Continued Success for Space Elevator Tests 572
Jacki O writes "According to their Web site the Space Elevator company Lifport recently managed to get their platform and climbing robot to the mile-high mark over the Arizona desert." From the announcement: "A revolutionary way to send cargo into space, the LiftPort Space Elevator will consist of a carbon nanotube composite ribbon eventually stretching some 62,000 miles from earth to space. The LiftPort Space Elevator will be anchored to an offshore sea platform near the equator in the Pacific Ocean, and to a small man-made counterweight in space. Mechanical lifters are expected to move up and down the ribbon, carrying such items as people, satellites and solar power systems into space."
I can top that. (Score:5, Funny)
1500 feet not a mile (Score:5, Informative)
Re:1500 feet not a mile (Score:5, Funny)
The robot only made it around 1500 feet. The cable was a mile long.
Rule Number 1: Don't let the facts ruin a good story.
Re:1500 feet not a mile (Score:3, Insightful)
So they spun it as a success because they bet their last lame effort.
They still have some way to go to make 62000 miles.
Heres a question (Score:4, Funny)
Why don't we just build a 500 mile high pyramid of some description? And maybe run a ramp up it, and a pulley system maybe so we can use very simple earthbound techniques to get projectiles to an incredible speed before liftoff? Alternately, its surely easier and cheaper to get a launch from 500 miles up, or put the tail end of a space elevator there. And we could do it with existing technology easily. Its like the question, if there were stairs going to the moon, could you walk it... the answer to that one is yes.
Mure musings (Score:3, Interesting)
Hate to reply to myself, but when you have an idea... Eh you could even put a couple of hundred pulleys going up one side, with a couple of nuclear power stations buried in there to power them (and internal elevators going up and down, as well as any other power requirements). Surely you could reach escape velocity with ease and en masse by using very cost effective nuclear power like this... and also it could be based in a sea somewhere, so returning vessels could splash down nearby. Now that would be a s
Even more musings (Score:4, Funny)
Alien tourists would come to see the only planet in the galaxy that looks like an ice cream cone...
Re:Heres a question (Score:5, Funny)
Indeed! Then we shall be like gods!
Effettivamente! Allora saremo come i dii!
In der Tat! Dann sind wir wie Götter!
En effet! Alors nous serons comme des dieux!
Re:Heres a question (Score:5, Funny)
Are you kidding? I've got a stele full of them!
Re:Heres a question (Score:5, Funny)
Re:Towers as part of space elevator (Score:5, Informative)
Space Elevator workshop, and been on a science panel with one of the Liftport
guys - I guess that makes me a relative expert)
A tower going up from the ground meeting a cable coming down from orbit is
more efficent than a cable going all the way to the ground, if, and this is
important, the strength of the cable is substantially less than the depth
of the earth's gravity well.
Here's why: As you build a longer cable or a taller column of constant area
under gravity, the stress gets higher. In a column the maximum stress is at
the bottom, and in a cable it is at the top. Eventually you exceed the
strength of the material.
The Earth's gravity well is equal to one gee times the radius of the planet
= 6,378 km. A space elevator is centered at GEO, which is 97% of the way out
of the Earth's gravity well, so we need to span 6,167 km at one gee.
The strongest readily available carbon fiber that is not made of nanotubes
is about 1 million psi in strength. It has a density of 0.067 lb/in^3, so
if you had a cable 15 million inches long under one gee, it would be at the
limit of it's strength. 15 megainches = 381 km, which is a factor of 15
below what we need.
You can build towers or cables longer than the strength limit if you make
them progressively wider to keep the stress below the limit of the material.
Each 15 inches of length in the cable above adds one millionth to the stress,
therefore the area has to increase by one millionth. Over a 381 km length,
the area of the cable increases by a factor of e (2.718...). This length,
found by dividing strength by the density of the material, is called the
scale length. If you have 16.2 scale length to cover (6167/381), your
cable area increases by e^16.2 = ~10 million.
A graphite/epoxy composite is needed for a tower. Bare fibers are okay in
tension, but you need to stiffen them for a compression structure. Typically
using the same fibers, the composite will be 30% as strong in compression as
the bare fibers are in tension. Now assume you build a tower up and a cable
down with the same area ratios from bottom to top. The tower's scale height
is 114 km, so the combined scale heights for the tower + cable = 495 km.
Now you need 6167/495 = 12.5 scale heights. e^12.5 = ~250,000, which is
a factor of 40 improvement.
If you have carbon nanotube cable which has, say a 10 million psi strength,
your scale length is 3810 km, and your area only needs to grow by a factor
of 5 from bottom to top, so the reduction possible by using a tower is much
less helpful. Of course, we are not making 10 million psi cable in useful
quantities yet.
Daniel
Re:Towers as part of space elevator (Score:5, Informative)
..\/
_/\_
has a lesser mass than
/....\
\..../
_\/_
Aside from that, if you build the tower first, you can launch from the tower to build the rope, and start getting significant returns much sooner.
Last of all, it's easier to blow the second example free in a case of terrorist attack. It's rather hard to do much to the first. And if it does break free, it does tons less damage in the first case (the tower+rope).
Re:Towers as part of space elevator (Score:4, Insightful)
Megainches??? Do real scientists seriously use such a measurment?
Re:Heres a question (Score:4, Informative)
v[f]^2 = v[i]^2 + 2ad
So, from a standing start, taking optimistic values for acceleration (say 10 G's), and the length of the ramp (say 100 km):
v^2 = 2*10g*d
v^2 = 2*10*9.81*100000
v^2 = 19620000
v = 4425 m/s
Which isn't even close to what you need for orbit, so you still need a significant rocket. Except now, you need a rocket that can handle your launch ramp, which isn't trivial.
You'd end up spending a lot of money for not much gain. You'd save some fuel, but complexity is already the expensive part and you're increasing that quite a bit.
Re:1500 feet not a mile (Score:5, Informative)
Seriously, that's what this is like. The challenges of a space elevator aren't in the climber; they're in the cable. We're not even remotely close to such a cable. To be realistic, you need a mass producable cable with a tensile strength of over 100GPa at a density similar to SWNTs. That's well more than the strongest *individual* SWNT measured thusfar, let alone the strongest bundle of tubes, let alone the strongest continuous fiber producable. It may well not even be possible with physics as we know them.
Re:1500 feet not a mile (Score:5, Insightful)
C'mon. That's not true. The main reason it seems like this is because you think you know how to build the climber, but you have no idea how to build the cable. Ask a materials scientist who's working on carbon nanotubes, and they might disagree with you.
Plus, you do not need a 100 GPa cable. You need a 100 GPa cable for a small taper. At 50 GPa the taper becomes
There are a lot of issues with the climber design. A lot. Speed, reliability, weight, and power. Reliability in particular will take a lot of time to nail down. It makes sense to tackle that one first, because it can be done in parallel with the cable design, and in addition, the third major challenge (power delivery) can't really be done until the climber design is finalized.
So you've got three difficult tasks - the cable, the climber, and the power delivery system. The last two are coupled. What makes sense is having two separate tasks, one of which handles the cable, the other the climber, and then the power delivery system. Oh look! [liftport.com] That's exactly what they're doing.
Given our lack of experience in building cheap vehicles that can travel 100,000 km with zero failures (with low power, in vacuum) I think it's safe to say that all parts of the elevator are difficult.
Re:1500 feet not a mile (Score:3, Insightful)
You're telling this to a person who's followed every bit of news she can get her hands on about SWNTs (and to a lesser extent, MWNTs and non-carbon nanotubes, plus novel interlinked structures).
50 GPa
You only get *realistic* taper factors at over 100GPa. I encourage you to check out spelsim or the gizmonics calculator. A 50GPa elevator weighs ten times as much as Edwards' calculation, and Edwards' calculation wasn't cheap. Even 50GPa isn't realistic, however. The s
Re:1500 feet not a mile (Score:4, Interesting)
Wait, so you do know how to build the cable? You should get in touch with these people!
You took that comment the wrong way - it wasn't meant as "you don't know what you're talking about" it was meant as "since we don't know how to build it, we don't know how hard it is going to eventually be." Unfortunately the two have the same wording.
I encourage you to check out spelsim or the gizmonics calculator. A 50GPa elevator weighs ten times as much as Edwards' calculation, and Edwards' calculation wasn't cheap.
Edwards's calculation was feasible for a business. A 50 GPa elevator would be feasible for a government. And I have checked out spelsim. I know the deal. I just have different views on "feasible" than you do. What was the estimated total cost of Apollo in modern dollars? $200B or so? And the US GDP is 4 times larger than it was then (adjusted for inflation). Feasible for the US, today, is roughly $1 trillion dollars. (*)
*: Now, whether or not it's sane to invest $1T in a space elevator - that's a different matter. Many people would argue that it wasn't sane to invest in Apollo either. I also know if you use percentage of GNP for Apollo - ~3%, and the years it took - ~10, you get about oh, half a trillion or so in current dollars. Close enough for me. And I know the reason we invested in Apollo was for military reasons. Don't shatter my deepfelt optimism that one day we'll invest as much money in exploration as we did in a giant pissing match.
The climbers are.
The climbers are not realistic present-day. Did you read the presentations from the Space Elevator conference on climber design? There were concerns that they might be impossible from power dissapation concerns. And the reliability requirements were way, way above what exists anywhere else.
You can't go out and buy the climbers off the shelf. Therefore it makes sense to figure out exactly how much work they'll need to get working. Which... is what they're doing.
Plus, as I said, the climbers block the development of the power system, since the power system needs to know how much power the climbers need.
Frankly, I'm really baffled by the derision. If it takes 20 years to figure out the cable, then they have 20 years to develop the climber. Which means it costs less per year, so it can be funded via simpler methods - including volunteer time.
Re:1500 feet not a mile (Score:4, Insightful)
Liftport doesn't have a "get out of physics free" pass.
Don't get me wrong here... (Score:5, Interesting)
Re:Don't get me wrong here... (Score:5, Insightful)
Far from it. All of the components of a space elevator will be revolutionary, not just the ribbon. The climber's mechanical parts have to work flawlessly for about 100,000 km. The actual problem of gripping a cable isn't trivial, either. And it needs to be very low weight. Oh, and very low power. And just to make things even more fun, it'll need to work in vacuum as well.
If you read some of the papers on concerns for the climber at the space elevator conference, you realize that there's nothing easy about this. It's unsurprising that the climber is seeing the most progress first, but that first concern (perfect reliability over 100,000 km) will take a long time, so better to start now.
Re:Don't get me wrong here... (Score:3, Informative)
Of course it does. For one thing, you can understand how a climber can climb. So if you see one climbing, you say "hey, that's easy, I could've built that." But designing something that reliable and that optimized is very, very difficult.
I'd imagine if you were a material scientist working with carbon nanotubes, you might feel that the ribbon is easier. Especially because we really don't have to get all the way to 50-100 GP
Re:Don't get me wrong here... (Score:4, Interesting)
Re:Don't get me wrong here... (Score:4, Insightful)
Oh, and I didn't see this. Fundamentally, this is a bad idea. First off, the idea of a modified Howitzer? That's just explosive propulsion. This is fundamentally the same idea as a rocket - it's just that a rocket is far, far more effective in terms of thrust per unit mass.
You could imagine electromotive propulsion - a rail gun - but the problem with that is that you're imparting all of your momentum in the thickest part of the atmosphere, at which point it would just be bled away as air resistance. You'd need to supply a ridiculous amount of energy to do it, and the craft would have to have a ridiculous amount of stress support and heat resistant material. It gets to the point where there is no way that it would ever be economically feasible.
On an atmosphere-free planet, though, it does become pretty feasible, though a space elevator is likely to be more generically useful for large cargo.
Re:Don't get me wrong here... (Score:3, Interesting)
Uh, yes. That's kindof what the Shuttle uses.
I guess you could but it's probably an even worse return; which you seemingly agree on.
No - that's my point. If you want to launch the thing to say, 100,000 feet, there's no way a rail gun would compete with a direct rocket launch. Sure, you lose 70% of your energy in splitting water into hydrogen and oxygen - but you'd lose 90% in air resistance by only giving an initial impulse.
Besides, you can't launch something to 100,000 feet easily
Re:Nanotubes and Power (Score:3, Interesting)
Don't laugh. Building one today is quite impossible, of course, because we
Re:Nanotubes and Power (Score:3, Interesting)
1 down, 61,999 to go! (Score:5, Insightful)
Re:1 down, 61,999 to go! (Score:3, Funny)
Re:1 down, 61,999 to go! (Score:3, Informative)
All the climber (elvevator car) needs to do is go up to 100 miles to do what the space shuttle does and only 62 miles to do what Spaceship-One did. So in the case of the climber part it is 1 down and 99 to go.
Re:1 down, 61,999 to go! (Score:3, Informative)
But you saved on the lower stage and you don't have to worry about atmosphere anymore, so it would be a good Shuttle replacement. Even now when a sattelite is released from the shuttle, a booster is required if you want to get it to a higher orbit. On the other
Re:1 down, 61,999 to go! (Score:3, Insightful)
1500 feet != 1 mile (Score:5, Informative)
Re:1500 feet != 1 mile (Score:3, Insightful)
One issue I have yet to see addressed is the issue of speed. Rockets make it up to geosynchronous orbit (22,240 miles) very quickly by moving really, really fast. Somehow, I don't think a robot climbing a ribbon will be very fast. Even at 1,000 mph, it'll take almost an entire day to get there. I don't know what the actual expected speeds will be, but I don't think
Re:1500 feet != 1 mile (Score:3, Interesting)
Re:1500 feet != 1 mile (Score:3, Interesting)
Agreed about the attitude. Actually, I expect the attitude was much the same when we invented boats. Fortunately the Polynesian explorers got tired of the naysayers and went off to live in paradise. The Vikings took a slightly different approach to those too lazy to master the waves.
Acme (Score:5, Funny)
Oh no... (Score:2, Funny)
Lightning Rod? (Score:3, Interesting)
Re:Lightning Rod? (Score:2)
Re:Lightning Rod? (Score:3, Interesting)
It's probably too diffuse to conduct well enough into the elevator tether easily, but I wouldn't be surprised if the tether is differentially charged to significant potentials, which could create interesting problems.
On the other hand, it could be an interesting way to generate power for lifters, if you could find a way to have two strands with different potentials along them run the length of the e
Re:Lightning Rod? (Score:3, Interesting)
True, but the shuttle and the satellite were moving fast through the Earth's magnetic field. Granted the field fluctuates on it's own, but I think that is relatively insignificant compared to changes due to traveling at the speed needed for LEO. What's my point, I think the magnetic flux throug
Ah, the first robot in the Mile High Club (Score:4, Informative)
For those who have not experienced this particular pleasure: the obligatory Wikipedia [wikipedia.org] reference.
Lifter didn't climb one mile (Score:3, Informative)
Is the robot powered by linux? (Score:2, Interesting)
Re:Is the robot powered by linux? (Score:3, Interesting)
Does the ability to power it with a laser exists? Sure. We can build tuneable 10kW lasers now (think FEL). Attach some optics to focus. Put collectors on the bottom of the lifter. Tune the laser to match the frequency the collector is most efficient at. Go...
High altitude balloons? (Score:2, Funny)
Uhm, how useful will this be when they try to extend the elevator outside the atmosphere? Presumably, they have alternative methods worked out for stabilizing the zero-gravity portions, but somehow, Space Elevator == balloons is not nearly as exciting as Space Elevator == really cool new future technology.
I'm afraid I can't do that Dave (Score:3, Funny)
Oh come on, they're just asking for it.
video (Score:2, Insightful)
One mile down. (Score:2)
Re:One mile down. (Score:2)
I'm sure the hardest miles are 0-to-1, the mile where you leave earth orbit, and the last mile."
I'm pretty sure mile 47 is not much harder or easier than mile 54.
If this thing snaps..... (Score:5, Funny)
Re:If this thing snaps..... (Score:2)
Re:If this thing snaps..... (Score:2)
What if it is in paractical to build them that way? Will they scrap the project, or will they look at the fact that they might be paying less the a dollar a kilogram to get things in orbit and cross their fingures?
'They' being the varies project managers whos jobs will be lost if the project is stopped.
Re:If this thing snaps..... (Score:2)
We don't know if it's practical yet, but there are scientists and companie
Re: (Score:2)
Re:If this thing snaps..... (Score:3, Insightful)
62k mile rope... what if it breaks? (Score:2)
Is there any type of "backup" system in case a portion of the ribbon breaks?
I assume the way this works is that the end goes so far out that the inertia of the Earth spinning keeps the rope taut... but if a small part of that 62k mile ribbon breaks... the thing gets shot into space.
It doesn't seem viable to just have one long ribbon going up to space... seems too prone t
Re:62k mile rope... what if it breaks? (Score:2)
Wrong. The non-Earth end would be in orbit and if the tether parted, the section in orbit would continue to orbit. The downside would be that the end of the tether attached to the orbital station would set up a drag in the Earth's atmosphere and would eventually cause the station to begin a slow spiral
Re:62k mile rope... what if it breaks? (Score:3, Interesting)
Volume ~ 4/3 * 3 * (3,000,000)^3 ~ 115,000,000,000,000,000,000 m^3
Mass ~2xvolume tons: ~300,000,000,000,000,000,000 t
To take a billionth part out would be 300 billion tons.
Much of a problem?
Re:62k mile rope... what if it breaks? (Score:3, Funny)
I wonder... (Score:4, Funny)
in other news (Score:4, Funny)
In other news today, Denver-based Space Elevator company Black Shaft Industries have succeeded in achieving a height of 35 feet with their platform and climber, still easily besting their rivals Lifport. "We had a head start," acknowledges Chief Engineer, Michael Wesznick, "but our elevator didn't really need it. Plus, it has a cooler name." Wesznick went on to claim, that the elevator in question (named "Darth-Vator" to those of you who were wondering) will be the "father of all other space elevators", and, adding to this reporter's confustion, will at some point in the future "betray the Emperor to save it's son's life." Personally, I'm rooting for Lifport.
Wow! That's .... (Score:3, Insightful)
Only another 99.99954% of the way to go! . Wohooo!
Worst problem (Score:5, Funny)
Re:I'm a little confused. (Score:4, Informative)
Re:I'm a little confused. (Score:5, Funny)
and shoot laser beams out of your head that powers the robot...
and have safety procedures in place in case the string breaks, and the robot comes plummeting towards your head...
and have the multinational population living on the surface of your head come to some agreement about who's going to finance, maintain, and operate the thing...
Re:I'm a little confused. (Score:3, Informative)
Re:I'm a little confused. (Score:3, Informative)
The most common proposal is a tether, usually in the form of a cable or ribbon, that spans from the surface to a point beyond geosynchronous orbit. As the planet rotates, the inertia at the end of the tether counteracts gravity and keeps the tether taut. Vehicles can then climb the tether and escape the planet's gravity without the use of rockets. Such a structure could eventually permit delivery of great quantities of cargo and people to orbit, and at costs only a fraction o
Wait a second... (Score:2)
Of course I'm not sure what use a non-geostationary polar orbit is.
Re:Wait a second... (Score:3, Informative)
Other facts about geostationary orbits:
Re:I'm a little confused. (Score:2)
Re:I'm a little confused. (Score:2, Interesting)
Re:I'm a little confused. (Score:3, Informative)
The critical factor is how fast you're going in relation to how hard gravity is pulling on you. When you're in geosynchronous orbit you're moving fast enough to stay forever at the same height. If you're HIGHER than geosynch, but still moving at the same speed (1 rotation / 24 hours) you're going to drift AWAY from Earth if you let go. If your cable is long enough you can go a LONG way away. A 62,000 mile cable is more than enough to go
Re:I'm a little confused. (Score:4, Informative)
There was an article in Analog (WAAAAY back when) on the math behind space elevator cables, and they indicated that unless a material such as carbon fibers (nanotubes and the like weren't even on the horizon then) were developed to commercial viability then the required strength to weight ratio would make the cable waaay too wide at its halfway point.
Re:I'm a little confused. (Score:2)
That said, these space elevator stories give me the tinglies like visiting the Air and Space museum did when I was a kid. I *believed* when I was a kid that space was mankind's future. I still do, but between Challenger, the ISS boondoggle, etc, etc the gusto is gone. Space elevators, I think, are the logical next step for a true, permanent -- democratic -- future in spac
Re:I'm a little confused. (Score:2)
What happens when it comes crashing down? (Score:2)
If I recall correctly, there was a book published, where an event like this occured (fiction of course), yet the outcome was pools of bucky ball forming in impact zones, plus all the damage of that much material impacting the earth (the carbon material being heat resistant enough to not burn up during re-entry
Re:I'm a little confused. (Score:2)
Well, you know what they say about assume... (Score:4, Funny)
A space bird.
Space Bird! (Score:2)
(Sorry, it's angelfire and might notlike hot-linking, but if you enter the URL directly, it ought to work...)
Re:Well, you know what they say about assume... (Score:2, Funny)
Re:I'm a little confused. (Score:5, Informative)
Re:I'm a little confused. (Score:3, Interesting)
Your strange example of tar is pretty easy to explain. When a car is in the process of a turn, it has forward inertia. As the law states, "an object in motion tends to stay in motion", but the action of the tires and their friction with the pavement counteracts this tendency, thus the car turns instead of continuing straight instead of running off the road. Over time,
Re:I'm a little confused. (Score:3, Insightful)
This quote from http://en.wikipedia.org/wiki/Centrifugal_force is perhaps instructive:
"Because ro
Re:1 mile down.... (Score:2)
Re:1 mile down.... (Score:3, Insightful)
Re:1 mile down.... (Score:3, Insightful)
> significantly more difficult than the next 61,999?
Er...except it's not. As you leave the atmosphere there's temperature extremes...radiation...vacuum. Not to mention every mile you extend the elevator increases the strain the structure must support. The first mile is the *easiest*.
Chris Mattern
Re:Don't you mean 62 miles? (Score:5, Informative)
Re:Don't you mean 62 miles? (Score:3, Interesting)
For the simple case, yes. But (IIRC) Robert Forward proposed a modified concept that utilized solar sails to stabalize the orbit and allow for them to be in other orbits. Or it may have just allowed for non-equatorial placement, or both -- I don't recall exactly and I'm certainly not a rocket scientist/orbital mechanics expert.
Re:Don't you mean 62 miles? (Score:2)
Yes. That's long. But it's not as insane as you might think. The biggest concern is the tensile strength of the cable itself. Once (if, and it's a tough "if") that gets solved, it's just a matter of a really really big spool of cable.
Don't get me wrong. It's still moderately insane. It'll be #1 on the Discovery Channel's modern engineering marvels if it's completed - by a large margin. But it's not completely ridiculous insane.
Re:Don't you mean 62 miles? (Score:5, Informative)
We don't use rocket to get above the atmosphere. Planes can pretty much do that. Balloons can (and regularly do) do that. That's the easy part.
We use rockets to get velocity, because you need a ridiculous velocity in order to actually orbit the Earth at a low height.
You do not, however, need a ridiculous velocity in order to orbit at a very, very high height. At geosynchronous orbit, you need no velocity, because you've already got the speed from the Earth's rotation.
So yes, they do mean 62,000 miles (100,000 km). And the benefits you get from a cable like that are insane. Costs/pound to launch things into space become negligible. Transit to the Moon becomes cheap and fast, because the end of the cable is actually moving faster than orbital velocity.
In fact, if you climbed all the way to the end of the cable, and let go with good timing, you'd end up past Jupiter (and on a direct trajectory, too, no mucking about in Lagrange points).
Yes, it's moderately insane. Yes, it's ridiculously difficult. But it would also end up being one of the biggest changes in human industry that has ever occurred. Space solar power plants beaming down power becomes feasible. Large-scale structures built in space become easy.
Plus, once we get the technology, we can build them on other planets as well. The Moon. Mars. It basically eliminates almost all of the serious difficulties of space flight.
Re:Don't you mean 62 miles? (Score:4, Insightful)
I word things very carefully. Read it again. I said "planes can pretty much do that." I was actually thinking about commercial airlines, which fly above 72% of the atmosphere.
But, of course, there's this nugget from Wikipedia:
Balloons typically reach altitudes of 100K feet, which is above all but a fraction of a percent (it's a few Torr).
simply by building our velocity high enough to escape velocity while in the atmosphere and letting inertia take us out.
Ignoring that whole "air resistance" and "speed of sound" thing.
And curiously, if it wasn't for those two things, we could do that right now.
We use rockets for velocity, not altitude. If you doubt me, consider that the Space Shuttle's two solid rocket boosters shut off at lower altitudes than the X-15. Why don't we use a jet to boost the Shuttle to that altitude? Because the SRBs get the Shuttle to a much, much higher speed.
There's nothing "special" about Geosynchronous orbit which means you can "get the velocity from the Earth".
I get velocity from the Earth all the time. It's called standing on the ground. (Curiously enough, if I didn't, I would start flowing in these little circly patterns, called Hadley cells, which are what happens when you have a viscous medium gravitationally sitting on top of a rotating sphere. If the atmosphere extended enough, it essentially wouldn't be rotating.)
That's what special about geosynchronous orbit. Orbital velocity is slow enough that I can use the Earth's rotation to supply it.
You DO have velocity.
Which I got... from the Earth. Like, when a plane lands, after heading west, how the Earth speeds it up in a matter of seconds?
The idea is at that height, escape velocity is negligable.
It's not "negligible" - it's two thousand miles an hour (curiously, roughly 1 km/s). It's just neglible in the rotating frame of the Earth.
Re:Don't you mean 62 miles? (Score:3, Insightful)
I will if I keep holding onto a giant pole. Which is what this is.
Re:Don't you mean 62 miles? (Score:3, Informative)
The Shuttle SRBs shut off at nearly the same altitude as balloons reach. Scientific balloons are up at 40-50 kilometers. At that point, you're above 99.9% of the atmosphere. If you really wanted to, you could get almost arbitrarily high - it's just a question of how large you'd like the balloon to be. Like I said. But you don't use balloons instead of the SRBs, because the SRBs supply humongoid amounts of velocity as well.
To orbit, you have to get a
Re:typo (Score:2)
Re:So what? (Score:4, Insightful)
While we don't have the ribbon yet, we don't have the climber, and we don't have the power delivery system either. That's why it's called inventing. They're doing something that hasn't been done before.
And when you've got multiple independent difficult problems, you might as well work on all of them at once. Which they are doing.
Go and read the talks on building the climber at the last space elevator conference before you call it "trivial".
Re:So what? (Score:4, Interesting)
It's just a bit silly really... like building the lunar lander for Apollo but having boosters no larger than a bottle rocket.
Get closer to the Saturn V THEN build the lander!
Re:So what? (Score:3)
You don't know that. Ask a materials scientist working on carbon nanotubes how long it will take to get that cable, and you might get an answer of "5 years". Ask an engineer how long it will take to design that climber (and the subsequent power delivery system) and they might say "5 years" as well.
It's a difficult problem, and the climber's power needs drive the power delivery system. So it makes sense to work on the climber first.
When we are 75% of th
Re:And if it falls? (Score:4, Funny)
Yes. They're going to deploy a massive cushion [wikipedia.org] around the Earth, consisting of a total of about 5000 trillion metric tons of gas. Roughly 78% will be nitrogen, and 21% will be oxygen.
If the cable breaks, the lower half will encounter this cushion at extremely high velocities, ripping it apart and causing it to flutter harmlessly to the ground.
No news about whether or not they'll patent the idea.