he hinted at in his presentation. And all that assumes the ITS even works, which I'd say is a 50-50 proposition, and only that knowing SpaceX's superb history and determination. Guess what options I'm hoping/praying for? Regards, Northstar

I never said that the human population would continue growing (although I posit things will end in disaster if it does) or that colonizing Mars would substantially alleviate population pressures on Earth... I posited that having more people would create piles of new intellectual property, scientific discoveries, etc. and then compared the cost/benefits to supporting those people on Earth vs. colonizing Mars. My point was and is that colonizing Mars is the best way to expand the human population size, and therefore there IS a strong economic motivation to develop Musk's dreamed-of self-sufficient Mars colony. See, not off-topic at all. Regards, Northstar

And what about the collapse of the biosphere due to population pressures on the envuronment and global-warming? Eventually, humans are going to come smashing into one limit or another if we just keep trying to cram more poeople into our one planet rather than seeking to colonize the solar system... Also, very cool that your wife's a surgeon with a PhD (where did she get her MD?). I'm currently applying to medical schools myself, and have a Master's (long story there- but the reasons I went for a Master's instead of a PhD were mostly fiscal)- but medical schools are *ungodly* picky these days... (comes from not growing class-sizes to meet population expansion, and hospitals trying to replace MD's with PA's and Nurse-Practitioners rather than pressuring med schools to turn out more doctors...) Regards, Northstar

Wouldn't take long for the cryos to heat up, vaporize, and explode the tanks due to overpressurization doing that (or simply all boil off, if you vented the vapors quickly enough). You'd need to simulate an actively-cooled fuel system to realistically work out the issues... Regards, Northstar

There won't be an "end of effective antibiotics" if we're smart and make the needed investments now. You're talking to the wrong person to try such scare-tactics/hype on (I'm a biologist with some background in microbial studies, and exposure to both veterinary and human medicine circles where solutions to such issues were actively discussed.) The major reasons that this is currently a problem are: (1) Doctors prescribe antibiotics like candy, even to diseases they KNOW are viral (pharma company "gifts" might be related to this in some cases, shutting up whiny mothers is in others). (2) People don't take their entire course of antibiotics to completion (they stupidly try to "save" some for if they get sick again), leading to the survival and spread of resistant strains. (3) Doctors only prescribe one antibiotic at a time in most cases. They SHOULD be prescrbing cocktails containing a half-dozen antibiotics or more, so that if a bacteria survives one antibiotic, it is killed by another before it lives to spread its resistant genes. (4) Farm-factories routinely make prophylactic use of antibiotics in crowded animal living sutuations, at low doses. This leads to the rapid development and spread of progressively more resistant strains. All of these issues can be solved. And bacteria with antibiotic-resistance genes lose them over time and generations (many bacteria reproduce as often as once a minute- so a single day can represent literally thousands of generations for natural selection to do its work) in the absence of antibiotic exposure, as there is a fitness penalty to carrying around useless genes in bacteria... (bacteria face heavy selection pressure to develop and maintain small/minimal genomes, as they can be more quickly replicated, and require fewer nucleotides to replicate...) If we take needed precautions and invest in the development of new antibiotics while the prevalence of resistance to older types declines as they fall out of use (we will eventually need to cycle back to them), and are careful to control the spread of multi-resistant strains, then the end of effective antibiotics shouldn't be an issue. Farming enough food to supply an ever-growing global population will ALWAYS be an issue, by contrast- and eventually famine and food shortages will prevent further population-growth. Not before famines lead to global economic collapse, though- and colonizing Mars no longer is an option... Far better to colonize Mars and eventually the rest of the solar systen than to try and see how far we can stretch Earth's biosphere and agricultural capabilities before population pressures lead to a collapse of one or the other...

Exactly. But it hasn't been done before yet. Which is why I think Musk's whole ITS plan is a little risky and he should focus on developing refueling technology first...

The arm was just to move things together rather than docking. The bigger problem is that, like I said ages back on this thread, that mission (which was one of the ones I was thinking of/ referring to) only transfered hypergolic propellanrs such as MMH/NTO. Not cryogenics like CH4/LOX. It's not living space that's the issue, it's farmland. At current average global development levels, it wouldn't matter if you moved the entire world population to Australia like you said (also, never going to happen)- you would *still* have trouble feeding 7 billion people. In fact, more so, as you'd get food spoilage shipping crops across the globe... When we get up to 12 or 15 billion, we'll have pretty much hit the Earth's carrying capacity without improved agricultural techniques... Regards Northstar

Yes, yes, technology can increase Carrying Capacity up to a certain point. That's actually one of the fundamental premises of the concept- that technology can increase it, but not raise it without limit... The thing is, I don't know about you, but I don't want to see this entire planet covered in biodomes and greenhouses (at least what's not covered in solar panels and wind turbines to power it all). The technologies that allow us to colonize Mars would completely destroy the environment here on Earth if we applied them on a large enough scale. On Mars, by contrast, there *is* no environment to destroy. You can only make the planet more hospitable (by providing food and shelter in pressurized habitats), not less. Additionally, some Mars tech is poorly suited for Earth. Mars doesn't have weather you really need to worry about. The harshest dust storms carry a few mm of dust and theforceof a light breeze (The Martian was stupid unrealistic). There are no tornados, hurricanes, cyclones, tsunamis, flash floods, earthquakes, volcanoes, or hailstorms that could wreck fragile closed habitats. By contrast to Earth's disasters, the occasional meteorite is small potatoes to deal with... Additionally, any new development on Earth has to replace some type of pre-existing development. Cities replace farmland, tourist resorts replace lumber operatioms. And we've already mapped out most of the easily-found metals on Earth and mine the economical deposits. By contrast, Mars is a whole planet of unused land and untapped mineral deposits... So, in order to preserve Earth's environment, and because Earth's biosphere is much more difficult to control to the same degree as Mar's (nonexistant) one, it makes much more sense to colonize Mars than it does to try and support twice as many people back here on Earth... Regards, Northstar

Humans are still animals. Sophisticated and technologically-advanced animals, perhaps, but we still need to eat, mate, find shelter, and not die of disease. Carrying Capacity still applies to the human species, and the planet as a whole, as literally any competent ecologist will tell you. There is a limit to how many humans the Earth can sustain.

Stock KSP is nothing like real life in its balance, sadly. I would strongly recommend trying to re-create the ITS infrastructure in RSS 64k with RealFuels installed to get a better feel for it. Even then, there are serious problems with the mass-size relationships of things like the Mk3 parts (almost all the parts in KSP are much, much, much heavier than they should be for their size. And the fuel is far too dense as well. And the parts are a fraction the size of their real-life counterparts. All of which means you won't get the right performance for a rocket that 'looks" right, and trying to replicate real life craft in stock is *very* hit-or-miss...) Regards, Northstar

See above please. My answers take so long to write I often post them in segments before my login times out... EDIT: Answer should be more or less done now.

It's not about space, it's about *Carrying Capacity*. Those ywo things are entirely different, as any biologist can tell you... Carrying Capacity is about a variety of things, including the availability of food and other resources. Almost none of the planet, except the parts covered by snow most of the year, or inhospitable desert (and with desalinization of seawater and irrigation of the desert to grow crops on a massive scale in the wealthier desert nations like Israel, even THAT is starting to change), is actually empty. Almost all of the planwt is utilized for some economic purpose- be it seal-hunting, seasonal grazing of camels during the rainy season in semiarid deserts, lumber-sourcing, mining, or most important of all for population limits- farming. Only the most marginal areas see no economic utilization at all- and even that is only because the planet hasn't reached a sufficuent level of global economic development to incentivize reclamation of such land (political instability often prevents foreign investment from accelerating this). It's also worth noting that the Carrying Capacity of the planet is the MAXIMUM # of people it can sustain. As in, everybody living in extreme poverty to the extent that disease doesn't limit the population levels of resource utilization by killing hundreds of millions in massive plagues (far more likely if people are wretchedly poor due to living close to the limits of other natural resources. Population-density is also a direct risk factor for the spread of disease). If people don't choose to have more than replacement levels of children past a certain point, then for all intensive purposes the Carrying Capacity is even less than this. On the other hand, technology tends to raise the Carrying Capacity for humans- in that it allows us to access and efficiently utilize a larger feaction of the planet's resources (for instance the ability to covert wind-->electricity-->growth lamp power-->underground crops) but there will alwats be limits- for instance the availability of certain rare trchnologically-vital elements... Eventually, we WILL reach our planet's Carrying Capacity. We can only feed and clothe so many people with so much land (once again, how densely that land is actually inhabited is irrelevant- less densely populated nations just end up exporting surplus resources to more populoys ones anyways, so the resources still find their way into the global market). Having an entire additional planet at our disposal means we can comfortably support a much larger population... Regards, Northstar

You mean Musk, right? Anyways, people miss a key point- Mars is an entire seperate planet with just as much land as Earth! (due to its lack of oceans) This means that, eventually, it should be able to sustain a significant fraction of Earth's population (Mars also receives similar insolation at the surface, despite its distance from the Sun, due to its lack of atmosphere to reflect or absorb light- so there's also a similar amount of renewable energy available compared to Earth). Eventually, Mars could sustain BILLIONS of people. I think most people miss the massive economic benefit that would provide to Earth. Even if hard goods are never economical to transport back to Earth, there is nothing to stop the transfer/trade of intellectual property. When Mars,is a thriving world millions strong, it will generate software, media, and scientific research that will all benefit Earth- and since the colonies will eventually become self-sufficient, this won't come at any actual cost to Earth other than the IP we trade in return. THAT is the main economic reason to colonize Mars. In the short run, it will generate hope, innovation, and strengthen either America's leadership or global unity (depending on whether it ends up receiving more US or UN financual support). In the long run, it increases humanity's sustainable population limit by providing us the carrying capacity (this is an ecological term every competent biologist is taught- basically it means the maximum sustainable population of an area) of an entire second planet to live on, and should generate immense trade of knowledge, engineering, software and media! Regards, Northstar P.S. If I relate everything back to biology, that's because I'm a biologist in real life, if you hadn't guessed by now... Biology, like physics, is particularly unique in that it teaches you how to think about problems in a fundamentally different manner. In a way, I have something in common with Elon Musk in that I have advanced education in a scientific discipline that allows me to view the world differently than those around me, and come up with fresh insights. Sadly, I lack Musk's skills with programming and entrepreneurship (and luck to be born at the right time to take advantage of the .com bubble) that gave him the chance to make his mark with that unique viewpoint... I may also seem deficient at persuasion- but trust me, I am *far* better at it in person when I wish to be... (I have a proven track record as a highly-skilled and award-winning debater, dealmaker, and political organizer)

Mars is a destination for passengers. People will move there in ever greater numbers if there is a colony, and return in large numbers as well. Like I said before (once again, you are ignoring the most important and relevant points in my post in favor of attacking auxiliary points out-of-context), people often were the only profitable cargo. Cargo transport *to* Mars would also be in major demand, however- and due to the unique requirements of manned space travel (fast journey, low g's, crew accomodations, radiation protection, etc.) should actually be more profitable than sending the actual colonists that create a demand for it in the first place. The fledgling colony will need food, medical supplies, electronics, construction materials hard to obtain without a developed industrial base, and countless other things. Things which can all be shipped seperately, and on a much slower and therefore cheaper trajectory than passengers. I shouldn't even have to explain that the colonists eould pay to have these things shipped to them rather than die alone on a lonely planet. But only if they could afford it out of whatever savings they had left on Earth. So the initial cost of getting the colonists to Mars in the first place needs to be low enough that the colonists have some savings left- otherwise they all die. THIS is why the ITS plan, as it currently stands, is inadequate. Not because people won't be able to afford the ticket, but because they won't ALSO be able to afford to have the things they need to survive the early years shipped to/with them as well. Regards, Northstar