Tuesday, July 20, 2010

Somewhere We've Been

Apollo 11 on the Moon
Forty-one years ago we landed on the Moon. I don't have a lot to add to the observations I made on that subject two years ago. The plan to return by 2020 looked exiguous then, and has subsequently been canceled. On the other hand we have discovered evidence of water - increasing the chances that we will go back, in due course, when the time is ripe.

For now, consider this an open discussion thread.

22 comments:

Citizen Joe said...

My birthday is coming up. July 22, 1969. Born into the Space Age. I think they were on the way back at that time.

Jim Baerg said...

It's an appropriate date to make this announcment.

It actually sounds like a practically cheap way to start space development, with a single launch of an existing rocket to put it up.

Winchell said...

The Apollo program was the gateway to the stars.

Next time we ought to open it.

Rick said...

I take all space geeks' time and cost estimates with a whole dry lake's worth of salt, but the fact that a lunar elevator can be built with known materials does get my attention.

Apollo was a proof-of-concept test on an enormous scale. Subsequent development is taking more time and a lot more money than the rocketpunk era dreamers imagined, but we DO have an orbital station, and robotic craft exploring all over the Solar System.

Thucydides said...

The Pearson space elevator is a solution looking for a problem.

It is a potentially inexpensive way to deliver bulk payloads from the lunar surface to destinations in cis-lunar space or LEO (or even deep space if you care to build the elevator at the L2 point on the far side of the Moon), but the article seems to have it reversed; it isn't a great way to catch payloads and deliver them to the moon.

I have read various analysis of the Pearson elevator, and the low gravity and spin rate which allows the elevator to be built from here and now materials like Spectra, Kevlar, Zylon or M5 (probably the best of all possible materials due to its ability to survive intense solar radiation) also limits the amount of tension that is developed on the cable even with a massive counterweight. The Pearson elevator is limited to a stream of small containers:

According to Pearson, Levin, Oldson, and Wykes in their article The Lunar Space Elevator, an M5 ribbon 30 mm wide and 0.023 mm thick, would be able to support 2000 kg on the lunar surface (2005). It would also be able to hold 100 cargo vehicles, each with a mass of 580 kg, evenly spaced along the length of the elevator.

This sort of thing seems perfect for lifting small dewars of 3He or water, or machined parts made of highly refined titanium or other extreme value added products if you already have the infrastructure in place to mine and refine it. Bluntly, this is the final step in the process, not the first.

I am thinking that advances in material science will make it easier to recreate a launch vehicle to actually get to the Moon (less mass means less engine power and fuel is needed), and look forward to seeing man walk on the Moon again in my lifetime. Maybe the elevator will also be built, but I've waited 41 years for another "small step for a man", so I won't hold my breath too much.

Jim Baerg said...

"This sort of thing seems perfect for lifting small dewars of 3He or water, or machined parts made of highly refined titanium or other extreme value added products if you already have the infrastructure in place to mine and refine it."

My thought was more along the lines of delivering raw moon dust for radiation shielding, or delivering O2 extracted from moon dust for rocket fuel for movement around cis-lunar space. Ie: the sort of low value per unit mass stuff that would be the easiest start for in space industry precisely because the cost to launch from earth is far greater than the cost to manufacture it.

Albert said...

Yes! A chain of buckets getting up Moon dust to the Solar Furnace in orbit that uses them to build rocket fuel and construction materials for spaceships and/or space habs.

This way you can have orbital tugs zipping around without all the pain refueling them would be with fuel boosted from Earth.
Lunar landers using lunar fuel will be awaiting in lunar orbit awaiting for any cargo that cannot fit in the Lunar Lift (the Lunar Elevator).

No silly Big Huge Rocket that must lift from Earth both the orbital tug, the lander and their fuel. That's a great mass and cost cut.

With a little of luck (i.e. the orbital tugs are employed to do something useful in the down time like carting around or refueling satellites and are payed for it) you can even get Lunar Turism at current Space Station Tourism prices.
And the moon is a much better place than the Space Station. :)

-Albert

Sabersonic said...

"And the moon is a much better place than the Space Station. :)" - Albert

Considering that one is highly vulnerable to solar flares radiation wise out in the open and one is extremely limited to the amount of radiation shielding and types while on vacation, define "better".

And I had hearsd of the lunar space elevator/beanstalk/whatever, though from what I've been hearing, it's not exactly what one would call practical for Heavy Lift Cargo from the lunar surface, sans an industry to legitimize space structure not withstanding. At least not all at once.

P.S. I'm still waiting on Rick's post on Magi-tech or posts if one is for the discussion and debate of such physics breakers and the other to help others create limitations to their own magi-tech and how to resist the urge to break them, ect.

P.S.S. I don't suppose that there's a mobile phone version of this blog? One can only do so much on a dumb pone that can't scroll left to right.

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Thucydides said...

A Pearson elevator on the Moon could lift small buckets of regolith, and also serve as the anchor for a mirror farm which illuminates the base during the 14 day periods of darkness.

We're still groping for the financial "x" factor; what space activity would require kilotonnes of lunar regolith to be winched into cis-lunar space, either as raw material for industry or as shielding mass for inhabitable constructs? Gerard K. O'Neill's "High Frontier" had a sort of circular argument about using manned facilities to support solar energy production in space, which would require large maned facilities....Like the Rocketpunk dreams of the '50's, the ability to find smaller, faster and cheaper alternatives squelched the dreams of maned space activity (RoBo needed a pilot to drop a nuclear weapon from orbit because there there was no other means of accurate delivery at the time. While the RoBo program eventually morphed into DynaSoar with a projected in service entry date in the mid 1970's, computers miniturized and became more powerful; ICBM's as capable as the projected Dynasoar were operational in the 1960's and by the mid 1970's, MIRV (Multiple Independent Reentry Vehicle) technology allowed a single submarine or ICBM squadron to devastate entire nations.

While I don't expect to be nuking the Moon anytime soon, small robotic and teleoperated systems will probably be doing the jobs "we" were supposed to get when we grew up in the heady days of the 1960's. The occasional ace space mechanic might have to go for a short trip (kind of like the guy who comes to fix the photocopier in your office), but aside from the sort of living pods you find in Tokyo, a bottle of air, a drink and a ham sandwitch, no real long term space infrastructure is going to be needed for people in this future.

M. D. Van Norman said...

If writing fiction, you can simply skip all that. Few would care or remember how their grand spacefaring civilization got started after 10,000 or so years.

Albert said...

Sabersonic said...
"Considering that one is highly vulnerable to solar flares radiation wise out in the open and one is extremely limited to the amount of radiation shielding and types while on vacation, define "better"."

If you are moving around large quantities of lunar dust to build rocket fuel and other commodities, it won't be exceptionally hard to place some of it around a pressurized shelter to use for solar activity.
Or a full blown recreational complex, if you find that people like it and you think an investment could be good.

I'm not going to care a lot about background space radiation, because it's highly unlikely people will stay there for more than a month at a time (at least without the "full blown recreational complex" that will be under enough regolith to be shielded from anything. It is also even more unlikely that they will spend more than a few days (total) time in a space suit.
There are no risks for a such small exposure.

On the Moon you can go visit some "attractions" (i.e. the first step on the moon, all the stuff they left there, all the probes and machinery Mankind threw on the moon in the past.
You can play with the low gravity and with the fine lunar soil (although you would need a decent spacesuit to do that, NASA ones are a little too cumbersome and fragile), you can do some pratical simple experiments to see how things are different on the Moon, you have an amazing view, and it is probably the closest thing you will ever get to step on another planet.
Ah yes, and if you were a good tourist you will be allowed to bring back home a lunar rock of your choice. (or some Lunar Dust)

Thucydides said...
A Pearson elevator on the Moon could lift small buckets of regolith, and also serve as the anchor for a mirror farm which illuminates the base during the 14 day periods of darkness.
I was thinking more of a "ground robotic mining operation" that loads the buckets you send to an orbital industry that manufactures rocket fuel or something else.

Now, the orbital station may have an handful of techs to keep everything running or not, but the only human presence on the moon would be tourism in my concept.

-Albert

Rick said...

Thucydides underlines the core paradox of the space age so far. We have gone farther and seen more than most 50s era rocketpunk dreamed of for the early 21st century - landing on Titan, for example. But nearly all of it is robotic.

Truth to be told, for now the only reason to send humans up is learn how humans can live and work in space. The Hubble repair missions were tres cool, but it probably would have been much cheaper to replace it, even several times, than to repair it.


Mobile access to this blog is something I'm clueless about! (I'm purely a desktop user.) The RSS feed might be easier to read on a mobile device, and there may be smartphone apps for Blogger, but I know nada. Does anyone know their way around mobile, and have suggestions for Sabersonic?

Sabersonic said...

Rick: I'm more of a Desktop guy myself, though when reliable internet access is limited to a cell phone, one works with what one has.

Anyway, here's an interesting inquiry to those with sufficient knowledge in particular fields of science to answer. I recall some spacecraft designs that have hydrogen stored in tanks as a "slush". Would it be possible to store Anti-Hydrogen in a slush state as well?

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Zachary said...

Interesting post on the history of private space exploration at Marginal Revolution. Hadn't really thought observatories as a precursor to space flight before. At least not in an economic sense, anyway.

http://www.marginalrevolution.com/marginalrevolution/2010/07/the-history-and-future-of-private-space-exploration.html

Thucydides said...

It's all done with mirrors.

If you have an industrial base or tourist base on the surface of the Moon, it will make operations easier if there is a constant illumination, especially during the 14 days of darkness. The mirror farm could beam down electrical energy in the form of laser or microwave power, or the cable itself might be treated to become a superconducting power cable as well.

This also becomes another value added proposition; the mirror farm will probably generate enough energy to beam power to spacecraft in cis-lunar space, so the various space tugs can be much smaller and lighter as well. As traffic increases, the mirror farm can be expanded (rolls of aluminum foil lifted by the Pearson elevator make this very easy to do).

Anti-hydrogen could be stored as "slush" in theory, just do it in a far off location. I suspect the extra layers of effort and equipment to bring anti hydrogen down to that level and store it in large quantities will make any ship operator or safety inspector blanche in horror. I'm not very big on the idea of metastable elements like spin polarized helium either; one molecule reverts to ordinary matter and the entire stock detonates at once in a massive and probably non linear energy release.

Sabersonic said...

So I'll assume that Anti-Matter has a kind of half life to which it degrades back into normal, mundane matter. Not really sure how or why that happens, my physics isn't advanced enough to understand.

But back to another weird idea that mulled around in my mind. The general consensus is that FTL equates to time travel and that FTL communication is just as bad as FTL travel paradox-wise. Then a weird thought occurred after some marination in my brain that suggests that FTL communication is potentially sending messages back in time, but due to the great distances in between star systems the effect is almost nullified so that it gives the illusion of near-real time communication.

So is this a plausible thought pattern? Enough techno-babble worthy of any Space Opera or scientifically horrible enough to regulate the idea to 1930's pulp fiction?

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Jim Baerg said...

"So I'll assume that Anti-Matter has a kind of half life to which it degrades back into normal, mundane matter."

No. Left to itself antimatter is as stable as ordinary matter.

The problem is that if matter & antimatter meet they mutally anihillate (releasing a LOT of energy). So storing antimater is difficult because you need to stop it from touching any ordinary matter.

VonMalcolm said...

Ignore this comment: just 'bookmarking'.

Rick said...

I'm with Thucydides here, skeptical about the safe storage and handling of antimatter. As Jim B said, it is stable so long as you keep it away from ordinary matter, but that's the tricky part.

On FTL, anything having to General Relativity is waaay above my math pay grade. But I gather from comments, for example on 'Rapid Transit,' that FTL need not imply time travel of the disruptive sort, i.e., to your own past.

That discussion was about travel, not communications, and involved time dilation, but there might be equivalent models for GR-compliant FTL comms. (Luke, are you following this thread?)

Jim Baerg said...

"That discussion was about travel, not communications, and involved time dilation, but there might be equivalent models for GR-compliant FTL comms."

Point a communication laser through a wormhole that is set up as in the earlier discussions about using wormholes for FTL travel. For this application the wormhole can have a much smaller apperture, but you might as well just use the same large wormhole for both communications & sending objects.

Thucydides said...

So far as is known, causilty violation takes place when you try to use multiple wormholes to return to the point of origin.

This is countered by the stress the approaching wormhole mouths place on spacetime, which generates clouds of virtual particles and forces a collapse of the wormholes (with negative consequences to everyone around, there is a great deal of mass and energy involved here).

Even earlier work such as the Tipler machine hinted at this, a T machine can only take you as far back as the origin of the machine, and you can only go as far forward in time to the point the machine ceases to exist.

It would seem that wormholes can only work under a very tightly limited set of circumstances (so far as we know). Perhaps the other solution is wormholes which set up causilty violation actually take you on a one way trip to a parallel universe, and you effectively cease to exist here the second you step through to kill Hitler or set up Grandpa with the winning lottery numbers...

Sabersonic said...

So wormhole-based FTL communications or similar is possible without violations to causality so long as not too many wormholes are involved. Though I wonder if there's a non-wormhole centered possibility, that is to say the "broadcast" version of FTL interstellar communications as so featured in sci-fi and space opera.

And I'm pretty sure that there isn't anyone to monitor this thread considering how old it is compared to newer ones, let alone those that would be able to comment, but I might as well ask this other question since the chance is still open. Back during the Good Shepherd Blog Entry I asked about a potential Alcubierre Metric-esque based Interplanetary Drive for my setting whose basic operations were given technical detail by Citizen Joe's response.

My inquiry comes from how much energy was required to produce such a warpage of Time-Space to have such a drive be the sole propulsion system of a starcraft. How I imagined it was that though the Alcubierre Metric could theoretically propel a craft to FTL velocities, it could not practically move that much mass to such velocities by such means alone. That it requires a reaction engine to push the ship forward and displace the warped space in relation to the rest of the universe while the spacecraft itself and the warp bubble are relatively stationary (in which the assumption is that the warp bubble is relatively fixed to its position around the spacecraft instead of being loose and "disconnected" from each other). This combination propulsion for rapid interplanetary travel not unlike a ramjet or similar.

My question is that if this is a plausible answer to the whole "negative energy" requirement of the so-called warp energy or not?

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