Space Elevators and Other Alternatives

[clope023]

Sure, we can do whatever we want, but why would people want to? You implied that space travel was a long-term need. If it's just something we would do for fun, then there is no need for it and you'll have a hard time convincing people to spend trillions of dollars on it when there are things we actually need to spend that money on.

Sagan called this idea your perpetrating a fallacy of the excluded middle

 

[sophiecentaur]

I looked at the movie. Sagan disappointed me a bit, with his attitude. He implies that young people would have "something to aspire to" in the shape of space exploration. The actual exploration or colonisation would be open to a tiny part of the Earth's population (condemning the majority to vicarious appreciation only) the majority and the entertainment value of the activity would be no more than what's available from Football on TV on a Saturday afternoon (which is far more of a feasible aspiration for your average young lad and far less in £ per head).

Science is a vast field with many potential contributions to the future of Humankind. Space travel is not the only sexy thing to investigate and the cost/benefits are questionable. How come people seem to be determined to treat Space Exploration as the equivalent to the Wild Frontier? The ideas get fuzzier and fuzzier when they are challenged with the actual timescale involved. There's nowhere out there which is near enough to take surplus millions of population. I'm sure people have the Azimov trilogy in their minds when they talk of a 'future in Space'. Or is it 'warp drive' that will solve the problems? Without ftl, we are pretty well stuck in the Solar System.

Space, as a source of materials, is attractive but can you really imagine the quality of life of a long-term colonist on Mars? Sounds like more exploitation followed by eventual demands for Independence , followed by revolution.

The space elevator is a fantastic thought exercise but could we get the food situation sorted first, please?

 

[Carrock]

There is plenty of evidence a space gun is feasible but not necessarily economic. eg
http://www.astronautix.com/lvs/maret2g1.htm"

No, there really isn't. That link, for example, is a rocket fired from a gun, not a gun alone.

Since it's never been done, it is certainly a stretch to say it is feasible, in any sense of the word.

Many scientists believe that a large satellite was succesfully launched from Earth some time ago using inter alia processes that could be used in a space gun. (see below)
So if something is feasible once it's been done then such a satellite launcher is feasible.

Besides the fact (again) that a gun alone can't put an object in orbit (the payload needs to contain a rocket in order to shape the trajectory into an orbit), the theoretical limits that haven't been dealt with yet would include g-forces on materials, frictional heating (both in the gun and out of the gun) and gas dynamics. I wouldn't consider an object to be in orbit unless it's trajectory carried it around the Earth at least once without crashing. Otherwise you could throw a baseball and consider it to be in orbit. While it may be instructive to do that in some contexts, quibbling about it in this thread seems like trolling to me. No matter what label you put on it, you obviously do see the vast difference between what the ISS is doing and what a gun on Everest could do.

I had thought that saying "neglect air friction" would be enough to indicate I didn't think one spacegun could launch a satellite to above launch height; if there is no additional source of kinetic energy you need two.


Part of the tried and tested mechanism of launching a large satellite:
Hit the Earth with a very large object.
This will cause large parts of the Earth ( and the impactor) to be ejected upwards from many places at various angles and velocities (much like meteors are believed to have expelled Martian material).
A typical mechanism for getting some of this material into orbit:
Some material traveling horizontally(say) at 'sufficient height' is hit by more energetic material from another launch site traveling forwards and upwards; both projectiles are fragmented in an inelastic impact; some of the debris ends up traveling in a closed orbit which prevents it hitting the Earth indefinitely.
(Because of the large scale, friction between clouds of gas and debris was more significant.)
The debris then self assembled into a satellite.
The satellite is currently being boosted into a higher orbit but is still the second brightest object in the sky.
I agree there is a vast difference between what the ISS is doing and what that satellite launcher did.

Wile hitting the Earth very hard in one or two places to launch a satellite is neither safe nor economic nor desirable, if you think it an unfeasible way to create a one use only gun I believe you will be in a minority.

In a world of fininte money, "cost effective" is a component of "better". It's part of the reason the space program is structured the way it is.

Is it really "better" to have people in the ISS proving it's still possible to live in space rather than back on the ground or actually going somewhere?

Incidentally, is it really trolling when people repeatedly disagree over how to misuse the word 'orbit'?

 

[JaredJames]

Many scientists believe that a large satellite was succesfully launched from Earth some time ago using inter alia processes that could be used in a space gun. (see below)
So if something is feasible once it's been done then such a satellite launcher is feasible.

Do they believe it or is it fact?

I had thought that saying "neglect air friction" would be enough to indicate I didn't think one spacegun could launch a satellite to above launch height; if there is no additional source of kinetic energy you need two.

Two guns? So you'd fire the projectile and then catch it in another to shoot again?

Part of the tried and tested mechanism of launching a large satellite:
Hit the Earth with a very large object.
This will cause large parts of the Earth ( and the impactor) to be ejected upwards from many places at various angles and velocities (much like meteors are believed to have expelled Martian material).

Tried and tested? We've never tried nor tested this method. It takes a major impact to do this.

A typical mechanism for getting some of this material into orbit:
Some material traveling horizontally(say) at 'sufficient height' is hit by more energetic material from another launch site traveling forwards and upwards; both projectiles are fragmented in an inelastic impact; some of the debris ends up traveling in a closed orbit which prevents it hitting the Earth indefinitely.
(Because of the large scale, friction between clouds of gas and debris was more significant.)
The debris then self assembled into a satellite.
The satellite is currently being boosted into a higher orbit but is still the second brightest object in the sky.
I agree there is a vast difference between what the ISS is doing and what that satellite launcher did.

What is this non-sense? Sounds like a poor way of describing a potential origin of the moon.

Wile hitting the Earth very hard in one or two places to launch a satellite is neither safe nor economic nor desirable, if you think it an unfeasible way to create a one use only gun I believe you will be in a minority.

Sources please. Show us how it is feasible (check the definition of that word before you reply).

Is it really "better" to have people in the ISS proving it's still possible to live in space rather than back on the ground or actually going somewhere?

The ISS is not even close to space travel. They are not comparable.

Incidentally, is it really trolling when people repeatedly disagree over how to misuse the word 'orbit'?

It is if you are nit picking just to perpetuate the argument.

 

[mistergrinch]

Sophie, you should read "Mining the Sky" by John Lewis and "The High Frontier" by Gerard O'Niell if you don't think there's much potential in the near future for space colonization. Lewis estimates that the solar system could support 10^16 humans! The asteroids are a fantastic opportunity; one small asteroid may have precious metals worth trillions of dollars, and the elements needed to support life are all out there in abundance. A hollow asteroid for example would be a *much* safer and more stable place for humans to live than this planet, because there wouldn't be any tsunamis, climate change, super-volcanoes, etc. and they would be out Earth's gravity well so space travel would be very cheap.

 

[JaredJames]

A hollow asteroid for example would be a *much* safer and more stable place for humans to live than this planet, because there wouldn't be any tsunamis, climate change, super-volcanoes, etc. and they would be out Earth's gravity well so space travel would be very cheap.

Are you just ignoring all the problems that go with such an idea?

Let's just start with radiation - we have a lovely atmosphere to deal with the majority of it, what does an asteroid have?

 

[mistergrinch]

A hollow asteroid has thick rock walls to block cosmic rays and solar storms, obviously...

 

[JaredJames]

A hollow asteroid has thick rock walls to block cosmic rays and solar storms, obviously...

How sweet, you make it sound so simple.

 

[mistergrinch]

Simple? Definitely not, but clearly possible once our space industry has reached the asteroids. In general, colonizing space will be the hardest thing human beings have ever attempted, but it's also the most necessary thing if we want to have any kind of long-term future, wouldn't you agree?

 

[JaredJames]

Simple? Definitely not, but clearly possible once our space industry has reached the asteroids. In general, colonizing space will be the hardest thing human beings have ever attempted, but it's also the most necessary thing if we want to have any kind of long-term future, wouldn't you agree?

It's going to be a lot easier to get our food / population under control than to colonise space.

Once we've got those two out of the way, we're good for a few billion years. Long enough for you?

 

[mistergrinch]

We will never get things under control on this planet. There is no reason why we have to accept random catastrophes like tsunamis and super-volcanoes killing millions of people, other than a lack of imagination and ambition!

 

[JaredJames]

You do realize that no other place in the solar system is as hospitable as Earth?

You're only plagued by those things if you live in areas prone to them - when was the last time London was destroyed by a natural disaster?

Obviously, we can't stop them, neither can we relocate everyone. We can work to limit damage and it's a hell of a lot easier to solve our problems here than simply overflow into space - where the problems will continue.

 

[mistergrinch]

Sorry but I don't see what is inhospitable about a suitably designed space habitat like a rotating hollow asteroid. A network of such worlds with an independent industrial base should be able to maintain its technology and population long after Earth civilization has returned to a post-industrial Stone Age or been wiped out by some catastrophe!

 

[Nano-Passion]

Its interesting, across space exploration arguments I usually see two sides. Enthusiasts vs. pessimists of the idea.

I stand somewhere in the middle, though the idea of space exploration/colonization is very exciting to say the least.

 

[JaredJames]

Its interesting, across space exploration arguments I usually see two sides. Enthusiasts vs. pessimists of the idea.

I stand somewhere in the middle, though the idea of space exploration/colonization is very exciting to say the least.

I love the idea of space travel and exploration.

But, I also see the more pressing needs of the planet.

It's a balancing game and on these scales, space travel just doesn't weigh up.

 

[Vanadium 50]

when was the last time London was destroyed by a natural disaster?

Um...1666?

Seriously, while not London, people often forget Lisbon was destroyed by an earthquake in 1755.

 

[sophiecentaur]

What makes me smile is the assurance of the pro-spacers that humans will, somehow, change their basic nature and create ideal environments by starting from scratch on assorted asteroids and small planets. The only reason that we haven't died out already is surely because the Earth is (even now) still capable of absorbing the worst of our irresponsible behaviour.

It may well be possible to battery-rear humans in artificial worlds but to what end? This figure of 10^16 humans all 'living' in the solar system is just so grotesque. What would be the point? Who would benefit from it? How would that solve the situation on an over-crowded Earth? However you do the sums, the cost in energy of getting a person from Earth to somewhere else in the Solar System would be more than they would consume, in other ways, in a lifetime down here. How could one suggest we ship them all off to Mars (equivalent to Australia and the new world as in the past)?

Humane (with an 'e') population regulation is the only solution to a happy future for our life on Earth. It's only the wealthy few who promote such extravagant expense as Space Tourism. Unmanned investigations are such good value for finding out about our universe compared with Buck Rogers type zapping around the Cosmos. Perhaps, when we can honestly say that everyone 'down here' is catered for adequately, there may be a time for a large off-Earth presence.

btw, I am heartened by the number of other contributors on this forum who share my skepticism about all this stuff. A very mature population; not just boy racers.

 

[sophiecentaur]

Um...1666?

Seriously, while not London, people often forget Lisbon was destroyed by an earthquake in 1755.

The 'great fire' was man made and could just as easily be caused in a space station. The difference with Earth bound disasters is the inherent healing process in the natural system of which we are a part. Just leaving Earth wouldn't solve the problem of disasters.

 

[JaredJames]

Um...1666?

My point exactly (although I'm not entirely sure I'd go with it being a natural disaster, a tad too man made for my liking ).

Seriously, while not London, people often forget Lisbon was destroyed by an earthquake in 1755.

Wow, as close as 1755

My point is that there are places on the planet that are relatively 'inactive' so far as these things go and other places that are built right on top of the fault lines.

I agree that there are natural disasters that could affect these areas, but they are 1 in a 10,000 year (or what ever the rather large number is) events that we really don't consider or have need to.

I subscribe very much to the thought of "you build on a volcano/fault line etc, you accept the risk". Poor or otherwise, we know the dangers and it is constant pro vs con.

Anyhow, back to my point, mistergrinch is making far too big a deal out of natural disasters so far as the planet goes. As sophie says, Earth is very good at absorbing the crap we through at it and frankly, I'm not surprised it "lets off some steam" every now and then and don't see how anywhere else in the solar system offers us a safer / more hospitable environment.

 

[bonker]

The thing that gets me with the space elevator is the basic physics. How is angular momentum conserved? The glib response is usually that the Earth is slowed as the payload rises to conserve angular momentum. But this does not address the possibility of the orbiting station being slowed and essentially dragged back to earth, also conserving angular momentum. You'll need to keep sending fuel to keep the station moving to counter this, yes?

 

[mistergrinch]

Sophie that's always the argument of the timid, the fatalists and the non-visionaries, that we have to wait for everything to be perfect where we are before we look for new frontiers. You could have said the same thing to the first humans who left the east African plains, the first Americans who walked over the land bridge, the European explorers or even to the first fish who crawled onto land, and where would you be now? That's just not how these things work, sorry!

In fact it probably will be the mega-rich who make this happen, since they will have the resources and the motivation to leave our chaotic planet if & when things start to get really bad. This drive to expand is some kind of evolutionary imperative that is more powerful than anyone's do-gooder moralizing. Space pioneers will have the opportunity to become the progenitors of a vast population which dwarfs Earth's current population, or even to become the saviors of our species in the event of a truly apocalyptic event, so trying to talk our selfish genes out this adventure is just silly.

 

[mistergrinch]

As far as natural disasters go, do I need to bring up the last super-volcano eruption, Toba, which nearly wiped out the human species? These things are very rare, but potentially so devastating that it makes perfect sense to have a backup population off Earth.

And if you're worried about overpopulation of the solar system, it seems fairly likely that if our civilization reaches that level we will have figured out how to get ourselves to other star systems, and by then we will undoubtedly have found *many* habitable planets which we can settle. The point is, there are probably no practical limits to growth in this universe for the foreseeable future, and since it's not clear that there is any desirable steady-state for our species, the choice is to grow or die. I prefer growth.

 

[sophiecentaur]

The parallel with Earth exploration is just not there, I'm afraid. The cost of the most costly Earth expedition has never been, in real terms, anything to compare with the simplest space adventure. Migration on Earth has always been achievable with very low tech means and the huge numbers of failed attempts didn't cost the rest of a population much. The timescale involved for round the World exploration was not great and there was always the possibility of somewhere to stop for R&R.
What vision is it that the 'visionaries' have? Can you paint a picture of a typical day in the life of a Mars Colonist? Would you really like to be there? The Pilgrim Fathers moved to somewhere which was very very similar to the place they came from and the trip was self-financed.

This space thing is just an extension of the survivalist thing. It's much easier to fantasise about escaping from a poor situation than to think about improving it. Space is not the 'backwoods' and it's nto a way out of a bad situation here.

Why should we want to be "progenitors of a vast population"? How many people can one person relate to? Have you no idea of "pioneering" in your head and exploring what can be done to improve the world a bit? The simple "selfish gene" notion has superceded, didn't cha know? The idea is now that co operation accounts for as much evolutionary success as competition. When populations of an organism get too big, they tend to run into more problems than they can deal with.

Words like adventure, pioneer, evolutionary imperative,explorers all bring to mind past excitements and glories (and which cost a lot of people a lot of grief). It's time to grow up and to see the present, more complex situation which just may not be soluble by buying bigger guns and bigger rockets, fun though they may be.

 

[JaredJames]

mistergrinch, you do realize that "sweeping the problems under the carpet" only solves things in the short term don't you?

So we put colonies in space, why don't they become over populated? Why don't we start having problems with growing populations? At what point between being here and then up there do we suddenly 'forget' our nature and stop doing what we are currently doing to ruin Earth?

You are talking about extremely rare occurrences, so rare that they aren't worth planning for - it's a waste of money.

You have to realize that people don't care what happens 1000, 10000, 1000000 years down the line, they only care about the here and now. They don't care that spending trillions now *may* (and yes, spending the money guarantees nothing) give some person a chance to live off Earth under identical conditions that we have now, minus the threat of natural disaster.

And this is all before we factor in the other dangers of living in space and how only minor problems on Earth are incredibly serious and potentially deadly in space. We effectively take a natural, 1 in a 10,000 year event and replace it with a far more serious and far more likely problem to arise in space.

 

[mistergrinch]

I can paint a picture of a day on Mars, and I'd love to be there! I understand that not everyone has this sense of adventure and curiosity, and those folks can do what such people have always done: stay home where it's safe. This is why I'm putting my hopes in bold entrepreneurs more than dull, risk-averse space bureaucracies at this point -- governments tend not to attract the kinds of people you need for this enterprise.

Debating this issue is like debating religion and just as pointless -- people just see the world differently. Having said that, I won't stop evangelizing for space exploration, because for me it literally is a kind of religion, part of a cosmic religion I subscribe to, inspired by great thinkers like these:

"We have lingered long enough on the shores of the cosmic ocean. We are ready at last to set sail for the stars." —Carl Sagan

"There is no way back into the past; the choice, as Wells once said, is the universe—or nothing. Though men and civilizations may yearn for rest, for the dream of the lotus-eaters, that is a desire that merges imperceptibly into death. The challenge of the great spaces between the worlds is a stupendous one; but if we fail to meet it, the story of our race will be drawing to its close. Humanity will have turned its back upon the still untrodden heights and will be descending again the long slope that stretches, across a thousand million years of time, down to the shores of the primeval sea." —Arthur C. Clarke

"Teetering here on the fulcrum of destiny stands our own bemused species. The future of the universe hinges on what we do next. If we take up the sacred fire, and stride forth into space as the torchbearers of Life, this universe will be aborning. If we carry the green fire-brand from star to star, and ignite around each a conflagration of vitality, we can trigger a Universal metamorphosis. Because of us, the barren dusts of a million billion worlds will coil up into the pulsing magic forms of animate matter. Because of us, landscapes of radiation blasted waste, will be miraculously transmuted: Slag will become soil, grass will sprout, flowers will bloom, and forests will spring up in once sterile places. Ice, hard as iron, will melt and trickle into pools where starfish, anemones, and seashells dwell — a whole frozen universe will thaw and transmogrify, from howling desolation to blossoming paradise. Dust into Life; the very alchemy of God". —Marshall T. Savage

“If the human species, or indeed any part of the biosphere, is to continue to survive, it must eventually leave the Earth and colonize space. For the simple fact of the matter is, the planet Earth is doomed… Let us follow many environmentalists and regard the Earth as Gaia, the mother of all life (which indeed she is). Gaia, like all mothers, is not immortal. She is going to die. But her line of descent might be immortal. . . . Gaia’s children might never die out–provided they move into space. The Earth should be regarded as the womb of life—but one cannot remain in the womb forever.” —Frank Tipler

 

[ngc1333]

Air pollution kills millions of people every year, just to put things in prospective.

I sort of see where you're coming from but two wrongs don't make a right.

Are you certain that air pollution was "wrong"? The only alternative I can see would have been to avoid the industrial revolution.

The number of deaths caused by some sources of pollution has been reduced greatly, by legislation.

That's true, but we could still do a lot more. We could shut down all non-essential industries to reduce our power needs, outlaw non-essential driving . . . Nobody wants to do that. We accept pollution as the cost of our lifestyle. I don't see why we should insist on zero casualties when it comes to space travel.

 

[russ_watters]

A hollow asteroid for example would be a *much* safer and more stable place for humans to live than this planet, because there wouldn't be any tsunamis, climate change, super-volcanoes, etc. and they would be out Earth's gravity well so space travel would be very cheap.

It also wouldn't have any of the good things about living on earth: soil on which to grow food, air to breathe and water to drink.

We will never get things under control on this planet. There is no reason why we have to accept random catastrophes like tsunamis and super-volcanoes killing millions of people, other than a lack of imagination and ambition!

Don't let your imagination control you. It's making you think illogically. The only natural disasters ever to kill millions of people have been diseases and living on an asteroid doesn't help with that. In the grand scheme of things, few natural disasters are really that big of a problem and most of those that are are only a problem to 3rd world countries - so the way to deal with them is to fix third world countries. Ie, the earthquake in Hati and the tsunami in Indonesia each killed about 250,000 people. The earthquake and tsunami in Japan was about the same intensity and appears to have killed on the order of 10,000 people. There are many reasons for the difference, but the main reason is that Japan is more developed. So, for example, their buildings don't all collapse in an earthquake.

So we don't really need to move to an asteroid to deal with natrual disasters well enough for them to be only minor problems, we just need to have countries be developed enough to prevent them from being major problems.

 

[russ_watters]

It may well be possible to battery-rear humans in artificial worlds but to what end? This figure of 10^16 humans all 'living' in the solar system is just so grotesque.

Agreed. The idea isn't even science fiction, it's fantasy. We have no clue if such things will be possible, much less what such a society would even look like. Fantasizing about such things - which if even possible are at least hundreds if not thousands of years in our future - are a far cry away from evaluating the still science fiction but at least theoretically possible in the next 50 years space elevator concepts.

 

[russ_watters]

As far as natural disasters go, do I need to bring up the last super-volcano eruption, Toba, which nearly wiped out the human species?

If you think it's relevant, by all means...But as much as you're fantasizing is wildly disconnected from current reality, I don't expect you'll succeed in making it connect.

These things are very rare, but potentially so devastating that it makes perfect sense to have a backup population off Earth.

Heh. No. What do I care about the survival of the species? I live on earth, so if a massive comet comes and wipes us all out, I wouldn't much care if there is a "backup" somewhere else. I'll be dead, so it won't provide me any comfort.

And that's besides the fact that we have no capability to do it, so it certainly does not make any sense.

...and since it's not clear that there is any desirable steady-state for our species, the choice is to grow or die. I prefer growth.

Population growth is already leveling-out and has a good chance of reaching that steady-state this century.

I can paint a picture of a day on Mars, and I'd love to be there! I understand that not everyone has this sense of adventure and curiosity, and those folks can do what such people have always done: stay home where it's safe.

I thought you said it was safer in space? So now you acknowledge it isn't?

This is getting silly.

Having said that, I won't stop evangelizing for space exploration, because for me it literally is a kind of religion...

On that much, at least we agree. The trouble is, this is a science forum, not a religion forum. So unless this discussion can return from the realm of religious fantasy to the realm of scientific reality, it will need to be shut down.

 

[Nano-Passion]

Wait wait, I love your enthusiasm mistergrinch, but please don't get my topic shut down. :( So let's keep this to the realm of scientific reality. ^.^ With that said:

Farming a new Earth environment in a different habitat sort of speak seems scientifically feasible. I wonder if we have the scientific capabilities ( such as air circulations, growing food, soil, water circulations, etc. )?

I mean, the knowledge and technology seems to be there. We can take zygotes of different animals aboard the space shuttle. Perhaps we can engineer a large amount of soil from surrounding atoms by combining and arranging them in a certain way (nanotechnology anyone?). With that, we can farm whole lands and have a big growth in animals. With 3d printing (strong enough?) or perhaps engineering the material needed in the selected habitat of choice we can extend our living space as long as we collect the elements we need. We can also farm our own energy with our ever better increasing energy technology.

The only thing that seems to hold us back is energy usage to get there (money) and the question: is it worth it?