Northstar1989

Actually, there IS a magnification of time in a way. At least a magnification if today's decisions far into the future... You lose 2 years of progress now, and 2 years of progress 20 years from now, and 2 years of progress 200 years from now, and so on and so forth. At EVERY point in the development of Mars, from here to infinity (even after humans leave the solar system, it will likely be 2 years later, or with 2 years less Martian scientific knowledge at least...) humans will be less advanced, because we delayed colonizing Mars. Right now, space exploration is one of the single best investments we can make- yielding an estimated 10 dollars of economic activity from commercialization of associated scientific breakthroughs for every dollar spent on a space program. And that's just data on NASA from messing around in Low Earth Orbit. Going to Mars (the RIGHT way, anyways- fueled by innovative approaches to getting there and looking for scientific opportunities every step of the way) will UNDOUBTEDLY prove more valuable in the long run... Which numbers? You know it's impossible to answer your question when it's phrased as an unspecified, confrontations statement...

A failure of imagination on your part is not Mars' fault, nor mine. Mars could someday TEEM with life, after it is terraforms, and support close to a Billion people once it no longer becomes necessary to live in domes there. That kind of population could prove MASSIVELY useful to Earth in terms of all the scientific progress they will produce. Technological breakthroughs can be transmitted to Earth for very little cost- and are one of the primary long-term benefits of colonizing Mars for Earth. In the short-term, however, the main benefits of colonizing Mars are the scientific breakthroughs we will make attempting to get there, particularly in aerospace sciences (I just spent a consiserable amount of time explaining why SpaceX should invest in breakthrough electric propulsion methods for its plan to colonize Mars, for instance) and the MILLIOBS of young people in the USA and around the world thst going to Mars will inspire to pursue a career in STEM (Science, Technology, Engineering, and Mathematics) fields... A secondary benefit I haven't even mentioned is the way going to Mars will alter our collective social consciousness. Earth-centric thinking does an ENORMOUS amount of damage- particularly among religious people (who find it MUCH easier to justify fanaticism when the *only* planet humans can live on is one they think God created specifically for us...) How will going to and settling Mars change the way we think about ourselves and the world- think of thst the next time you go to church... (IF you go to church)

Nothing is a "proven" benefit until it's actually been done. By that logic, nobody should ever go out to socialize with friends, or apply to a better job, or attend college- because none of those are PROVEN benefits, for that particular person, before they happen... There are however many extremely valuable SPECULATIVE benefits that we can be almost completely certain of. Any colony on Mars will eventually become self-sustaining (it may take a couple hundred years, but it WILL hapoen). And when it does, Earth will no longer need to send anything to Mars (that doesn't mean it shouldn't- commerce is generally beneficial to all) and in return will receive one extremely important product that is likely to be the only thing Mars ever exports... KNOWLEDGE. The MAIN benefit to Earth of colonizing Mars is that Mars will eventually produce its own Science. Which means Earth won't have to work nearly as hard to maintain the same rate of technological advancement (or, ideally, can maintain a FASTER rate of scientific advancement for the same expense). For a few hundred Billion dollars or less, if done efficiently, Earth should be able to set up an entire new self-sustaining civilization that will eventually produce more scientific breakthroughs than the entire United Ststes and Europe combined (Martians will HAVE TO- life will be hard on Mars, even after 2 centuries of colonization- and science, technology, engineering, and mathematics will be the ONLY ways to make it easier. Necessity, as they say, is the mother of invention) Right now, the US spends $31 Billion annually on the NIH and $7 Billion annually on the NSF. Mars could probably be colonized for less than $300 Billion with SpaceX at the helm, and will eventually (600 or so years down the line and 400-500 years after self-sufficiency) produce just as much science as all the scientists in the USA and Europe combined every year with no additional. Do the math. It's a long-term investment to be sure, but pays handsome dividends in the long run on this basis alone. Not to mention all the scientific breakthroughs investing in actually GETTING TO Mars could produce... A global crisis of apathy. Americans, in particular, have become dangerously myopic and focused only on living a comfortable life. Going to Mars could change that, and inspire MILLIONS to become scientists, engineers, or entrepreneurs... If Mars experiences a famine (and at some point it will- so will Earth. Famines are an inevitability given a long enough stretch of time...) it won't harm Earth in any major way. On the other hand, BILLIONS of dollars worth of scientific data and MILLIONS of new scientists and engineers could prove incredibly useful on Earth...

Like I said, not all tradeoffs are equal. Sometimes you trade off something not very useful for something MASSIVELY valuable. Not to mention you've yet to show any actual trade-offs in any of your posts- the Cycler architecture doesn't need a lander, which was your main "tradeoff". In fact, the Cycler architecture doesn't actually need any more types of spacecraft than the ITSy- just swap a Cycler for your Tanker, and remove all the long-term orbital habitat from the ITSy and put it on your Cycler to make it an Interceptor. You even have the same number of docking-capable craft for each plan: two. Though the Interceptor only has to dock with the Cycler ONCE, and the ITSy has to dock with its Tanker 4-5 times at a minimum... You can even launch less mass to LEO with the Cycler architecture- since the Cycler doesn't have to have any more amenities than the ITSy, as both only support a crew for 5 months... The Cycler can be accelerated to its Cycler Orbit once over the course of months or years and left there, however, whereas the ITSy must make its Mars-transfer in a few weeks or less, and land all the orbital habitation equipment on the surface of Mars... In short, you failed to identify any trade-offs (there are some, but none of them you mentioned)- there is no way you identified that the ITSy architecture as proposed is significantly "better" than the Cycler one. In its bare-bones version, the Cycler architecture requires no more types of spacecraft than the ITSy, less mass to orbit, and is just as effective as the ITSy. There ARE potential drawbacks- but you didn't hit on any of them, and in my opinion they are well worth the primary benefit: MASSIVE cost-savings.

Two vehicles (plus slowboated colony infrastructure). The Cycler Ship architecture gets everyone to Mars and back with two vehicles- a Cycler and an Interceptor- exactly the same number of spacecraft that are needed to transport humans to Mars with the ITSy (the new name commonly being used for the new, downsized vehicle that will only be 9 meters in diameter and thus smaller than the originally-proposed ITS) The Interceptor doesn't need a dedicated Lander to get to the surface of Mars- it can do it on its own (but doesn't have to- the use of a dedicated lander is still an *option*) just the same as the ITSy. Slightly easier in fact, since it's a smaller spacecraft (due to not containg long-term orbital habitat equipment), and thus likely has a lower Ballistic Coefficient. Nor does thr Interceptor need a dedicated fuel tanker, like the ITSy does. Since the Interceptor is substantially smaller than the ITSy (though a very significant fraction of its mass in LEO is still fuel) if it launches on a first stage the same size as the ITSy it can carry all the fuel it needs for its mission with it in a single launch, without requiring any additional tanker-launches (a reusable upper stage can be used to insert the Interceptor into Low Earth Orbit, ensuring all its fuel tanks are full when the upper stage decouples). Of course, just like with a dedicated lander, I would argue that while you CAN launch the Interceptor in a single launch with all its fuel from an ITSy-sized booster, launching the Interceptor dry (with just enough fuel to reach Low Earth Orbit) and then refueling it in orbit is actually beneficial, mostly because it allows use of a smaller launch-stage (you could even use a Falcon Heavy, if you relied on a small flotilla of Interceptors with a few people in small capsules each, instead of a single large one cramming in 40-50 people like sardines in a can...) and future-proofs the design against the development of a very low-cost launch architecture with a small maximum payload (so it is cheaper for launching fuel, but can't possibly lift the Interceptor itself) like a reusable spaceplane (planes don't scale to larger sizes very easily), a Mass Driver launch system (Mass Drivers need to amortize their costs over a lot of launches to beat the costs of rockets to orbit- which means they need to be sized to launch only normal-sized payloads rather than the rare monster-sized one), or anything relying on Microwave Beamed Power (the driving cost of a MBP system is the ground-array, so once again you want to build a smaller array and only launch the most common payloads using BMP alone- although it *is* still capable of powering smaller side-mounted Microwave Thermal boosters on larger chemical rockets...) As for the Cyclers- they would probably be launched to orbit in multiple pieces and then assembled together, just like the International Space Station (in fact, you could literally use *THE* International Space Station as one of your Cyclers - just strap an array of electric thrusters and enough propellant to it and push. Since electric-thrusters produce *VERY* low g-forces, they won't cause damage to the fragile structure of the ISS when active; and since the Cycler doesn't need to have a crew aboard when it establishes itself in its Cycler Orbit, the amount of time it would take to get the ISS to a Cycler Orbit is largely irrelevant...) So there's no reason your Cyclers would need to be refueled in orbit either- just launch the propulsion module (with electric thrusters) as one of the many modules of the Cycler- you can take as many launches as you want to assemble it. Since the Cycler's structure never needs to survive high g-forces (literally the only times it will ever be under Thrust would be from an electric thruster, if you opt for electric over chemical propulsion) and it never needs to land or enter an atmosphere- it's a craft that will remain almost permanently in microgravity, much like a space station... Because the Interceptor is capable of being launched wet, and the Cycler Ship in multiple pieces, a Cycler Ship mission architecture requires literally only one size of launch vehicle (the Cycler can be designed to be launched in Interceptor-sized pieces) in the bare-bones scenario. Or two, if you want to minimize the amount of docking and assembly for the Cycler by launching it in larger pieces. And the colony infrastructure can be slowboated to Mars using whatever launch vehicles you have available, in as many pieces as necessary- there's no reason you have to launch it all in one go... So, with only two types of spacecraft and as few as only one ITSy-sized launch vehicle as a minimum requirement, the Cycler architecture doesn't necessarily require any more types of vehicles than the ITSy plan (one launch stage, a manned spacecraft and a tanker.) Even colony infrastructure can be included in a cargo-hold on the Interceptor for no more cost than including it in a cargo-hold on the ITSy (the ITSy and Interceptor require *almost exactly* the same Delta-V to reach Mars. Remember, a 5-month Mars transfer is a 5-month Mars transfer, it doesn't matter if you meet up with another spacecraft on the way by carefully timing your launch...)

The Wikipedia link lists a number of ALTERNATIVE Cycler designs to the Aldrin Cycler. Just because there are msny alternatives doesn't mean one option isn't the stand-out best option among them all. When you have trade-offs, that doesn't mean both options are equally good- often when you make a tradeoff you are trading one thing that is not very valuable (in this case frequency of use, non-useful journey time, *AND* the fuel costs to establish the Cycler Orbit in the first place) for something that is MASSIVELY more valuable (the ability to re-use the Cycler ever Earth-Mars transfer window, and intercept the Cycler with an Interceptor Ship for a fraction the Delta-V cost of any of the other Cycler orbits). I'm pretty sure the only reason Wikipedia even lists the other orbits at all despite how obviously inferior they are for reaching Mars is to preserve the knowledge, give credit to the people who discovered the other Cycler orbits, and because many of the other Cycler orbits were discovered BEFORE the Aldrin Cycler Orbit... (so Buzz Alsrin did not truly discover the concept of a Mars Cycler- only the first, and perhaps only, truly useful Earth-Mars Cycler Orbit...) Also, some of the other orbits could one day be more useful than the Aldrin Cycler for mining the Mars-Jupiter asteroid belt...(but are CLEARLY inferior for reaching Mars from Earth...)

Unfortunately you don't understand the entire idea correctly- your difficulties in understanding evident in this paragraph mainly center around the "shuttles" as you call them (by which I assume you mean dedicated landers). Separate landing-craft simply aren't required in an Aldrin Cycler arrangement. They can prove beneficial, if you can amortize their R&D costs over enough flights, but they are not at all required to complete the mission successfully. Assuming, like Elon Musk did, that there is no reason a craft capable of bridging the Delta-V gap between Earth and Mars can't also re-enter and descend to the surface, there is also no reason your Interceptor Ships- the craft that ferry the crew from Low Earth Orbit to the outbound Mars Cycler, and then from the outbound Mars Cycler to Low Mars Orbit- can't make the descent and land/takeoff from Mars as well. The Delta-V needed to rendezvous with an Aldrin Cycler, and then to capture into Mars Orbit and land on the red planet is in fact nearly identical (differing only in the small amounts of Delta-V needed by the RCS system for docking and undocking with the Aldrin Cycler) to the Delta-V needed to make a 5-month journey to Mars and then land on it. In fact, an Aldrin Cycler Orbit is really just a 5-month transfer journey where the orbital habitat doesn't enter Mars' atmosphere, and instead just keeps on going in its orbital trajectory around the Sun, with a slight gravity-assist from Mars. Think of it as what would happen if the Mars transfer-burn were the correct length but a little off in starting-time, or the mission were just to make a flyby of Mars rather than land... Don't get me wrong- a fleet of dedicated landers CAN be used to ferry the crew from Low Mars Orbit to the Martian surface, and in fact would be preferable for economic and safety reasons (if the Interceptor Ship doesn't have to also land on Mars and take off from it again, it can have smaller fuel tanks, no landing legs, lighter heat-shielding, and be designed in shapes that wouldn't make for good landing-craft, but are fine for aerobraking and docking; and if you have a dedicated lander it can be much smaller, only ferrying 2-3 people to the surface of Mars at a time, so that it has a lower Ballistic Coefficient, and doesn't risk the entire crew of the Interceptor Ship dying if a single thermal tile, or a single critical engine part, fails during re-entry or landing...), but landers are not NECESSARY any more than they are for Musk's base-plan with an ITSy that, like the Interceptor Ship, makes the whole Mars journey and then lands on the Martian surface, before returning to Earth. The Interceptor Ship is basically just an ITSy without the capability for sustaining humans for a 5-month journey. Other than that it's basically the same craft, with the sane capabilities. The MAIN ADVANTAGE of a Cycler Ship mission architecture is that you only need to accelerate your orbital Habitat on the Delta-V equivalent of a 5-month Mars journey (establishing a Cycler Orbit or making a transfer-burn for a 5-month journey to Mars require *exactly* the same amount of Delta-V: and indeed the "short" leg of an Aldrin Cycler's Earth-Mars cycle takes 5 months to complete. It is essentially the same orbit with a slightly more distant Mars-approach...) and you can do so ahead of time, a full transfer-window or more before the crew ever leaves Mars, using electric thrusters and however long you like (limited only by the shifting phase between Earth and Mars that give the transfer-window a limited duration). Not only do you only have to accelerate your orbital habitat ONCE, you can in fact take 27 months to do it if you want (assuming by the end of this you can end up in the correct orbit), and use nothing but electric thrusters to make the change from Low Earth Orbit to an Aldrin Cycler Orbit... The crew can board the Mars Cycler 27 months after launch, when it swings by Earth during the next transfer-window. The Interceptor Ship, to re-iterate, can double as your Mars lander.

Slowboating infrastructure is ABSOLUTELY a no-brainer. It's so obvious that even NASA adopted it for their Constellation mission plan (and later for the Design Reference Missions), despite their relative conservatism in adopting new ideas about how to travel space (it took them until the 90's to fully embrace the usefulness of the Interplanetary Transport Network in the Earth-Moon-Sun system and use it to collect solar wind samples at low cost, for crying out loud...) With a slower transfer-trajectory, you can drastically decrease your Delta-V requirements and send the same exact infrastructure in fewer or smaller launches- with no real associated costs to doing so. Infrastructure doesn't care if it takes 12-18 months to reach Mars, only humans do... The rest will take some time to explain/prove as to why it's so clearly superior, though. The reasons are a little complicated...

Developing better electric propulsion is a one-time cost. Being able to launch fewer refueling missions for each ITSy, and thus able to launch more crew/cargo with the same number of launch stages in rotation (thus requiring fewer total launch stages be built, or allowing for a more rapid timetable on getting crew/cargo to Mars- allowing SpaceX to rake in revenues from sale of tickets to Mars faster, and pay off their loans for developing the ITS sooner) is a permanent economic benefit. As is the value of the intellectual property- which can be licensed out to NASA (for their interplanetary probes) and perhaps eventually other space sector startups, such as those looking to pursue asteroid-mining... If SpaceX Doesn't pursue better electric propulsion technology, eventually some other company will (because NASA has proven they're never going to be cost-effective or at all rapid in their electric propulsion research), and chances are good SpaceX will end up paying whoever develops it to use it on their ITS, missing out on the opportunity to own the relevant patents forever... (because if it's cheaper to pay licensing fees for cutting-edge electric propulsion developed by somebody else than to use chemical rockets, why WOULDN'T they do it?) ISRU infrastructure is the same thing- a one time cost for a permanent cost benefit. You must remember, SpaceX doesn't plan to just send one flag-and-footprints mission to Mars and be done with it- they plan to send rockets there for DECADES or even generations of time, and slowly build a permanent colony there... Over so many launches (over 1000 launches over 60+ years), the costs of electric propulsion or ISRU amortize to a negligible cost pre-mission. If they can raise the money to research them, they should. It doesn't take a published study to prove this to you, and indeed it's highly likely nobody has ever published on the topic in the specific context of SpaceX's mission-plan (there ARE studies that look at whether the costs make sense when you amortized them over a single one-off NASA flag-and-footprints mission, but that's nit what we're talking here...) So.e simple napkin-math should be more than enough to prove this to you... Alright, so let's say, first of all that it would cost $10 Billion in R&D money for SpaceX to develop an ITSy with chemical propulsion... And let's say that a cutting-edge electric propulsion system capable of handling large power-inputs (such as from a massive solar array 10x the size of what they already have planned) and operating at high efficiency under those conditions (this would probably mean a plasma thruster- plasma thrusters tend to scale well to high power-levels) enabling a 1-month burn time to reach a Mars transfer-orbit would cost an additional $2 billion to develop. Now, let's say the cost of BUILDING each ITSy were, say $70 million (not accounting for any associated R&D costs) with chemical propulsion, capacity for 40 passengers (for the downsized, 9-meter ITSy), a 5-month Mars journey, and the ability to re-use the launch stage 40 times and the upper stage 10 times... (once every 2 years) Adding electric propulsion to that upper stage for its Mars-transfer could easily allow for an increase of the payload to 50 people for each launch (because you can upside the payload, add an electric thruster and solar panel system, and *STILL* reduce the mass of everything above the Launch Stage with all the propellant you save for the transfer-trajectory as electric thrusters have 10-1000x the ISP of chemical rockets...), and the ability to re-use the upper stage two additional times due to not needing to fire the chemical rockets as many times each mission (for the Mars-transfer or the Earth-return, reducing the number of major chemical maneuvers each mission from a minimum of 7, to a minimum of 5). Now let's say adding electric thrusters and propellants (likely Argon or Nitrogen, for their lower ISP and higher Thrust than Xenon), extra solar panels, extra crew-space and radiation-shielding (both for the larger crew, and the additional month spent in orbit to initiate the Mars transfer: you don't want crew getting over-stressed or over-irradiated) and extra crew provisions added up to an additional $20 million per mission, for a total cost now of $90 million to build and equip each new ITSy (this is NOT including any R&D costs...) Now, if SpaceX were going to build 120 ITSy craft and send just 40,000 people to Mars over the first 45 years (with the first 15 years being for R&D, the next 5 years for building the first ITSy craft, and 20% of possible launches with these 120 craft either not occurring during this timeframe or being cargo-only launches to get their Mars base started) in their original plan, then with a 25% increase in cargo capacity and the ability to re-use craft 2 additional times (all due to electric propulsion) they might be able to send 50,400 to Mars with 120 craft in 45 years with the same assumptions about mission-cadence (except now, 30% of possible launches either don't occur or carry cargo during this timeframe, due mostly to the longer lifespan of each ITSy). So, when you amortize the R&D costs over the number of passengers sent, they decrease from $250,000 per passenger to $238,095 per passenger. Additionally, amortized construction-costs for each ITSy increase from $210,000 per passenger, to $214,286 per passenger- but this is due to the higher percentage of launches that do not occur during this timeframe: the amortized construction costs per-passenger for an ITSy able to perform ALL its 10-12 lifetime launches, with 85% of them being for passengers become $205,882 per-passenger for an all-chemical ITSy, vs. $176,471 per passenger with an ITSy with electric thrusters for its Mars-transfer. With these assumptions, the TOTAL COST PER PASSENGER when accounting for construction and R&D costs (Note: fixed costs associated with the # of launches, such as ground crew cost, also DECREASE by 4% relative to the number of passengers for the lifetime costs of an electric-assisted ITSy, as it launches 20% more, but carries 25% more passenger per launch...) DECREASE from $460,000 per passenger with an all-chemical ITSy to $452,381 per passenger with an electric-assisted ITSy over this timeframe- with more aggregate lifetime-launches remaining for the ITSy's that have not yet been retired at the end of this timeframe, and a lower marginal cost of $176,471 rather than $205,882 per passenger for additional ITSy's constructed after this timeframe (assuming, once again, 15% of passenger-capacity is instead used for cargo in future missions) And before you suggest that it's not fair to compare the two approaches with different #'s of passengers, and the chemical ITSy should also be used to transport 50,400 passengers in this timeframe- it would cost $2.17 Billion to build the 31 additional all-chemical ITSy's necessary to do that- more than the additional R&D just to develop electric propulsion (sticking with the same ratio of 15% of all launches being used for cargo that has been adhered to all along in this analysis to determine the # of additional chemical ITSy's required)- meaning that is that case, the electric propulsion would have paid for itself as soon as the fleet of ITSy's was completed, rather than needing to rely on transporting more passengers with the same-sized fleet over time to pay for itself... SUMMARY: So, given some conservative assumptions about costs that are likely less favorable to incorporating electric propulsion than reality, in a period of 45 years (with no ITSy launches during the first 20 years), with 120 ITSy's built and flown during that period and 40k-50.4k passengers, utilizing electric propulsion on ITSy's manages to not only pay for its research-costs, but increase the profit-margins for each launch by $7,619 per passenger, with even larger cost-savings of more than $29,000 per passenger further in the future once all R&D costs have been paid for...

You have no basis for that assertion at all- SpaceX has already openly considered deploying the Raptor as an alternative upper stage engine for the Falcon 9 to fulfill an Air Force tech development program's requirements for advanced upper stage propulsion with alternative fuels (interestingly, testing a new engine on a suborbital trajectory like this is about as close to a KSP part contract as the real world ever comes...) and it's not like there is any fuel-crossfeed between the upper and lower stages that would prevent them from developing a rocket with different upper and lower stage propellants...

SpaceX doesn't have remotely near the capital available to it to develop the ITSy upper stage just yet. It's not just a matter of focus or logistics- they simply don't have enough available funding to finish the ITSy design if they begin it right now. Which is why I think they will focus most of their efforts on the Falcon Heavy and reusability (of both upper and lower stages- they still haven't got launch stsge turnaround-times and refurbishment costs down to where they need to be...) for now. If they are SUCCESSFUL in not only launching a Falcon Heavy, but in eventually learning to recover all its stages, then I think there will be a lot more government and investor-confidence to invest in the ITSy. They also need to demonstrate they can successfully launch human crews to orbit, and recover them safely, with the Dragon 2 before public and private partners/investors are even remotely likely to provide the funding to develop the ITSy... I agree, final stage reusability will ABSOLUTELY require a re-design of significant parts of the upper stage. In particular, they will need to add landing-legs, grid fins, heat-shielding, sensors, and more advanced guidance systems. The Merlin engine is already throttleable down to 60%, but I suspect they will also need the 20% throttling that the Raptor is supposed to be capable of (which will also require a re-design of the upper stage to run on Liquid Methane and LOX instead of RP-1 and LOX...) However all this is even more reason why they need to get started on all this now- because they have a lot of work to do to enable upper stage recovery, and the potential economic rewards are MILLIONS of dollars in cost-savings on each launch. Successfully completing such a mammoth undertaking as upper stage re-use (remember, except for the Shuttle it has never been done before) will also be an excellent way of building public/private investor confidence that they can successfully build the ITSy... Speaking of the Raptor engine, has anyone heard any news about it recently? I heard hints that it might be capable of even better performance than previously anticipated by the final design...

No mass is added to the final stage because, once again, any mass reserved for upper stage recovery is removed from payload to keep the total upper stage mass the same (which was already maximized in previpus steps of rocket design if you did it right- there's no real way to increase the mass of the payload+upper stage further without improving engine thrust or ISP...) As for the upper stage, you should expect *LESS* Delta-V from it on the Falcon Heavy, because it will be roughly the same size as the Falcon 9 upper stage but have more payload atop it. I would expect the center core will have to boost-back from at least Mach 12- which means *A LOT* of fuel will be required, though still not nearly as much mass as will be needed for upper stage recovery... This will invariably have to come at the expense of payload, because the more fuel you reserve on the center core, the more Delta-V the upper stage will have to be capable of, and the only way to do that (aside from upgrading its engine further) is to reduce its payload- simply adding more fuel to the upper stage would only make the upper stage heavier, and require it to cover an even LARGER gap in Delta-V and require more fuel for recovery... "Moar Boosters" is simply a crude way of expressing the idea of making up for a hit to payload-fraction by launching a larger total rocket. It ABSOLUTELY still applies in real life, up to a certain degree (lose too much payload-fraction and you won't have any left). Launching a 16 ton payload to LEO on a Falcon Heavy (capable of 63.8 tons in expendable mode) just so you have enough reserve fuel and can modify each stage enough to enable recovery of all stages is an example of precisely this- you settle for 1/4th the payload-fraction so you can recover and re-use all your stages. If Elon Musk's predictions about 1/10th the cost for reusability hold true, then this should still be cheaper than a expendable Falcon 9 launch capable of carrying the same 16 ton payload to orbit... There's absolutely no reason the Falcon Heavy core stage should have to end up being overcooked if you reduce the payload and provide it with enough reserve fuel. Keep in mind, I don't think Elon Musk will DO THIS on the first Falcon Heavy launch- he will probably push the limits and see if he can recover the core stage under extremely marginal conditions (spoiler: the first time around he probably won't be able to). But after allowing his engineers to see at what point the core stage becomes nonrecoverable, all he has to do in future launches is direct them to reduce the rated payload capacity enough to give the core adequate reserve fuel for recovery. With enough reserve fuel, you can give the boost-back burn for the center stage more of an upward component, so it stays above the thickest part of the atmosphere for longer while it has a high lateral velocity, and execute a larger burn at the beginning of re-entry so the maximum re-entry heating is reduced. With enough reserve fuel, the heat loads on the core stage can be kept within tolerable limits to allow for recovery. Falcon Heavy core stage recovery might end up taking just as long to figure out as Falcon 9 first stage recovery did. But the physics absolutely allow for it (upper stage recovery too, with enough mass-budget. But in practice saving enough mass for this might not leave any mass for payload, making the whole thing irrelevant until the development of orbital fuel depots filled from asteroid-mining or Propulsive Fluid Accumulators...) and I have no doubts it will eventually be accomplished. Just don't expect it on the first Falcon Heavy launch is all...

The Falcon 9 stages are already far more developed than anything used by their competitors. The difference is, SpaceX has remained dedicated to continuous improvement and refinement of their rocket designs, whereas companies like ULA tend to only refine a design until it works reliably and then freeze it... As for upper stage reuse- not if you reduce the payload by an equal amount, which I was already *extremely* clear about (raising questions as to how carefully you read my reply before responding). You cut 1 ton out of payload and add that ton to the upper stage for reusability, leaving the same total mass for the lower stages to accelerate- that was why I referred to the 1:1 tradeoff between payload and upper-stage mass...

ITSy upper stage isn't designed for commercial satellite launches at all. Most obviously, it doesn't contain a fairing or deployable cargo bay to anyone's knowledge. Therefore, whenever it does materialize, it will serve one purpose and one purpose only- sending humans and cargo to the surface of Mars. Variants for extremely heavy orbital payloads (such as MENTOR, or now LEO station modules) with an alternate upper-stage have been discussed, but such a configuration may never materialize. And if it DOES, it is likely to take decades to reach flight-test status. A Falcon Heavy is absolutely necessary for full reusability of both upper and launch stages on many payloads. The Falcon 9 in expendable mode can only carry 22.8 tons to LEO. The Falcon Heavy in expendable mode can handle 63.8 tons, so I would imagine it could handle 22.8 tons or close to that with full reusability. For every ton of fuel, landing legs, etc. you retain on the launch stage of a Falcon 9 for recovery you lose 400 kg of payload, not to mention the lost payliad-capacity from the altered trajectory (more straight-up at first to reduce the boost-back burn to the launchpad). For every ton retained on the Falcon Heavy's inner core I would imagine it would be 600 kg or more. But for every ton retained on the UPPER stage of fuel, heat-shielding, fins, landing legs, batteries etc. you lose a ton of payload. I don't imagine full upper-stage reusability will be possible without a sideways re-entry profile (to decrease maximum re-entry heating and max-Q), grid fins to right it, landing-legs, heat-shielding all over the sides, extra structural reinforcement, and considerable fuel. I imagine you won't be able to accomplish all that on a FH upper stage without at least 16-18 tons dedicated to upper stage reusability... (the Falcon 9 is probably only capable of carrying 3-4 tons to LEO in fully-reusable mode at most, due to its relatively greater reliance on its upper stage to reach LEO than on the Falcon Heavy, with its 3 stages instead of 2...)

Because the satellite launch-market isn't going away, and will probably form the basis of SpaceX's Inco e for DECADES to come (I believe SpaceX will go to Mars someday, but not nearly as quickly as Elon Musk seems to imagine...) And actually, the manned section of the ITS is basically a giant landable upper stage, with a non-detachable payload. It shouldn't be drastically different to recover the upper stage and to recover the ITS (indeed a sideways re-entry might be the best one for a reusable upper-stage as well...)

This thread is for the discussion of Aldrin Cycler Ships. First of all, an introduction to the topic- since most readers on this forum are undoubtedly unfamiliar with the concept, and the last time I wrote about it (many months ago) I received a lot of responses from people who clearly had no idea what they were talking about... Please read ALL of the following first, before commenting, I would really appreciate it. None of these are that long, and are only meant to provide a preliminary introduction to the topic: https://en.m.wikipedia.org/wiki/Mars_cycler https://buzzaldrin.com/space-vision/rocket_science/aldrin-mars-cycler/ https://space.stackexchange.com/questions/3880/what-uses-would-the-aldrin-cycler-have And, for more context I HIGHLY RECOMMEND reading these articles: http://www.popularmechanics.com/space/moon-mars/a333/2076326/ https://www.damninteresting.com/the-martian-express/ Please read through at least the first three links, and the fourth and fifth ones if you can, and let me know your thoughts on the concept: advantages or disadvantages, synergies with other approaches/technologies, etc. Regards, Northstar

Now if only Musk would implement some other cost-saving measures, like relying on Solar Electric propulsion to get to Mars... (if they're really planning on sending as many people as Elon claims, designing a state-of-the-art electric propulsion system and adding enormous solar panels to the ITS craft will pay for itself MANY times over...) Of course if we assume that he's really going to send enough people to fill a few hundred ITS flights or more to Mars, developing Cycler Ships to carry people from Earth to Mars and sending the surface habitats ahead of the crew on a much slower trajectory a full transfer-window ahead also becomes a no-brainer... Why accelerate your orbital and surface habitation modules to Mars on fast trajectories over and over when you can just accelerate your orbital habitats ONCE (and over the course of many months, with low g-forces on the Cycler Ship, at no risk of crew-loss, and a full transfer-window ahead of the crew with electric propulsion at that) and then re-use them over and over, and your surface habitats on super-slow (18 months with multiple gravity-assists) trajectories, unmanned and ahead of the crew?

Nibb, there is a massive opportunity cost to NOT going to Mars. If we start a colonization effort just 2 years earlier, then at every point of that colony's development it will be 2 years further along. You lose a MASSIVE amount of economic development over time just by a tiny delay. We should be thinking of the future generations here, not our own, which is PRECISELY why we should get ceacking on colonizing Mars today- because that goal might take 100 years to accomplish from the time we initiate it, and every second counts for the future of the human species... Just imagine the economic value of a fully-developed Mars with a population on the hundreds of millions in a *single second*. THAT is why we must start trying to colonize Mars immediately- so we can get to that point as soon as possible... Regards, Northstar

By the way, you heard he decided to downsize the rocket to "just" 9 meters in diameter? I'm really excited about that, actually, because it helps ensure a higher launch-volume (split the same payload among more launches) and the ability to still use existing manufacturing facilities- which are both excellent ways to save money... (and it's money, more than anything else, that will ultimately determine if humans ever colonize Mars...) Now if only somebody could convince Elon to make use of Cycler Ships, or electric thrusters, or dedicated Mars landers... (all potentially HUGE cost-savers)

Tater, you *DRASTICALLY* underestimate how much payload-fraction you have to lose for reusability. Particularly upper-stage reusability, which Musk badly wants to pursue, but isn't even remotely possible for many of the Falcon 9 payloads. With the Falcon Heavy they can achieve FULL reusability for a much wider variety of payloads. The Falcon Heavy can lift 50 tons to LEO, but 30 tons of that might have to be sacraficed for full reusability of ALL stages... CORRECTION: Wikipedia says the Falcon Heart's expected mass to LEO was recently updated to 63.8 tons in expendable mode. Still, I exoectbthey could lose more than half of thst with reusability of all stsges, maybe as much as 75% of payload-capacity... But, if that can enable upper stage reusability, it might be worthwhile. After all, fuel is dirt cheap compared to the cost of building a rocket, and they could bring down some of the refurbishment costs by increasing the design's safety-margins on future updated versions... "Most Boosters!" is always one way to overcome a loss of payload-fraction, like is necessarily required for full rocket reusability...

Sunk costs are a known economic fact of decision-making, and you are completely reversing sunk cost theory- which you probably do not understand (and which theory shows *I* am correct, not you). The "Sunk Cost Fallacy" is the human tendency to treat costs which are, in fact, already "sunk" (sunk costs) in future decision-making as if they have not already been spent. I.e. to not finish developing a launch-system that is already $300 million in the hole because the additional, say, $250 million to do it would add up to a "higher" cost than starting over on a different design which might cost $450 million from start to finish, but that had not yet been started. In that scenario abandoning the project and starting from scratch on a new rocket design would cost more- simply finishing the system already $300 million down is the cheaper option as it costs just $250 million, not $450 million (so you save $200 million). Starting over would be an example of the Sunk Cost Fallacy. The fallacy actually SUPPORTS my point here, as finishing the Roc is a cheaper option than starting on a new launch system from start to finish, regardless of how much money has already been sunk into the project- at this point it is cheaper to proceed than to start over with a new project. Put a different way, the costs of developing the Roc have already been spent, so that carrier plane is essentially "free" from a standpoint of future decision-making as no course of action will change that cost. And, it will be cheaper to develop and build/operate an air-launched rocket to be released by the Roc due to the smaller size needed to attain orbit than a ground-launched rocket with the same payload-capacity. The disadvantage of an air-launched rocket over a ground-launched one is the R&D costs of developing the carrier-plane: but the carrier plane has already been developed, so those costs can be forgotten- and going forward it's cheaper to develop an air-launched rocket for the Roc than to develop a ground-launched rocket (as bigger rockets are more expensive to debelop). Already expended R&D costs don't matter- only the remaining costs to project completion. You don't seem to understand the meaning of the fallacy, as it actually supports my point, and by bringing it up you have actually given me ammunition to use against you, since it illustrates why I am right: given that building an air-launch rocket for the Roc is the cheapest option going forward; any past costs are already "sunk" and it would be an example of the fallacy to incorporate them in determining the cheapest option going forward... https://en.m.wikipedia.org/wiki/Sunk_cost#Loss_aversion_and_the_sunk_cost_fallacy Nothing about selling a product and not being responsible for whether the consumer can put it to good use constitutes destruction, which is what THIS fallacy is about (specifically, falsely thinking that destruction is good for the economy). The Falcon Air was and is a good product. SpaceX could sell it in good faith. It really doesn't matter to them whether Stratolaunch can find a use for it or not- they're not intentionally selling them a faulty product in the hopes it will break, nor would they be trying to destroy the company itself in the hopes of gain. Nothing about this decision generates destruction or somehow dooms Stratolaunch. In fact, the Broken Window Fallacy works in my FAVOR here, since refusing to sell a rocket to Stratolaunch is actually what has the greatest risk of generating destruction. As has Bern said by multiple people multiple times, Stratolaunch is likely to go under if they can't find somebody to build a rocket to air-launch from the Roc for them. They are LEAST likely to go under if SpaceX designs them a Falcon Air-launch as it is the best posdible product for the Roc they can hope for. You clearly don't understand what I wrote. My entire point was that you get the SAME payload to orbit with fewer engines, not a smaller payload with fewer engines. My response you quoted was in reply to the incorrect assertion that it wouldn't cost that much to just build a larger first stage rather than air-launch the rocket: in reality it would cost MILLIONS more, *per launch*. A Falcon Air as proposed would have 4 engines, but launch just as much payload to orbit as a 6-engine ground version. The heavier, theoretical 6-engine rocket I was also referring to as a Falcon Air at times would have the same payload-capacity as a Falcon 9, but only require 6 engines... Either way, it's a third less launch stage engines for the same payload (for a design where you just cut in half the size of the first stage- in reality you might want to cut mass off both the first AND second stages for even greater mass-savings...)

First Stage mass is NOT cheap. Mostly because it's not just all "tankage and fuel" here- you also need additional engines and turbopumps- which are the single most difficult, failure-prone, and expensive part of a rocket to manufacture... 6 engines instead of 9 reduces the chance of launch-failure. Using a tried-and-true jet engine on a plane body that while large, let's be honest here, really isn't that revolutionary also means the carrier plane itself really doesn't have much chance of failure. The most difficult aspect here BY FAR is the actual air-launch itself: the process of decoupling a plane and a rocket in the air, and firing the rocket off without crashing into the plane or a failure of the rocket engines to ignite... As for the $300 million, that's about what SpaceX spent developing the Falcon 9 v1.0 (before the later upgrades and reusability-testing), a cost thst simply knocked the socks off any of their competitors (which typically spend 3-4x that much for a comparable rocket). It's not really that much money in R&D costs at all. If Paul Allen is not fudging his figures here at all then that's a BARGAIN for the cost of developing one half of a launch system- and even cheaper compared to R&D costs for most large commercial passenger or cargo jets... So, $300 million for the plane and another $300 million for a Falcon Air rocket (maybe less- since SpaceX already has a mature design for the Merlin engine). That's still only $600 million for a 6 ton to LEO rocket- still less than the maybe $750 million to $1 billion pricetag that a comparable payload-capacity would cost for a more traditional rocket... What's more, half of those R&D costs are already SUNK- meaning that Stratolaunch won't be able to take back all the spending they've done on the Roc no matter what happens from here on out. So only $300 million more to develop a rocket in the 6 ton payload range is a great bargain, and they would be stupid not to take therm up on the offer if SpaceX came back to them and offered to develop them a Falcon Air (with further launches provided at a much lower price) for $300 million... And SpaceX would be even dumber not to make such an offer in the first place, as they get the R&D money no matter whether the Falcon Air finds a market or not. If they could develop a Falcon 9 v1.0 for $300 million from scratch, they could certainly build a Falcon Air with only 6 engines for less than that- and the experience working with the unusual aerodynamic regime of air-launch would probably also be beneficial to their later developing a landing-system for the ITS. SpaceX could PROBABLY even experiment with building a 2-engine rocket based on their upcoming Raptor Meth/LOX engine design instead: which would be lighter and have a higher payload-capacity due to the higher ISP (334/361 seconds SL/Vac for the Raptor vs. 282/311 seconds for the Merlin), higher initial thrust (6,100 kN vs. 5070 kN), deeper throttling (down to 20% vs. A minimum of 60%), and even a higher expected Thrust--Weight-Ratio for the Raptor than the Merlin, which might equate to lower engine-mass despite the increased thrust... Note that the Raptor's higher chamber-pressure means they could equip an even higher expansion-ratio nozzle for air-launch to the Raptor than the Merlin (the ability to use higher expansion-ratio nozzles is one of the PRIMARY advantages of air-launch, even Elon Musk has noted this despite his criticism of the concept). And, it would be a great opportunity for SpaceX to flight-test their Raptor engine WITHOUT needing to throw out a perfectly good Falcon 9 configuration to replace it with one based on the Raptor instead of the Merlin... Ultimately, I believe the Roc will fail, but not because of any inherent weakness of the Stratolaunch plan- simply because SpaceX, the only company that could make this work, is simply too reluctant to work on the development of an air-launched rocket: which is ironic for a company thst seems so remarkably audacious the rest of the time... Regards, Northstar

These are baseless accusations. The Delta II had a MAXIMUM payload of 6,100 kg with a full booster array. The Falcon Air, launched from the Roc, would have been able to carry 6 tons without any modifications (that's BEFORE you account for engine-upgrades to the Merlin since Falcon 9 v1.0, now making it one of the best Kero/LOX engines in the world). Size is clearly not an issue here. CRS requires 4-5 tons of mass to LEO. Falcon Air could deliver 6. Payload capacity is just a straw-man here, and for the record, SpaceX has a MASSIVE back-log of pre-ordered commercial launches: they are hardly at risk of going bankrupt. I hate to say it and don't mean to sound mean or rude, but your entire argument here boils down to "it can't launch enough payload" with some mild hating on SpaceX sprinkled in. But, with a payload-capacity that EXCEEDS the Delta 2 in any of its configurations, despite that being the rocket you point to as a contrast, your argument really doesn't hold up here... I hope we can agree to amicably move to further points of discussion here: size and payload-capacity are simply NOT an issue... Regards, Northstar

The physics make sense (>50% reduction in first-stage mass, fewer engines, shorter burn-time). There are PLENTY of payloads in the size-range this thing can launch (6 tons to LEO with a "Falcon Air" sized rocket). And it's just REALLY COOL (TM). I have no doubt that it COULD be made to work, if they could rope SpaceX back into building them a rocket. I'm not sure any other company has the gusto and daring to build something that will do the job well enough, though...

Looks like the Peace Corps won't be taking me (at least not for the position they were considering me for... I believe I'd have to re-apply to be considered for something else...) much to my ire and disappointment- it seems that EVERYTHING I apply for is snatched from right before me, even though I'm hardworking, have done nothing wrong, and am a highly-qualified candidate for most things I apply for... So, the good news for you guys is I won't be spending 2 years in rural Africa without internet, and won't need somebody to completely take over the mod. The bad news is my laptop is pretty much on its last gasp anyways (and the USB port I use for the mouse is no longer really working at all- making playing KSP *much* more difficult), I'll hopefully soon be starting a new job, a new (or rather old, used) car and apartment as an EMT, and I might not have much time (or patience) for modding- at least until I get a new laptop with a FUNCTIONING port for my mouse... So, progress might be a little slow for a while, although I still mean to officially finish bug-testing Freethinker's port of the mod to the latest version of KSP and re-release it as the official new version of the mod (it appears to be working without issue, though, from my limited playtesting), and later, eventually, update the model to one of the extended-length part models (and configs I've been working on to go with it, if I can ever find where I put them...) that will allow players to build longer (and more powerful!) tubes with a more reasonable part-count... This will comprise a new, not backwards-compatible release of the mod I hope to have out sometime in the next year (12 months, *not* Jan 2018). Regards, Northstar