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.