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Water Found Deep Inside the Moon

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Re: Water Found Deep Inside the Moon

#221

Post by stcredzero »

ChuckMcM wrote: post #189
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…

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

if we established a space elevator for the moon

Wouldn't you get the same benefit from a Mass Driver, since the moon is a vacuum body?

Re: Water Found Deep Inside the Moon

#222

Post by aptwebapps »

ChuckMcM wrote: post #189
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…

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

There would still be some delta-v. Anyone have a handle on how much? I'm too lazy to look up the data and do the math.

Re: Water Found Deep Inside the Moon

#223

Post by Endy »

kbenson wrote: post #192
ribosometronome wrote: post #163

Earlier quoted context omitted.

It sounds like you value the persistence of understanding in a way that just isn't particularly important to me. The survival of my loved ones -- and that's a category that can go across species -- is absolutely important to me. The survival of evil space Nazis? Eh. That said, I also don't really think I see being an evolutionary dead end as too huge of a concern. Many of us appreciate things that aren't truly keen f…

> The survival of my loved ones -- and that's a category that can go across species -- is absolutely important to me. The survival of evil space Nazis? Eh. The idea is that if it's between all people dead, or all people except evil space Nazis, I'll take evil space Nazis. Just because they are evil space Nazis now doesn't mean they will be hundreds of years from now, but they'll never get that chance if all humans ar…

If it's up to me between no humans and evil space Nazis? I'll take no humans every time. We're a stain on the face of existence, we pollute and destroy our environment, we abuse our own species and others as a matter of course, and we're just overall destructive. The only thing that changes that is that sometimes one or two people rise up and decide that they will resist that status quo and do something about it. To allow a group of people who are evil in the conception of a default-destructive species to be the only ones left? Better to let the species die.

Re: Water Found Deep Inside the Moon

#224

Post by ChuckMcM »

stcredzero wrote: post #221
ChuckMcM wrote: post #189

Earlier quoted context omitted.

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

if we established a space elevator for the moon Wouldn't you get the same benefit from a Mass Driver, since the moon is a vacuum body?

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.

Re: Water Found Deep Inside the Moon

#225

Post by persimmon_b »

aptwebapps wrote: post #222
ChuckMcM wrote: post #189

Earlier quoted context omitted.

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

There would still be some delta-v. Anyone have a handle on how much? I'm too lazy to look up the data and do the math.

Translunar injection needs about 10.8 km/s, Earth's escape velocity is 11.2 km/s.

Re: Water Found Deep Inside the Moon

#226

Post by aptwebapps »

persimmon_b wrote: post #225
aptwebapps wrote: post #222

Earlier quoted context omitted.

There would still be some delta-v. Anyone have a handle on how much? I'm too lazy to look up the data and do the math.

Translunar injection needs about 10.8 km/s, Earth's escape velocity is 11.2 km/s.

I mean to hook up with the elevator.

Re: Water Found Deep Inside the Moon

#227

Post by ChuckMcM »

aptwebapps wrote: post #222
ChuckMcM wrote: post #189

Earlier quoted context omitted.

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

There would still be some delta-v. Anyone have a handle on how much? I'm too lazy to look up the data and do the math.

First, I've neither done the requisite orbital mechanics calculations nor have I simulated this. But with that caveat, this is how I imagine it would work.

Assuming your tug is in the translunar orbit (going in a figure 8 around the Moon and Earth with the intersection being the Earth-Moon L1 point. And assuming the tug is significantly more massive than your cargo. As you cross the L1 point you can use a mass driver on the tug to 'shoot' the cargo out behind you which would decelerate it to a low delta-v relative to the elevator base (and slightly boost the tug on its way) and when you came around the other side you hook the cargo through a loop like the old mail planes did [1] and pulling it away (which would impart a small deceleration on the tug as it headed back to earth). Depending on masses and how closely you could match things, the amount of delta-v you would need for the tug to keep its orbit true should be very manageable.

[1] https://postalmuseum.si.edu/collections/object-spotlight/sky...

Re: Water Found Deep Inside the Moon

#228

Post by pcmaffey »

hnlmorg wrote: post #165
andyfal12 wrote: post #142

Earlier quoted context omitted.

Meteor impacts and supervolcanoes seem to be the near-term worst case scenarios, neither which change the state of living on the moon. I don't know that the metaphor of them being under the same roof works.

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?

Re: Water Found Deep Inside the Moon

#229

Post by hyperpallium »

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.

And it's right bang smack in the habitable/goldilocks zone.

Would digging a big valley (no dome), and putting air in it be ridiculously inefficient? Of course you'd lose some over time, but at what rate?

Re: Water Found Deep Inside the Moon

#230

Post by OtterCoder »

Robotbeat wrote: post #175
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.

Years? Absolutely not. Transfer can be done in about 90 days, less (30 days) if you pursue aggressive entry, high orbit refueling, and nuclear thermal propulsion. Assuming you're settling the place and not just doing flags and footprints, transfer time is the important part.

That's astoundingly quick. 30-90 days is in the same range as crossing the Atlantic via tall ship. With transfer time that low, it really does seem feasible. The two year gaps are a bit rough, but there are plenty of ways to plan for it.
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