# I Moon vs Earth for launch to Mars

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1. Jan 3, 2018

### Al_

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!

2. Jan 3, 2018

### Al_

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

3. Jan 3, 2018

### Staff: Mentor

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.

4. Jan 3, 2018

9. Jan 3, 2018

### Al_

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!

10. Jan 3, 2018

### Al_

I refer you to the reference in my previous post.

11. Jan 3, 2018

### Staff: Mentor

That's a little lunar research "plan". It doesnt have anything to do with the subject of the thred other than having the word "moon" in it.
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.
So let's build a trillion dollar fuel depot now in hopes they do it sooner?
So, let's build a trillion dollar fuel depot, because "maybe"? C'mon. I'm having trouble believing you are serious.

12. Jan 3, 2018

### Staff: Mentor

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.

13. Jan 3, 2018

### Al_

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

14. Jan 3, 2018

### stefan r

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.

15. Jan 3, 2018

### Al_

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.

16. Jan 3, 2018

### Staff: Mentor

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

17. Jan 3, 2018

### Staff: Mentor

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
18. Jan 3, 2018

### stefan r

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.

19. Jan 3, 2018

### 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.

20. Jan 3, 2018

### rootone

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.

21. Jan 4, 2018

### Al_

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.

22. Jan 4, 2018

### Al_

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
23. Jan 4, 2018

### PeroK

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

24. Jan 4, 2018

Staff Emeritus
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?

Last edited: Jan 4, 2018
25. Jan 4, 2018

### Al_

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