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Water Found Deep Inside the Moon

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Re: Water Found Deep Inside the Moon

#261

Post by adrianN »

Fej wrote: post #188
Robotbeat wrote: post #172

Earlier quoted context omitted.

It's questionable that it's really much lower cost. The Moon, as a vacuum body, doesn't give the option of aerobraking or atmospheric entry, which dramatically reduces delta-V. You can get a payload to Mars' surface with less propellant than getting it to the Moon's surface. And because atmosphere is everywhere (which includes oxygen in the form of CO2 and also water vapor), propellant is way easier to make, so it's…

Mars has the radiation problem while in-transit, which is still unsolved. We have already gone to the Moon. Given that the travel time is relatively short, radiation is far less of a concern. This is why the Moon is attractive. We know how to get there already and it's not too difficult, all things considered. The problem of how to get there and back with humans aboard has already been solved. It's never been done to…

IMHO the radiation problem is solved by telling the astronauts that a journey to Mars increases their risk of dying of cancer in the next ten years by 30% or whatever the right number is and asking for volunteers. I'm pretty sure you'd find plenty. I would go, for example.

Re: Water Found Deep Inside the Moon

#262

Post by adrianN »

foxylad wrote: post #220
WalterBright wrote: post #68

Earlier quoted context omitted.

You need a far bigger (heavier) craft to get to Mars. You'll need years worth of food, water, air, you'll need radiation shielding, much more space per crewmember, more redundant systems and backups, etc. Look at the size of the Apollo.

For the journey, yes. But for permanent settlement, in both cases you'll need of the order of years-worth of supplies while you become self-sufficient. Back on-topic, the discovery of water on the moon makes this more achievable there; otherwise Mars's resources might have actually meant less resources were required.

You don't have to send all the supplies at once though (you shouldn't actually). You can send many small missions, each providing some parts of a Mars base before sending any humans. See for example the Mars Direct plan by Zubrin: https://en.wikipedia.org/wiki/Mars_Direct

Re: Water Found Deep Inside the Moon

#263

Post by jhgb »

Fej wrote: post #188
Robotbeat wrote: post #172

Earlier quoted context omitted.

It's questionable that it's really much lower cost. The Moon, as a vacuum body, doesn't give the option of aerobraking or atmospheric entry, which dramatically reduces delta-V. You can get a payload to Mars' surface with less propellant than getting it to the Moon's surface. And because atmosphere is everywhere (which includes oxygen in the form of CO2 and also water vapor), propellant is way easier to make, so it's…

Mars has the radiation problem while in-transit, which is still unsolved. We have already gone to the Moon. Given that the travel time is relatively short, radiation is far less of a concern. This is why the Moon is attractive. We know how to get there already and it's not too difficult, all things considered. The problem of how to get there and back with humans aboard has already been solved. It's never been done to…

I was under the impression that the intricacies of creating a small biosphere on Mars pose a vastly larger obstacle than the simple issue or radiation (which can be eliminated by simply shoving enough regolith on top of your colony).

Re: Water Found Deep Inside the Moon

#264

Post by adrianN »

keenerd wrote: post #75
Obi_Juan_Kenobi wrote: post #69

Earlier quoted context omitted.

Mars has atmosphere for aerobraking and ISRU possibilities that the moon does not. In many ways, it is much more practical from a spaceflight standpoint. That's not to say that there aren't possibilities for both, but Mars is seen as the preferred choice for a variety of sound reasons.

The Martian atmosphere is next to worthless for aerobraking human-scale infrastructure. One of the most significant points in the Moon's favor is the (relative) ease with which a space elevator could be built. It doesn't need unobtainium, current structural materials are strong enough.

If your plans for an extraterrestial base require building something as expensive as a space elevator, you'll never get the funding. Any plan for human settlement must be splittable into reasonable annual budgets. Being to ambitions is what killed many previous missions.

Re: Water Found Deep Inside the Moon

#265

Post by elsonrodriguez »

tambourine_man wrote: post #7

I've always been more excited about a Moon colony than a Mars one. I mean, compared to Mars, the Moon is ridiculously close. Many of the same benefits Musk seeks (backup for Civilization, excitement) for a fraction of the cost. Low gravity and atmosphere on a dome would be more complicated, but again, compared to Mars, it's right there . It would be a more humble and realistic first step, IMO.

The Moon can be useful as an outpost, like Antartica. In contrast Mars can be made into an actual home for us.

Also, as others have pointed, closer/further is a tricky thing when talking about interplanetary travel: http://www.marssociety.org/home/about/faq/#Q12

There's at least one colonization plan floating around using what's essentially Apollo-era hardware for getting to Mars for that Delta-v related reason.

Re: Water Found Deep Inside the Moon

#266

Post by jhgb »

foxylad wrote: post #220
WalterBright wrote: post #68

Earlier quoted context omitted.

You need a far bigger (heavier) craft to get to Mars. You'll need years worth of food, water, air, you'll need radiation shielding, much more space per crewmember, more redundant systems and backups, etc. Look at the size of the Apollo.

For the journey, yes. But for permanent settlement, in both cases you'll need of the order of years-worth of supplies while you become self-sufficient. Back on-topic, the discovery of water on the moon makes this more achievable there; otherwise Mars's resources might have actually meant less resources were required.

But the presence of water on the Moon is more limited than the presence of CO2 and H2O on Mars. That could be significant for self-sufficiency. Especially if we could find a way to make plastics from CO2 and H2O in a reasonably small mobile device. Just grow your colony out of the stuff you suck out for the atmosphere...

Re: Water Found Deep Inside the Moon

#267

Post by elsonrodriguez »

pcmaffey wrote: post #228
hnlmorg wrote: post #165

Earlier quoted context omitted.

I know the risks are astronomical (literally), but anything significant enough to alter Earth's mass would also alter the moons orbit. I just think if we are talking about an extraterrestrial base for the sake of "backing up" the human race then it is prudent to pick a location that isn't in any way dependant on the master copy. However I appreciate other concerns also take priority as well (cost, practicality, etc)…

What's the point of a backup though if you can't restore?

If there's humans, the possibility to restore exists.

If there's no humans, the possibility to restore is gone.

Re: Water Found Deep Inside the Moon

#268

Post by stcredzero »

adrianN wrote: post #250
tveita wrote: post #245

Earlier quoted context omitted.

You could run the mass driver in reverse for landing, but you'd have to aim well.

That would be an amazing feat with the risk of destroying an extremely expensive piece of equipment.

Is it any more amazing than doing an orbital rendezvous?

Re: Water Found Deep Inside the Moon

#269

Post by adrianN »

stcredzero wrote: post #268
adrianN wrote: post #250

Earlier quoted context omitted.

That would be an amazing feat with the risk of destroying an extremely expensive piece of equipment.

Is it any more amazing than doing an orbital rendezvous?

You brake before getting close to whatever you want to rendevous with. You couldn't brake if you wanted to hit the nozzle of your mass driver to use it for braking.

Re: Water Found Deep Inside the Moon

#270

Post by ChuckMcM »

tveita wrote: post #245
ChuckMcM wrote: post #224

Earlier quoted context omitted.

A mass driver doesn't let you land cargo. But as a way to get raw material off the Moon it is an excellent solution.

You could run the mass driver in reverse for landing, but you'd have to aim well.

That would be rather difficult :-) I wonder sometimes however if you've ever dropped a magnet down a conductive pipe you see how the eddy currents prevent it from falling through. If you had series of conductive rings that were of a large diameter and you had electromagnets on the outside of your cargo container could you make a landing pad that primarily used the eddy currents to slow you to landing velocity? That would be a fun problem to give the physics class.
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