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Space Elevators

I have seen proposals for an acceleration track supported in the stratosphere by balloons;

there is also the Lofstrom Loop, which is supported by momentum and magnetism alone
(seen here in an image I made a few years ago)
med_lofstrom.png
 
Another way that an inflatable tower might be useful is as a support, or a buffer, around the lowest section of a geostationary space elevator. The lowest 12 kilometers is the most vulnerable to weather - wind, lightning, oxidation - and the balloon could protect it (or replace it) in that region.

To stop the balloon tower blowing about you could restrain it with guy ropes.
 
I feel we're talking about climbing a giant wavy arm chap outside a garage. Going up one, I dunno, it would be bad enough being seasick...
 
Do we need these impossible structures?
I mean, we've got the Em Drive/Cannae Drive now.
 
Yeah, well even if it works (which is unlikely) the EM drive has a micronewton thrust, far too weak to lift itself off the ground.
 
eburacum said:
Yeah, well even if it works (which is unlikely) the EM drive has a micronewton thrust, far too weak to lift itself off the ground.
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The inventor Roger Shawyer seems to think otherwise. He reckons that in Earth's atmosphere it'll fly at somewhere between 200 and 300 mph.
No idea how he worked that out, mind you.
 
I'd not come across this one. It has the classic signs of a con. at first sight. It's been around long enough to have been validated independently but for 'some reason' never quite has...it's a tiny effect, easily lost in background noise or that could be generated (say) by ionization of one of the bits used by the ridonculous power being pumped in...and so on.

Make it work without any ambiguity and I'll buy it.
 
Coal said:
I'd not come across this one. It has the classic signs of a con. at first sight. It's been around long enough to have been validated independently but for 'some reason' never quite has...it's a tiny effect, easily lost in background noise or that could be generated (say) by ionization of one of the bits used by the ridonculous power being pumped in...and so on.

Make it work without any ambiguity and I'll buy it.
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What makes it credible is the fact that Shawyer is an established space technology consultant. He's not just some guy with faked credentials.
 
I'd argue that gives it credibility, but it's yet to be unambiguously proven it really works - don't misunderstand me, I'm a fan of these fringe ideas and keep hoping someone figures out a way we can stop burning sh1t to power our PC's, but this so far just doesn't ring true.

I hope I'm proved wrong!
 
Coal said:
I'd not come across this one. It has the classic signs of a con. at first sight. It's been around long enough to have been validated independently but for 'some reason' never quite has...it's a tiny effect, easily lost in background noise or that could be generated (say) by ionization of one of the bits used by the ridonculous power being pumped in...and so on.

Make it work without any ambiguity and I'll buy it.
Click to expand...
On the other hand, NASA itself said they got results (in the micronewton range), here is a direct link to their paper:
http://ntrs.nasa.gov/search.jsp?R=20140006052
They couldn't rule out experimental errors and such, particularly given the small size of the measured force, but they did get results they were unable to explain.
 
kamalktk said:
On the other hand, NASA itself said they got results (in the micronewton range), here is a direct link to their paper:
http://ntrs.nasa.gov/search.jsp?R=20140006052
They couldn't rule out experimental errors and such, particularly given the small size of the measured force, but they did get results they were unable to explain.
Click to expand...

Actually (thank you), that's given it rather more credibility, this becomes more interesting!
 
Many propulsion concepts do not produce enough thrust to lift a spacecraft off the Earth; the electric ion propulsion system used by the Dawn mission (currently at Ceres) has a thrust-to-weight ratio less than one, so could never fly on Earth, no matter how much fuel you used. EM thrust would probably be the the same. Maybe Shawyer is imagining his copper flowerpot attached to a glider...
 
kamalktk said:
On the other hand, NASA itself said they got results (in the micronewton range), here is a direct link to their paper:
http://ntrs.nasa.gov/search.jsp?R=20140006052
They couldn't rule out experimental errors and such, particularly given the small size of the measured force, but they did get results they were unable to explain.
Click to expand...
Note that Eagleworks is associated with NASA, but is not actually part of NASA; it is a research group (consisting of five people or so) who are investigating unconventional propulsion systems with what appears to be very limited resources. NASA proper has not got involved yet. presumably so they can wash they hands of it if they eventually find that it doesn't work.
 
Is there a theoretical reason why you couldn't use a space elevator to escape a black hole?
 
Xanatic* said:
Is there a theoretical reason why you couldn't use a space elevator to escape a black hole?
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Yes ... Under conventional interpretations of black holes (which we've never visited, rendering claims merely speculative ... ) anything material that gets to / past the event horizon is 'gone' in two senses:

(a) Sucked into a gravity well of effectively (for practical purposes ... ) asymptotically infinite strength; and
(b) Crushed (in some sense) so as to not be what it fundamentally was as a material object, if it still exists at all.

As a result, the hallmark track (cable / tower structure / whatever) that's central to the conventional space elevator concept would be useless within the black hole.

Another angle ...

Some versions of the space elevator concept require a counterweight at the 'upper / outer' end to keep the tether / cable / etc. taut and erect.

How do you provide such a counterweight / anchor against a black hole's gravitational pull without putting the anchor inside another black hole? And what conceivable material would provide a linear object capable of resisting being pulled apart by presumably unimaginable forces operating on both ends?
 
I have run across the idea of travel to the moon by going up and down a physical wire stretched to the moon twice - once I think in a Larry Niven story and once in a ST episode. Apparently there is actual science behind this. Does anyone know if it's being worked on?
 
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Lb8535 said:
I have run across the idea of travel to the moon by going up and down a physical wire stretched to the moon twice - once I think in a Larry Niven story and once in a ST episode. Apparently there is actual sience behind this. Does anyone know if it's being worked on?
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Yes, there are still people who think it's possible (although it would require unobtainium).
There are Google competitions to design a lift mechanism every year.
The best depiction in fiction that I have read is The Web Between the Worlds by Charles Sheffield. That highlights the huge engineering challenge that it would be.
 
Lb8535 said:
I have run across the idea of travel to the moon by going up and down a physical wire stretched to the moon twice - once I think in a Larry Niven story and once in a ST episode. Apparently there is actual science behind this. Does anyone know if it's being worked on?
Click to expand...

Anyone with two connected brain cells will point out that as the Moon rotates around the Earth, It simply will not work.
 
Mythopoeika said:
there are still people who think it's possible ...
The best depiction in fiction that I have read is The Web Between the Worlds by Charles Sheffield. That highlights the huge engineering challenge that it would be.
Click to expand...

I haven't read that, but I have read Arthur C Clarke's probably better-known The Fountains of Paradise, that employs a Space elevator to take payloads into earth orbit. Does Sheffield use the same concept?
 
Lb8535 said:
I have run across the idea of travel to the moon by going up and down a physical wire stretched to the moon twice - once I think in a Larry Niven story and once in a ST episode. Apparently there is actual science behind this. Does anyone know if it's being worked on?
Click to expand...
Hmmm.... even with the best rawl plugs, cheese is impossible to keep a screw in for any amount of load bearing. I can't see it working.
 
oxo66 said:
I haven't read that, but I have read Arthur C Clarke's probably better-known The Fountains of Paradise, that employs a Space elevator to take payloads into earth orbit. Does Sheffield use the same concept?
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Yes, it's exactly the same. Sheffield's and Clarke's books came out at exactly the same time and contain similar elements.
 
Kim (Stanley Robinson, not the other one) used the space elevator to good effect in his Mars Trilogy. I think he introduced it in 'Red Mars', then used it's destruction in 'Green Mars'.
 
Lb8535 said:
I have run across the idea of travel to the moon by going up and down a physical wire stretched to the moon twice - once I think in a Larry Niven story and once in a ST episode. Apparently there is actual science behind this. Does anyone know if it's being worked on?
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Sorry Lb8535, I know I've quoted your post already, but I think it's a good time to add an observation. Due to our appalling human sense of distance and a variety of illustrations that support that deficiency, many people have no idea just what distance it is between the Earth and Moon. So;


If we're building a tether between the two, we need to start getting the nylon together quick smart.
 
oxo66 said:
I haven't read that, but I have read Arthur C Clarke's probably better-known The Fountains of Paradise, that employs a Space elevator to take payloads into earth orbit. Does Sheffield use the same concept?
Click to expand...
Yes clicking on the link that was basically it. I forget how it dealt with the moon
 
Lb8535 said:
Nope that worked out.
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I haven't read the story.

Could you briefly explain how the Moon and the Earth were connected. Bearing in mind that, in reality, if they were then the link would get wrapped around the Earth as the Moon orbited.

The only even remote possibility I can envisage is that you have a track running around the Earth that lay beneath the Moon's orbit., and have your base station rolling along it.

Even that would be impossible for a number of engineering reasons. Not to mention the track would have to pass over oceans.

INT21.
 
INT21 said:
I haven't read the story.

Could you briefly explain how the Moon and the Earth were connected. Bearing in mind that, in reality, if they were then the link would get wrapped around the Earth as the Moon orbited.

The only even remote possibility I can envisage is that you have a track running around the Earth that lay beneath the Moon's orbit., and have your base station rolling along it.

Even that would be impossible for a number of engineering reasons. Not to mention the track would have to pass over oceans.

INT21.
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Neither of those SF books mentions a connection from Earth to the Moon. Rather, it is a space elevator to a mass in geostationary orbit. The final leg of the journey would be achieved using a spacecraft travelling from Earth orbit to the Moon.
 
If we're building a tether between the two, we need to start getting the nylon together quick smart.
Click to expand...

I can't work out how to multi- quote but answering several previous at once:

The tether 'only' takes you to Earth orbit. Getting from there to the moon is relatively easy. (Recall the sizes of the Saturn V rocket; the bit that actually went to the moon; and the bit that came back)

Oh I see Mytho's beaten me to it
 
I was thrown off course by Lb8535's post (#215 above) stating that there was a connection from Earth to the Moon.

..by going up and down a physical wire stretched to the moon twice ..

Is the offending line.
 
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