space technology

[nasher168]

I wonder if one day people will look back into history and hypothesise on the migration routes of humanity from Earth...

 

[MRaverz]

I wonder if one day people will look back into history and hypothesise on the migration routes of humanity from Earth...

I think that if we got to that point, we would have had to have lost track of each settlement and therefore are likely to have diverged into separate species. Then the aliens we imagine through sci-fi would be creatures which share an ancient common-ancestor with us.

Or perhaps that's already happened?

 

[Master_Ghost_Knight]

Large solar collector arrays to power the installation, a ground based linear catapult to launch from the surface, powered by the sollar array which can produce enough power to launch small craft back into lunar orbit, from there you can dock with another ship to take you back to earth meaning the actual pods would need hardly any fuel, and you'd be launching a lot of them, because you'd be mining the moon for resources.

You would need a very very large array or else it would take years, more then I am willing to stick arround.
But the worst problem here is, you can't get into orbit without manuvering or else you will just crash back on the surface, and that requiers fuel. It takes less fuel because you saved on the energy that took to gain altitude. But before you say "hey but I said that you could dock with a ship in orbit", but to be in orbit you need a certain speed which is much much higher then an elliptical orbit razoring the surface and the desiered orbit, meaning that the ship in orbit will aproach to hot whatever you wanted to put in orbit transforming everything in a pile of space garbage.
Manuvering=fuel is necessary.

The last thing you'd need to eventually build is a small space elevator. Most of the difficulties inherent in making one don't apply on the moon. It wouldn't have to be nearly as long and there's no atmosphere to interfere with it, it's just a matter of building it out of lunar materials instead of terrestrial ones and that would be a whole other problem entirely, seeing as how the only thing we can postulate as ever being strong enough to build a space elevator on earth is carbon nanotubes... and there's almost no carbon on the moon. There's Iron, but that doesn't have the tensile strength and there's silicon which does but is ridiculously heavy and brittle.
Unless of course it turns out that silicon is just as maleable a material as carbon is, but I'm pretty sure it isn't.

I don't think you comprehend the size of the structure, even without atmosphere, even with a smaler gravity the structre would still need to be several miles in heigh and I don't think there is even any kind of material capable of suporting that, we are talking millions of tones of materials that may not even exist, and if the structur flinches just a tiny bit (which most then certainly will) you endout with only a pile of ruble. It is just pratically undoable with current technology. Unless you find another form of elevator you can scratch that out.

 

[aeroeng314]

But the worst problem here is, you can't get into orbit without manuvering or else you will just crash back on the surface,

Unless, of course, you hit escape velocity. You actually wouldn't even have to do that, since you'd really only need to get up high enough for Earth's gravity to catch you. You'd definitely need maneuvering thrusters at some point, but the fuel costs for maneuvering in the vicinity of the moon are considerably lower than those for maneuvering in the vicinity of the Earth.

but to be in orbit you need a certain speed which is much much higher then an elliptical orbit razoring the surface

If you go to an orbital altitude of 50 km above the moon, the difference in orbital velocity between a circular orbit and a transfer orbit to the surface is about 12 m/s.

 

[Ozymandyus]

Space elevators are a lot more possible than you would think, actually. I argued against the possibility in another thread a while back, but apparently many scientists think its possible. Particularly on the moon, where gravity is lower and thus the tensile strength of the structure can be much lower.

http://www.spaceward.org/elevator2010
http://en.wikipedia.org/wiki/Space_elevator
Japan's plan to build a space elevator.:
http://www.timesonline.co.uk/tol/news/science/article4799369.ece
http://www.spaceelevator.com/docs/521Edwards.pdf
Lunar space eleavator:
http://www.niac.usra.edu/files/studies/final_report/1032Pearson.pdf

The Earth-based elevators seem to require some materials technology advancement - mainly count on carbon nanotube structures that they hope will be available.

 

[aeroeng314]

I argued against the possibility in another thread a while back, but apparently many scientists think its possible. Particularly on the moon, where gravity is lower and thus the tensile strength of the structure can be much lower.

Especially since you can hang a lunar space elevator down below the Earth-Moon L1 point and make it easier to reach the moon.

 

[Master_Ghost_Knight]

Erhm... Never in a million years.
The L1 point is not even stable, secondly it is about 56300 Km over the surface of the moon, you can make your cable of whatever material you like, the cable will simply break just by standing there.

 

[nasher168]

Erhm... Never in a million years.
The L1 point is not even stable, secondly it is about 56300 Km over the surface of the moon, you can make your capable of whatever material you like, the cable will simply break just by standing there.

Is there another way of doing it on the moon? Or will it just not work?

 

[Master_Ghost_Knight]

Is there another way of doing it on the moon? Or will it just not work?

If I knew I wouldn't probably be here talking to you (but conducting a study and gathering funding to put it in practice). I can not say what will work, I can only say what will not work given that some of the keypoints have failed.

 

[Ozymandyus]

Erhm... Never in a million years.
The L1 point is not even stable, secondly it is about 56300 Km over the surface of the moon, you can make your cable of whatever material you like, the cable will simply break just by standing there.

You clearly have not done the math. Read the resources I linked to and then come back before claiming it cannot ever happen in a million years.

I know it seems impossible at first thought, I had the same reaction. I still don't understand how NASA and Japan's Space Elevator Association think its possible to build one for less than 10 billion dollars, but thats the claim.

 

[Ozymandyus]

No one has mentioned Skylon here either, which is a single stage to orbit vehicle that shows some promise and is in the late stages of development.... Hopes for 66-330$ per pound sent to orbit.

Edit:
Links: http://nextbigfuture.com/2009/01/progress-to-skylon-single-stage-to.html
http://www.reactionengines.co.uk/skylon_vehicle.html

 

[sgrunterundt]

Erhm... Never in a million years.
The L1 point is not even stable, secondly it is about 56300 Km over the surface of the moon, you can make your cable of whatever material you like, the cable will simply break just by standing there.

No L1 is not stable. However an elevator with a tension cable and a counterweight slightly on the earth side of L1 would be.

And as has already been pointed out you need to do the math. An L1 lunar space elevator could be build today. Commercial cables are more than strong enough. We don't even need to wait for super strength nanotube cables, glass fibre will do, and there is no shortage of SiO2 on the moon.

This one claims that a cable capable of lifting 200kg of payload could be send up with one rocket launch. Once it is there we can strengthen it with moon produced fibers.

http://www.universetoday.com/2004/11/18/space-elevator-build-it-on-the-moon-first/

 

[Master_Ghost_Knight]

You clearly have not done the math. Read the resources I linked to and then come back before claiming it cannot ever happen in a million years.

I know it seems impossible at first thought, I had the same reaction. I still don't understand how NASA and Japan's Space Elevator Association think its possible to build one for less than 10 billion dollars, but thats the claim.

For a matter of fact I haven't, let me get my hand on some more reliable data and i will comeback to you with a number.
Edit: Whit a coarse calculation, I guess you can technically do it with nanotubes, some other problems where aparent like how to keep the cable in it's place which will stress the cable even more, but I will entertain the concept that it is possible, go nuts...

 

[sgrunterundt]

Edit: Whit a coarse calculation, I guess you can technically do it with nanotubes, some other problems where aparent like how to keep the cable in it's place which will stress the cable even more, but I will entertain the concept that it is possible, go nuts...

That must have been a very coarse calculation. Keep in mind that the gravity drops off quickly it does not stay 0.17g all the way to L1. When adding together the gravity of the moon and the earth and the centrifugal force of the rotating coordinate system and integrating it, I get a necessary specific strength of 2800 kN*m/kg (or a breaking length of 285km under one g). A commercial spectra fiber could do that. Without taper!

How do you get numbers that suggests it is only a far out theoretical possibility with nanotubes?

And of course as I already stated it is stable. The instability of L1 is in the direction along the line joining the two bodies (a little to close to one of them and you fall towards it). The other two axes are stable. That means in order to keep stability you just make the counter weight a little too heavy so that the cable is under a slight tension even at the surface. The counterweight then wants to fall towards the earth but is stopped by the cable.

 

[Master_Ghost_Knight]

Coarse as in, Ignore the effects of earths gravity, ignore the efects of the centrifugal force, ignore elasticity, ignore that the cable must be locked in position, ignore cable thikness, ignore colapse via shearing stress, assume cable density equal to water and assume that cable tenacity as expressed here: http://en.wikipedia.org/wiki/Carbon_nanotube
I was expecting it to break in such condition but unless i misscalculated by an order of magnitude it seams to hold.

 

[leephawk]

On the consideration of carbon nanotube or boron nitride nanotubes: the ability to create them and to have their functionality (physics only) has been proven to theoretically work. What keeps it near-impossible for the time being is the cost, manufacturing time/resources, and, most importantly, no means of declaring kilometers-long cable safe from breaking and damaging an equal distance of landmass and how detrimental it would be to human life if such a catastrophy happened.

On the topic of the effective use of a lunar station/base: It has been proven that there is water which can be used for both fuel and for human consumption/resources for sustaining life thus greatly minimizing necessary transportation of cargo in order to keep the station/base sustained. Space exploration--manned and unmanned--would benefit from launching from the moon's orbit as the energy required to break orbit is much less. The telescopes/satellites alone would be able to be maintained more easily and cheaply.

On the ideas for other forms of space travel/propulsion/etc: I love this topic and have toyed with a few ideas regarding this.
-The questions of why we haven't progressed as fast as we should is due to the limited amount of funding for these programs.
-Ion thrusters have been made and have been used: Deep Space 1, Hayabusa, SMART 1(used to propel itself into the moon to find (which it did) water, Dawn, GOCE, for examples. Plasma thrusters may be used for the first manned mission to Mars.

My first failed attempt at a new propulsion idea was to geometrically combine EM multipoles so that the created field could be directionalized to propel an object at high rates of speed with the bonus of having a strong enough field to possibly repel ("repel" isn't the best term) small debris that may be in the way. My idea mathematically failed as the energy required to make such a thing is astronomical and to thoroughly calculate the precise multipolar geometries seems to be curretly beyond my ability--if it can be done at all (without relying on n-dimensional theory)-- as the field "center" is minutely small. I still toy with this thought and am currently learning the skills needed to attack this idea at other angles (vice relying on my PhD acquaintances to tell my my math is one lengthy piece of garbage). Heh.

 

[Sinue]

I'm sure the cost of sending human beings to Mars within the decade would pay off exponentially, as the new technologies and innovations we're forced to come up with find application in the private sector. The problem with cost is that returns on the investment would be non-linear, and those footing the bill in the short term would likely loose their financial asses on the endeavor. Even were the US and allied nations to face a prominent political opponent in an arms race, the conditions would not replicate a "Space Race" scenario. ICBMs are now too effective to be used as motivation for dominance of space, and military operations today tend towards high tech integration and precision strikes. Any resultant "space race" like scenario would probably manifest in man-machine/animal-machine interfaces, robotics, nanotech, tissue engineering, and genomics. The kinds of fields we don't want being pressured (moreso than they already are) into producing vulgar political/military displays of aggression/supremacy.

The Space Race was a grand endeavor for mankind, and a triumph for our species. But let's not kid ourselves. Were it not for the Cold War tensions underlying the space program, we'd probably still be exploring the Moon with probes and wondering when we were going to see a manned mission.

I think a mission to Mars needs to be undertaken, and fairly soon. That we go to Mars isn't in itself the important thing. The importance of a Mars mission is to recapture that spirit of adventure and rekindle our inspirations for space exploration as a nation and global community. That public and policy push is needed to generate the interest in curiosity driven fundamental research which has been lacking (imo) since the Bush Administration, as well as the increasing industrialization of science pushing product-oriented research. Granted, while it was the Bush Administration which did the most in recent memory to set a goal of a Mars Mission, the endeavor seemed to be little than back-burner project that was more intended as bolstering his public perception. If not, then it's (imo) just another well intended, but ultimately botched Bush Policy. History will not remember Bush as an inspiration to Mars as it does Kennedy inspiring us to the Moon.

 

[Louis TH]

There is just one problem. There is no fuel on the moon.

Well, we've observed no fuel on the moon--doesn't mean it's not there. We only have, what, a thousand kilos of rocks and some spectroscopy--and only very recently did we even obtain impact spectroscopy, so we really only have albedo spectroscopy.

Actually there IS fuel on the moon, in two forms. The first is alumnium oxide, which when decomposing may have a low specific impulse, but because it is found on the moon, and due to the lower gravity, using it would be more than worth it.

The second type is Helium-3, which can theoretically be used in fusion reactions.

Oh and by the way, the Orion Capsule has been reassigned to just being used as an escape system for the international space station. Reason for this being is that President Obama feels like it is not advanced enough. He probably wants something BETTER.

But is it possible that we may one day revisit the National Aerosapce Plane (NASP) project?

Anywho what we need is a better way to leave the earth, just as we needed a to leave the ground before we could enter space. And we also need ways to make things more capable while being lighter at the same time. But progress has been made, as when the space shuttle first launched, the lightest music player was a casette playing walkman. Now its the ipod shuffle.

 

[Netheralian]

I suggest the people making the claims about the Space Elevator as being infeasible, should really read the links that Ozymandus posted. Or did arguments from ignorance become a valid argument when its nothing to do with God? This is complex topic where a lot of research money has been spent - there is even an international coference on it each year as well as the space elevator games which is supported by the various national space organisations. It is not a guess or a wild fantasy.

Coarse as in, Ignore the effects of earths gravity, ignore the efects of the centrifugal force, ignore elasticity, ignore that the cable must be locked in position, ignore cable thikness, ignore colapse via shearing stress

That's a pretty poor calculation if you are ignoring the main loading factors. Space elevators are feasible based on the theoretical strength of Carbon Nanotubes - although there are clearly still some practical issues to resolve (manufacture of sufficient nanotube length and cost effectiveness namely). And what collapse via shear stress are you refering too? The cable is under tension and is flexible. You seem to be under some massive misaprehensions about what a space elevator is based on your earlier posts.

no means of declaring kilometers-long cable safe from breaking and damaging an equal distance of landmass and how detrimental it would be to human life if such a catastrophy happened.

Neither are they a problem for the surrounding landscape if there is a breakage - nothing is going to be crushed under its fall as the typical mass density of the elevator is around the order of 1kg/km.

And clearly there is plenty of fuel on the moon - its called water. Although getting it may be difficult, but probably no more difficult than mining He3.

 

[Deleted member 1004]

Anyone remember the X-33?

This Shuttle replacement was the proposed advancement, into a fully reusable single stage launch system with the Aerospike engine. It was such a kicker to see this beast cancelled to budget constraints and a fuel storage issue, almost 10 years ago now (resolved a few years later with carbon fibre composite tanks). The project was (on all aspects) something like 80-90% complete at the prototyping and testing phase.

To add to the original discussion, I too wish there was more development in this field. It's such a pain to see a budget 10 times the size of the total ISS cost (ESA Estimation of $100billion) to go into the war machine. With money like that, 10 ISS's would be plausible, and incredibly quick to deploy over the 30 years it's taken from planning - launch of the current ISS layout. At that stage one has to wonder... why not say, 5 ISS's and a moon base? Not only that but how about backup missions - have a double or even triple launch in case the first one fails or gets KO'd on route by a rogue meteor for example.

I would hate to see Carl Sagan's face with such figures... I really would.