Can a spaceship, shuttle, or satellite shoot a cable to the earth or is there research?

a reply to: stormbringer1701

The moon is 238,000 miles from the earth..

Being 26,200 miles out from the earth, puts you above any "useful" range above the earth. Also, you'd then have to worry about the plethora of space debris, satellites, ISS, and any number of other things "cutting" the line as it zips past, underneath".

originally posted by: tadaman
I think they experimented with a tether on the ISS. It got super charged and exploded or something. If I remember correctly they were looking into using the concept as an energy source: Just extend a cable out while in orbit and have it get charged with energy.

I think thats a huge issue. The heat as well as the charge that builds up are greater than current material science can overcome. It would all still be going really fast to stay in orbit.

that had nothing to do with skyhooks, they were hanging a long superconducting wire out into space, superconductors do not loose energy, they conduct it perfectly, the idea was hanging such a wire out into space ought to absorb energy from the environment which they can just leech right off the cable for use in their station,

problem was they severely underestimated how much energy it would gain, it gained so much so fast the damn thing started glowing red hot and melted itself off the station, that was the end of that experiment...

after the tether detached it continued gaining energy thats when the ufo's started appearing around it.

this has been discussed on ATS plenty of times and the mainstream excuse is they are ice particles (making really nice autonomous 180+ degree turns...) but lets think about this whole thing, if they really are just ice particles, nothing nefarious or covered up at all, then why did we scrap the experiment? to me TO MUCH ENERGY does not sound like a problem to avoid, rather it sounds like the perfect problem for this energy starved planet to tackle....

such boundless energy could be very useful in an actual skyhook idea

a reply to: Cygnis

The only possible way to achieve a geosynchronous geostationary orbit is at the earth's equator at an altitude of 26,199 miles. As far as a space elevator goes, or tethering any object to the earths surface, the craft in space has to be in a GEO.

Geostationary orbit


If the craft in space is slower or faster than the earth's rotation, the cable will wrap itself around the earth, snap under tensile stress, or drag the craft out of orbit. There's no way around a GEO for a space elevator or space to earth tether.

originally posted by: Cygnis
a reply to: stormbringer1701

The moon is 238,000 miles from the earth..

Being 26,200 miles out from the earth, puts you above any "useful" range above the earth. Also, you'd then have to worry about the plethora of space debris, satellites, ISS, and any number of other things "cutting" the line as it zips past, underneath".

that depends on your mission. geosynch orbit is quite useful real estate. quite coveted.

yeah in LEO you have some protection against radiation but correcting for orbital decay is a bear and actually there is far more debris in lower earth orbit that out at geo-synch orbit. one other thing about LEO right now is logistics is simplified and is cheaper. But the point of an elevator is moving stuff into space easily and cheaply so that advantage goes away given an elevator in the first place. given that then your stations hull can be as heavy and dense as you need to make up for the protection you lose vs radiation or impacts. your station will not fall out of orbit onto hapless people and nations below. they are effectively permanent and you can make orbital dry dock facilities to build that USS enterprise thing.

I would lower a thin strong cable with a power cable in it.
at the end would be 3 or 4 blade side mounted propelers.
when it gets low it will use this to keep it in line.
or stop it blowing about. with a resister wire with a wait on the end.
that would help dischardge volt build up.
then that would be use'd to pull up the next cable.
in turn use'd to pull up the next cable.
un till you have the last cable in pleace.

but we DONT have a cable that would be as strong as you need.
Or that we can make all that we need.
maybe in 30 or more years.

oh! one more thing.
this Would put a Great pull on any space ship holding it up.
so the space ship would need to be Very high and use a LOT of fuel.
you would need to put the fuel up there First.
and it would need to be Big to off set the pull.

a reply to: EternalSolace

Yes, that is for satellites, and things not physically tied to the planet.

With a tether, centrifugal force would be more in play then a speed/distance issues is currently for satellites being places in orbit.

Think of spinning in a circle with a yo-yo fully extended from your body.. the further the rope, the faster you have to spin to achieve keeping the item in line, to slow and it drops behind, and falls or wraps around your legs.

The closer the yo-yo, you are able to spin slower, and still maintain the objects proper velocity.

Could a cable be attached to a series of lighter than air craft or blimps up to the edge of space then a very light space craft take the cable out further? I think this may have been considered at one point. The cable could then be heavier and stronger as the airships could take a lot of the weight.

originally posted by: Cygnis
a reply to: EternalSolace

Yes, that is for satellites, and things not physically tied to the planet.

With a tether, centrifugal force would be more in play then a speed/distance issues is currently for satellites being places in orbit.

Think of spinning in a circle with a yo-yo fully extended from your body.. the further the rope, the faster you have to spin to achieve keeping the item in line, to slow and it drops behind, and falls or wraps around your legs.

The closer the yo-yo, you are able to spin slower, and still maintain the objects proper velocity.

it actually goes for anything in space..

the ISS circles the earth in about 1.5 hours..

if i was to apply your thinking and put a tether on the ISS and use centrifugal force then i have to make the orbit of the ISS LESS than 1.5 hours..

but that would mean that the point on earth at which the ISS is tethered to is rotating around the globe in less than 1.5hours also.

objects in space stay in their orbit because the rate at which they fall to earth is matched by their forward speed so that they are perpetually falling their entire time in orbit.

so the lower the orbit the faster forward they need to travel to stay in orbit.

a reply to: Cygnis

I'll have to take some time to read up on that. I can see how that would work, but something isn't sitting quite right about that. Likely just my lack of comprehension. Good call though.

originally posted by: charlyv
a reply to: randomthoughts12

It is actually a fascinating subject.
I would think that the stress forces in the cable, if extended from say 200 miles up to Earth would be enormous. It certainly could not free-fall, as it would wind up like space junk. I also imagine you would have to synch your speed and direction with a spot on Earth, and this would be tricky while still being able to maintain orbit altitude.

There are some on here that know a lot more about orbital velocity than I do... Would like to hear more.

BTW: SkyHook was more like science fiction, but a great idea and a lot of theoretical papers. They did not have the equipment to test any of those theories of operation at the time.

You are looking for a geosynchronous orbit.

That is established at about 21,000 miles out. So it would take a 21,000 mile cable.

originally posted by: randomthoughts12
a reply to: tadaman

Awesome info I will look into it. I stopped myself when I started thinking about any uses. There was way to many ideas so I started back at the idea at hand.

I would think yes temperature and charge would be two big factors to overcome. Material cost and length as well. You would have to find the right material and take baby steps most likely. I would imagine if they started some tests may be on the table still.

Carbon nanotubes.

This is a real material, and it is strong enough to get the job done.

They just can't make them in large enough quantity to do it yet.

Unless the cable stretches down from a geostationary spacecraft, you have the orbital velocity to deal with. A cable reaching down into the atmosphere from the low-earth orbit (LEO) will be moving through air at 7.8 km/s (28,080 km/h), because that's how fast a spacecraft in LEO is moving. At such speed, the cable will burn up in the atmosphere (unless it's made of heat-resistant material), and in any case will slow down considerably and snap. It might even damage the spacecraft it's hanging from.

In any case, you definitely don't want the end of the cable striking anything in the air or on the ground at 7.8 km/s.

a reply to: randomthoughts12

The main problem with any space elevator scenario is with materials. That being said some of the new carbon nano fiber/other meta materials doing the rounds these days its probably becoming tenable.

Thing is that any ship that launched and fired/tethered a cable to our Earth would have to expend the energy/fuel to get the stuff in to orbit.

moar Carbon:

www.gizmag.com...

In terms of mechanical properties its tensile strength, or its ability to withstand stretching, is double that of graphene. According to the computer model, carbyne is also twice as stiff as graphene and three times as stiff as diamonds and, interestingly, carbyne's torsional stiffness can be modified by attaching appropriate molecules at the end of each carbon chain.

originally posted by: Cygnis
a reply to: EternalSolace

Yes, that is for satellites, and things not physically tied to the planet.

With a tether, centrifugal force would be more in play then a speed/distance issues is currently for satellites being places in orbit.

Think of spinning in a circle with a yo-yo fully extended from your body.. the further the rope, the faster you have to spin to achieve keeping the item in line, to slow and it drops behind, and falls or wraps around your legs.

The closer the yo-yo, you are able to spin slower, and still maintain the objects proper velocity.

You have that exactly backwards.

The longer the rope the slower you must spin.

Because of leverage. If I spin at 1RPM, and that is equal to 1 MPH, at the end of a 100 foot rope it would be moving much faster than 1 MPH.

Hence LEO requires much faster speeds than HEO.

a reply to: randomthoughts12

It would have to be from a satellite at about 23,000 miles up, which is about the altitude from which a satellite can achieve geosynchronous orbit (orbiting the same speed as the rotating Earth). Otherwise, the cable would be moving along the ground.

For example, the altitude of the International Space Station or the altitude at which the shuttles usually flew was much lower -- about 200 to 400 miles -- but at that altitude, a craft must be moving at about 17,000 mph relative to a point on the ground to remain in orbit. So a cable dangling from that height would also be zipping along the ground at 17,000 mph.

If the satellite up 200 miles up were moving only the same speed as the rotating Earth (about 1000 mph), allowing the end of the cable to be tied to one spot on Earth, then that satellite would fall to the ground, because it would be moving too slowly to remain in orbit.

So you would probably need a 23,000 mile-long cable instead of just a 200 mile-long cable.

a reply to: tadaman

I believe this is the mission your talking about.

STS-75

It's not a bad read pretty quick.

It wouldn't be feasable for a few reasons.

The discrepancy between earths rotational velocity and a static orbital velocity would be toi great.

1,675 km/h = Earths equatorial surface velocity
28,080 km/h = The average satillite orbit velocity

You see we would not be able to keep an object in orbit moving at earth ground speed. The object simply would not have enough escape velocity to keep it orbiting around earth. Instead it would fling to earth at the instance it was connected to ground like an upside down pendulum.

This can be overcome by increasing the distance from which the object is placed from earth. By increasing the distance you can slow the orbiting velocity because the gravitational pull is lessened. However you'd have to increase the distance on the order of 20x's or more to achieve a stable velocity. Which means you'd have to find a material 20x's stronger and 20's lighter to keep the object in a locked static orbit with the earth.

Then you'd have to do calculations to make sure the tether could still hold together when forces like solar winds and the moons gravitational pull, geo magnetic anomolies and the like would not cause the tether to shear.

With that said there is another way one could achieve having an object in satellite orbit range tethered to the ground while matching earth's rotating velocity. Use thrusters on the object at all times supplying a tangental force angled and away from earth for the duration of its time in orbit. Requiring no less than an infinite amount of energy over time. Not very feasable.

Unless zero point energy is discovered where by gravitational effects can be nullified, there will be no such tether ever created.

Also mind you. If a tether were created over time this would throw the earths natural rotation out of wack. Some what like a brick in a washing machine or dryer. Effectively changing the earths center of mass slightly and altering its orbit.

Wouldn't be a bad idea if say we had to avoid an earth killer asteroid. However the energy required to sustain such a feat would be immense.

Nanotubes son.

a reply to: stormbringer1701

This is some of my bigger questions. Speed and inertia vs gravity and a small mass or any mass or friction on either end.