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How does one anchor a cable to and orbital platform, without pulling the platform from orbit?
By having another, equally heavy cable going the other way. Thus the center of mass is in geosynchronous orbit. The cable need not be rigid, and the end is not supported by being on the ground. If it is too be tapered at all, the wide end is at the top.
I'm optimistic that we're on our way! Smile
So am I. I'm kind of surprised NASA hasn't been putting much thought, that I know of, into a space elevator. If a private company builds it, NASA and other parts of the government (such as the military) will be paying them every time they want to launch something, while if a government owns it it can reap in the tax dollars from private use.
Consequently (and there are legal cases that back this interpretation) it permits weapons of military value.
Can I get a tank for self-defense? How about an ICBM?
The "loop" idea doesn't work because the cable has to be tapered - much fatter/wider at the top.
I see the reason for tapering, but I would think it would create problems for the climber. Any climber that grips around the cable will need to constantly be readjusting the size of its grip. And CNT doesn't give much traction, I think. Would a non-tapered cable be possible, or would the weight simply be too much?
-- Is there any reason why a sufficiently broad cable could not be able to accommodate cars moving up and down simultaneously, which is how I'd always visualized the system working?
Interesting; I'd never thought of using a broad cable like that, but I don't see any real reason for it. Is there any advantage over two cables with it? Even for the power transfer idea, you would need to have a power line running the length of the cable. With two cables you could still have the power line running the length of each and connect them at the bottom to transfer power. But if you're running a power line up the elevator, you might as well just build a power plant at the bottom.
The tracked climber design is limited in speed - a trip up to GEO will take about a week if I recall correctly.
I'm not sure if this would be practical, but could you have the cars stop in LEO, and unload passengers and cargo at a space station attached to the cable there. The cable would still continue to GEO and beyond, to put the center of the orbit in GEO. But only the lower part of it is used.
Sometimes I wonder just what percentage of humanity is certifiably nuts!
This especially applies to criminals, particularly those who commit really horrible crimes. I sometimes wonder how anyone in their right mind could do some of these things. But only a small portion are actually found to be mentally unstable and are put in psych-hospitals rather than regular jails. Ultimately, I suppose, insanity is rather subjective anyway.
Interestingly, a simple statistical correlations shows that, in Western countries at least, the places with the strictest gun control laws have the highest crime rates and further that crime rates increase as restrictions are tightened.
This seems surprising, although I don't have any hard data on it. The US, for instance, has high crime rates and it is fairly easy to get guns here. Also I would compare specifically violent crime rates, rather than crime rates in general. If you have, say, more burglaries and fewer murders, you may have slightly more crime of less severity.
While I do not propose denying people the right to keep and bear arms, I think that if we all carried weopons all the time, we would go back to the age of "gentlemen" dueling over an insult.
It would probably make the most sense to build an elevator with two cables: one for traffic going up and one for traffic going down. This will be initially more expensive, but will save money on atmospheric reentry and will more easily facilitate the transportation of people. Building the second cable will also be easier once the first has been built since the first can be used to bring material up.
Another possibility is to have a single, moving loop of cable with stationary cars on it. This puts all power requirements at the bottom or top, makes it easy for cargoes to be carried up and down at once, and makes monitoring and repair of the cable easier.
When we get to the point where Earth is importing things from space (PGMs, He3, etc.) and when ordinary people regularly travel to orbit or the moon for vacations or even for work, down as well as up transportation will be absolutely crucial.
I once suggested that since a space elevator would require cables going in the opposite direction from Earth to keep it in the correct orbit, these could be used for a rail gun launcher like what Dragoneye describes. However, I forget about the problem of recoil, and when I was reminded of that it essentially killed the idea. I do wonder, however, if recoil could be dealt with somehow, that is by using something to push stuff back in the other direction. Shooting something back at Earth seems like a simple solution, but it might annoy the guys down there. Rockets could be used for repositioning, but would require a lot of fuel. Perhaps some system where you could send payloads both directions without having any of them aimed at Earth would work. I'm not really sure what, if anything, would be a viable solution to this.
For some of the other problems:
Construction: If this is part of a space elevator you will need the basic cables anyway so the extra work will be mostly adding the magnets (still, admittedly, quite a bit of work). If this is not part of a space elevator, then having a space elevator will still be crucial for bringing up the parts. Rockets would be unable to bring up all the material in a decent number of launches. The good new is that the chances for carbon nanotube space elevators are looking better as discussed in Space Elevator, Ho! http://www.newmars.com/forums/viewtopic.php?t=3801
Aiming: It might be possible to make the last few kilometers of the track adjustable to allow aiming without moving the whole length of the thing.
Power: Since you will need a long track anyway, you could attach solar panels along the length of it to make a very large solar array. Each electromagnet could perhaps have its own solar panel and relatively small battery. The downside is that this would cost a lot and be a lot of work to put together and more weight to bring up. Using a reactor and a solar array together and having all launches at times of maximum sunlight would minimize the need for power storage.
For something like this, there are a lot of hurdles to overcome, but I am not giving up on it just yet.
I'm not opposed to gun ownership (my father had two shotguns, my husband has a pistol and a shotgun), but if we "have to" arm everyone then you're implying (which sort of scares me) that the overall crime issue is so terribly out of control...
I agree. I tend to feel that police carry guns so the rest of us don't have to. The government is supposed to provide a trained, professional force to deal with crime. Giving that responsibility to the citizens, who are not trained in law enforcement, seems both irresponsible and a bad idea. Further, I think that the right to own weapons also basically includes the right to not do so.
If everyone is armed, it may help to keep down crime, but it also may lead to vigilante violence or dueling in the streets. Also, having a gun in every home greatly increases the risk of domestic violence.
If everyone has to have a gun, it's a problem not a solution.
Alright, lets say the nanofibre ribbon is useful in constructing what is essentially a km long, 100 m diameter sock and is of sufficient material strength to allow light while having earth air pressure and temperature on the inside and mars pressure and temperature on the outside. We could use it as a greenhouse and the airpressure difference would keep it inflated. We would then need to mix our own growing media from the Mars top soil.
Such things have been suggested with other materials, but the nanotubes would probably be stronger than other materials. It might also make sense to use nanotubes in constructing habitation domes and other structures besides greenhouses.
The nanotubes tangle together just enough to keep a ribbon growing
Doesn't sound very strong to me. No cable stuff, I'd guess. Still, a very interesting development.
The full sentence was "The nanotubes tangle together just enough to keep a ribbon growing, without jumbling up into a huge ball." A scientist was then quoted as saying "They've found the magic spot." The implication, I think, is not that they tangle together just barely enough, but that they tangle together enough but not too much.
I don't know if these ribbons will be strong enough for space elevator cables. But I suspect that strong enough nanotube cables will be available eventually, probably soon. The technology is still developing and there is still plenty of room for improvement.
True freedom is the right to do unto others as I wish without effective judgement or reproach.
Yes, I guess that would be freedom, but it is also undesirable. Perhaps we must clarify what we mean when we say we want freedom.
Actually its called freedom...
Anarchy would be where I didnt respect your right to the same.
Such freedom would never work, because not everyone would respect everyone else's rights. When this happens and there is no government to step in, the system collapses, and you have regular old anarchy. In this case, groups of people start banding together to protect first their lives and then their rights. They will follow those who can protect them, even when it involves sacrificing some rights. Gradually the groups most able to survive and to gain power do so, and the other groups are destroyed, repressed, or assimilated. The simple governing structure of groups evolves to form the governments of states either instituted to protect the rights of the people or forced upon the people by their protectors who have become corrupted by power.
Another problem with all respecting each other's rights is that we disagree on what these rights are. Martian Republic has a very good point that we need to determine what freedom is.
*Has been on my mind, might as well say it:
Doesn't it seem that believing entirely in evolution has thwarted us? The 18th century Enlightenment was a heady period of nearly unbounded potential and promise. Sure, certain elements of that philosophical period were overly optimistic, but most of its philosophes were logical and realistic (for the time); not all got carried away with optimism.
Along comes Darwin...and it seems we've fallen on our faces. In some respects (politics aside), the Apollo Program was borne of the Enlightenment "can-do" spirit.
The overall human reaction to evolution seems to be: "This is all we can ever be." (Fatalistic, why bother?) Apathy, stasis, "who cares?" seems to have followed as a result.
The non-evolutionary "explanations" of our existance do, despite their inherent flaws (and ignoring the fossil record), seem to continue to hold out the concept of "this isn't all that we are; we can be better" (self-determination).
I certainly like a lot about the enlightenment spirit, but I don't think that Darwin killed it or that a belief in evolution has slowed human advancement. The enlightenment was mostly before Darwin's time, I think, and yet to come were the revolutionizing inventions of the late 19th and early 20th century (electricity, automobiles, telegraphs, and great advances in railroads, steam ships, and industrial technology, among many other things) as well as those of the later 20th century (computers, spacecraft, and lots more). Of course, at first few people beleived Darwin's theory and even now many don't. But advancement, in technology at least, has been mostly brought about by scientists who tend to use reason and logic and who are more likely to accept evolution than other segments of the population. It seems to me that those in modern times who carry on enlightenment ideas (Carl Sagan comes to mind) tend to be those who accept evolution. Finally, for the human reaction to evolution, many people, as responses on this board indicate, react not with fatalism but with empowerment (e.g. Cobra's "Rather than being merely a reflection of God we can through our own toil and genius become Gods.")
Not to mention that other nations would rightly be a little worried if some nation started mass producing thousands of new nuclear warheads and then placing them in orbit.
On the other hand, if the US or another major nuclear power started using its bombs to propel a spaceship rather than keeping them as an ever-present danger to humanity, other nations would have little to complain about. I tend to think that Orion is rather impractical, better options for similar amounts of money and work exist, but one advantage is that it could be a way to decrease the nuclear arsenal. American and Russian bombs being used together to push humanity into space seems particularly nice.
Tell us all why you have a right to a market share of resources.
It is generally assumed that everyone is born with a right to life. Some people beleive this right is inalienable, a view I tend towards, while others say it may be lost if abused. I will assume we are talking about someone whom we all agree has the right to be alive. From this premise we naturally arrive at the conclusion that one has a right to enough resources to stay alive. After that it gets trickier and more subjective. Does one have the right to only enough to stay alive? Or enough to have a real chance of accomplishing something? If the latter, how long should one be provided with opportunity if he does not avail himself of it. And to the original question: While we all have a right to something, I think that some have a right to a greater share of resources that others. Hard work should pay off. Great accomplishment should be rewarded. Ideally we should all get a good start with plenty of opportunities and should be able to advance ourselves from there based on merit.
I prefer to govern myself, and not be governed by others.
That sounds more like Anarchism than Communism. Certainly it would be nice if we needed no government, but human nature won't allow it to work. And it can be argued that it is good to have a government to look out for its people rather than making it everyone for themselves. The ideal, I think, would be a government that protected the people's rights and, to a limited degree, looked out for their well-being but did not intrude very much into their lives. It's a tough balance to get right, and we won't all agree on what the perfect balance is. Honestly, I'm not sure what the perfect government would be, but I'm sure it will never exist.
The trash would also keep ships carrying colonists or supplies from getting through. If it was thick enough to block some of the sun's light, then it will also cool Mars -- probably the last thing the planet needs if people want to live there.
Escape pods could probably not be made with the propulsion power to reach a planet from somewhere far between two (such as Earth and Mars). However, if starships fly regular routes, you can escape in something small but with life support and wait for them to pick you up.
String theory is a natural progression to a certain technological point. Matter is made up of strings.
Strings are possibility branches.
If technology advances to a certain point, we will have the ability to shape possibility.
Twisting a string in a given direction apparently defines matter from antimatter.
If we achieve the advance, we discover a way to change the path we are on.
If we change the path we are on, we create a twist in the strings that make up our existance.
A change in possibility thus becomes a conversion from matter to antimatter.
Suddenly our existance in the possibility we have left behind is nulified by matter changing into antimatter.
The Other us goes boom, taking every one with us...So Scienetific advancement to a certain stage of technology could essentially wipe intelligent life from from existance.
That means that string theory is the number one anihillator of civilizations-up there with home made Black holes.
To many of the steps of this proof are conjectures for it to be taken as anything more than just one more possibility. In particular it seems to much to assume that there is a technology to turn large quantities of matter easily into antimatter by twisting there strings. Also if you're antimatter, and everyone and everything around you is antimatter, you don't go boom. You don't even notice.
A good question is can you send plans to get to you.
Plans for a space ship or just a map? And what if they just say "Yes."
If they cant then they probably aren't worth talking to.
Don't bother trying to talk to those Earthlings.
Seriously, I think any extraterrestrial civ would be worth talking to. Unless we knew a lot anyway; then we might have to pick and choose, and your rule would work fairly well since those we can visit will probably be the most interesting.
My question:
What do you know?
Seems like that gives us the most bang for our interstellar buck.
I agree. That is a great question to ask them.
Sounds like a good idea. In the spirit of mutual cooperation we could then broadcast all the info we can think of about Earth, ourselves, our history, our ideas and philosophies, and our knowledge of the universe. If we receive a similar database of knowledge, likely a larger one, it will occupy us for centuries.
Two thoughts to apply generally to the idea of communication with extraterrestrials:
1) We should be very specific and perhaps even redundant. Even when we find a way of communicating complex ideas, that is develop a common language or learn each other's, different linguistic conventions could lead to misinterpretation especially where something is not meant literally.
2)Why send one message every 100 or whatever it might be years? Send one every day. After an initial delay we will also be getting one every day. Thus we will sort of have a constant dialogue; that is there will be a constant exchange of information.
I'd rather have been created in the image of a supernatural being than a monkey.
I prefer humanity being the best yet (in our own minds at least) of everything that has lived on Earth over millions of years, but perhaps not the best ever to come, than a flawed clone of an ideal being. In my opinion, evolution fits well with the spirit of advancement.
Anyway, whatever we may personally prefer, evolution by natural selection appears to have happened. Large quantities of data appear to prove it, and there are no data with which it is incompatible -- something that cannot be said for creationism, intelligent design, or any other hypothesis that I know of.
Inertia reduction certainly seems like a great way to launch spacecraft, perhaps too good to be true. Since it's still theoretical, it may come to naught. Nevertheless it's worth looking into. It would really revolutionize our world.
I wouldnt recommend it. If you do that to people, they are likely to go insane. Side effects could be very bad. Not in the slightest bit healthy. The last thing you want is a bunch of realy smart people going insane while they are incharge of a "bomb".
Can you just reduce the inertia of a craft and then put people in it?
-- As I understand it, there are different ways of looking at how a Higgs Boson imparts mass to an object. I believe one way is to imagine a universal sea of these strange particles which interact with matter when you try to accelerate it - perhaps somewhat like glue (not a great analogy in many ways, I'm sure, but just for illustrative purposes).
I'm not sure if it would be possible, but if somewhere in space there is a hole in this field, an area where the Higgs Boson is not present, or if such a thing could be created, it would make for some rather weird physics. Even if there are no holes is the density of this "sea" equal in all places? If it is not, the gravitational constant is no longer constant, and calculating the interactions of bodies in other parts of the universe becomes a whole lot harder.
This reminds me of something I once read. Supposedly a Russian scientist discovered a reduction in the weight of objects above a spinning superconductor disk. I'm not sure if this experiment was ever repeated by anyone else, though. Would a spinning superconductor have any effect on the Higgs field?
As for the jihadis, who do wish us harm, former CIA analyst Marc Sageman estimates the number of radical Muslims who can and would do significant harm to the US in the hundreds.
I know that most can't and wouldn't, but the number still seems a little low. I would be more inclined to guess in the thousands. But that's just a guess, without much of anything to back it up.
They cover the actual costs above a certain level, every worker can opt to pay into the system, or not at their discretion.
What about those who have no jobs or those who make too little to afford it. You will still have people "dying in the streets from TB," since the people in the streets don't have the money to pay into the program. Theoretically this program could provide a better alternative to private healthcare for middle class workers since it would not be concerned with making a profit, but considering that the government is running it, it would probably end up costing more. And it does nothing to solve the problems of those who cannot afford insurance.
Perhaps a system where the government makes sure that everyone has healthcare, but where it is not the only service provider would work well.
Michael Savage says Bush is too liberal!
I don't think the left wants to take him, though. And he still has the support of many on the right. I guess that some of what he does isn't really conservative by definition, but in other areas, especially the "moral values" stuff, he is definitely conservative. And I certainly wouldn't call the war a "liberal exercise in nation-building."
PS - - Hillary Clinton wants to expand the army by 80,000 soldiers, so we can "stay the course" in Iraq!
Where does she expect to get the soldiers. The army is already not meeting its enlistment goals as people, quite reasonably I think, don't want to risk death in a war with no end in sight and no apparent benefit to the country. To get more they would have to resort to a draft, an unpopular and unjustified step clearly not worth it for this war.
In the thin Martian atmosphere of today, liquid CO2 on the surface would evaporate very quickly. It wouldn't flow well, certainly not across any great distance. And CO2 coming out of the ground would erupt forcefully out into the air, not flow out in a river. Furthermore, most of the large outflow channels and valley networks do not look very recent and have been dated to Noachian or early Hesperian times (within the first half of Martian history), when Mars was probably warm enough and had a thick enough atmosphere to allow liquid water to exist on the surface for long enough to carve these features. Also, riverbeds and flood channels are not the only evidence for water. Opportunity and Spirit have provided geological and chemical evidence, such as the "blueberries", for surface water in the areas they are exploring. We keep learning more about Mars's past, and we keep seeing more signs for water. CO2, as the major agent of erosion, presents many more problems than does water and is thus a less likely explanation.