Continued Success for Space Elevator Tests

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."

Don't get me wrong here...

[Skyshadow]

...but it seems like the climber is the easy-ish part of a space elevator. If they were doing work with the carbon nanotubes, I'd be much more impressed.

Lightning Rod?

[dorpus]

I'm just wondering, won't these things become a lightning magnet? You say it can be grounded, but what happens when these things stretch into higher parts of the atmosphere with more ions flying around?

Is the robot powered by linux?

[beoswulf]

Seriously, what does the robot on, what type of power supply does the robot have? It only made it 1500' on a mile long cable. Is that because it's energy supply ran out? Science fiction writers usually say ground based "lasers" or "microwave transmitters" but is that more feasible than 62,000 miles of carbon nanotubing?

Re:I'm a little confused.

[JazzCrazed]

It's useful in that objects can use it to climb up and out of the Earth's atmosphere and into orbit, thus saving in the exorbitant costs, financial and environmental, in using rockets. From orbit after escaping Earth's gravity, it's a much easier prospect to jet off to the moon. Although there's use in just sticking things in orbit, as well.

Re:Lightning Rod?

[Anonymous Coward]

That is one of the outstanding questions WRT the space elevator: What happens when you ground the ionosphere?

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 elevator.

I can see the signs now: "Beware the third braid."

Re:1500 feet != 1 mile

[interiot]

Considering that rocket launches can be delayed for several days due to bad weather, and have a 1+ year lead-time, just shipping your project to the launch site probably takes several days at the very least (and for smaller cargo, means shipping it to Russia, and shipping high-tech gear across borders can take time), and that most space projects are currently planned several years ahead of time (besides the significant difference in launch cost, obviously), it doesn't really matter if it takes a day or three to get your object to space with a space elevator. Yeah, rocket launches will still be used for strategic nuclear war, but that doesn't mean that a space elevator doesn't have significant upsides of its own.

Re:62k mile rope... what if it breaks?

[Anonymous Coward]

Do the maths: taking the earth as 6,000,000m across and an average density of 2t/m^3:

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:I'm a little confused.

[balsy2001]

While traveling to the moon will be easier you have not escaped from the earths gravity well at 62000 miles.

Space elevator alternatives

[yahyamf]

There are other ways to get into space without extending a strucuture beyond geosynchronous orbit. Check out launch loop [launchloop.com] and this [wikipedia.org] wikipedia page.

Re:Don't you mean 62 miles?

[Zathrus]

By necessity, the center of mass (radially from the surface of the Earth) must be at or near geosynchronous orbit, so it naturally remains centered over its ground anchor

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.

Mure musings

[Darkman, Walkin Dude]

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 serious spaceport! :D And all readily doable and not making the greens shriek or anything (except for a 500 mile by 300 mile strip of ocean that we weren't using anyway :D). Or if that doesn't sit right, the equatorial third world nation of choice would be more than happy to make itself richer than America and Europe combined by hosting the world's first true spaceport...

Re:Don't get me wrong here...

[Rei]

Yes, you refer to the exploits of Gerald Bull [std.com], who actually was working on what you mentioned [slashdot.org]. A fascinating bit of history, really.

Re:What happens when it comes crashing down?

[fjf33]

I remember seeing an article (don't remember if online or a periodical) that said essentially that it would depend where the break happens. The stuff high up will burn on reentry and the stuff way down would wrap around earth very slowly, kinda like a leaf falling down. The counterweight would either escape earth or go into a higher orbit but moment would be conserved. I don't think a nuke would do much to it. More than likely an attach at the anchor point on earth or an attack on the strand itself is what would happen. Then there is the problem of all this junk that is in orbit between earth and the counterweight that would also like to snap the strand. Some kind of protection would have to be developed. Once one strand is up then redundancy can be built in by putting even more strands. Safety wise, the most dangerous object was the elevator cabin itself since it would be bulkier.

Re:So what?

[Big_Breaker]

The point is that the cable is by far the hardest part. We aren't even close. When we are 75% of the way to producing an adequate cable we can start the other parts. I bet we would still finish those other components before the cable is ready.

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:I'm a little confused.

[Grishnakh]

Sorry, no. There is no such thing as centrifugal force, period. It's a convenient construct for laymen to think of things, and that's it.

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, the asphalt deforms due to this frictional force (again, caused by the forward inertia of the cars).

Re:Nanotubes and Power

[Grishnakh]

A space elevator is theoretically feasible, but the challenges are far from trivial. I laugh at people who suggest one can be built starting today for $10 billion. Some of the estimates I've heard put the cost of developing all the technology for and building the first elevator at several $trillion, or equivalent to the federal government's entire annual budget. Of course, if we ever get one up, subsequent elevators are far cheaper.

Don't laugh. Building one today is quite impossible, of course, because we haven't yet developed the technology. But it could be feasible in ten years if we worked hard enough at it.

For comparison, look at the manned space program. JFK proclaimed the US would put a man on the moon before the decade (60's) was over. That was in 62 or 63. Armstrong set foot on the moon in 69 IIRC. The technology didn't exist when JFK made his speech, but with the enormous amount of funding the USA put into the space program after that, it was all developed on a very fast timescale.

If the US (and better yet, some partner countries) put forth the enormous funding necessary now like was done in the 60's, I don't see why a space elevator being constructed by 2015 couldn't be a reality.

Re:Lightning Rod?

[hador_nyc]

Well, they did have those two tethered satellite experiments that they ran on the Space Shuttle, and even in LEO with a relatively short tether the potentials between the satellite and the shuttle were pretty big.

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 through the "elevator cable" would be significantly lower than that of through the wire between the two orbital objects. Still, the problem remains, and I don't know enough to guess on this one, is the flux generated by the natural fluctuations great enough when operating on a cable that long to cause a problem(induce a strong current). Also, there is a possibility of an interaction with the solar wind. Let's plug into the Arora Borealis(sp?).

Re:1500 feet != 1 mile

[ceoyoyo]

Even in the atmosphere we're rather familiar with traveling faster than 100 mph. When I was in Europe I had a Kia Picante (otherwise known as a cardboard box) going that fast.

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. ;)

Re:Nanotubes and Power

[iamlucky13]

I don't deny that it may be possible to build a space elevator in 10 years if we start throwing money at it like crazy, but developing the technology will be expensive. I seem to remember reading somewhere that the amount of money invested in the manned space program from Mercury up through Apollo 11 was around $100 billion, in 1960's dollars. I would classify this effort on the same level. We've seriously never done something like this before. Goddard launched his first liquid fueled rockets around the 1900's. I don't really know whether to say our current progress is on par with his, 60-70 years before we walked on the moon, or closer to that in the 1960's when Kennedy declared his vision, less than 10 years before it happened. Meanwhile however, Liftport is operating on a few million dollars a year, at best, and CNT companies a little bit more.

Re:Don't get me wrong here...

[barawn]

Use that how? As a rocket?

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. The object would be travelling very supersonically, and the air resistance would be wacky beyond all measure.

Besides, improved safety is only of the other tangibles of the rail approach.

No, it isn't. Now, the fuel wouldn't fail - but the structural supports might. You're upping the structural requirements of launch by orders of magnitude. That's just not feasible.

Again, that's exactly why people get excited about a rail gun launcher.

What? I mentioned that because it's not possible to have an arbitrarily high thrust from a rail gun. At some point you're just asking way too much current.

Re:Is the robot powered by linux?

[confused one]

They're powering the climber with on-board batteries, I believe.

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...

Re:1500 feet not a mile

[barawn]

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).

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.