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I Moon vs Earth for launch to Mars

  1. Jan 3, 2018 #41

    russ_watters

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    At least.
    Huh? "Other robotic missions" have nothing at all to do with a lunar fueling station.
     
  2. Jan 3, 2018 #42

    russ_watters

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    Smarter than launching from Earth? For what mission? That's what the problem here is: you're speculating wildly about missions that aren't on any kind of time horizon. It's been said that anything 30+ years away is essentialy "never" for planning purposes. But what you are speculating toward is likely hundreds of years away. Backing-up:

    Ok, so the OP asked: "Would it not make sense to launch [to Mars] from a base on the moon [instead of Earth]?"

    The OP did not state for what purpose one would be going to Mars, which left members to speculate. You can see how this can lead to wild hypothetical mission plans, I'm sure: Perhaps we need to amass an invasion force to attack the Galactic Empire's Death Star factory on Mars? How should we fuel it?

    Here's the chronological reality:
    1. Humans have never visited Mars and we don't yet know what even the first exploratory missions will look like. We *might* make such a visit within the next few decades. It seems fairly obvious that for individual (one? ten?) exploratory missions, the cost of building infrastructure on the Moon to assist those missions would swamp the cost of the mission.

    2. After a succesful exploratory mission, then "we" can decide what the next step is. For the moon, it was a 50 year and counting pullback. Perhaps it will be for Mars too.

    3. 50-100 years from now, after our successful exploration program ends and we take however long to re-assess the next step, Elon Musk and Donald Trump are dead and assuming SpaceX and the USA still exist, whomever is running them can look into the merits of colonizing the moon or Mars. But even then, such an effort would almost certainly start with decades of small test colonies of dozens or hundreds of people. Probably still not large enough for an infrastructure on the moon to be of help. But maybe. We'll probably have really good robots by then!

    4. Then, 100-150++ years from now, if colonization has demonstrated to be doable and there is a need for it, people might start real colonization. And then perhaps a low-g fuel depot on the moon or an asteroid might be worth pursuing.

    tl;dr: There is no large-scale fuel need on the forseeable future time horizon (our lifetimes) and speculation about that need, if it ever even happens, is fairly pointless. So for the forseeable future, the idea of a lunar launch site/fuel station is not viable. But it is reasonable to believe that there is a break-even point of scale somewhere -- but let's not let our minds wander too much into what that might look like.
     
    Last edited: Jan 3, 2018
  3. Jan 3, 2018 #43

    stefan r

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    Nothing wrong with the question IMO. The physics involved will not change 50, 100, 10,000 years from now. The energy involved in launches from Earth and from the moon to other planets stays the same.

    You can formulate civil engineering questions for cities on earth. Does it make sense to fly between cities? Rail might be more fuel efficient. For short distance it is faster to walk than it would be to walk all the way to a car, drive, park, and then walk again. A subway system makes sense in Manhattan but an underground rail system would not be a good way to connect ranches in Wyoming. I am not trying to switch the conversation to transportation on earth. As traffic increases the type of infrastructure that is optimum changes. That trend applies to space travel too.

    How much traffic do you need in order to justify various schemes? You can address the physics or engineering behind various answers. It does not matter if the traffic flow is unlikely in the near future.

    Right that is the question. What benefits would be gained from a fuel depot? Which one first the moon or asteroid?

    I disagree. If there is reason to believe that "there is a break-even point of scale somewhere" then it is worth talking about. Stating(or estimating) the limits according to known science is appropriate. Even if there was no break even point it would still be interesting to measure how bad various suggestions are.

    The vast majority of astronomy is out of reach for the foreseeable future. I was hoping to learn more of it anyway. The time I spend on this physics forums does not have any specific production goal that I am aware of.
     
  4. Jan 3, 2018 #44
    Lunar base will not start as fuel production facility. It will most likely start as a tourist destination. If you track space news closely, you can read between the lines that SpaceX discovered that while a few wealthy people are interested in "tourism-type" lunar flybys, significantly more of those people are interested on being "tourists" _on_ the surface of the Moon. Selfie of you standing next to a lunar boulder has x100 cool factor than selfie of you in a tuna can capsule allegedly flying past the Moon.
     
  5. Jan 3, 2018 #45
    My phone doesn't have that, but I'll need to get a new one soon anyway,
    I think the battery is giving up and can't be replaced.
     
  6. Jan 4, 2018 #46

    Al_

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    Surely they do. The OP does not specify that the "base" needs to be manned.
    A refuelling depot need be nothing more than a couple tanks and hoses, filled by a cracker with solar panels, and robot diggers going to and fro to fill the hopper.
    A trillion? I think not.
     
  7. Jan 4, 2018 #47

    Al_

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    I reckon the EU and the Chinese will already be on the Moon by then. One pole each, maybe.
    Full house.
     
    Last edited: Jan 4, 2018
  8. Jan 4, 2018 #48

    PeroK

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    Shouldn't cost much more than a small town petrol station, really.
     
  9. Jan 4, 2018 #49

    Vanadium 50

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    Since this thread seems to be comparing "Starting on Earth" with "Starting on the Moon with all necessary materials pre-positioned there", might I suggest an even better answer is to start on Phobos? :woot:
     
    Last edited: Jan 4, 2018
  10. Jan 4, 2018 #50

    Al_

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    Am I? In which forum?
    I am merely assuming that there will be future (robotic) space missions, to Mars or points beyond. Is that unreasonable?
    The OP does not specify humans on the Mars mission.
     
    Last edited: Jan 4, 2018
  11. Jan 4, 2018 #51

    Al_

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    Great idea!
    To get the required infrastructure up there, may I suggest first sending robotic mining equipment to the Moon...:biggrin:
     
  12. Jan 4, 2018 #52

    Al_

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    We seem to be getting somewhere.
    About a million for a small town gas station perhaps? And if I may be allowed to say that a trillion is too high, that gives us a range of 10^6 to 10^12.
    Anyone got anything that could pin it down further?
     
  13. Jan 4, 2018 #53

    PeroK

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    There are two sorts of project. A project that essentially you have done before, perhaps many times, and for which you can accurately estimate the costs. And a project that is significantly beyond anything you have ever done before. The latter project comes not only with an almost unlimited potential for cost overruns - whatever budget you put on it - but also with the significant chance of eventual failure.

    I wouldn't bet on an EU project that attempted to deliver a Moon base being an eventual success. As an EU citizen (for the time being at least) I might feel it was beyond the capability of the ESA and was a project with too high a risk of failure.

    The only sense in which I would disagree with the $1 trillion is that you might spent all of it and still not have your Moon base.
     
  14. Jan 4, 2018 #54
    Historical examples of exploration and colonisation relied on proven, economically viable technologies that were in every day use. They also went to places where basic necessities already existed in familiar forms and in abundance; whilst the lunar "exploration" was purpose built technology, it also overlapped broadly with ongoing development of other aerospace technologies. And whilst the Moon landings certainly qualify as exploration it was never purely for that reason or done comprehensively by sending people there. Manned missions were never the best and most cost effective way of doing exploration. Other motivations figured highly. If there is a historical precedent for colonisation where everything had to be purpose built using technology in advance of what was in common use I'm not aware of it.

    Tourism to the Moon is not going to be a fantastic demonstration of the richness of the resources of the moon, I think it will be a fantastic demonstration of the richness of Earth. As a staging post for Mars the Moon would only work if there is already advanced industrial capability in place there and the people there want to send a mission to Mars - ie the moon has to have an advanced economy of significant size and complexity first, which developed for other reasons. Otherwise it's an extra complication to an already complex mission; it would add to the costs and difficulties rather than ease them. I don't think that kind of development will happen unless there are resources that can be exploited and exported to Earth at competitive costs and frankly I don't think there is anything on the Moon or Mars that cannot be mined, refined, processed and produced - and delivered - far cheaper locally.

    I think one of the most fundamental things that has to be in place for any large scale activities in space - including Moon or Mars - is a comprehensive and compelling business plan. One that demonstrates the potential for a good financial return based on exploitation of space resources - financial returns, not necessarily for the colonists but for the Earth based investors. Spin off earnings may help but I think that only if the economics of the core activities are compelling will it work - the spin off's won't be sufficient.
     
    Last edited: Jan 4, 2018
  15. Jan 5, 2018 #55

    stefan r

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    Here is a picture from 2012 of field tests Hawaii:

    290509main_PILOT.jpg

    Oxygen production is certainly proven. We do not see a lot of commercial machinery that extracts oxygen from rocks. That is because oxygen is available from in an atmosphere everywhere on earth.

    SpaceX claims that it can use the BFR for launch to orbit, land on + launch from the moon, and launch to Mars. They also intend to use the BFR for earth to earth traveling. (video) They currently plan to start launching in 2022. They drew us a picture of it on the moon:
    bfr-moon-380x214.jpg

    The plan for launching to Mars includes several rendezvous for refueling. (video, refueling at 2:20)

    SpaceX has not built a BFR yet. But the schedule will either be on time in 2022 or get delayed. The rockets will either work or fail. If we assume that BFR works then we can talk about the best source for the LOx. We can also contemplate which orbit would be best for the rendezvous.

    Phobos should be the destination IMO.

    Why do you say Phobos instead of Deimos? More generally: is it better to have the fuel depot/station higher or lower in a gravity well? Would that apply to Callisto vs Europa? How much of a detour is too much?
     
  16. Jan 5, 2018 #56
    50
     
  17. Jan 5, 2018 #57
    Building the First Spaceport in Low Earth Orbit

    Watch John Blincow from Gateway Foundation and Tom Spilker from JPL discuss constructing The Gateway, a spaceport through the method of "Block Construction." This lecture took place at the Keck Institute for Space Studies/Caltech on January 13, 2016.



    Even though this lecture was two years ago, it seemed pertinent to this thread.
     
  18. Jan 6, 2018 #58

    Vanadium 50

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    Reason 1: I said Phobos because I didn't think people would get the point if I said "start on the Martian surface". My point (which seems to be missed) is that this is essentially the same as answering the question "How does one best get from New York to LA?" with "Start in Anaheim!"

    Reason 2: If I said funding a trillion-dollar moonbase with tourism is like Judy, Mickey and the orphans' "Hey, let's put on a show!" people wouldn't understand the reference.
     
  19. Jan 6, 2018 #59
    Stefan @55 - those are not pic of technology that are economically viable and in every day use. The technologies to get people to Mars safely, provide essential for them there and return them are not what I call proven and in every day use.

    This is probably stretching the discussion beyond the initial subject even if I didn't start the stretching, but - I remain very doubtful about the worth of manned missions to Mars or Moon - doubtful that it can be done except at great cost or that any of the proposed missions can deliver any financial returns that are not the recycling of Earth's wealth back to people on Earth. Especially, I can't see it as a viable pathway to colonisation in space - which I think can only be an emergent outcome of an enduring history of commercially successful exploitation of space based resources - those core activities being commercially viable in their right - in the service of a large and successful Earth economy.

    I don't believe that establishing colonies can work as a primary motivation; like I said in previous post, I don't think there will be anything on either Moon or Mars that can be turned into something that can profitably be exported to Earth. "Lifeboat" scenarios compete directly with Deep Bunkers and I think Deep Bunkers (many already in existence) will remain the preferred choice. Enduring survival of any space colony requires that it have all it's own, widely comprehensive industrial and technological capabilities; it needs to be a large, successful, resourceful and broad based economy, the equivalent (I suspect) of a large industrial nation's economy. Or else it's not going to survive long past when it's equipment wears out.

    But then, I don't count Mars or Moon as particularly worthwhile targets in the first place. Tourism isn't enough despite the hype and apparent willingness of some people to pay very large amounts of money. Souvenir Mars rocks won't be enough. The Reality TV broadcast rights won't be enough. Being able to make water and air or other materials for on-site use using equipment brought from Earth won't be enough. New patents developed along the way won't be enough. Proving the viability of mining of asteroids with actual refined ingots delivered to Earth cheaper than can be obtained on Earth would be a real step forward - and I suspect that is something still far beyond our current or near future capabilities.

    A tourist destination on the Moon or Mars would be like having a resort at the South Pole or at the top of Mt Everest - it may be viable as a outside owned, outside operated, outside investor profiting venture but it won't and can't make the backbone of a viable, self-reliant colony.
     
    Last edited: Jan 6, 2018
  20. Jan 6, 2018 #60

    sophiecentaur

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    This has been discussed many times, already. The Earth has readily available raw materials on or near the surface as a result of volcanic activity. The surface of the Moon is very different as there has been little or no such activity. Perhaps meteorites could be a source of some useful elements but where would the other elements and compounds come from for the chemical extraction processes?
    People seem to ignore just how totally different every aspect of life would be away from Earth.
    My comments would possibly not apply in the extremely long run but the OP is discussing the initial steps of planetary exploration.
     
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