Hard Light Productions Forums
Off-Topic Discussion => General Discussion => Topic started by: Flipside on January 05, 2009, 09:43:41 pm
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http://news.bbc.co.uk/1/hi/sci/tech/7792297.stm
I still think this is the best way to go with exploration, our biggest enemy is our own atmosphere, so if we can start from outside of it, we remove almost 90% of the mass of current orbital vehicles.
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Next up: Gundam 00? :p
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what people fail to realize is that when we have materials capable of such a construction, those materials would be better used to make lightweight and therefore more efficient spacecraft.
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Why waste all that thrust? Even with lighter ships, why bother using all that fuel to get outside our own gravity field when a ship exactly the same size, but taken up on the Elevator would have something like 20 times the range.
Our biggest Achilles heal when it comes to Space Exploration isn't travelling between between planets, it's getting from the ground to orbit, that takes almost all the resources that are put into the programme. Eliminate that and putting a satellite in orbit is the cost of building a satellite, just a satellite, and the price of a lift-ride. You've reduced the costs and resource demand by a massive amount for each launch.
Even better is the fact that you don't have to waste all those fancy new lightweight materials, because the Elevator will always be there, whereas most of the vehicles themselves are a one-shot wonder, why use hi-tech expensive equipment that will vanish, when you can use moderate tech materials and send it up in a high tech launch platform that is permanently available?
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It would also be a safe way to transport radioactive materials to power spacecraft. Also building lightweight spacecraft for long journeys isn't feasible even with the current materials. You need something that's not only strong but can shield against cosmic rays. Just line the walls with the lead from the containers that are used to transport the radioactive material. Kills 2 birds with one stone.
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I still think we're better off with a SkyRamp (http://www.g2mil.com/skyramp.htm), since we can do it with modern technology. It's no more significant an engineering feat than dozens of others we've done in the past. I'll grant you, it's not the kind of permanant solution a space elevator would provide, but it's a good intermediate step, and it's somehting we could start tomorrow if we had the budget and political will.
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to anything that brings space elevators closer to reality, there can be only one possible response
[attachment stolen by Slimey Goober]
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to anything that brings space elevators closer to reality, there can be only one possible response
:lol:
Another advantage is that it will make the possibility of getting some of that junk in orbit cleared a lot more likely.
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Why waste all that thrust? Even with lighter ships, why bother using all that fuel to get outside our own gravity field when a ship exactly the same size, but taken up on the Elevator would have something like 20 times the range.
Because surface-to-orbit spaceships look much cooler? :p
Seriously, though, the article is interesting on the small-scale, but I'm curious as to how feasible it would be once you work up to the size of an actual elevator, and how long transport would take if it did work. It's one thing to say, "Oh, let's just shake the cable;" it's quite another to actually be able to do it.
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This is starting to remind me of the Great Glass Elevator. ;)
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Lofstrom launch loop would be better (http://en.wikipedia.org/wiki/Launch_loop), since we can do it with our current technology.
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... Gundam 00 sudden no longer seems like such a distant possiblility ...
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The idea rests on making use of the outward centrifugal force supplied by the Earth's rotation. Imagine fixing a short length of string to a football and spinning it - the string flies outward and remains taut.
*facepalm*
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It's centripetal force, isn't it?
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Well, to be absolutely accurate, I can't find the reference to where this is from, so I'm not sure what the statement is referring to, but my physics teacher had a total fit one day when someone talked about a centrifugal force (he's now retired)!
It's centripetal force, isn't it?
The idea rests on making use of the outward centrifugal force supplied by the Earth's rotation. Imagine fixing a short length of string to a football and spinning it - the string flies outward and remains taut.
*facepalm*
In reality, you're pulling the ball to you, not the ball pulling on you... the ball just wants to go on its merry way.
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Just don't park it on my backyard..
It all sounds too massive to be practical/resource efficient. And (as much as I gather) you need to go with a full scale implementation from the beginning - the risks are astronomical.
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What it comes to centripedal or centrifugal force, while the physical definition is different, but luckily most of the people are smart enough to figure out what was actually meant with either of the terms in different contexts. The situation is the same with "intensity" in Optics and radiometry - it is almost always wrong even in the publications. But it doesn't matter since it is almost always conceivable what was meant with the term given the context. The biggest shocker is that there is no such SI unit as "intensity" in radiometry.
Mika
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Why waste all that thrust? Even with lighter ships, why bother using all that fuel to get outside our own gravity field when a ship exactly the same size, but taken up on the Elevator would have something like 20 times the range.
Our biggest Achilles heal when it comes to Space Exploration isn't travelling between between planets, it's getting from the ground to orbit, that takes almost all the resources that are put into the programme. Eliminate that and putting a satellite in orbit is the cost of building a satellite, just a satellite, and the price of a lift-ride. You've reduced the costs and resource demand by a massive amount for each launch.
When it comes to energy conservation, I'm not sure how much this could change the general energy budgets. In Physics, the work (unit energy) is defined as a line integral of potential field multiplied by the trajectory of the moving particle. Since the trajectory is approximately the same in both cases, the only energy that can be saved is caused by air friction. But some amount of energy is required to keep the space elevator up and running. So in total, I don't see much difference in the energy itself.
However, this doesn't mean that it wouldn't be a cheaper method to lift things on orbit since there is not that much of need to construct the delivery vessel again.
Mika
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Just don't park it on my backyard..
It all sounds too massive to be practical/resource efficient. And (as much as I gather) you need to go with a full scale implementation from the beginning - the risks are astronomical.
Well, to be honest, it would need to be set in around 10-20km2, just to be on the safe side, though I'm not too certain what would happen in the event of a catastrophic failure, since, as far as I can visualise it, it would start travelling at different speeds depending on how close to the centre of gravity it is.
That, however, might be completely off-base, since it's easy to fall into the trap of visualising it bending as the Earth spins, which wouldn't happen, since geostationary orbits don't work like that.
I suppose it's theoretically possible that, like the ball on a string, if it broke, it would fall 'upwards' from our point of view...
Why waste all that thrust? Even with lighter ships, why bother using all that fuel to get outside our own gravity field when a ship exactly the same size, but taken up on the Elevator would have something like 20 times the range.
Our biggest Achilles heal when it comes to Space Exploration isn't travelling between between planets, it's getting from the ground to orbit, that takes almost all the resources that are put into the programme. Eliminate that and putting a satellite in orbit is the cost of building a satellite, just a satellite, and the price of a lift-ride. You've reduced the costs and resource demand by a massive amount for each launch.
When it comes to energy conservation, I'm not sure how much this could change the general energy budgets. In Physics, the work (unit energy) is defined as a line integral of potential field multiplied by the trajectory of the moving particle. Since the trajectory is approximately the same in both cases, the only energy that can be saved is caused by air friction. But some amount of energy is required to keep the space elevator up and running. So in total, I don't see much difference in the energy itself.
However, this doesn't mean that it wouldn't be a cheaper method to lift things on orbit since there is not that much of need to construct the delivery vessel again.
Mika
True, I'm not certain of the exact energy requirements as such, depends how the Lift itself is powered, but I would have thought that a simple ratchet system would prevent the requirement for 9.8m/s2 thrust to achieve escape velocity, which means that you don't have to burn all that fuel fighting against Gravity.
I think the current idea is to hook up a few orbital Solar Panels to the exit-point of the elevator, and they would provide the pulling power, but as to whether Solar Panel tech can provide that kind of power, and how big those panels would have to be in order to do so, I really couldn't say.
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True, I'm not certain of the exact energy requirements as such, depends how the Lift itself is powered, but I would have thought that a simple ratchet system would prevent the requirement for 9.8m/s2 thrust to achieve escape velocity, which means that you don't have to burn all that fuel fighting against Gravity.
Sorry, made a mistake with the definition of work. The line integral is actually force multiplied by the trajectory, not the potential. Don't know what I was thinking. It's six years since I last read mechanics, but that is a basic mistake which should not happen (multiplying scalar with a vector in a line intergral should have warned me).
But what it comes to the force itself, it would be dictated by Newton's gravity law, where the other part of the equation is the mass of the object that is going to orbit. If that mass can be decreased, then this would obviously result in energy advantage. Add on top of that energy losses caused by air friction.
The other question is then the conversion efficiencies of chemical energy in rocket fuel and the mechanical vibrating energy.
Mika
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It is relatively hard to imagine solar panels using electrical energy driving something up 36000 kms. Transforming the electrical energy produced by those cells into a mechanical vibration sounds far more inefficient (at least to me). And loose vibrant energy in buildings raises hairs up.
But in any case, if that space lift was ever constructed, it would be monumental task and probably the greatest achievement human kind has ever done so far.
Mika
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bit more significant than the Millenium Dome then ?
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i think i would just wrap the carbon nanotube cable with aluminum wire and just use the same kind of induction that maglev trains use. this would allow you to climb the tether without actually touching it, and you could actually achieve a greater speed so you could get to the station faster and wouldn't spend the whole trip twiddling your thumbs. this would also allow you to decouple at velocity relative to the cable so you can actually accelerate along the cable in the absence of atmosphere and have a nice bit of exit velocity when you disconnect. this would save alot of delta v when getting to the outer solar system.
still i think the real answer to utilizing space would be orbital fuel manufacturing. surely you can scoop up enough usable material from the solar wind, and process it into fuel and other essential items. surely there is hydrogen, helium, helium 3, deuterium and tritium there could all be gathered and separated. couldnt run chem engines but fusion reactors would love the helium 3, the rest could be used as propellants for electrical engines. scatter such automated stations across the solar system, and the requirement for disposable spacecraft would soon vanish. lunar and asteroid mining would produce the metals needed. linear accelerators would work well for lunar launches.
nanotube fiber composites coupled with hybrid rockets and air-breathing reusable first stage engines would be used for human transport to space. once all this infra structure exits i don't think you'd really need a space elevator. everything you need for space exploration would come from space, only requiring human transportation through the atmo. stop looking at the cost of shuttle missions as how much space costs. the shuttle is a brutally inefficient launch system.
when you look at the problem of deploying the cable, you cant just raise it from the ground, you'd have to lower it from the asteroid we use to anchor it (assuming asteroids are stable enough), which would mean it would have to either be manufactured in space, or lifted in sections. so you see the problem, installing it would require more space infrastructure, yet that infrastructure would so greatly reduce the cost of space exploration that it would be hard to justify the space elevator.
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It is relatively hard to imagine solar panels using electrical energy driving something up 36000 kms.
Isn't solar energy more efficient in super-atmospheric conditions?
But in any case, if that space lift was ever constructed, it would be monumental task and probably the greatest achievement human kind has ever done so far.
Until we discover and utilize a feasible FTL method, at least.
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Well, I think the Space Elevator will be one of the greatest physical/architectural achievements, it certainly surpasses big pretty piles of rock, but I think FTL will be a milestone in our mental evolution.
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I honestly don't think FTL is possible. I think it exists somewhere around the same place as wee fairies and god.
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That, I think, is why it will be a milestone.
I think the actual act of going faster than the speed of Light is, as you say, impossible, however, that's not necessarily the same as leaving one place, and arriving at another in less time than it would take light to travel between the two. I have a lot more faith in pseudo FTL than true FTL.
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The way I see it, out of all of these hyperdrives and warp cores and subspace nodes and other assorted technobabble that sci-fi has come up with over the decades, someone somewhere must have accidentally stumbled across something that could actually work. :p
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i said we should capture apophis for this, but everyone thought i was psycho
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Well, we've got about 25 years before it gets here, you never know, if we can get some kind of system in place like the elevator or the ramp, there may well be ships headed there, after all, it's not often you get a chance to look at an asteroid that closely.
Capturing and examining it may well tell us some interesting information about the origins of the Solar System, and possibly even help answer questions like 'was there a planet between Mars and Jupiter once?' (Last I heard, unlikely, since there aren't enough asteroids to make any planetary mass, but not impossible, since it cannot be told what was swept up by Jupiter and other bodies, and what got sent out on vastly eccentric orbits etc)
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well i was thinking about using it for an anchor
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Well, we'd probably only need a little bit of it to analyse, I suppose it depends if we catch it or simply land on it. If we capture it, then it's not a terrible idea, it saves getting a lot of bulk up there in the first place, you could prep a station on/in the asteroid and possibly even feed the line down from orbit, rather than try to raise it from the surface.
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lunar manufacture might be a better option though, not sure how readily available carbon is there.
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It is relatively hard to imagine solar panels using electrical energy driving something up 36000 kms.
Mika
It couldn't do it reliably, and even if it could you would need a huge number of solar panels. Nuclear is probably a better choice for something like this since it can supply as much as you need on demand.
Long term orbital and off world manufacturing and mining is the way to go, but first we have to get that crap into space before we can start doing things with it.
think i would just wrap the carbon nanotube cable with aluminum wire and just use the same kind of induction that maglev trains use. t
A lofstrom loop does the same thing, but using the maglev tech we have now.
From wikipedia:
A launch loop or Lofstrom loop is a design for a belt based maglev orbital launch system that would be around 2,000 km (1,240 mi) long and maintained at an altitude of up to 80 km (50 mi). A launch loop would be held up at this altitude by momentum of the belt as it circulates around the structure, in effect it transfers the weight of the structure onto magnetic bearings at each end which support it.
Launch loops are intended to provide a way for non-rocket spacelaunch of vehicles weighing 5 metric tons by electromagnetically accelerating them so that they are projected into Earth orbit or even beyond. This would be achieved by the flat part of the cable which forms an acceleration track above the atmosphere.
Economics
For a launch loop to be economically viable it would require customers with sufficiently large payload launch requirements.
Lofstrom estimates that an initial loop costing roughly $10 billion with a 1 year payback could launch 40,000 metric tons per year, and cut launch costs to $300/kg, or for $30 billion, with a larger power generation capacity, the loop would be capable of launching 6 million metric tons per year, and given a 5 year payback period, the costs for accessing space with a launch loop could be as low as $3/kg.[1]
(http://upload.wikimedia.org/wikipedia/commons/thumb/b/b8/LaunchLoop.svg/800px-LaunchLoop.svg.png)
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I remember reading awhile back about a way to generate electricity by using a tether in space to collect free electrons or something like that. They weren't talking about small amounts of electricity either. If that is possible it probably could be used to power the elevator and a lot more.
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I honestly don't think FTL is possible. I think it exists somewhere around the same place as wee fairies and god.
"Any sufficiently advanced technology is indistinguishable from magic"
Arthur C. Clarke
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"Any sufficiently advanced technology is indistinguishable from magic"
Arthur C. Clarke
I thought FreeSpace 2 was magic when I first saw the trailer. :D
Just a question. Can the technology used in a railgun be used in a mass driver or this space elevator?
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Isn't solar energy more efficient in super-atmospheric conditions?
Yes, but not enough to make the difference.
The difference can be calculated from AM0 (Air Mass 0) and AM1 (Air Mass 1), both are available for public use. The data contains a lot of different averaged measurement sets from the orbit (AM0) and from the equator (AM1). If memory serves, maximally a factor of 2 could be expected from that - but there is also need to protect the photovoltaics from more powerful radiation.
Mika
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It couldn't do it reliably, and even if it could you would need a huge number of solar panels. Nuclear is probably a better choice for something like this since it can supply as much as you need on demand.
Oh, but then you meet again the Green movement which most likely protests against launching any nuclear thingies in space. Though they tend to forget that this stuff has already been done from the 1960s.
Mika
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It couldn't do it reliably, and even if it could you would need a huge number of solar panels. Nuclear is probably a better choice for something like this since it can supply as much as you need on demand.
Oh, but then you meet again the Green movement which most likely protests against launching any nuclear thingies in space. Though they tend to forget that this stuff has already been done from the 1960s.
Mika
I recall there was a huge uproar about 10 years ago or so about the Cassini and Galileo space probes being launched with radiothermal generators on board. It was total scare mongering and typical anti-intellectualism and anti-science from the environmental movement. Apparently they never realized that solar panels don't work when you get past Mars, not that such details are important to them.
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Scaremongering? How? You're launching the thing into space, aren't you? What's the worst that could happen?
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It blow up while still in the atmosphere creating a huge dirty bomb. Fish become radio active, mutate, develop super intelligence, and create weapons to enslave the human race.
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oh. :blah:
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Scaremongering? How? You're launching the thing into space, aren't you? What's the worst that could happen?
It was scaremongering to push their agenda. They want to make everyone afraid of anything remotely related to nuclear power. Not surprisingly greenpeace, the same group who said nuclear fusion is dangerous, was also in on the protesting. Facts mean nothing to those people.
In fact here is an except from a newsletter (http://www.animatedsoftware.com/cassini/nltrs/nltr0057.htm) that was going around at the time, which has thankfully be archived on the net (the first sentence was from someone else contributing, the rest is about greenpeace. I included it to show the kind of scaremongering we're dealing with):
Cassini is an unnecessary hazard and could even spark a war if it lands in the wrong place. American prestige will plummet if Cassini fails.
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*** Greenpeace Joins the Fray
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INCOMING EMAIL:
FOR IMMEDIATE RELEASE
GREENPEACE DIRECTORS APPEAL TO CLINTON TO POSTPONE CASSINI SPACE LAUNCH - URGE USE OF SOLAR TECHNOLOGY
Washington, October 10, 1997 (GP) - The Directors of Greenpeace International and Greenpeace USA have appealed to President Clinton to postpone the launch of the Cassini space probe to Saturn until NASA can implement a solar-powered alternative. Greenpeace considers the Cassini probe a grave threat to global health and the environment.
Cassini, scheduled to be launched by NASA on Monday, October 13, carries 72 pounds of plutonium in devices that generate electricity. Dispersal of the plutonium in the event of a launch pad accident or disintegration in the atmosphere could pose a grave health risk. Minute particles of plutonium are carcinogenic if inhaled and atmospheric disintegration could lead to exposure of this deadly material to the global population.
In the letter sent on October 8, Thilo Bode, Greenpeace International Executive Director and Kristen Engberg, Acting Executive Director of Greenpeace USA, appealed to Clinton to display global leadership by reconsidering the impact of plutonium dispersal beyond the US borders. The two directors further urged Clinton to direct NASA to develop solar-powered cells to replace the Radioisotope Thermoelectric Generators (RTGs), which produce electricity based on the decay heat of the nuclear substance.
"A plutonium-fueled spacecraft not only creates a potential global hazard, but also sends the wrong signal regarding our energy and resource future," said the letter to President Clinton.
:rolleyes:
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I laugh whenever I hear the term "dirty bomb".
As if that amount of radioactive material could pose any threat after being dispersed over such a huge area.
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Nothing says it has to be a huge area. If it blows up seconds after lift off then the area would be a lot smaller. Also it could just crack the containment vessel and dump the whole thing into one spot. Elevator vs rocket for hazardous material. Elevator wins hands down.
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Nothing says it has to be a huge area. If it blows up seconds after lift off then the area would be a lot smaller. Also it could just crack the containment vessel and dump the whole thing into one spot.
We've actually had RTGs burn up in the atmosphere and we've had them fall back to earth......no one was ever hurt and there was no ecological damage.
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Still tell me you don't think the elevator is safer for something like this. I'm not against putting it up there at all it's just common sense not to pack it on top of a big bomb.
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the elevator would require a huge counter mass in orbit. you could inadvertently pull it out of the sky and slam it into the ground. should the cable snap near the top, im sure the effects of it falling to earth wont be pretty either.
72 pounds of plutonium, considering how heavy the stuff is that cant be that much. and how do we know that natural space debrits doesnt contain any plutonium. how many tonnes of that enter the atmosphere daily.
i do like this lofstrom loop concept. but its kinda hard to get your head around.
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Still tell me you don't think the elevator is safer for something like this. I'm not against putting it up there at all it's just common sense not to pack it on top of a big bomb.
What are you going to use to power the elevator with then? It still needs large amounts of reliable electricity to operate.
Besides, an RTG would not be used for this since they don't put out that much power. It was just an example of the kind of hysteria and scare mongering that surrounds anything related to nuclear.