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Japan is taking us one step closer to a space elevator.Elon Musk may not believe in space elevators yet, but Japan is taking a step forward to realise the dream of travelling to space by elevators instead of the traditional rocket.A team of researchers from Japan's Shizuoka University and other institutions will conduct the first test in space this month as part of a project to build a space elevator, Japan's The Mainichi reported last week. The space elevator essentially ferries people and cargo shipments in an elevator car travelling on a cable connecting Earth to a space station.This test is the first exploring the movement of a container on a cable in space. Two ultra-small cubic satellites measuring 10 centimeters on each side connected by a steel cable about 10 metres long will be carried from Kagoshima's Tanegashima Space Center to the International Space Station on Sept. 11.From there, the connected satellites will be launched and a motorised container acting as an elevator car will travel along the cable and have its journey recorded via a camera attached to the satellites.The project's technical advisor, Japan's construction giant Obayashi Corporation, is also working on a similar project, though it previously said it expects to deliver a space elevator by 2050.
Japan is taking us one step closer to a space elevator.
Elon Musk may not believe in space elevators yet, but Japan is taking a step forward to realise the dream of travelling to space by elevators instead of the traditional rocket.
A team of researchers from Japan's Shizuoka University and other institutions will conduct the first test in space this month as part of a project to build a space elevator, Japan's The Mainichi reported last week. The space elevator essentially ferries people and cargo shipments in an elevator car travelling on a cable connecting Earth to a space station.
This test is the first exploring the movement of a container on a cable in space. Two ultra-small cubic satellites measuring 10 centimeters on each side connected by a steel cable about 10 metres long will be carried from Kagoshima's Tanegashima Space Center to the International Space Station on Sept. 11.
From there, the connected satellites will be launched and a motorised container acting as an elevator car will travel along the cable and have its journey recorded via a camera attached to the satellites.
The project's technical advisor, Japan's construction giant Obayashi Corporation, is also working on a similar project, though it previously said it expects to deliver a space elevator by 2050.
"Super strong material discovered with molecular bonds so strong it could make a space elevator "
Yep let's all live in The Culture where everything is held together by forcefields. How come nobody's named an AI Mind after Elon Musk yet.
Their cute little experiment here doesn't require such a material.
I'm assuming that their cute little experiment builds on the results of the TSS-1R mission.
Then they can make a sky hook first.
Indeed. Skyhooks are commonly considered a form of space elevator, just not quite as iconic as a geostationary beanstalk.
On the bright side, they're potentially considerably more efficient than a stationary beanstalk since they're largely passive structures with no friction or motorized components to waste energy. And if you can manage the millisecond coordination required to dock with the top end to de-orbit, they can offer 100% efficient asynchronous orbital momentum transfer from returning payloads to launching ones.
They also have the slight advantage of being possible to build, since as AC alluded, even carbon nanotubes aren't nearly strong enough to make a beanstalk. As I recall multiwalled carbon nanotubes, the strongest material we've developed, are just barely strong enough to support their own weight over the 36,000km to geostationary orbit, with something like a 20-40% safety margin. Unfortunately, safe engineering practices generally call for a 900% safety margin even for comparatively low-risk structures like bridges.
And even bridges fail occasionally. If a beanstalk breaks, it'll potentially wrap around the Earth one and a half times, unleashing massive devastation across the path of its fall. The top end at least might burn up in the atmosphere - then again, it might not: after all it'd be FAR wider than the base, to support the weight of all the cable beneath it. After falling 36,000 km it might well manage to get through the atmosphere before most of it has burnt away. Especially since carbon nanotubes are quite possibly the best thermal conductors known to man - that cable might barely burn until the whole length is approaching it's flash point - at which point flames might end up racing down the length of the preheated cable, rapidly creating the largest fires humanity has ever dealt with (though the portions in the ocean would offer both a firebreak and cooling to the remainder.)
And if you can manage the millisecond coordination required to dock with the top end to de-orbit, they can offer 100% efficient asynchronous orbital momentum transfer from returning payloads to launching ones.
Why not make a "sky ferris wheel" then and dock whenever you like?
1) it's *far* more expensive.
2) you still need the same millisecond coordination unless the entire wheel rim is completely uniform and passive so that you can dock literally anywhere ("claws" on your ship to grab onto the ring? Supermagnets capable of holding your ship against the potentially multi-G centripetal force?)
3) even if the wheel rim is uniform, you still haven't dramatically improved the timing window in the challenge of passing through exactly the right piece of space at exactly the right moment. The top of the ring is traveling far in excess of orbital velocity, it's not like you can just drift close to it and grab it when handy - you've got to coordinate the lowest, fastest point of your very elliptical incoming orbit to reach the upper-wheel elevation at exactly the same moment as the top of the wheel is passing through that point. Get there a few seconds too soon and the wheel won't be there yet - too late, and it will have already passed.
What a a "wheel" really gains you is a spatially continuous selection of rendezvous points, meaning you can launch from, and return to, anywhere on the skyhook's orbital path without having to wait until a tether is in the appropriate alignment for your desired region (very handy, and well worth having if you can afford it). The rendezvous timing still needs to be nearly perfect though, you just have a bit more leeway in the exact position. And at the speeds you're traveling for a reentry rendezvous, even a full burn of your rocket isn't going to allow for much in the way of last-minute corrections.
My own preference to widen the rendezvous window is to use "docking harpoons" to buy a bit more leeway - as you approach a skyhook docking site you fire a harpoon at a "docking target" which securely grabs the harpoon and drags you along at the end of the attached tether (obviously your ship needs to be designed to support its weight on the harpoon tether). That buys you at least a few dozen meters of allowable imperfection, maybe even a few hundred, which means your timing can be off by at least a sizeable fraction of a second, and potentially several seconds, depending on the precise orbital dynamics of the skyhook.
Wonder where you got 36,000 km? You don't have to go that far to be in space. The ISS is only ~410 km up.
That's the elevation of geostationary orbit - the only distance at which objects can orbit above a fixed point on the Earth's surface (necessary for a surface-to-orbit elevator). And all beanstalks have to connect to a counterweight beyond that point in order to hold them up (by necessity they're lowered from orbit, not supported from below). It's also the "balance point" height at which maximum beanstalk tension is reached.
Anything orbiting closer is moving faster than the Earth's surface, and thus can't be connected to the surface. Much faster by the time you get as close as the ISS, whose ground speed is over 27,000 km/hour.
There have been some experiments using tethers to lower things into the atmosphere from orbit, but as you can imagine dragging a cable through the atmosphere at Mach 22 introduces some serious drag and turbulence issues - assuming you can avoid having the tether disintegrate from re-entry-style heating.
Also, the circumference of the Earth is a bit over 40,000 km, so a 36,000 km cable would not wrap around Earth once.And the Earth spins west to east so a cable falling from geosynchronous orbit would wrap to the west across central Africa before reaching the Atlantic Ocean then across Northern Brazil, and parts of Columbia and Ecuador With the top end landing among the Island of the South Pacific.
Right you are - I carelessly overlooked the fact that Google gave me the circumference in miles rather than km.
I'm less certain about the direction the cable would fall though, I'm thinking it would be to the east. Consider: the cable isn't stationary, it's not being dragged down by the spinning of the Earth, it's *also* spinning west-to-east, and doing so considerably faster than the Earth's surface. Just like the outside of a spinning record moves faster than the inside, so does the outside of the cable - at geostationary orbit it's traveling east at about 3000m/s, versus the 460m/s of the Earth's surface, and it will be picking up speed the whole way down. As it loses altitude (and the associated moment of inertia) it must gain angular speed to conserve its angular momentum.
If a beanstalk breaks, it'll potentially wrap around the Earth one and a half times, unleashing massive devastation across the path of its fall. The top end at least might burn up in the atmosphere - then again, it might not: after all it'd be FAR wider than the base, to support the weight of all the cable beneath it. After falling 36,000 km it might well manage to get through the atmosphere before most of it has burnt away. Especially since carbon nanotubes are quite possibly the best thermal conductors known to man - that cable might barely burn until the whole length is approaching it's flash point - at which point flames might end up racing down the length of the preheated cable, rapidly creating the largest fires humanity has ever dealt with (though the portions in the ocean would offer both a firebreak and cooling to the remainder.)
Also wouldn't the cable impacting the ocean (assuming it doesn't completely burn up) cause a giant tsunami along the length of the cable?
This would make an epic disaster film!
I seem to recall some design variants that proposed the lower portion not be rigid and allow arc in the tether so there is some slack to work with. I think the idea was shock absorption and to allow a refueling boom like ability to 'fly' the lower end slightly to make capture less fraught. I didn't find the discussion with a quick search though, dammit.I want to live to see this stuff work, dammit!
Then it might behoove them then to start negotiating with the WTO now to find out what country will host it. Because it sure as hell won't be built in Japan.
As I recall, space elevators must be built in an equatorial location to take proper advantage of centrifugal forces. So there are only a handful of locations that -might- host one, and that is before you start talking about geological considerations, and the potential blast path if the thing comes down. Probably Somalia makes the best choice, since it is centrally located to all the major players with well established shipping routes, cheap labor, and cheap government, and a blast path that will likely go out to sea. It also has the San Maddow Mountain range, which provides a foundation of 4000' MSL before even breaking ground.
We like your idea. And I think the world will tolerate a little colonialism, provided you stop at one country this time. Because there really is only one piece of real estate that is such a shithole that the rest of the world won't really care if you appropriate it. And conveniently it has all the attributes that you are looking for.
Have a nice day.
> a blast path that will likely go out to sea
At first, maybe. The problem is, the blast path will keep going, and going, and going... I'm sure that there'll be multiple blast points and failsafes to break it up and let the top part fly off into space, but in the worst case (the entire cable goes down), it will wrap around the equator, and more. Therefore, it doesn't really matter where you put it -- the entire equator is the blast path.
If it is segmented in the event of an emergency, then this not necessarily so. It will take a long time for the parts to come down, and the higher they are the more time you have adjust the descent trajectory. Which is to say 1000 segments can be dropped into the sea at 1000 different locations, over a period of many months, and still never hit land.
As I recall the top end of a beanstalk-style space elevator needs to be in geostationary (equatorial) orbit, but it is possible for the bottom end to be a considerable distance from the equator. I forget how much though, and 36* is probably pushing it.
On the other hand - you don't really need to have anything under the beanstalk. The whole thing is supported from orbit, so the bottom end could be tethered to a floating barge just fine. Except for the weather - the open ocean is known for its sometimes extreme weather, and you probably don't want to have to deal with that. An extremely tall mountain peak, close to the equator, but well inland would be ideal, but those are in extremely short supply.
At any rate, seeing how badly positioned Japan is for a beanstalk, combined with the fact that even the strongest multi-walled carbon nanotubes made by man are about 7x too weak to include adequate safety margins for such a thing, it seems like a safe bet that they're NOT talking about beanstalks. Especially since there's no safe place for the "blast path" of something long enough to wrap around the Earth one and a half times if it breaks. (Minimum length of a beanstalk is 36,000km - and that requires a massive counterweight just beyond geostationary orbit)
Unfortunately, I can't read Japanese to tell if the "connecting Earth to a space station" bit was actually included in the press release, or an editor's comment. It's possible that this is just more Japanese posturing - they do a lot of talk and "preliminary experiments" around far-future space technology, but there are also far more technologies that still fall under the umbrella of "space elevator" but never get anywhere close to the planet's surface (and are far more realistic with existing technologies) . The fact that they're talking about moving cars along the cable suggests that they're not talking about a tumbling-cable skyhook, though they could still be talking about a bi-level space station - connect two space stations with a long tether and put them in orbit one above the other - the top one will be orbiting too fast for it's altitude, and the bottom one too slow, providing both with pseudo-gravity and allowing you to dock with the lower one at (potentially far) below orbital speed for low orbit and then ride an elevator to the higher one.
"close to the equator, but well inland would be ideal, but those are in extremely short supply."
Yep. You can take a few minutes with Google maps, and the answer is obvious. And it isn't really just about a space elevator. The same attributes improve rocket performance as well.
Quite. But a rocket doesn't *really* care much unless your payload is pushing it's operational limits. Even the equator is moving at only 460m/s, while at 40*latitude it's moving at 356m/s. Meanwhile LEO speed is over 7,000m/s - a 100m/s boost is handy, but it's still just a difference of 1.4%. Saves some fuel, but fuel is the cheapest part of a typical launch, and it's a rare payload that pushes the limits of its launch vehicle.
"it's a rare payload that pushes the limits of its launch vehicle."
Building such a thing will require many flights with many international payloads. The infrastructure costs alone are enormous, and uneccessarily redundant. There really needs to be a space port in a free trade zone, with a WTO/UN sanctioned policy that it may be used for non-military flights, by any country. There are only a few places in the world that have natural economic advantages for this sort of thing. If any of them built such an FTZ, they could probably bring millions of dollars in trade to their shores. Because even if, we are just talking a 1% payload availability increase, that still represents millions if not billions of dollars over the lifecycle of something like the ISS, space elevator or skyhook.
The whole thing is supported from orbit, so the bottom end could be tethered to a floating barge just fine
It'd be the hell of a barge considering the "stalk" thickness. Feeling of guts, I don't expect anything thinner than 200m.Add to this the power stations for the elevators crawling along the cable. Add to this the "docking/warehousing" space required to store the goods that need to be loaded or have just been unloaded.Nope, my bet is a beanstalk will have the connection point on the solid ground.
Keep in mind that the cable is NOT going to be uniform thickness - instead it's cross section will increase... geometrically? exponentially? with height. I don't recall exactly - but much faster than linearly. The lowest section only has to be thick enough to safely support the maximum payload.
Lets call the cross-section area at that point A, required to support a mass of M. Now, some length up the cable, let's call it L, the mass of the cable below that point equals the mass of the payload. So at that point the cable needs to have a cross-sectional area of 2A, and thus twice the mass. Another length L above that the cable will need to support the payload, plus the first length of A cable, plus the second length of 2A cable, for a total mass of 4M, requiring the cable to have a cross-section of 4A. So the pattern is:
Height -- cross-sectional area -- Mass suspended below that point
0 -- A -- M
L -- 2A -- M + M2L -- 4A -- M + M + 2M3L -- 8A -- M + M + 2M + 4M4L -- 16A -- M + M + 2M + 4M + 8MSo, looks exponential in my oversimplified discrete sample estimate - might look better in a continuous analysis, but you get the idea
Trying to maintain a constant cross-sectional area would push the cable well beyond the limits of existing materials, even carbon nanotubes are only barely feasible with the exponential thickening, and that with basically no safety margins. The better the strength-to-weight ratio of the material the slower the thickening, and carbon nanotubes look to be about as good as is physically possible. Something less impresssive, like high tension steel? The exponential growth of the cross-sectional area with height reaches the point of completely encasing the planet long before it reaches geostationary orbit.
The lowest section only has to be thick enough to safely support the maximum payload.
Not gonna cut it. Rationale - the cable isn't going to sit in balance without a tension, the equilibrium is unstable, any perturbation is subject to positive feedback. And gosh, those cyclones/hurricanes/typhoons just can't wait to provide some perturbations.
Besides, I suspect the cable is going to need some controlled oscillations, be it only to get some hundred metres out of the way of some satellites or near-earth asteroids now and then. Too risky to control those oscillations without tethering one end.
So, looks exponential
So, looks exponential
Interesting, never thought about. But won't be a single exponential... Need to grow exponential up to geostationary (where the cable tension is max) then it can decrease exponentially to the distal end.
Yes, cyclones, hurricanes, etc. are going to provide some pertubations - quite possibly terminal ones. That's why most plans have the base of the beanstalk well inland and atop a high mountain - up above the worst of atmospheric disruptions. For maximum reliability you wouldn't want it to touch the ground at all - if it simply stops 40 or 50 miles above ground any hurricanes, etc. will simply pass harmlessly beneath it. Of course that means you'll have to take a high-altitude capable aircraft up to the base, which makes it a bit less convenient. On the other hand, that would also let you get a bit out of geostationary, so that the bottom end could slowly sweep across the globe to serve a much greater area,albeit only periodically.
And yes, it's only exponential up to geostationary, which is the point of maximum tension. As to whether it extends much beyond that - it might, it would come in handy as a "snap the whip" style interplanetary launch system. On the other hand a 36,000km cable made of exotic materials is already going to be incredibly expensive without making it twice as long, and there's *lots* of alternative interplanetary launch systems once you're in orbit. The cable might just end at a small moon (large captured asteroid) a bit above geostationary - makes for a much cheaper counterweight, and a well-shielded base of orbital operations.
A space elevator is like Niven's Ringworld, a big dumb object that requires impossibly strong material. It's one of those ideas that seduces people with simplicity, but remains just out of reach, like the idea of a flying aircraft carrier, or building a big gun to launch payloads into space. Heck, we've been dreaming of flying cars for nearly a century now. Still nowhere near practical. At least these could someday be possible, unlike, say, the Star Trek FTL propulsion idea of warp drive that requires impossible amounts of energy, like more energy every second than the sun has produced in its entire 4.5 billion year lifetime.
The Moon landing missions started with direct launch ideas, but had to complicate things. The whole reason for the Saturn rocket having 3 stages is to shed weight. And the idea of skipping the bit about orbiting Earth and just going directly to the Moon had to be scrapped. Took too much fuel to do that.
Maybe better is the carrier airplane approach Virgin Galactic uses. Combine that with a hypersonic skip jet concept, perhaps with scramjet engines, and a spacecraft could be launched from the top of the atmosphere and already traveling at a good percentage of escape velocity. It could go at least mach 10 and reach an altitude of about 40km.
"flying aircraft carrier"
We built a couple of those in fact. The most practical was used to break the sound barrier. (or wasn't, if you believe the claim that the F86 got there first)
"building a big gun to launch payloads":
As I understand it, the Germans came close. But that of course, was not their intention.
There have been a couple models that were practical. There just aren't markets for mass production. That you don't know how to use a tool, doesn't mean there isn't a use for the tool.
I'd like to see them move the project along. It doesn't really matter whether they are successful. What matters is that nationally, Japan starts taking a serious interest in deep space. If the space elevator works, great. If it doesn't, well there are plenty of other projects to contribute to. For the moment the more important thing is to get everybody contributing, even if it is a cacophany.
You get the people in a room first. Then you make the choir.
Hey, we're getting better at the "big gun to launch things into space" bit- heck, we've had some viable ideas for 50 years now - assuming you're willing to spend the cash. And Spinlaunch and others are working on more cost-effective technologies. And we've got a number of "flying cars" in late-stage production, though the price typically puts them well out of range of the masses.
Beanstalk space elevators though... yeah. Multi-walled carbon nanotubes seem to have the strength-to-weight ratio to do the job, barely, once we can mass-produce long lengths of them (could be quite soon with MIT having worked out industrial-scale graphene production). But they'd only have a ~30% safety margin, while considering the risks if the thing broke we probably want something better than the 900% margin commonly used for bridges and the like. And that's probably not possible as graphene appears to be pushing up against the theoretical limits of tensile strength for atom-based matter (and I'm not holding my breath waiting for stable neutronium). Could work great on Mars or the moon though, if/when we eventually get to the point that such a thing would make sense.
Skyhooks though could make great sense as space elevators, and could be made useful using current mass-produced carbon-fiber cable(assuming it survives in orbit okay). They could also complement well with other atmosphere based launching systems - you don't need to reach anywhere near orbital velocity to dock with the lower end, which could even match speed with the atmosphere. Skyhooks plucking cargo pods off of extreme-altitude dark-sky airship platforms?
Mars ... perhaps, but Moon? It rotates too slowly, thus lunarstationary orbit would require too large distance, requiring too long tether and the station at top of the tether orbit being unstable, prone to disturbances by Earth's and Sun's gravity.
You are absolutely correct. However there are still two spots where a Lunar beanstalk is possible - the closest and furthest points on the Moon, where the beanstalk will pass through the Earth-Moon L1 or L2 points with a counterweight somewhere beyond that. In those cases the gravitational dynamics of the Earth-Moon system will keep the cable stable, despite the fact that it wouldn't otherwise be possible.
There's even been talk of a Lunar L1 elevator whose far tip extends quite close to the Earth (relatively speaking) until it's moving at the same 460m/s as the Earth's surface, which would allow for pure-vertical launches to "grab on" to the tether and then climb to the L1 point through (potentially) much more efficient mechanical means.
The outer moon of Mars meanwhile is already at very nearly the right position for a beanstalk counterweight, though the inner moon might have to be eliminated, or some really clever resonances maintained in the beanstalk to keep out of its way.
we're getting better at the "big gun to launch things into space" bit- heck, we've had some viable ideas for 50 years now - assuming you're willing to spend the cash
Assuming you're simultaneously willing to spend the cash, and not on the "civilized world"'s shit-list; else we'll just kill your rocket scientist, and then where will you be?
I hope they don't attach it to the moon [xkcd.com]
singapore 6. september 2051:
"international commitment to the earth-first space elevator, which began more then 30 years ago, was today declared a success and open to public after chief engineer stavios teleported to the space-end anchor station and flipped the switch to energize the cables."
... would you mind showing me a time lapse video of the construction of "SkyLab"?
Also the "ISS", where is a time lapse video for that? There should be many for this pinnacle of human engineering, correct? Try as I might, found nothing. Or was there billions spent but not on videos? Why the secrecy on a civilian station?
A full, uninterrupted 24/7/365 4K should also exist, but it does not; how come the signal is lost, with 13,000 to 17,000 satellites "up there" to bounce it off of? And the "ISS tour" is also full of video cuts, why is that?
I am guessing the freshly-installed "multiplexor/demultiplexor" is not multiplexing/demultiplexing good enough. How about a "space walk" to fix it (and grab a 360 panorama while at it to finally show us where we live)?
Right there alongside the time-lapse videos of the construction of the Golden Gate Bridge, the Eiffel Tower, etc. What would be the point? These things were built before the internet video PR fest existed. Maybe there's a few photos, perhaps even some video clips here and there, but there's no engineering reason to capture it, and the media wasn't going to air more than a few minutes at most. So all you get is whatever happened to be filmed by people with future documentaries in mind.
What would be the point?
You cannot see the point of recording THE historical construction of THE alleged pinnacle of human engineering with THE insane budget that it has that has THE vantage point that shows you where YOU live?
Your "Eiffel Tower" and "Golden Gate Bridge" examples are irrelevant: not only they are not in "the vacuum of space", but they were not assembled there either. Moreover, cameras are way cheaper these days.
How did all this "skylab" and "ISS" material get there in the first place? I paid for it and I want to know: that, alone, can be a very good point.
Now, today, there are cameras covering all aspects of construction both for insurance and educational and also security purposes. There are simply too many things that can go wrong: construction workers get killed here, on Earth, all the time, and this is only part of the reason modern construction sites are constantly monitored. You want me to simply shrug and mumble "meh, nah, why record it? It's not like it is the first time ever humans are building a permanent orbital space station"? This does not make any sense.
Did you think of any of this before you gave your handwave "what would be the point" dismissal?