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20 minutes ago, StrandedonEarth said:

If you haven’t already, I recommend reading the Red Mars / Green Mars / Blue Mars trilogy by Kim Stanley Robinson. It includes space elevators. Good read

IIRC, construction has to start in GEO, extending up and down simultaneously. Orbital mechanics will want to start it rotating, so that would have to be countered somehow. Electromagnetics would be the elegant way; rockets near the ends would be the brute force way, and would probably require a stiffer cable 

It sounds to me like the author envisioned a more rigid structure... Like a Tower of Babel in reverse.  (Building from the heavens until you touch the planet) - although I'd guess you would have to build in both directions to have enough leverage on the working end to keep it pointing to the base... 

Imagine being a welder on the crew once the structure reached 60,000 feet and your butt is hanging out in a 250 mph wind! Yeep! 

 

For whatever reason, the cabling idea seems more practical to me (once leader connects CW to base, a cabling bot shuttles back and forth winding strand after strand) 

 

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Paging @mikegarrison since I think he's probably the best-informed about this topic.

My dynamics of aerospace vehicles professor claims that the X-29 had the ability to jettison its canards in-flight to give the vehicle static stability in the event of a FCS failure. Is this true? I couldn't find anything about such a system via a quick search on Google, NTRS, and Wikipedia.

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15 minutes ago, Silavite said:

Paging @mikegarrison since I think he's probably the best-informed about this topic.

My dynamics of aerospace vehicles professor claims that the X-29 had the ability to jettison its canards in-flight to give the vehicle static stability in the event of a FCS failure. Is this true? I couldn't find anything about such a system via a quick search on Google, NTRS, and Wikipedia.

That makes no sense to me. The X-29 had an ejection seat for the pilot to say, "it's been fun, but I'm outta here". I can't really  imagine any situation where jettisoning YOUR CONTROL SURFACES would improve your ability to control the airplane.

I guess it did have a set of elevator-like flaps on the wing strakes. So potentially it could have had something like static stability? But I doubt it. Really that whole idea sounds crazy to me.

According to wikipedia they did fit it with a spin recovery chute. That's a pretty standard way to recover stability in an emergency, though typically only an experimental airplane would have one.

Edited by mikegarrison
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36 minutes ago, JoeSchmuckatelli said:

How do you keep satellites from clipping the cable? 

Well, this is an issue. Although it would probably be more of an issue for the satellites than the elevator. The elevator would have to be built to be able to survive at least small meteorite strikes, and those would probably have way more energy than a satellite.

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21 minutes ago, mikegarrison said:

elevator would have to be built to be able to survive at least small meteorite strikes, and those would probably have way more energy than a satellite.

So... If the cable were struck by (and survived) a small meteorite... It would begin to vibrate. 

 

Imagine the sound! 

 

 

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58 minutes ago, JoeSchmuckatelli said:

It sounds to me like the author envisioned a more rigid structure... Like a Tower of Babel in reverse.  (Building from the heavens until you touch the planet) - although I'd guess you would have to build in both directions to have enough leverage on the working end to keep it pointing to the base... 

Imagine being a welder on the crew once the structure reached 60,000 feet and your butt is hanging out in a 250 mph wind! Yeep! 

 

For whatever reason, the cabling idea seems more practical to me (once leader connects CW to base, a cabling bot shuttles back and forth winding strand after strand) 

 

Anything going 36.000 km+ twice as long the other direction will behave like an cable anyway so only reason for something solid is to build something so dispersed it can handle micrometeorites. 
Having trains going up and down at once is an benefit to. 
 

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Yeah, such a "cable" would be made out of exotic materials and under a tension that has never existed in any man-made structure to date. It would not act like a guitar string or something. It would be flexible in the same sense that any structure is flexible, but it wouldn't be something you could tie into a knot or anything like that.

But really, I think maybe John Scalzi's point of view in Old Man's War would be correct. An Earth space elevator would probably be harder to make than it would be rationally worth. (In his book, he makes it clear that the space elevator is actually more of a propaganda device than anything else -- a statement by the people that made it reminding the other people on Earth that they themselves could not make it.)

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The only advantage of a space lift is that the energy can be delivered from a stationary powerplant.

So, any remote power transmission and any compact on-board powerplant is better than the space lift.

Everything but the space lift is better than the space lift.

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Does the solar reflector satellite in the Bond film "Die Another Day" actually makes sense in context of real-life application? It's said in the movie that the satellite is meant to focus solar energy on a designated area and provide year-round sunshine for crop development. Does this makes sense in real life concept of application? (even without the laser module, someone would came up with the idea to weaponize it). I mean, crop development is actually going normally today, with current day and night cycle. It's not like the crop needs sunlight exposure for 24/7 just for increased productivity, unless the daytime sunlight exposure is so dimly lit like post-nuclear winter that it necessitates direct sunlight reflection from space

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14 hours ago, ARS said:

Does the solar reflector satellite in the Bond film "Die Another Day" actually makes sense in context of real-life application? It's said in the movie that the satellite is meant to focus solar energy on a designated area and provide year-round sunshine for crop development. Does this makes sense in real life concept of application? (even without the laser module, someone would came up with the idea to weaponize it). I mean, crop development is actually going normally today, with current day and night cycle. It's not like the crop needs sunlight exposure for 24/7 just for increased productivity, unless the daytime sunlight exposure is so dimly lit like post-nuclear winter that it necessitates direct sunlight reflection from space

I've seen the idea bounced around many times. The actual concept - complete with weaponization - dates to at least, uh, 1930s Germany.

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On 1/28/2021 at 2:31 PM, JoeSchmuckatelli said:

Right - but think about how you get a cable from there to the ground - you would have to brute force the whole way. 

Traditionally, to lower the orbit, you slow down... Then the leader ship is now moving faster (relative to the ground) so it gets ahead of the CW - which no good, b/c you want the anchor dead below the CW... So you keep burning... Literally until you hit the planet. 

 

Even then, presuming you did that... How do you keep satellites from clipping the cable? 

Presumably the rigidity of the cable (it won't need much) will prevent any issue with the cable wanting to orbit on its own (it will be stable just hanging there).  The real fun begins when you hit atmospheric winds.

Sats will have to avoid the cable.  Lots of fun cleaning up space junk (especially Project West Ford: the one with  half a million needles in space).

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Rockets evenly spaced along the cable can help it oscillate to avoid satellites and such. The ascent/descent cars can repair and reinforce the cable as they climb and descend.

Many cable concepts start with a single strand which is then layered/laminated by subsequent climbers

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1 hour ago, Kerwood Floyd said:

This article is awfully light on details, but sounds intriguing:

https://news.sky.com/story/new-concept-for-rocket-thruster-exploits-the-mechanism-behind-solar-flares-12202285

Does anybody know anything more about this proposal?

When I read the title, I couldn't help but think of the spaceships from the Hitchhiker's Guide to the Galaxy.  The ones that would surf solar flares during a Disaster Area concert.  Fortunately, this research is completely unrelated (but expect prototype naming to remember it).

I'm guessing it is one of those things where we wouldn't need any new physics, but the engineering and the finance needed would be out of this world.  You'd need a fission reactor to power it, and a fusion spherical torus (and someway to cool both).

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9 hours ago, StrandedonEarth said:

Many cable concepts start with a single strand which is then layered/laminated by subsequent climbers

That's a plan.

Fibers. A column made of multiple fibers. Every fiber is a road for its own cabin,

And we need a counterweight mass on top. It should be big.

And we need power. A lot of power.
Say, the solar power. It should have solar panels. A lot of panels. Oriented like leaves.

The proper space lift should be a giant tree.
The cabins move up and down like ants. The leaves absorb the solar power and power the whole tree.

It shouldn't be constructed, it should be grown.

Eywa.
Eywa is what we need.

And druids.
https://en.wikipedia.org/wiki/Son_of_the_Tree

Edited by kerbiloid
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As far as know - there is no class of organism on the planet that we (humans) cannot consume.  There are many things that we cannot eat and convert to energy (woody plants, for example) but we can certainly eat lots of different plants, most animals, many fungi, insects and so on. 

 

So if we find a planet out there that supports life - how different would that life have to be, before we couldn't eat most everything on that planet as well? 

Edited by JoeSchmuckatelli
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1. Are the helminths counted?
We can eat them, but not digest. Then it's their turn to eat.

2. We can eat any organics at least by turning it first into H,C,O,N.

Edited by kerbiloid
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2 hours ago, JoeSchmuckatelli said:

As far as know - there is no class of organism on the planet that we (humans) cannot consume.  There are many things that we cannot eat and convert to energy (woody plants, for example) but we can certainly eat lots of different plants, most animals, many fungi, insects and so on. 

 

So if we find a planet out there that supports life - how different would that life have to be, before we couldn't eat most everything on that planet as well? 

All biologically generated proteins on earth are right handed proteins, some inorganic processes create both right and left hand proteins, and left hand proteins are highly toxic. 

If the new planet uses left handed proteins, then even if they are otherwise identical to us(which I suspect may not be possible), they will be 100% toxic to us and we will be 100% toxic to them.

(might have the right and left swapped, but the principal is the same regardless)

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1 hour ago, Terwin said:

All biologically generated proteins on earth are right handed proteins, some inorganic processes create both right and left hand proteins, and left hand proteins are highly toxic. 

If the new planet uses left handed proteins, then even if they are otherwise identical to us(which I suspect may not be possible), they will be 100% toxic to us and we will be 100% toxic to them.

(might have the right and left swapped, but the principal is the same regardless)

It was some idea once to make left hand fat as you could make fat whit no calories but taste as fat. Well nothing else would eat it either ;)
Now  its plenty of stuff who is poisonous and its not much issue imagining an biochemistry who have stuff who is poisonous to us. 
It has been an long tug of war there plants tried to make themselves hard to eat and animals wanting to eat them, this war might tilt a bit and we get stuff we could not eat. 

Main issue is an sample size of 1, smarter to wait until sample size is larger and hope your probes are not eaten.
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