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To me the moon would be the obvious place to start, especially as the NASA plans I've seen for Mars have been based on using a space station at a Earth-Lunar La

To me the moon would be the obvious place to start, especially as the NASA plans I've seen for Mars have been based on using a space station at a Earth-Lunar Lagrange point, and associated moonbase, as ideal staging post. That and I might one day afford a ticket. I guess direct to Mars is sexier. :) (I'm behind live too.)

imglorp 10y ago
Go to the moon for its own rewards--a lunar base or whatever--but don't go there as a stepping stone. The challenges of landing on the two bodies are vastly different and you'd throw away half your effort reworking for Mars after you got some moon landings.
david-given 10y ago
I agree --- Mars is a pit. It's a barren desert at the bottom of a great big hole. Its biggest, and perhaps only, advantage is that it has an atmosphere, and gas is so much easier to deal with for ISRU than anything else, as you don't need to mine it: just open a valve and suck it in. I notice Musk's ISRU plan is to mine ice; I do wonder how he's going to do that, as it won't be easy. But... you know what... if you can get to Mars, you can get anywhere. If you can get to Mars, getting to the Moon is so trivial you might as well build and maintain a base there just to test the equipment. If you can get to Mars, you can get to near-Earth asteroids with enough spare capacity to take a whole a mining plant in tow. If you can get to Mars, Ceres is only 400 m/s further away. (And Ceres is interesting.) If you can get to Mars, then the outer solar system is reachable (with preparation and some disposable boosters). If you can get to Mars, anyone who can afford a IST ship can have a space station. So, hell yes, let's go to Mars. (And I'll cheerfully wave goodbye to you from my ice-mining cometary habitat.)
- anexprogrammer 10y ago
  I've nothing against Mars, more surprise that it's not via lunar orbit staging as the last several explanations of how we'd get there that I've seen. Like it was a big obvious advantage. Mars first has the enormous advantage that it's tangibly in progress, however early, rather than being a great NASA idea that isn't getting funded. So I don't actually care which if only one is having rockets built. I saw enough artist impressions in the 80s. ;) My recollection of the NASA idea was a Mars voyage would reconfigure/refuel at the space station but never land on the moon. The moonbase is the warehouse, fuel and whatever else would be needed to keep space station fed, and gets developed into manufacturing. Lower G meaning larger vehicles, lower launch cost and so forth. The station at L2 was supposed to be a good jumping off point for anywhere - Mars, asteroids, rest of solar system - supposedly the most fuel efficient way to all(?) of them from here. It's a while since I last read about that, so I may be mistaken on details.
  - david-given 10y ago
    Mars is sexy and looks like a place --- people can see the pictures from the Mars rovers and imagine themselves being there. It's got weather and wind and interesting landscapes. It's featured in myths and legends for so long that it has a special place in people's heart. I can totally see it being used as the end goal of a fairly long plan. The Moon's not very sexy. It's all dusty blacks and greys. Everyone knows it's a dead rock, we've already been there, and public consciousness is dominated by the Apollo program pictures of astronauts in gigantic, bulky spacesuits. (This is mostly perpetrated by NASA unaccountably not sending any decent rovers to the Moon. Even the most recent lander, China's Chang'e, deliberately landed in the most boring place they could find. There aren't any interesting pictures of the moon because we haven't been anywhere interesting.) ISRU's hard there, too. There's water ice you can mine, but carbon? I don't know where you'd get that. But... if I were building a water ice mining plant destined for Mars, I'd want to test it somewhere. The Moon's a good place. So now I've landed an ITP ship with a mining rig. I'm going to load it with scientific instruments, too. And scientists. In fact, I might as well land two; it's good practice for Mars. And we're mining water, so we might as well use it, and help test the recycling systems. After all, the Moon's close enough that you can dash back to Earth in an emergency; it's the ideal place. We've got two ships; let's use one to recycle the crew on the other, and leave it there long term; there's plenty of interesting science to do, and it's all excellent practice. So I'd be really surprised if a long-term presence on the Moon didn't sneak into this plan by the back door. And then if a carbon source were to be discovered in large enough quantities for meaningful ISRU, then sourcing methane from the moon would slot neatly in.
    - nickik 10y ago
      Landing on the moon is just as difficult as la to mars. Operating on the moon is much much harder. Getting back is hard because there is no easy ISRU way to do it. Nobody will go to the moon to test stuff. Getting water on the moon is a completely different problem then getting water on mars. Testing these things on the moon is totally insane anyway.The moon has some water, we don't know how much, and not exactly were it is. Mining it would be extremely difficult, specially without a nuclear reactor. As for recycling systems, we are already good at them. We can and do test them on earth. We do test them on ISS. There is no need to go to mars, to these systems. On Mars the most important resources for ISRU is easily and everywhere available, on the moon that is not the case. The Science on Mars could answer fundamental questions about live, that is almost impossible on mars. Mars is clearly far more interesting from a scientific perspective. That is not even a point worth debating. I am all for going back to the moon eventually, but mars is far more important. If you want to go to mars, go to mars.
- sathackr 10y ago
  Going to a body with atmosphere is easier than going to one without. You get free braking (~8500m/s of delta-v according to Elon, for Mars) thanks to the atmosphere. Anything without an atmosphere you have to carry the fuel to stop after chasing it down, then land on it slow enough not to die. For robotic missions we can approach these objects in very favorable orbits with transit times measured in years, so the delta-v needed to slow down is manageable. For human-based missions we have to get there fast. Going there fast means you have to dump alot of speed to stop once you get there. Without an atmosphere, that takes fuel. Not as much as it took you to reach that velocity, since you're lighter now, but still just about as much in terms of delta-v. I learned this playing KSP. It will open your eyes to the real challenges of orbital mechanics. The hardest planet to land on in the entire game is the one with a mass/gravity approaching the game version of earth, except with no atmosphere. The in-game numbers aren't realistic, but the concepts are. And hell yes, lets go to Mars. Where do I sign up?
- simonh 10y ago
  > I notice Musk's ISRU plan is to mine ice; I do wonder how he's going to do that, as it won't be easy. Load up the icy dirt into a chamber using a digger, heat it up and precipitate out the water vapor. The only potential problem is separating out other volatiles, but fractionation is pretty basic tech.
  - david-given 10y ago
    D'oh, I totally should have thought of that. Provided you have a decent power source that's easy: the hardest part is getting your raw material into the chamber and disposing of the debris afterwards. Humans driving flat-pack bulldozers, most likely. Would work on the Moon, too.
    - simonh 10y ago
      You could probably heat up the regolith while it's on a conveyor belt and use a negative pressure system to draw off the vapour through cooling tubes, so it could operate continuously.
natosaichek 10y ago
Not sure why you'd go out to the lagrange point? Or the moon? It's much farther away (a few days travel instead of a few minutes), it's way outside the limited shielding the earths magnetic field gives, and there's nothing there. Why's it better than LEO?

imglorp 10y ago

Go to the moon for its own rewards--a lunar base or whatever--but don't go there as a stepping stone. The challenges of landing on the two bodies are vastly different and you'd throw away half your effort reworking for Mars after you got some moon landings.

david-given 10y ago

I agree --- Mars is a pit. It's a barren desert at the bottom of a great big hole. Its biggest, and perhaps only, advantage is that it has an atmosphere, and gas is so much easier to deal with for ISRU than anything else, as you don't need to mine it: just open a valve and suck it in. I notice Musk's ISRU plan is to mine ice; I do wonder how he's going to do that, as it won't be easy. But... you know what... if you can get to Mars, you can get anywhere. If you can get to Mars, getting to the Moon is so trivial you might as well build and maintain a base there just to test the equipment. If you can get to Mars, you can get to near-Earth asteroids with enough spare capacity to take a whole a mining plant in tow. If you can get to Mars, Ceres is only 400 m/s further away. (And Ceres is interesting.) If you can get to Mars, then the outer solar system is reachable (with preparation and some disposable boosters). If you can get to Mars, anyone who can afford a IST ship can have a space station. So, hell yes, let's go to Mars. (And I'll cheerfully wave goodbye to you from my ice-mining cometary habitat.)

anexprogrammer 10y ago
I've nothing against Mars, more surprise that it's not via lunar orbit staging as the last several explanations of how we'd get there that I've seen. Like it was a big obvious advantage. Mars first has the enormous advantage that it's tangibly in progress, however early, rather than being a great NASA idea that isn't getting funded. So I don't actually care which if only one is having rockets built. I saw enough artist impressions in the 80s. ;) My recollection of the NASA idea was a Mars voyage would reconfigure/refuel at the space station but never land on the moon. The moonbase is the warehouse, fuel and whatever else would be needed to keep space station fed, and gets developed into manufacturing. Lower G meaning larger vehicles, lower launch cost and so forth. The station at L2 was supposed to be a good jumping off point for anywhere - Mars, asteroids, rest of solar system - supposedly the most fuel efficient way to all(?) of them from here. It's a while since I last read about that, so I may be mistaken on details.
- david-given 10y ago
  Mars is sexy and looks like a place --- people can see the pictures from the Mars rovers and imagine themselves being there. It's got weather and wind and interesting landscapes. It's featured in myths and legends for so long that it has a special place in people's heart. I can totally see it being used as the end goal of a fairly long plan. The Moon's not very sexy. It's all dusty blacks and greys. Everyone knows it's a dead rock, we've already been there, and public consciousness is dominated by the Apollo program pictures of astronauts in gigantic, bulky spacesuits. (This is mostly perpetrated by NASA unaccountably not sending any decent rovers to the Moon. Even the most recent lander, China's Chang'e, deliberately landed in the most boring place they could find. There aren't any interesting pictures of the moon because we haven't been anywhere interesting.) ISRU's hard there, too. There's water ice you can mine, but carbon? I don't know where you'd get that. But... if I were building a water ice mining plant destined for Mars, I'd want to test it somewhere. The Moon's a good place. So now I've landed an ITP ship with a mining rig. I'm going to load it with scientific instruments, too. And scientists. In fact, I might as well land two; it's good practice for Mars. And we're mining water, so we might as well use it, and help test the recycling systems. After all, the Moon's close enough that you can dash back to Earth in an emergency; it's the ideal place. We've got two ships; let's use one to recycle the crew on the other, and leave it there long term; there's plenty of interesting science to do, and it's all excellent practice. So I'd be really surprised if a long-term presence on the Moon didn't sneak into this plan by the back door. And then if a carbon source were to be discovered in large enough quantities for meaningful ISRU, then sourcing methane from the moon would slot neatly in.
  - nickik 10y ago
    Landing on the moon is just as difficult as la to mars. Operating on the moon is much much harder. Getting back is hard because there is no easy ISRU way to do it. Nobody will go to the moon to test stuff. Getting water on the moon is a completely different problem then getting water on mars. Testing these things on the moon is totally insane anyway.The moon has some water, we don't know how much, and not exactly were it is. Mining it would be extremely difficult, specially without a nuclear reactor. As for recycling systems, we are already good at them. We can and do test them on earth. We do test them on ISS. There is no need to go to mars, to these systems. On Mars the most important resources for ISRU is easily and everywhere available, on the moon that is not the case. The Science on Mars could answer fundamental questions about live, that is almost impossible on mars. Mars is clearly far more interesting from a scientific perspective. That is not even a point worth debating. I am all for going back to the moon eventually, but mars is far more important. If you want to go to mars, go to mars.
sathackr 10y ago
Going to a body with atmosphere is easier than going to one without. You get free braking (~8500m/s of delta-v according to Elon, for Mars) thanks to the atmosphere. Anything without an atmosphere you have to carry the fuel to stop after chasing it down, then land on it slow enough not to die. For robotic missions we can approach these objects in very favorable orbits with transit times measured in years, so the delta-v needed to slow down is manageable. For human-based missions we have to get there fast. Going there fast means you have to dump alot of speed to stop once you get there. Without an atmosphere, that takes fuel. Not as much as it took you to reach that velocity, since you're lighter now, but still just about as much in terms of delta-v. I learned this playing KSP. It will open your eyes to the real challenges of orbital mechanics. The hardest planet to land on in the entire game is the one with a mass/gravity approaching the game version of earth, except with no atmosphere. The in-game numbers aren't realistic, but the concepts are. And hell yes, lets go to Mars. Where do I sign up?
simonh 10y ago
> I notice Musk's ISRU plan is to mine ice; I do wonder how he's going to do that, as it won't be easy. Load up the icy dirt into a chamber using a digger, heat it up and precipitate out the water vapor. The only potential problem is separating out other volatiles, but fractionation is pretty basic tech.
- david-given 10y ago
  D'oh, I totally should have thought of that. Provided you have a decent power source that's easy: the hardest part is getting your raw material into the chamber and disposing of the debris afterwards. Humans driving flat-pack bulldozers, most likely. Would work on the Moon, too.
  - simonh 10y ago
    You could probably heat up the regolith while it's on a conveyor belt and use a negative pressure system to draw off the vapour through cooling tubes, so it could operate continuously.

natosaichek 10y ago

Not sure why you'd go out to the lagrange point? Or the moon? It's much farther away (a few days travel instead of a few minutes), it's way outside the limited shielding the earths magnetic field gives, and there's nothing there. Why's it better than LEO?