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I Moon vs Earth for launch to Mars

  1. Jan 8, 2018 #81

    mheslep

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    Musk has four kids, several ongoing business concerns where thousands depend on him, and yet says things like

    He increasingly sounds more like the alienated kid who went to live in the Alaska wilderness (never seen alive again) than, say, Neil Armstrong.
     
  2. Jan 8, 2018 #82

    stefan r

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    That increases the payload ~25%. That removes the infra-structure for 20% of the rockets. Some parts of the "payload" would not be delivered (controls, frame etc). So passengers and cargo arriving and remaining at Mars would increase more than 25%.

    Shuttles should be traveling back and forth from Mars. The launch to EML1 does not need food production, waste recycling or exercise spaces. You could pack people in tight.

    I think methane is coming back from Mars. The Delta-v for Sending it to EML1 is only slightly higher than sending it to LEO. Maybe send it to both?
     
  3. Jan 8, 2018 #83

    mfb

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    So we can spend 20% of the project cost on the Moon if it delivers enough fuel. I don't see what you would save elsewhere - you would just put fuel in the now empty last stage. The filling hardware might lead to additional mass.
    I don't think using more than the absolute minimum to get back from Mars makes sense. It is so much easier to send it to space from Earth.
     
  4. Jan 8, 2018 #84

    stefan r

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    Somehow we got that backwards. The astronauts need an extra 0.7 km/s to stop off in L1. See post #71.

    Is hard to make it work without non-rocket assist.
     
  5. Jan 8, 2018 #85

    mfb

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    The astronauts need extra fuel but that fuel was supposed to come from the Moon. The rocket that launches from Earth can be smaller as it only has to go to EML 1. Unless we refuel in LEO with fuel from Earth, in that case we don't save rocket mass, we only save a bit of LEO refueling.
     
  6. Jan 9, 2018 #86

    ISamson

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    In terms of my concern of my own safety... Definitely the Moon!
    I don't wanna be blown up by 'a bunch of crazy "experimental" scientists doing "important development work" next door or in my city'.
    No thank you!
     
  7. Jan 9, 2018 #87

    mfb

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    All rocket launches are done in safe distances from everything not related to the spaceflight.
     
  8. Jan 10, 2018 at 5:40 AM #88
    First, about fuel part. I thought "why O2 must mean oxidation, why not oxygen ion thruster?".
    Then i googled this paper:
    "OXYGEN-PROPELLANT PLASMA THRUSTERS FOR CIS-LUNAR ELECTRIC PROPULSION MISSIONS"
    https://deepblue.lib.umich.edu/bitstream/handle/2027.42/76753/AIAA-1998-3994-519.pdf?sequence=1


    Anyway, it's still discussion about Moon base for space travel facilitation.
    Including assumption that humanity needs to become spacefaring in the long run, all that with supervolcanoes, asteroids and whatnot.
    Considering current political dynamics, "long run" may be a teeny bit misleading term - read up on https://en.wikipedia.org/wiki/Bronze_Age_Collapse, then http://www.sciencedirect.com/science/article/pii/S0921800914000615?via=ihub

    Again, what Moon is and space station isn't - raw materials.
    (Also, a point with stationkeeping costs for low mass/high surface area orbital structures like solar, mirror or EM funnels.)
    Yup, we need products, not raw mats.

    So yes - a (business) plan for making usable products out of regolith/craters. Products with a discount of >6km/s deltaV.
    https://i.stack.imgur.com/ZLpuN.png - cislunar orbits and deltaV budgets in 1 pic.
    >6km/s discount, because fuel used to get to GEO is not wasted, spacecraft within the scope of this discussion is going to NEO and beyond.
    >6km/s discount, because getting to LLO from Moon is not just smaller gravity well. It's also no drag = no impulse loss over time.

    We're not talking about "life" - living there, we're talking about industry.
    1.25s lag is not significant for remote operation.
    Robotic assemby chambers are way beyond prototype phase.

    For industry, vacuum is beneficial - no convective heat loss(more problems with cooling but Mr.Stirling may help in more than 1 way), no pesky oxidation for materials and machines.
    I also consider vacuum as a "product". Deep vacuum is expensive to make and maintain; it's necessary for quite a number of industrial applications, and desirable but not cost effective for a lot more(including 3D metal printing). Distilling with "free" vacuum and "cheap" heat/insulation would look different. Quotes because deltaV tax.

    What products?
    Structural materials, shielding, tanks, wiring.
    https://www.sawe.org/papers/3662 - "...Most spacecraft structures represent approximately 20% of the total spacecraft mass..."
    3D printing is way beyond prototype phase.
    And yes, fuel - it needs not be oxygen. No drag = high ISP low thrust shines.
    Ion thrusters are way beyond prototype phase.

    Drone ion tug(solar powered), shuttling LEO - EML1.
    Modular engineering, 3 drones, 2 teleoperated assembly chamber, 2 3D printers(using lunar dust to print more drone frame parts, for starters).
    Hi-tech parts for more drones/printers/chambers.
    Plus, almost insignificant moment of power/heat supply infrastructure for all this (:
    1 Falcon9 lifts 8300kg to GTO.
    Unspecified amount of years and failed attempts later - our first Moonshine distillery/melt separator is up and running!

    If we need to lift only hi-tech from Earth - electronics, drives, batteries, sensors, coatings, specialized alloy parts - the price of spacecraft, industrial machinery and drones in situ drops. Mass (relative) abundance would change a number of considerations in design stage.

    I am obviously aware of multitude of technical challenges - material properties in vacuum like outgassing and sticking and ablation, moon dust, statics, solar wind, etc. And challenges bring opportunities(ex. sticking = welding things together).
    Also I am obviously aware of multitude of technical challenges we're not aware of (: - because we're not there to look.

    Huge pile of know-how is needed to make it all feasible and afterwards profitable.
    Yet, there is no other way to get this know-how - only testing engineering solutions in practice works.
     
  9. Jan 10, 2018 at 7:50 AM #89

    sophiecentaur

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    I found this link which shows people have been thinking about the problem of prospecting on the Moon. It makes quite good reading but it is a shame that there is no mention of timescale. At least, none that I could find. As timescale is a 'known unknown', I would have expected it to be discussed.
     
  10. Jan 11, 2018 at 11:23 AM #90

    Al_

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    Erm, I wouldn't go that far.
    It is very hard to control things consistently without collisions etc. with that degree of lag.
    But, combining recent driverless car collision avoidance, and robotic manipulation skills that exist today, with human oversight and slow control where needed, I think we could have lunar robots controlled from Earth doing pretty much anything in the fields of prospecting, mining, refining, manufacturing and construction. That is, without a huge leap in the technology from where it is today.

    Furthermore, a lag like that can be simulated on Earth. Is there a lab somewhere that has simulated lunar soil, vacuum, the lag, smart robots, VR, AI, and some prospecting tools? Surely not too expensive to do?
     
  11. Jan 11, 2018 at 12:39 PM #91

    sophiecentaur

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    I would assume that any robot prospecting / mining equipment would be pretty well autonomous and would not need to be micromanaged. A 1.25s delay would be of no more consequence than if the managers on Earth were telling the staff at the coal face what to do.
    I am very impressed by what Curiosity has done, despite the long delay in the loop. Reliability has been pretty stunning and that is a really essential requirement for anything that has to operate away from Earth. In an environment where there are no life forms to speak of, the problem of bugs getting into the system and causing unforeseen problems. No much fun to live in but benign for a robot.
     
  12. Jan 11, 2018 at 9:06 PM #92

    russ_watters

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    This would depend on one's definition of "success". As a launch provider company, mine would require them to be profitable over a long-term so they don't go out of business 10 years from now. They are not publicly traded yet but best I can tell, they are not profitable. What is definition/criteria that leads to "wildly successful" as a result?
    I don't think I've ever seen a cost analysis, so where did you get that from? E.G., what is the cost per pound to LEO vs, say, a Titan IV -- keeping in mind that if the company isn't profitable, the price is for some reason being kept impossibly low and my have to rise.
    Those are all start-ups. Many if not most start-ups "crash and burn", so you appear to be setting the bar of "wildly successful" right on top of the bar for "crash and burn". To me, if you want to judge SpaceX as "wildly successful", you should be comparing them to Lockheed.
     
  13. Jan 11, 2018 at 9:20 PM #93

    russ_watters

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    This is badly backwards. For the vast majority of machines and other electrical devices we use, convective heat loss is not a problem; it is a requirement to keep them functional. Cooling equipment on the moon will be a massive problem. A quick calc tells me that 1MW of heat dissipation (a small manufacturing plant) at 50C requires a 45x45 meter radiator -- which will only function at night; 2 weeks a month. So, double that and add thermal energy storage.

    A small piece of mobile equipment (a digging machine for example) with a 10 kW motor would require a 4.5x4.5 meter radiator - and again, could only function 2 weeks a month. Mobile, daytime operation would require "cold" tanks or some exotic form of cooling such as the ice sublimation system (needs water) that the astronauts used.

    This type of problem is why building an entire industry on the moon is a monumental challenge, even without the extremely high cost of getting it there. An awful lot of engineering will need to be invented just to make it work, at very high cost.
     
    Last edited: Jan 11, 2018 at 9:57 PM
  14. Jan 12, 2018 at 12:10 AM #94

    mfb

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    As far as I see, SpaceX and Orbital Sciences/Orbital ATK are the only launch providers worldwide with self-developed rockets with (a) no guaranteed government launches and (b) more than a couple of launches. I'm not sure if Orbital Sciences never had cost+ contracts from the US but let's give it the benefit of the doubt.
    The 43 launches of Pegasus had a combined maximal payload of about a single Falcon 9 launch, and all Minotaur launches combined have about the same payload, and the 7 Antares launches together have the payload of 2 Falcon 9. In other words, Orbital ATK launches much smaller rockets. SpaceX is the only fully commercial company launching large rockets (with the largest existing rocket sitting on the launch pad at the moment). That alone is quite some success.

    SpaceX makes money. The Motley Fool comes to that conclusion as well. Despite having the cheapest rocket in its size class. The first estimate is from June 2017, the second is based on launches until October and not including booster reuses. SpaceX now reused five, and out of the next five missions four will reuse a booster (one satellite is too heavy for that). Not reusing boosters is getting the exception, and you can use the reusability numbers from the first link for the costs per launch. That increases the profit a lot.
    Titan IV: 21700 kg to LEO for $432 million (1999 dollars), or $630 million in 2017 dollars. $30,000/kg.
    Falcon 9: ~16000 kg to LEO for $62 million (2017 dollars), or $3800/kg. Note that the payload is an estimate because you don't get the $62 million any more if the rocket has to fly expendable.

    I don't know why you picked Titan IV, as it is a particularly expensive rocket. You can get an Atlas V lifting 15,000 kg to LEO for $130 million, or $8700/kg (if you take the very cheapest option everywhere), and Ariane 5 can lift 16,000 to 20,000 kg for $165 to $220 millions, roughly $10,000/kg. Both ULA and Arianespace have guaranteed launch contracts from the US and the EU, respectively, unlike SpaceX they only have to pay for the rocket and launch itself with these prices.
    Proton, ULA and Arianespace are not start-ups. Proton is not even a company.
    Lockheed (now launching via ULA) is officially a company, but the financing looks like a government project. They get a lot of money every year even without any launches just to keep existing, and have additional "cost+" contracts: "Whatever you have to spend for the rocket, we pay it, and then give you x% extra". That is not what you would expect from a company.
     
  15. Jan 12, 2018 at 5:07 AM #95
    I rather had in mind teleoperated repairs of machinery and navigation path/task forming(like current military drone operators), not micromanagement.
    I imagine moon dust(+statics) will be in a category of "aggresive sandpaper environment" rather than "nuisance", for moving parts/joints.

    I work in a chemical industry, so it was rather industrial process angle - 50cm of insulation for chemical reactor with quite a surface area. Same with (s)melter.
    Orbital processing facility would be superior to Moon one - you wouldn't actually need tankage/high temperature materials. Structural required only for inertia, not weight. Heating raw material into a blob held together by surface tension and some magnetic fields, and heat loss limited to radiative cooling by vacuum and volume/surface ratio.
    Some angular moment(maybe applied during heating by precision targeting of solar mirrors) and you have a melt pie or bar for easier processing/cooling.

    Disposing of waste heat - yes it's a big problem, when you can't have evaporative cooling tower with free convection (:
    Waste heat accumulation in nearby regolith is not a trivial problem either. Same with industrial vacuum contamination.
    But your 45x45 meter radiator(i assume) is passive and flat(also scaling up = more engineering challenges).
    "which will only function at night" - print an umbrella, pick coating and angles, then it's "reduced efficiency during day".
    Heat pumps will require power but will be smaller/ligher.
    Making fractal surface radiator might be easier, if manufacturing is not machining but vapour deposition.
    Heat pump is a Stirling engine backwards, in functionality but not in design - it can be engineered as dual purpose lego module.
    If heat transfer is mostly conductive - you can guide heat like electricity(wires not pipes).

    I have read about sealed Stirling engine, using ultrapure water both as medium and lubricant. But i can't find any reference to it now so might be fake.

    Timescale, i consider to be not within the scope of this discussion, so i adressed it in a roundabout way.
    Again - http://www.sciencedirect.com/science/article/pii/S0921800914000615?via=ihub

    I take gold member question as a permission to speculate about it:
    Building up mountains of know-how, making those shoulders of giants to stand on.
    In a nutshell - no director board will approve of investments of this timescale, gaming economical/political/financial system is currently uncomparably more profitable and reliable.
    Board of directors - because corporations are bigger and more aggresive than national governments, money/influence wise. For ex. United States are not rich, US banking and war corporations are.
    Changing current political\economical system gradually is not realistic, entrophy is undoing changes faster than they happen and accelerating.
    Economics/manufacturing is global now, so replacing parts is not viable - pull one string and ripples spread everywhere, to an extent and delay.
    And radical change will involve transitionary period - no old system already and no new system yet.
    This means crash and burn, and new society will be shaped not by will but by ruins of old system.
    So, as of now - never? Sorry for offtopic.


    IMO, purified question of OP would sound:
    "Elon, what the hell? Why Mars, why are you skipping steps???" :)
     
  16. Jan 12, 2018 at 6:12 AM #96

    sophiecentaur

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    I think timescale is extremely relevant to any such discussion. The word 'investment' appears everywhere when non-governmental projects are involved. Investors always want a return on their investment and time is as big a factor as how much they invest.
    Whenever space travel is discussed, the enthusiasts have a habit of moving goalposts in order to justify opinions. They switch from specific details to generalities, as it suits. When pushed, the response is to allow extra time. That's fine (or at least more reasonable) for governments with deep pockets and long term (relatively) plans but a private company can easily fold or withdraw interest and a project can sink without trace (along with minor investors' money). History often repeats itself.
    Energy is a huge factor and we do not have fusion yet. When it does arrive, we could make some real progress but . . . .timescale?
     
    Last edited: Jan 12, 2018 at 3:25 PM
  17. Jan 12, 2018 at 6:13 AM #97
    ILS is a launch company, though, currently launching exclusively Protons.
    2012: 8 launches
    2013: 7 launches
    2014: 3 launches
    2015: 4
    2016: 2
    2017: 3

    Aug 4, 2014, Forbes. "International Launch Services Reduces Staff By 25%"
     
  18. Jan 12, 2018 at 4:53 PM #98

    mfb

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    ILS is a company, but it is not a startup either. They used an existing rocket, with existing resources and expertise of the companies that founded ILS.
     
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