NASA Power Beaming Challenge is On For November 2nd

carstene writes "The NASA Centennial Challenge Powered Beaming competition, to develop technology for uses such as a space elevator, or to power a rover in a shadowed crater on the moon, was delayed indefinitely due to trouble setting up the kilometer-high race track. It has now had the kinks worked out and is rescheduled for the week of November 2nd. The competition involves using a high-power laser to beam power to a robot that climbs a kilometer-high cable attached to a helicopter. The competition was previously covered on Slashdot."

Comments

Why not just use wires?

[slifox]

Why must we beam the power to a space elevator?

Wouldn't it be reasonable to use wire conductors? If we will be able to build the support lines that can span from the earth to orbit, why couldn't we also make a couple of smaller ones inside the main one for carrying power? Or why not just use the support lines themselves to provide power (assuming there are multiple support lines for redundancy)?

Can anyone provide some more insight into this? I haven't been able to find a decent explanation

Re:Why not just use wires?

[beefnog]

The tensile strength of an eventual space elevator material is not related to its electrical conductivity or resistance. 10,000 miles of a conductor will (currently) weigh more than its own tensile strength could support.

Re:Why not just use wires?

[decipher_saint]

I believe that the cable used for a space elevator must be as lightweight and strong as possible. Running power through that infrastructure will add weight and weaken the structure (maintenance access, etc). Not to mention drive up costs and add complexity.

I dunno, just shooting from the hip here.

Re:Why not just use wires?

[jimbolauski]

Carbon nanotubes are conductive so the same lines that could be used to hold the elevator up can be used to transfer electricity, the problem is that the elevator would need the lines exposed to use them for power which would make it highly vulnerable to lighting.

Re:Why not just use wires?

[vertinox]

Wouldn't it be reasonable to use wire conductors?

Because a space elevator will have cables over 90 km which will either need repeaters every so often or some hellacious voltage to push power that far over high voltage power wires.

And if you have seen close up on those high lines... Are rather thick bundles.

And 90km of that stuff is not going to be able to support its own weight.

Re:Why not just use wires?

[fred fleenblat]

aside from the weight issue, shouldn't the cable specifically be designed to be an insulator anyway? Shorting out the fair weather return current and/or tapping into particle storms in the upper atmosphere seems like it could lead to some nasty little electrical issues.

Re:Why not just use wires?

[lobiusmoop]

um, what? I'm assuming the OP meant bonding a separate conductor pair to a high-tensile elevator cable. If the cable is strong enough to support its own weight, it should really be strong enough to support a few extra tonnes of wire.

Re:Why not just use wires?

[Anonymous Coward]

10,000 miles? I thought space was only 20 miles up.

Re:Why not just use wires?

[Anonymous Coward]

There are limitations to the length of power lines for other than mechanical reasons. It is 36000km (22000miles) to Geosynchronous orbit, which is where we ultimately want to go with this thing. Using cables for anything near that is highly problematic. (longest power line on earth is about 1700 km)

http://en.wikipedia.org/wiki/Electric_power_transmission

Re:Why not just use wires?

[Rei]

Yeah, even if you use ridiculous voltages, it's just not going to happen.

Plus, these competitions always seem like putting the cart before the horse. The elephant in the room is that we have no material close in terms of properties to what is needed to make a remotely feasible space elevator on Earth (at least 100GPa at the density of graphite), and it may not even be physically possible. Some people have theorized that SWNTs could be that strong, but the strongest SWNTs measured so far are about 60GPa -- and that's for *individual nanotubes*, let alone nanotube bundles, let alone composites made out of nanotube bundles many thousands of miles long. MWNTs have been measured somewhat stronger, but they're a lot denser, so that doesn't help. I mean, even if you ignore the other issues that have been shown to be huge stumbling blocks with space elevators, such as oscillations, that's really a killer.

These competitions come across as though someone started promoting their new "Levitation Shoes" with the following exciting announcement:

"Good news, Levitation Shoe engineers! We will be hosing a Levitation Shoe shoelace-development contest. As you all know, we need to solve the issue of shoelaces being able to withstand the wearer getting buffeted around by high altitude winds without breaking or becoming untied, so we've reserved a site with a huge fan that you can test your shoelace prototypes on! This will bring us one step closer to the dream of Levitation Shoes."

Honestly, much more realistic than a space elevator appears to be a Launch Loop. No nonexistent (and possibly even impossible) materials required.

Re:Why not just use wires?

[mcrbids]

Carbon nanotubes in the "armchair configuration" AKA 5,5 configuration, are excellent conductors of electricity along with having fantastic tensile strength properties.

To see this at work:

1) Get a metal, NON-magnetic tube (eg aluminum)

2) Get a magnet.

3) drop the magnet down the tube. The magnet will go VERY SLOWLY down the tube because of the magnetic field it generates. It never touches the tube. That's because of the electricty inducted by the magnet creates its own magnetic field. Since there's nowhere for the electricity to go, the magnet drops very slowly.

If we make the space elevator a loop, where there are two points touching the earth (perhaps a few hundred miles apart) then we could use the flow of electricity and a magnetic field to provide both power and propulsion, and "get it back" when an elevator goes back down to Earth, without ever touching the nano cable. And we can control the rate of ascent/descent just by adjusting how much resistance we put on the loop circuit.

Re:Why not just use wires?

[Rei]

"a few extra tonnes"? First off, space elevators aren't exactly high payload devices; the margins in most designs are generally tiny compared to the elevator's mass. But the big problem with what you wrote is that geosynchronous orbit is 26,199 miles up; a space elevator must be *at least* that long. You're looking at something like one ton per 10,000 miles, or one pound per five miles, or 17 milligrams of conductor per foot. Do you really think that's going to power anything? Even if you only provide power for part of the way up, it's still just not going to happen.

Re:Why not just use wires?

[Gerzel]

Really I'd rather see the beam being used w/o the cable. You should be able to move the beam and get correction for trajectory information sent back on a wider down stream beam. I think that would be a lot safer, and technically more reasonable than a full fledged elevator and signifigantly cut the fuel load.

Re:Why not just use wires?

[Rei]

Let's say you're looking at a 100GPa cable (I can show you why you need a cable this strong later if you need me to). That's 14.5 million pounds per square inch. Let's give it a two-fold safety margin, so we have 7.25 million psi to work with. Let's say we want to carry a payload of 10 tons. That means we need a cross-section of 0.00275790291 square inches. Don't think that makes our cable super-light, mind you -- it must thicken as you go up, and will weigh hundreds or thousands of tons in net weight.

I don't know the resistivity of 5,5 armchair CNTs, but let's just go with copper for now. As we all know:

Resistivity = (Resistance * Cross-Sectional Area ) / Length

If we only care about the craft climbing up to GEO (42,164km), that means we have:

0.0000000168 = Resistance * 0.0000017792886414156 / 42164000
Resistance = ~400,000 ohms

Good luck with that. :P

Re:Why not just use wires?

[Gerzel]

Agreed but beamed power does have other very real and current day uses so the competition isn't entirely moot.

Re:Why not just use wires?

[Rei]

Oh, and a couple more things:

1) I was generous and assumed a cylinder for the cable rather than a ribbon, as most designs call for, for easier climbing. If you go with a ribbon, you'll get a lot more resistance.
2) If your solution is "superconductors", that'll help, but they break down at high currents, so it's still not a solution.
3) If your solution is "extremely high voltages", you get coronal discharge (which occurs even in the partial vacuum of near-space).

Re:Why not just use wires?

[gurps_npc]

It is totally correct that we can't make a space elevator right now.

But we could make a space elevator.

1. Take a particle accelerator, preferably one built at a high altitude. You should be able to start at least 4000 meters above sea level (China's Qinghai-Tibet Plateau averages 4,500 meters.

2. Put a bend in the output - straight up.

3. Detach the final u turn that bends the particle stream down again.

4. Add some magnets to recover power from the particle stream. Use it to power the magnets in the final U bend, that is now detached.

5. Focus the energy so that the it is self-centers the now detached final U.

6. Up the power. The detached U bend now floats.

7. Keep raising the power. U bend keeps going up.

8. At low altitudes, the atmosphere will drain massive energy. So build an air-tight 2000 meter tower around the particle stream. At the very least this should take you 6000 meters above sea level. Air pressure is now 50% sea level. This will reduce power consumption

Problems: 1. Power requirements will be HIGH. We will need to build a Nuclear power plant (probably a 2nd on as a backup). 2. We will building the tallest man made structure on Earth, at one of the highest points on Earth. 3. A lot of untested engineering, although the physics is known.

Re:Why not just use wires?

[pixelpusher220]

It will not have to support it's own weight. No more than the wire running to the rooftop antenna of a skyscraper supports it's own weight. The power cables would be attached to the elevator ribbon along the way.

Now, whether that adds too much weight to make the space elevator unworkable is an entirely different concept. But the power cables wouldn't have to support themselves. As other posters have said, other issues exist with it, such as electrical interaction with lightning (1.21 gigiwatts anyone?) or repeaters being necessary are also valid concerns to a power cable or 'rail' solution.

Re:Why not just use wires?

[Rei]

That's not a Space Elevator. That's a Space Fountain. And the power requirements of actively-suspended structures don't need to be high -- you only need to "pay" for any initial increase in gravitational potential and kinetic energy, and from there on, any leakage.

Re:Why not just use wires?

[Anonymous Coward]

The conductor would not be supporting it's own weight. It would simply be attached to the elevator ribbon along the way.

Re:Why not just use wires?

[Anonymous Coward]

Exposed? Just use electromagnetic induction, no exposure necessary.

Re:Why not just use wires?

[jfengel]

Or, as I read here on Slashdot once:

First, build a bridge that goes 40,000 millimeters across a ditch on a college campus out of this material. Then we can start to discuss how we're going to build 40,000 kilometers of it straight up.

Re:Why not just use wires?

[Tiger4]

No, space is 50 or 62 miles up, depending on who you ask.

Re:Why not just use wires?

[gurps_npc]

Namewise you are correct, I meant to say space fountain, not elevator. Power costs will only be low if we can keep air outside of the fountain core. I am not as sure as some people are that this will be cheap. In general, power costs tend to be higher than people estimate. Note, the power costs are only really high when we are raising the U bend. Once it gets up there, costs become minimal. The most important part is that we have the technology to build one TODAY.

Re:Why not just use wires?

[ImitationEnergy]

You have raised an interesting question. Would using a hollow wire allow the cold of Outer Space to plummet down the inside of the cable like a Mini Day After Tomorrow? If true perhaps the cold would enable smaller wires -like you suggested- to carry more current, a partial superconductor. But you'd have a partial vacuum inside the cable, requiring it to be very strong (heavier). Now if those small wires were to be made of a metal that goes superhard in the cold, or had a liquid center, you could actually have a machine feeding soft cable into the larger wire that would be turning harder the farther up it went, with the outer cable being a guide keeping it from falling over. So hmm, the ISS would need to drop a real big Slinky. Is it cheating the contest to have the thing lowered from Space? I think the cable would need helium in the walls, on the outer side so the cold didn't make it collapse. Whew, you're stretching my imagination. But if they put wings on the cable that would use the high wind speed.... Hmm. Wings. You could make an Archimedes screw with wider wings spinning at a high enough speed to raise its own self pretty high, and then fire a rocket up the center that would finish the trip into Space pulling a wire. You have to remember that as the rocket climbs it would be riding upward on the pressure of its own exhaust. hehehehe

Re:Why not just use wires?

[ImitationEnergy]

Basically what they're trying to do is drill upwards anyway. Lifting a drill is harder than dropping one down but that should be overcome by a high enough rotation of the wings and spiral staircase that sucker straight up through the clouds. Of course it would only go so far as the air thinned. I reckon that's the point where you'd launch the rocket up inside it... riding atop its own steam heat contained in the shaft. Hmm. Perhaps the awesome heat could be secondarily used to harden the "tower" on the way up. I couldn't do it, so maybe we need to resurrect Werner von Braun. I imagine he might use more than one rocket, consecutive rockets.

Re:Why not just use wires?

[khallow]

Why must we beam the power to a space elevator?

Unless you're using superconducting wire in your tether, beamed power loses far less energy. Common loss rates for regular copper wire is something like several percent per 100 km. That's about as good as it gets. And the mass is way too heavy.

Re:Why not just use wires?

[Anonymous Coward]

Yeah because we have already invented all the materials needed to build a space elevator. Err... Or not.

You certainly speak as if you know how its all going to work, kudos to you. However, I imagine that NASA is simply trying to advance the state of the art for power transmission, with a space elevator a possible use for it, but by no means is it meant as a design property of said elevator.

Maybe they should hire you since you have the whole thing designed already.

Re:Why not just use wires?

[Anonymous Coward]

One thing I haven't seen any explanation on yet, and that I just can't wrap my head around is:
How would you even get the fracking support lines spanned out there. I don't know exactly how many hundreds/thousands of tons of material that's supposedly involved, but I reckon we'd need an elevator just to build the elevator?...

If the support lines were lowered down from geoorbit, wouldn't the weight pull themselves down? If they were raised from ground up, wouldn't they topple down? Strap them to a rocket? Shoot them up? Build a scaffold/ladder? Raise them with a turban, flute and groovy tunes? Have genetically altered spiders/ants weave and build them for us?

Here I was thinking getting the ISS up there was hard.

As always, the trust placed in the capabilities of our engineers is incredible. They can do anything, (anything).

Re:Why not just use wires?

[Anonymous Coward]

A mass driver is by far the more reasonable method of cheapening space travel not only with a space elevator do you have to worry about what mentioned below you have to worry about what happens when you fail to get the line up 26,000 miles of cable will literally wrap around the earth and overlap now even of the thinnest material possible your talking probably a mile or more wide and how can that mass be anchored to the earth cant just pour a foundation to keep 300 tons of rock on a string from pulling loose. Plus the counterweight how will it be placed into orbit around the earth in geosynchronous orbit...

A type of mass driver rail launch system is far more feasible to shoot payloads into orbit.

Re:Why not just use wires?

[Anonymous Coward]

If a camel is strong enough to support its own weight, it should really be strong enough to support a few extra tonnes of wire.

Re:Why not just use wires?

[Anonymous Coward]

If you dont have a geosync orbit , the orbit isnt sustainable for an elevator. You HAVE to get 26,199 miles up, or the weight falls to earth, instead of spinning around it.

At 50 miles up, it would literally be like a lead balloon.

Re:Why not just use wires?

[Rei]

The Edwards design calls for launching a reel that weighs several hundred tonnes up to GEO and lowering it down. The initial tether would be tiny, feather-light. You'd then have a series of increasingly large climbers that "glue" additional strips onto the side of the ribbon, carrying the ribbon up with them instead of payload, and very slowly expanding it. After a couple years, it's ready for cargo.

Obviously whether that's even possible depends strongly on what the mystical elevator material is like.

Typo?

[n3v]

"or to power a rover in a shadowed creator on the moon"

s/creator/crater/

?

htmm

Because The Wires Can Be Cut By Al-C.I.A.-da

[Anonymous Coward]

In Afghan-Pakistan.

Remember, the Pentagon's budget (including non-line items) is U.S. $1,000,000,000,000 per year.

Years In Petrograd,
Kilgore T.

In other news....

[snspdaarf]

High-powered laser shoots down helicopter. Film at eleven.

I see a problem.

[WoRLoKKeD]

This is all well and good, but how are they going to keep the sharks focused on the kilometer-high robot?

Why a helicopter?

[AJWM]

Wouldn't it make a lot more sense and be a lot easier to hold the cable up with a balloon? (Or rather, hold the balloon down with the cable.)

Re:Why a helicopter?

[NoYob]

Wouldn't it make a lot more sense and be a lot easier to hold the cable up with a balloon? (Or rather, hold the balloon down with the cable.)

Because a balloon can't be held stationary? It will be blowing around with any wind up there.

Re:Why a helicopter?

[jimbolauski]

1 m^3 of helium has about 1kg of buoyancy, to lift 1km cable along with the elevator would require a very large balloon, the winds at 1KM are much stronger then on the surface so the giant balloon would be blown all over the place with a laser pointed at it I'm sure you can figure out the rest.

Re:Why a helicopter?

[UnglueD]

They could have some kid, preferably named falcon, sit in the balloon to make sure it stays put.

Re:Why a helicopter?

[quercus.aeternam]

And what happens if you miss and hit the balloon?

Balloons are a lot more susceptible to lasers than helicopters (or so I hear...)

Re:Why a helicopter?

[PitaBred]

Warning: Do not look into laser with remaining eye

Re:Why a helicopter?

[jnaujok]

I dunno, reflective mylar? If only we could build a balloon that could reach the stunning altitude of 1 kilometer (that's about 3000 feet) and be large enough to hold up that cable (guessing around 1000 to 2000 pounds) and keep itself still...

Why, what a miraculous craft that would be!

Re:Why a helicopter?

[Zerth]

They want to be able to screw with the contestants, which sort of requires a self-moving endpoint.

Re:Why a helicopter?

[quercus.aeternam]

That's just crazy talk. Everybody knows that you can't /really/ fly. They just do it in movies and stuff to speed up plot...

Oh, and the Hindenburg was just some aliens crash landing. Because they can't fly, you know.

On a more serious note, it's probably easier to get a hold of a helicopter than a suitable airship, but who knows? I've never tried.

Regardless, it would seem that NASA thought so - though that is very much debatable considering the status of manned spaceflight...

Re:Why a helicopter?

[palegray.net]

And what happens if you miss and hit the balloon?

I'm still trying to work out how you can miss and hit it at the same time. Is this like some story I once heard about a cat?

Re:Why a helicopter?

[pwmonroe]

The original plan was to use a tethered blip type balloon, but leasing a helicopter was deemed less expensive. It to comes with its own issues, not the least is the copter hovering at ~1km maintaining a constant tension on the cable as the climber ascends. I too expressed concerns about a manned aircraft having a 5KW laser beamed at it, but that seems to have been addressed. I was very briefly involved with one of the teams until my main job intruded, think that there is a lot to be learned from the effort.

Re:Why a helicopter?

[Anonymous Coward]

The tested plan is to use a 'virtual bob' for tension control. Essentially that mean the cable comes down and divides into three split cables, to chains heavier than the helicopter can lift.

One of the reasons to choose a helicopter over a balloon is active control. The rules require us to limit our laser to only 7 1/2 degrees off of the center point, not much room to move. the angles of laser and climber have been carefully selected to always shoot past the helicopter. the race is to 1km high, but the helicopter is 1.5km high to help with safety.

After a couple days of prep, the first day of the actual competition is Wednesday, Nov 4th. The KC Space Pirates are scheduled first for a 7am run.

Science and engineering principles are great, but in testing I trust.

Weight

[NoYob]

I'm guessing it's a weight issue. Putting a conductor necessary to carry that much current in with the carbon-nanotube ribbon (that is still the preferred tech isn't it?) would just add so much weight as to make the elevator impracticable. Just look at the size of the copper to power a 120v outlet. Could they make the carbon strip itself conductive?

Shadowed Creator?

[pavon]

The NASA Centennial Challenge Powered Beaming competition, to develop technology for uses such as a space elevator, or to power a rover in a shadowed creator on the moon, was delayed indefinitely due to trouble setting up the kilometer high race track.

Yes, well they should have known that you can't build Barad-dûr in a day.

It's watching

[get quad]

Our shadowed creator is always present with its noodly appendages at the ready.

Re:It's watching

[Anonymous Coward]

It looks like good clean fun, but you know that some hundred years in the future, there will be an actual Church of the Flying Spaghetti Monster. People always take things like this too far.

Re:It's watching

[Anonymous Coward]

better that than those damn trekkers

simpler test

[slashkitty]

why don't they just try a 1km ground based test first? I can't imagine this is safe for the chopper. Much needless complication for testing the technology.

Re:simpler test

[Anonymous Coward]

So, you're saying they just build a structure maybe 10 meters high and play out the ribbon as needed to keep the climbers roughly in the middle?

I think they're trying to compare the whole system, including power source tracking.

Re:simpler test

[mpoulton]

why don't they just try a 1km ground based test first? I can't imagine this is safe for the chopper. Much needless complication for testing the technology.

Because gravity goes down, not sideways? Seriously, that's simply not even remotely comparable. The entire challenge here is to climb a straight, vertical cable against a 1G vertical acceleration. Crawling along a horizontal catenary-shaped cable with a 1G sideways acceleration is a completely different problem to solve.

Re:simpler test

[pixelpusher220]

I think his point was that you could make a pretty straight 1 km bar along the ground. I thought the main thing being tested here is the ability to hit the target as it goes along the cable/bar to a distance of a km. Mimicing the resistance of gravity while moving in the horizontal plane is quite simple.

At some point though you do want a full system integration test, so perhaps that's what they are actually doing here.

I would wonder how 'stationary' the helicopter can actually be. I'd figure it would move around quite a bit given wind gusts at altitude; how much would an actual elevator ribbon move in the wind in practice?

Re:simpler test

[John Hasler]

No, they'd just have to do substantial construction work in a sacred national park.

I have no doubt that the helicopter is less expensive both financially and politically (not to mention that they would probably like to carry out the tests some time this century).

Why use a beam?

[Rough3dg3]

Surely for the purpose of a space elevator orbiting the Earth it would be more suitable to power it using solar panels that are also in orbit and just hook it up via that.

Re:Why use a beam?

[criptic08]

IANAE but, transmitting power from cables has several drawbacks 1) Anything that adds weight to the cable is a very bad thing. 2) the power loss due to extreme length. 3) Redudancy directly affects 1 and 2. 4) 1 and 2 are mutually exclusive.

And as far as wireless power transmission goes, if its focused i think the powerloss is quite acceptable over those distance relatively to other means. The redudancy is exceptionnal too, you can have multiple beaming stations on the ground and/or in the air, ready to send their own beam in case the primary goes down.

More useful applications

[Monkeedude1212]

These guys are thinking way too small. Think if we really got this project going, we could sell handheld energy beaming devices to everyone! Imagine the applications!

Forgot to charge your cell phone? Not a problem!
Car Battery Dead? Easy Peasy!
Girlfriend not turned on? Eh... Well....

Re:More useful applications

[drjuggler]

That's when you call Big Jim Slade.

haha

[Anonymous Coward]

love the "typo" tag, haha. "shadowed creator on the moon"

I'm not sure if that shadowed creator...

[Anonymous Coward]

will appreciate us sending a rover inside him. I know I would be pissed...

Nuclear

[lobiusmoop]

Just equip the lift with a nuclear engine. If it's good enough for submarines it's good enough here. High power output and 40 year lifespan.

Delay

[SnarfQuest]

Was the delay caused by problems with the shark tank?

Re:perl vs. /.

[Anonymous Coward]

"WAAA, I'm an old man! WAAAA, I like to write code using only a number pad, with a few slashes and brackets thrown in for good measure!"

Comment removed

[account_deleted]

Comment removed based on user account deletion

I for one...

[Sawopox]

...will be staying inside, under my tinfoil hat on November 2nd.

Thank you.

(Also, need food, water, and ammo.)

Re:I for one...

[camperdave]

Tinfoil hat... Just what you need, a parabolic dish focused on your brain.

Allow me to elaborate...

[Xaedalus]

WHOOSH

your understanding of Kilgore Trout needs some serious work. I'm thinking orders of magnitude

Day of the Dead

[LordByronStyrofoam]

Coincidence? I hope so...

Finally!

[seanthenerd]

My older brother is the design head for the University of Saskatchewan team, the front-runners of the past competitions. Suffice to say they're really excited about it, since this competition has been delayed month by month since about a year ago! It'll be neat to see everything actually all come together.

You can watch a sweet (if cheesy) video about the team on their website.

The Space elevators is going to be

[geekoid]

the flying hover car of the 21st century.

Legal troubles ahead

[Anonymous Coward]

> The competition involves using a high-power laser to beam power to a robot that climbs a kilometer-high cable attached to a helicopter.

They will be sued by RIAA for this...

Count me out as an observer

[smoker2]

I wouldn't stand within a kilometre of this test. What if the helicopter has to ditch the cable in an emergency ? 1km of cable with attached crawler falling on your head would not be pretty.