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Water Found Deep Inside the Moon

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Re: Water Found Deep Inside the Moon

#181

Post by ars »

wellboy wrote: post #143
ars wrote: post #112

Earlier quoted context omitted.

> The universe doesn't care. And that's exactly why it's important. > Survival of humanity isn't important universally. Unless there is something there that cares about it, there is little reason for the universe to exist - nothing would know the difference. Which is why it actually is important universally. > But it's the most important thing for humans. No, it's more important for the universe to have humans, than…

Why are you saying that the universe might not exist if it were not for humans. I have a few questions for you. 1. What if humans become extinct in a few hundred years? Should the universe then not exist anymore and make more lifeforms? 2. What if there are billions of other "intelligent" species in the universe? Why should the universe care about one specific species that is actually not that great, and very destruc…

> Why are you saying that the universe might not exist if it were not for humans.

I didn't say that. I said there is no difference between a universe not existing, and one that has no one who notices that it exists.

Re: 1 and 2 I said "(or another sentients)".

3: I guess you are implying someone made the universe and is running it? In that case, they are the ones aware of it, so that counts.

4: Hu?? What are dark matter entities? We notice the universe and care that it exists. That's enough. The specific level of intelligence, (or aggression for that matter) does not matter.

> Again, the universe doesn't care.

That's the point. WE care, and we are the ones that give the universe a "voice" as you will. We speak for it, we do the "caring" for it. Without us (or other sentients) it might as well not not exist.

> Humans are just a blip among much larger things that are happening in the universe.

Just because someone is big doesn't make it important. Importance comes from meaning. A really big explosion in space, that does noting at all, is completely unimportant. While a tiny little seed that someone wanted to plant matters a lot.

Re: Water Found Deep Inside the Moon

#182

Post by kurthr »

andars wrote: post #36
munificent wrote: post #25

Earlier quoted context omitted.

People way underestimate how far away Mars is. To give you a sense of scale, the settlers of Jamestown came from London. As the crow flies, that's about 3,790 miles. If we treat that as equivalent to settling on Mars, then for them to settle on "the moon" would have been a mere 26 miles from London. Perhaps Canvey Island on the River Thames. If we can't manage settlements that close, we really aren't ready yet for th…

In terms of distance, sure. In terms of delta-v, the budget for the moon is upwards of 50% that for Mars. EDIT: The 50% figure is from memory, and upon further reflection is probably not quite right, so take it with a grain of salt. I just wanted to point out that distance is not the only relevant metric.

However, you might use a space elevator at L1 or L2 (or both) that allow capture of HEO or launch or inter-system vehicles with only efficient high impulse rocket motors.

Note that you could use Spectra/Kevlar or other common high strength materials with a taper ratio of only 4:1 with a lunar elevator. It might take "only" ~50 tons of spectra to hang the weight and allow lifts of a 1000kg or so... its much more doable than earth or mars.

https://en.m.wikipedia.org/wiki/Lunar_space_elevator

Re: Water Found Deep Inside the Moon

#183

Post by escape_goat »

sunflowerfly wrote: post #178
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…

For me the real advantage of a moon base first is safety. If something goes horribly wrong while we are learning to live on other planets, a return to earth or a rescue mission takes far less time. I am not a space expert though, so perhaps this is wrong?

I have head that moon dust is reputed to be a consideration, as it creates a type of environmental problem that would not be as extensive a problem on Mars. My understanding is that, due to a lack of fluid and chemical erosion, it tends to be extremely fine and abrasive, and it clings to everything due to static charge, making it hard to keep out of compartments and machinery.

They're both definitely too far for a rescue mission or evacuation that wasn't planned for in advance. In terms of the old eggs/basket metaphor, it becomes a question of whether you want to use half your straw to weave a second basket, just in case the first one breaks, or if you want to use all of the straw to make your one basket as strong, redundant, and well designed as possible.

Re: Water Found Deep Inside the Moon

#184

Post by i2shar »

Robotbeat wrote: post #172
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.

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…

[To put things in perspective] travel time to the Moon is about 3 days, Mars would be about 150 to 300 days (source: Google).

Re: Water Found Deep Inside the Moon

#185

Post by prawn »

cpeterso wrote: post #162
athenot wrote: post #34

Earlier quoted context omitted.

When the topic of Backup for Civilization comes up, instead of Wall-E, I tend to think of Elysium, i.e. the backup option is only for the wealthy, leaving the rest in a worse state. https://www.space.com/22287-elysium-space-station-science-na...

For another take on backing on human civilization, check out Neal Stephenson's novel Seveneves . Humanity evacuates 1500 people to orbit as moon debris decimates all remaining life on the earth's surface. As a story, it's pretty dry, but as a thought experiment, it's very interesting. https://en.wikipedia.org/wiki/Seveneves

I wouldn't call it dry. I thought the writing style was a little juvenile, but the ideas are generally interesting as you said, the descriptions of technology are fairly detailed and I thought of it as a rollicking adventure by the end.

Dry implies flat and drab to me. If anything, I think Stephenson's flaw as a writer is that he comes across as an excited boy who just wants to tell you everything he's been researching, rather than show you naturally with a well-written story.

Re: Water Found Deep Inside the Moon

#186

Post by khedoros1 »

ars wrote: post #179
khedoros1 wrote: post #155

Earlier quoted context omitted.

That seems like a circular argument. It's not important for the universe to have a purpose, or to "care"...except to us. Things don't need a reason to exist.

What is the difference between a universe that doesn't exist, and one that no one notices exists? There is no difference.

The difference is itself: one universe exists, one doesn't. Notice doesn't define existence. Measurability doesn't define existence. Meaning doesn't define existence.

Re: Water Found Deep Inside the Moon

#187

Post by keenerd »

drostie wrote: post #177
keenerd wrote: post #149

Earlier quoted context omitted.

Mercury won't be under any serious consideration for habitation for a long time. It is down at the bottom of the biggest gravity well within a few light years. Too much delta-V to come or go. It is the least explored inner planet for a reason. I think you are drastically overstating the difficulty of heating a lunar polar base. You are surrounded by vacuum, one of the best insulators around. It can be used. Of course…

A solar panel tower at the North Pole of the Moon might be a really good idea for solving these problems, yes. Vacuum is only one of the best insulators around if you're near other warm things, I'm afraid. Out in space the dominant form of heat exchange is the Stefan-Boltzmann law, which says that if you have a half-acre of total surface area on your moon-base, and it's at 300 kelvin, then you need to supply about a…

I still think you are overstating things. Stefan-Boltzmann is just a fancy way to say radiation. That is more or less a solved problem with nested shells. Each layer of shell cuts the losses in half. But let's ignore that for now, since more than one layer of shell complicates construction.

Historical aside: before we had good solar panels, people tried crazy stuff like the Phaeton satellite that used a generator spun by a heat engine powered by liquid mercury heated by parabolic reflectors. Let's bring that idea back.

1MW only requires a 30 meter by 30 meter thermal solar collector. Pump that 1MW of heat into the hab and run a heat engine, using the shell of the hab as the thermal sink. Now that constant 1MW drain is a required feature.

Re: Water Found Deep Inside the Moon

#188

Post by Fej »

Robotbeat wrote: post #172
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.

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 Mars.

Re: Water Found Deep Inside the Moon

#189

Post by ChuckMcM »

Robotbeat wrote: post #172
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.

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…

Per glindahl's comment from earlier, if we established a space elevator for the moon[1] it would make the delta-v issues moot. Drop off an pick up supplies at the elevator while swinging by on an continuous Earth/Moon translunar orbit.

[1] https://en.wikipedia.org/wiki/Lunar_space_elevator

Re: Water Found Deep Inside the Moon

#190

Post by [deleted] »

dragonwriter wrote: post #171
simonh wrote: post #169

Earlier quoted context omitted.

It only took that long because MGS was aerobraking into orbit and wasn't designed to survive the stress of lower atmosphere turbulence, so only used the uppermost layer of the atmosphere for braking. If your going to land, obviously you get to use all the atmosphere and also can use parachutes. Something a problem braking into orbit can't do. Surface probes do direct descent trajectories. There is no extended series…

> If your going to land, obviously you get to use all the atmosphere and also can use parachutes. Something a problem braking into orbit can't do. Also, you can use lithobraking.

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