I Moon vs Earth for launch to Mars

[Rednecknav]

Problem - we have to use large amounts of fuel/propellant to exit the Earth's atmosphere to enter Earth orbit, the moon or other planets...

Solution - would it not make sense to launch from a base on the moon?

Problems I see, potentially...
1) Is the moon’s orbit around Earth problematic for trajectory calculations ? (Earth orbit around sun plus moons orbit around earth, and Mars orbit around sun)
2) Are there less opportunities to launch from the moon to reach Mars? (Planetary alignment for shortest duration of travel)

 

[PeroK]

Problem - we have to use large amounts of fuel/propellant to exit the Earth's atmosphere to enter Earth orbit, the moon or other planets...

Solution - would it not make sense to launch from a base on the moon?

Problems I see, potentially...
1) Is the moon’s orbit around Earth problematic for trajectory calculations ? (Earth orbit around sun plus moons orbit around earth, and Mars orbit around sun)
2) Are there less opportunities to launch from the moon to reach Mars? (Planetary alignment for shortest duration of travel)

There's the small matter of getting to the moon and building a rocket and launch site there.

 

[Rednecknav]

Getting to the moon I don’t see as a problem. Trump has already signed documents allowing for more funds to go to our space program. Also Space X is planning on orbiting the moon with two people by 2020.

 

[PeroK]

Getting to the moon I don’t see as a problem. Trump has already signed documents allowing for more funds to go to our space program. Also Space X is planning on orbiting the moon with two people by 2020.

If getting to the Moon isn't a problem, how come getting to Mars is? Can't Trump just sign up to that as well?

 

[Arman777]

Problems I see, potentially...
1) Is the moon’s orbit around Earth problematic for trajectory calculations ? (Earth orbit around sun plus moons orbit around earth, and Mars orbit around sun)
2) Are there less opportunities to launch from the moon to reach Mars? (Planetary alignment for shortest duration of travel)

I am not an expert but If I compare the needed fuel to launch from moon-mars and earth-mars I think moon is better option. Even we need to make some adjustments for orbital motion or etc. the needed fuel will be much less then the current one.

 

[stefan r]

I am not an expert but If I compare the needed fuel to launch from moon-mars and earth-mars I think moon is better option. Even we need to make some adjustments for orbital motion or etc. the needed fuel will be much less then the current one.

If the petro-chemical industry, air separation plants (equipped with air) and rocket manufacturing industries were located on the moon then launching from Earth surface to Mars surface would be much harder. Establishing industries on the moon is something to think about. IMO best to start with something easier like a telescope on the pole.

Problem - we have to use large amounts of fuel/propellant to exit the Earth's atmosphere to enter Earth orbit, the moon or other planets...

Solution - would it not make sense to launch from a base on the moon?

Launching from lagrange 1 or 2 has advantages. Low lunar orbit would be worth considering. If the equipment/people/methane are coming from Earth then landing them on the moon certainly does not help with getting to Mars. You can make a case for extracting Oxygen from lunar soil. Also if the Mars transport is using soil to grow food then bulking up with lunar dust might help. Certainly need to test growing food in space a lot before depending on it. There has been research on extracting aluminum and iron from lunar regolith. An ingot of pig iron is not a spaceship.

If there is enough extractable water we could get the reducer from the moon too. Oxygen is most of the mass of a rocket so getting reducer makes much less of a difference. That would still be just the fuel tanks. The occupied cabins and equipment would still launch from Earth and rendezvous with the fuel in space. If you build a lunar industrial complex there is a good chance it will import hydrocarbons.

A fun idea to think about is the http://www.tethers.com/papers/CislunarAIAAPaper.pdf. You can take the moon's momentum and use it from an orbit close to Earth. Phobos is in a good location. It is much easier to launch off of Phobos.

1) Is the moon’s orbit around Earth problematic for trajectory calculations ? (Earth orbit around sun plus moons orbit around earth, and Mars orbit around sun)

That might be work instead of entertainment. An undergraduate should be able to do it for an upper level course project. It does not need to be exact. The main rocket burn will likely be near Earth to maximize the Oberth effect. There will be a short correction burn after leaving LEO space whether it was a flyby or started in LEO.

 

[nikkkom]

Getting to the moon I don’t see as a problem. Trump has already signed documents allowing for more funds to go to our space program. Also Space X is planning on orbiting the moon with two people by 2020.

POTUS can only direct NASA to change its priorities _within budget_ approved by Congress.

Some of NASA programs are also part of US laws, and thus can not be changed by POTUS. For example, SLS is whimsically called "Senate Launch System" exactly for the reason that Congress specifically directed NASA to build a heavy-lift launch vehicle using Shuttle-like components.

IOW: POTUS alone can't do much to improve US space program.

Thankfully, with SpaceX US space program is now gradually slipping out of government planning.

 

[Al_]

There is water ice at the poles of the Moon.
Once we have done the research and development of robot mining machines and H2 and O2 fuel producing plant, and sent them up there and started them working, we can go anywhere in the Solar System for much less cost than anyone else.

Who mines the moon, owns all the moons.

 

[nikkkom]

There is water ice at the poles of the Moon.
Once we have done the research and development of robot mining machines and H2 and O2 fuel producing plant

We'll just adapt our Earthly robotic mining machines and H2 and O2 fuel producing plants... oh wait. We don't even have those.

Seriously though.
You are, of course, right. Something along those lines would work.
Creating Moon bases and then industrial infrastructure is the main, and quite non-trivial task. One which makes Apollo program look easy-ish.

 

[nikkkom]

Star Trek probably got it right . A man made space dock could be a more practical idea than a moon base for preparing and launching deep space missions .

The point of the Moon is that it has raw materials (as a minimum, for fuel production). A space station/refueling depot does not.

It might make sense to construct spacecraft there (if it's too fragile and benefits from zero-G, for example), but all fuel, materials and components need to come from somewhere.

 

[PeroK]

The point of the Moon is that it has raw materials (as a minimum, for fuel production). A space station/refueling depot does not.

It might make sense to construct spacecraft there (if it's too fragile and benefits from zero-G, for example), but all fuel, materials and components need to come from somewhere.

It seems to me that once you propose/assume the technological capability of full mining and construction operations on the Moon, you may as well propose/assume sufficient advances in rocket technology to make launch from Earth equally feasible.

 

[russ_watters]

It seems to me that once you propose/assume the technological capability of full mining and construction operations on the Moon, you may as well propose/assume sufficient advances in rocket technology to make launch from Earth equally feasible.

I wouldn't. Launch technology has essentially stagnated for 50 years after fully maturing in 10. What is needed isn't "advances", but a totally new and radically better launch technology materializing out of thin air. Meanwhile, computers/robotics have advanced by leaps and bounds over the past 50 years and show little sign of stopping.

Don't get me wrong; I don't think robotic lunar mining is on the foreseeable horizon as something we WILL do, but it at least it is foreseeable as something we CAN. do.

 

[russ_watters]

There is water ice at the poles of the Moon.
Once we have done the research and development of robot mining machines and H2 and O2 fuel producing plant, and sent them up there and started them working, we can go anywhere in the Solar System for much less cost than anyone else.

Who mines the moon, owns all the moons.

Has this shown to be a real problem? It sounds to me like a Star Trek problem.

Using some made-up numbers to illustrate: if we built a totally autonomous mining and fuel depot on the moon for a cost of a trillion dollars and it reduced the cost of manned trips to Mars from a hundred billion dollars to eighty billion dollars apiece, how many trips to Mars would we need to make in order to break even on the cost of the lunar facility?

 

[stefan r]

There is water ice at the poles of the Moon.
Once we have done the research and development of robot mining machines and H2 and O2 fuel producing plant, and sent them up there and started them working, we can go anywhere in the Solar System for much less cost than anyone else.

Who mines the moon, owns all the moons.

There is water on the surface of the moon in the same sense that dry concrete has water on a clear summer day. Except that dry pavement has more. The equator has energy. You need power to mine, to refine ore into metals and oxygen.

Solar power can run the mass driver(s) that move product into orbit. A tether from Lagrange 1 or Lagrange 2 is shorter and simpler if it runs to the equator.

Who mines the moon, owns all the moons.

Sure. And some of the moons have surfaces made of water.

...
Using some made-up numbers to illustrate: if we built a totally autonomous mining and fuel depot on the moon for a cost of a trillion dollars and it reduced the cost of manned trips to Mars from a hundred billion dollars to eighty billion dollars apiece, how many trips to Mars would we need to make in order to break even on the cost of the lunar facility?...

I think it more likely that hydrogen (or hydrocarbons) will be routed back to the moon. You already invested over a trillion and you can multiply production if you reinvest a little more. Bagging volatile gas from asteroids/comets does not require sophisticated mining equipment. You may be able to use the same heat source you use for propulsion.

 

[rbelli1]

how many trips to Mars would we need to make in order to break even on the cost of the lunar facility?

That depends strongly what portion of the $1T is intended for Mars launch. It is a fair assumption that the lunar infrastructure would be useful for other endeavors.

BoB

 

[stefan r]

That depends strongly what portion of the $1T is intended for Mars launch. It is a fair assumption that the lunar infrastructure would be useful for other endeavors.

BoB

We can still do some calculations. Earth surface to Earth escape has a delta V of about 12.2 km/s. Lunar surface to Earth escape has delta-v around 2.6 km/s.

We could ball park estimate the cost change by cutting the boost to low Earth orbit. Suppose half of the mass launched to Mars comes from Luna and half from Earth. How much mass launched to LEO would cost $2 x10¹²? The money put into the Mars program would need to be larger. SpaceX is hoping to send 10⁶ colonists to Mars for $5 x 10⁵

I believe we could extract O₂ from the moon for much less than $10⁶.

 

[russ_watters]

That depends strongly what portion of the $1T is intended for Mars launch.

Since it's my scenario, let's say all of it. If you want to build a luxury hotel or low-g hospice center, spend your own trillion dollars.

It is a fair assumption that the lunar infrastructure would be useful for other endeavors.

I don't actually believe that, particularly since there is virtually no overlap at all between this refueling station idea and any other lunar base purpose. But either way it doesn't have any impact on my scenario, since ridiculously expensive, infeasible and pointless divided by 2 is pretty much still ridiculously expensive, infeasible and pointless.

I'm at least as entitled to play Star Trek Pessimist (if not moreso) as others are to play Star Trek Optimist considering I'm reflecting on the reality of why none of this stuff, which is technically possible(except for the Star Trek Propulsion Fantasy), has happened yet. There's a pretty obvious reason for it!

 

[russ_watters]

We can still do some calculations. Earth surface to Earth escape has a delta V of about 12.2 km/s. Lunar surface to Earth escape has delta-v around 2.6 km/s.

What this is telling us is that 80% of the energy required to escape Earth has to come from Earth. In other words, there isn't much benefit to launching from the moon unless we're building the spacecraft on the moon too.

SpaceX is hoping...

Elon Musk is rich, but that doesn't make his "hope" impress me. I'm convinced he's going to crash and burn.

I believe we could extract O₂ from the moon for much less than $10⁶.

So can I, but not enough to launch a spaceship! All kidding aside, unless I'm misreading, you're saying you can extract O₂ from the moon for a million dollars and put colonists on Mars for $500,000 (each?). Please tell me these were typos, because they are far beyond fantasy.

 

[|Glitch|]

All politics aside (this is a physics forum, remember?), if a manned-mission to Mars is the objective, would not building a facility in low-Earth orbit where astronauts still have some protection from solar and cosmic radiation be more practical and cost effective?

We do not have to go all the way to the moon to assemble, fuel, and equip a spacecraft for a manned-mission to Mars. Some sort of spacecraft construction facility in low-Earth orbit would seem to be the most practical and cost effective means of constructing and sending a spacecraft to Mars. Upon its return the spacecraft could dock with the space port and be used for future manned-missions. The astronauts could return to Earth like they do now from the ISS. Perhaps the ISS could be re-tasked for such a purpose, with more modules added as required.

 

[PeroK]

SpaceX is hoping to send 10⁶ colonists to Mars for $5 x 10⁵

Have you signed up then?

 

[stefan r]

So can I, but not enough to launch a spaceship! All kidding aside, unless I'm misreading, you're saying you can extract O₂ from the moon for a million dollars and put colonists on Mars for $500,000 (each?). Please tell me these were typos, because they are far beyond fantasy.

I am not seeing how you put that together from anything I wrote. You suggested $1 trillion.

There are many versions of experiments demonstrating oxygen extraction from moon rock. Here is one article.

Based on experiments with a simulated lunar rock developed by NASA, the researchers calculate that three one-meter-tall reactors could generate one tonne of oxygen per year on the Moon. Each tonne of oxygen would require three tonnes of rock to produce. Fray noted that three reactors would require about 4.5 kilowatts of power, which could be supplied by solar panels or possibly a small nuclear reactor on the Moon. The researchers are also working with the European Space Agency on developing an even larger reactor that could be operated remotely.

Read more at: https://phys.org/news/2009-08-scientists-oxygen-moon.html#jCp

At 10W/kg you need 450 kg of solar panels. Proof of concept would be to launch a little bit of oxygen from the moon. That should be closer to the billion dollar price range, less if it is attached to some other project. Producing a 8.6 x 10⁹ kg of LOx and launching it would require a lot of infrastructure. Oxygen needs to be delivered to L1 for around than $10 per kg.

We do not have to go all the way to the moon to assemble, fuel, and equip a spacecraft for a manned-mission to Mars. Some sort of spacecraft construction facility in low-Earth orbit would seem to be the most practical and cost effective means of constructing and sending a spacecraft to Mars. Upon its return the spacecraft could dock with the space port and be used for future manned-missions. The astronauts could return to Earth like they do now from the ISS. Perhaps the ISS could be re-tasked for such a purpose, with more modules added as required.

Where are the parts, fuel, and equipment coming from? If all of it comes from Earth then why not launch an assembled ship?

The plan according to spacex is to refuel the spacecraft while orbiting earth. For one trip to Mars there will be around 8 launches of the BFR. 1 launch for the spacecraft and 5 fuel launches. The BFR to Mars uses 1100 tons of propellant (CH4, O2), 250 tons cargo(150 tons reusable), 85 tons spaceship. The propellant is 78% oxygen. There is no reason we could not break that down into 1 spacecraft , 1 methane launch, 1 mixed fuel, and 5 oxygen deliveries. If you have Oxygen in space it can easily cut out half of the launches to LEO.

...where astronauts still have some protection from solar and cosmic radiation...

If you are going to Mars you need to have well developed radiation shields that do not depend on Earth. On the moon shielding is easy. Pile lunar regolith on top of the habitat modules, build with heavy masonry, or live underground.

Earth's magnetic field does not protect against x-rays, gamma rays, meteoroids, or neutral particles.

 

[Al_]

There is water on the surface of the moon in the same sense that dry concrete has water on a clear summer day.

On most of it, sure. But in some places, there's much more than that. See this article from NASA, towards the end it says:
"present in the form of small crystals at a very low mixing ratio: ranging from 0.3% to 1%"
https://web.archive.org/web/20061209110937/http://lunar.arc.nasa.gov/results/ice/eureka.htm

 

[|Glitch|]

Where are the parts, fuel, and equipment coming from? If all of it comes from Earth then why not launch an assembled ship?

The same place where they would originate if we built a moon base. It isn't like we are going to start building manufacturing facilities on the moon. We are going to build everything we need on Earth and then send it into space. The whole idea behind having a space construction facility is so we can make numerous trips into LEO in order to construct this craft over a period of time. We do not have to construct everything on the surface of Earth and go (like we have been), and we don't need to do that on the moon either.

The plan according to spacex is to refuel the spacecraft while orbiting earth. For one trip to Mars there will be around 8 launches of the BFR. 1 launch for the spacecraft and 5 fuel launches. The BFR to Mars uses 1100 tons of propellant (CH4, O2), 250 tons cargo(150 tons reusable), 85 tons spaceship. The propellant is 78% oxygen. There is no reason we could not break that down into 1 spacecraft , 1 methane launch, 1 mixed fuel, and 5 oxygen deliveries. If you have Oxygen in space it can easily cut out half of the launches to LEO.

If you are going to Mars you need to have well developed radiation shields that do not depend on Earth. On the moon shielding is easy. Pile lunar regolith on top of the habitat modules, build with heavy masonry, or live underground.

Earth's magnetic field does not protect against x-rays, gamma rays, meteoroids, or neutral particles.

SpaceX's plan makes a lot of sense. That is a lot of launches.

You are right about the radiation shielding. It is the primary reason we have not had a manned-mission beyond LEO since 1973. According to the Curiosity probe, it registered ~300 millisieverts (3,000 millirems) of radiation on the trip to Mars.

The highest recommended limit for radiation exposures is for astronauts-25,000 millirems per Space Shuttle mission, principally from cosmic rays. This amount is beyond the average 300+ millirems of natural sources of radiation and any medical radiation a person has received.

25,000 millirems per year level was the federal occupational limit during World War II and until about 1950 for radiation workers and soldiers exposed to radiation. The occupational limit became 15,000 millirems per year around 1950. In 1957, the occupational limit was lowered to a maximum of 5,000 millirems per year.

Source: Radiation, how much radiation is considered safe for humans? - MIT News, January 5, 1994

Dartmouth College has some interesting ideas with regard to radiation shielding for spacecraft and NASA published a technical report on the subject several years ago. We should not even be contemplating a manned-mission to Mars until we can ensure at least minimal protection against solar and cosmic radiation. I mean the purpose of the mission is to bring the astronauts home alive, right?

Sources:
https://engineering.dartmouth.edu/~d76205x/research/Shielding/ - Thayer School of Engineering, Dartmouth College
Revolutionary Concepts of Radiation Shielding for Human Exploration of Space - NASA Technical Report, March 1, 2005

 

[russ_watters]

I am not seeing how you put that together from anything I wrote.

$10^6 is a million dollars. I'm asking you if That's a typo or if you really think it is possible to mine and process any amount of fuel on the moon for a million dollars.

You suggested $1 trillion.

Yes. I think you number - if it wasn't a typo - is off by itself squared.

 

[stefan r]

On most of it, sure. But in some places, there's much more than that. See this article from NASA, towards the end it says:
"present in the form of small crystals at a very low mixing ratio: ranging from 0.3% to 1%"
https://web.archive.org/web/20061209110937/http://lunar.arc.nasa.gov/results/ice/eureka.htm

Modern concrete:

Typically, a batch of concrete can be made by using 1 part Portland cement, 2 parts dry sand, 3 parts dry stone, 1/2 part water. The parts are in terms of weight – not volume. For example, 1-cubic-foot (0.028 m3) of concrete would be made using 22 lb (10.0 kg) cement, 10 lb (4.5 kg) water, 41 lb (19 kg) dry sand, 70 lb (32 kg) dry stone (1/2" to 3/4" stone). This would make 1-cubic-foot (0.028 m3) of concrete and would weigh about 143 lb (65 kg).

4.5/65 = 6.9%

So dry concrete on a hot summer day has about an order of magnitude more water than the "wet" parts of the moon.

 

[Al_]

why none of this stuff, which is technically possible(except for the Star Trek Propulsion Fantasy), has happened yet.

Well, for many years after the Apollo program, we thought the Moon was as dry as a dinosaur bone in a dessicator.
Maybe ten years have passed since we learned differently, and many private and govt projects are in the pipeline.
So give it time! I think we'll see some Lunar activity pretty soon!

 

[Al_]

Modern concrete:

4.5/65 = 6.9%

So dry concrete on a hot summer day has about an order of magnitude more water than the "wet" parts of the moon.

Yes, but it's bound chemically. You can't just melt or separate it out.

 

[russ_watters]

Well, for many years after the Apollo program, we thought the Moon was as dry as a dinosaur bone in a dessicator.
Maybe ten years have passed since we learned differently, and many private and govt projects are in the pipeline.
So give it time! I think we'll see some Lunar activity pretty soon!

1. It is a stretch to say these projects are "in the pipeline".
2. Colonization is not step 1, exploration is. You're suggesting building a massive and absurdly expensive infrastructure to support a need that doesn't exist and can't exist until after the exploration.

 

[stefan r]

$10^6 is a million dollars. I'm asking you if That's a typo or if you really think it is possible to mine and process any amount of fuel on the moon for a million dollars.

Yes. I think you number - if it wasn't a typo - is off by itself squared.

Elon Musk is suggesting a colony of 1 million colonists. If you spend on $billion on anything then it is $1000 per person or $100,000 per flight. A $1 trillion infrastructure on the moon that has no purpose other than launching colonists to Mars would cost $1 million per passenger if we assume Musk's plans. What I meant in post #16 was that you could get oxygen for lower prices per passenger.

 

[PeroK]

Elon Musk is suggesting a colony of 1 million colonists.

You haven't said whether you are signed up yet. Do you personally fancy a life on Mars?

 

[Al_]

It is a stretch

There are lots of news reports, from many countries. Not just the US. The EU, China, Japan, etc.
http://www.newsweek.com/china-plans-far-side-moon-landing-2018-world-first-768519

You're suggesting building a massive and absurdly expensive infrastructure

It's the least cost route to the outer solar system. Sooner or later someone is going to take that route.
Maybe they will overtake some others who took a less efficient route?

 

[stefan r]

Yes, but it's bound chemically. You can't just melt or separate it out.

Lunar Prospector was using neutron spectroscopy. It detected neutrons slowed down by Hydrogen ions. Do you have any reason to believe Lunar Prospector would get a different result passing over modern concrete. Is there some reason to believe that water molecules are not bound.

You can heat portland cement and get water and CO₂ out. Not really "melting" it is "thermal decomposition".

 

[russ_watters]

Elon Musk is suggesting a colony of 1 million colonists. If you spend on $billion on anything then it is $1000 per person or $100,000 per flight. A $1 trillion infrastructure on the moon that has no purpose other than launching colonists to Mars would cost $1 million per passenger if we assume Musk's plans. What I meant in post #16 was that you could get oxygen for lower prices per passenger.

Got it; you meant you could get the fuel from the moon for $1 million per passenger. You left out the "per passenger" part! And that exactly bridges the gap between your million and my trillion.

 

[Al_]

Has this shown to be a real problem? It sounds to me like a Star Trek problem.

I don't understand this. I'm answering the question of how best to get to Mars, and mentioning the outer solar system as well.

Btw, I agree with some of the posts that launch from orbit or a lagrange point is better than either Moon or Earth - rocket assembly and fueling there too.
Robots that do this can be controlled from Earth, or semi-autonomous.
Colonisation of the Moon is not needed for this. Just robotic mining.

But - why go to Mars when you could find all the resources you want in low-g places like asteroids and small moons, and transport them much more easily from there. IMHO Mars is a dead-end gravity well!

 

[Al_]

Lunar Prospector was using neutron spectroscopy. It detected neutrons slowed down by Hydrogen ions. Do you have any reason to believe Lunar Prospector would get a different result passing over modern concrete. Is there some reason to believe that water molecules are not bound.

You can heat portland cement and get water and CO₂ out. Not really "melting" it is "thermal decomposition".

I refer you to the reference in my previous post.

 

[russ_watters]

There are lots of news reports, from many countries. Not just the US. The EU, China, Japan, etc.
http://www.newsweek.com/china-plans-far-side-moon-landing-2018-world-first-768519

That's a little lunar research "plan". It doesn't have anything to do with the subject of the thred other than having the word "moon" in it.

It's the least cost route to the outer solar system.

Says who? We haven't even done lunar mining much less human travel to the outer solar system; there is no way to accurately make that judgement.

Sooner or later someone is going to take that route.

So let's build a trillion dollar fuel depot now in hopes they do it sooner?

Maybe they will overtake some others who took a less efficient route?

So, let's build a trillion dollar fuel depot, because "maybe"? C'mon. I'm having trouble believing you are serious.

 

[russ_watters]

I don't understand this. I'm answering the question of how best to get to Mars, and mentioning the outer solar system as well.

Yes. The question is an open-ended "what benefits are there of launching from the moon?", which unfortunately has instigated Star Trek style fantasies about such benefits. That's a problem for the longevity of this thread. Even open ended questions have to have discussions constrained to reality.

 

[Al_]

let's build a trillion dollar fuel depot

Do you think it will cost a trillion? That seems high, when considering other robotic missions.

 

[stefan r]

You haven't said whether you are signed up yet. Do you personally fancy a life on Mars?

I do not have $500,000. I have strong aversions to becoming an indentured servant. I'm not sure how rational that is. I have to work here anyway and I like working. The illusion of freedom has some appeal. They need to establish a legal framework and clarify bankruptcy law.

Habitats in space might allow greater freedom of motion. Going out for a walk on Mars would still be inside of a bubble. I do not believe there is a long term motive to set up a Mars colony.

Working in a high technology green house does have a lot of appeal. Would have repetitive aspects that are "boring" but probably much less so than typical days in the last 5 years.

I am married to someone who is afraid when we travel by airplanes, will not ride roller coasters, and does not want to move out of the Northeastern USA because she wants to be close to her family. That complicates any plans to leave Earth. If I was married to someone interested in going I would sign up.

 

[Al_]

Says who? We haven't even done lunar mining

Fair enough, I should have been more cautious.
How about this: It seems to me that getting fuel from the Moon is a smarter way to proceed, and the problems of mining seem soluble.

 

[russ_watters]

Do you think it will cost a trillion?

At least.

That seems high, when considering other robotic missions.

Huh? "Other robotic missions" have nothing at all to do with a lunar fueling station.

 

[russ_watters]

Fair enough, I should have been more cautious.
How about this: It seems to me that getting fuel from the Moon is a smarter way to proceed, and the problems of mining seem soluble.

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 successful 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.

 

[stefan r]

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.

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.

... 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.
...

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

... 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.

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.

 

[nikkkom]

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.

 

[rootone]

x100 cool factor

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.

 

[Al_]

"Other robotic missions" have nothing at all to do with a lunar fueling station.

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.

 

[Al_]

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.

I reckon the EU and the Chinese will already be on the Moon by then. One pole each, maybe.
Full house.

 

[PeroK]

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.

Shouldn't cost much more than a small town petrol station, really.

 

[Vanadium 50]

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?

 

[Al_]

you're speculating wildly

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.