what kind of space mission would cause the same buzz as apollo?

[apis]

Definitely this is true, especially in Western Mediterranean/Western Europe- However, if I was trying to make the same point I would use different dates..  I am probably making some mistakes below and definitely leaving out a number of important other civilizations too elsewhere that also deserve mention..
Someday we'll have a much better picture, especially now with the huge advances people are making in technologies like synthetic aperture radar, photogrammetry and 3D reconstruction which is yielding a lot of information about what covered the Earth in antiquity that is new!

The romans had sewage systems, running freshwater, multi story apartment buildings, etc. Then it all collapsed (politically), the library of Alexandria was burned and the clergymen took over... It took almost 2000 years before any city was comparable. After that it didn't take so long until people figured out how to build steam engines and flying machines. Imagine if the romans would have kept going. What's holding humanity back is mostly politics and human stupidity, not physics.

I agree with the general thought you're trying to express here but I don't think the Western Roman Empire had it in them to get off their asses because of the continued existence of slavery, which was why the Sack of Rome was successful. The lure of coercive labor is very powerful corrupting influence which undermines innovation. And now we are very much falling into a very similar trap, with so called "Mode Four" (which is based on the Middle Eastern 'kafala' system) a stealthy shift which we all need to be aware of is happening to have any hope to prevent it! In short, we need to stand up for the rights of workers to be treated equally and paid equally when they are in the same country especially, and prevent the race to the bottom in all things which is occurring, turning it into a race to the top again, somehow.

Also, the sciences, math, and human civilization existed before the Roman Empire in a great many places, contemporaneously with it and afterward. Also, in Western Mediterranean there was a similar long period of reversal between the fall of the Minoan Crete civilization after the explosion of the Theran volcano (Santorini) in approximately 1600 BC and the rise of the Greek city state around a thousand years later. So really in the West there were two millennium long reversions of civilization each totaling around a thousand years.

Cities in China at the time of Marco Polo rivaled anything else that had ever been seen in the world by a European. The population of China was also larger than that of the US today more than a thousand years ago.

Also, when Cortez arrived in the valley of Mexico he described the Aztec city there (underneath present day Mexico City which is still the largest city in the Western Hemisphere, I think)

Anyway the Aztec civilization he found there was described as incredibly rich and complex and was I think described in the historical record as the equal of any in Europe at the time.

Contrary to what many believe the sum total of New World, pre-columbian, non-Christian technology was quite substantial and left a very large mark on the world which largely has not been acknowledged. In addition to a wealth of domesticated plants which totally changed the way humans lived in the rest of the world, (making possible a substantial increase in human numbers in areas which previously had not supported them) they also had agricultural technology which revolutionized agriculture. the Aztecs for example, used woven mats covered with soil upon which they planted crops in great variety) that seem to have produced more yield per unit of space than anything we do now except for hydroponic gardening which is based on it. Plus it was sustainable, not requiring any inputs which were not renewable. Of course the whole system fell apart very rapidly after the arrival of the conquistadors and much of its legacy was destroyed before anybody thought to try to save it. The first Americans also gave the world potatoes, maize, and made agriculture aware of the need to rotate crops (nitrogen fixing)

I want to mention here the legacy of Native Americans view of the world and where they fit into it, as steweards of the Earth, obligated to not take any more from it than they needed and incredibly attuned to the world around them in a great many ways which we live ignorant of today) Also their version of democracy (superior to the Greek version in every respect) and throw out that if we are to leave Earth and travel to the stars, we should strive to transform our society to be much more part of Nature, and living in harmony with other living things and in stewardship of the planet rather than obsessed with 'dominating' Nature. This is an absolutely crucial change I suspect we will not survive long in space without making. A number of posters in this thread have expressed sentiments along the lines that if we don't treat our planet and the rest of all of us well, we wont be successful in space either, or don't deserve to control other planets - where we may meet embryonic societies of intelligent life at earlier stages than our own, just as this may have happened to us in the past.  (and soon 'we' will also include our intelligent machines, who-if we don't make the mistake of reverting back to the worst kinds of coercive societies, may I hope become our friends as well as our 'children'.)

At that point the 'need' in economic terms for humanity to be hierarchical and 'work' will have long passed however, work will most certainly continue and be transformational and I suspect far more productive than today, freed as it may be of a lot of very destructive baggage.

So, I think we should think long and hard what we want the long term goals of humanity to be, what is the path which will bring out the best in people. As its our choice. We especially need to prevent the urge to try to lock the planet or nations into anything as we are seeing.

Honesty is the road forward, dishonesty the road back. And we could learn a lot from the first Americans about democracy and living in harmony with the planet and the other creatures that we share it with too.

We probably would have learned much more had Spain not been in the midst of its centuries-long Inquisition, and the UK and the rest of Europe in the grip of a inbred incestuous group of rigid monarchies that had endless wars with one another over what amounted to family quarrels and ruthlessly eliminated any talent it could not control.

So I think your main point totally right, as far as so called Western Civilization goes, the periods of time when it has not been deliberately handicapped - when there have not been these huge barriers to progress indeed have been short.

Absolutely. "Pythagoras' theorem" for example was known long before Pythagoras and it has been discovered independently around the world.

The history we learn in school here is very self centred, sadly we don't really learn anything about non-european history at all. We don't even learn that much about antiquity, it's mostly national history. Many historical sources from rome have been preserved only thanks to arab traders who kept and treasured literary and mathematical works from antiquity. The medieval christians had a bad habit of burning everything (and everyone) the priests in charge didn't like or understand, like they did with the written texts by the Mayan people they came across. That mathematics book by Archimedes they recovered a few years ago (the palimpsest) had been erased and overwritten by monks with some religious text, but thanks to modern technology it was possible to recover the original. Most such books were burned. Who knows what else have been lost.

[apis]

Are you saying a space station in LEO with a bit of spin gravity makes more sense for commercial space mining? But that isn't nearly as fun as a moon city.

I.e. it won't generate any buzz and it doesn't really have the same potential as a moon base for scientific purposes, etc.

It doesn't need to create buzz.  It will create money.

Money has a way of creating buzz all by itself.

Tim

I would get nervous if people start trowing rocks down at us though, doesn't sound all that safe to bringing large metal asteroids into LEO. What if a truster malfunctions or someone made a mistake when calculating/programming the flightpath.

[hamster_nz]

Are you saying a space station in LEO with a bit of spin gravity makes more sense for commercial space mining? But that isn't nearly as fun as a moon city.

I.e. it won't generate any buzz and it doesn't really have the same potential as a moon base for scientific purposes, etc.

It doesn't need to create buzz.  It will create money.

Money has a way of creating buzz all by itself.

Tim

I would get nervous if people start trowing rocks down at us though, doesn't sound all that safe to bringing large metal asteroids into LEO. What if a truster malfunctions or someone made a mistake when calculating/programming the flightpath.

An inch here, a cm there... Nah, that would never happen!

[apis]

can someone check that bootleg calculation of mine? it does not feel right for some reason. only 1500Watts?

the problem I think is that the orbital velocity is 7km/s. not sustainable for even the best boeing product

at geostationary orbit it would be 1500W still? since most of it is in space?

At an altitude of 100km the gravitational acceleration is almost the same as on the surface, i.e. ~10 m/s². F = ma, so for a stationary object at 100 km (roughly 20 km over the top of the atmosphere), 5 N can't lift more than 5/10 = 0.5 kg (or 1.1 pound). An ion-truster that generates 5 N + 100kW solar panels/reactor will have more mass than that, so it wouldn't even be able to lift its own weight.

Once you have something in orbit you could use an ion truster to slowly accelerate until you reach the speed you need, but it can't really be used to get out of the atmosphere.

An orbital ring only relies on the same principle as a normal low earth orbit satellite, nothing fancy. I.e. spin it fast so you generate enough centrifugal force to counteract gravity. Then you use that ring as a track for a platform that moves with the same speed as the earth is spinning, that way you get a geo-stationary platform over a point on earth at an altitude of only 100 km. It is possible to create a cable (and elevator) that is 100 km long with existing materials. A space elevator on the other hand would need to reach out beyond geo-stationary orbit (35786 km) which is not possible with current materials.

The spinning ring would need some stabilisers and extra energy added to replace losses, but aside from that it doesn't need any energy to keep it in place. Constructing it would be like putting a string of satellites into LEO and joining them together. I don't see why we couldn't build one such satellite module and launch it into orbit, the problem is really only that you need a whole lot of them to create a complete ring.

[coppercone2]

nah its not stationary I was assuming its moving at some high velocity to remain in orbit where it is but it comes out to requiring some absurd hypersonic platform I believe.

so at orbit which is relatively stationary to allow for a ground platform or actual slow moving aircraft or ship to carry a spool is going to require absurd tensile strength because of the length?

the idea being just to get material there cheaply without rockets rather then to carry anything of significant heft. A carbon fiber pump if you will. Can you still call it an elevator if there is no counterweight and it just retrieves material?

[apis]

I'm not sure what you are suggesting, but it sounds a little bit like a skyhook:
http://www.niac.usra.edu/files/studies/final_report/355Bogar.pdf

[coppercone2]

imagine they had a hypersonic plane that threw a teather to the ISS and the guys were pulling it in to make wicker baskets.

[apis]

Ah, yes, you need to get 36000 km out to have a geostationary target. ISS is only ~400 km out and has an orbital speed of 7660 m/s.

[Mr. Scram]

It should be noted that a space elevator still requires a fair bit of energy, as you still have mass which needs to be sped up or energised. It's just a lot more efficient than blasting out hot gasses and punching through the atmosphere.

[coppercone2]

Ah, yes, you need to get 36000 km out to have a geostationary target. ISS is only ~400 km out and has an orbital speed of 7660 m/s.

how do you calculate the amount of force you need to pull the string up, after its already in place? Do you just consider the first 100KM as weight affected by gravity?

so the geostationary spot is being pulled down by the energy transferred by the mass in the gravitational field? and the rest is momentum?

can you give me some realistic numbers? i want to get an idea how to calculate how much thurst you need so the station does not get pulled towards the earth and instead lifts the string. Math please.

It's an integral of the decaying field across the length of the string? then you superimpose the momentum on it (ie.. the amount of energy it would require to move a long string in space towards you)?

so you do two calculations and superimpose some how? and energy lost to flexing etc.

so you induce a momentum by integrating the field around the string with the gravitational field formula to get the voltage source lumped circuit kinda deal? and the matters physical presence is inductance?

[cdev]

Its a challenge in some ways similar to the challenge of laying the first transatlantic telegraph and telephone cables.

[StillTrying]

How would a space elevator work, the bob at the end of the string would have to be above geo-stationary to keep the string taut, but then the bob wouldn't be geo-stationary.

[apis]

Math please.

I think gravity acting on a hanging string string would be F₁ = int{ rho pi r² g(x) dx, from a to b}
x is distance to earth center, rho is cable density, r cable radius, g gravitational acceleration  = - (GM)/x^2 (G gravitational const, M earth mass)
Add a load at bottom as F₂ = m g(a)
F = rho pi r² (GM) (1/b - 1/a) - m (GM)/a² (I think, it's too late here.)

Does the forum have mathjax support or some such?

How would a space elevator work, the bob at the end of the string would have to be above geo-stationary to keep the string taut, but then the bob wouldn't be geo-stationary.

The center of gravity of the whole thing would be a bit under the bob, but overall you'd have that a bit above geosynchronous I believe so you have a net force acting outwards, that tensions the wire which counteracts that pull. Space elevators aren't really practical on earth, you could have one on the moon though.

[Nominal Animal]

Maybe wouldn't think titanium (or other valve metals) would be too bad, and its strength to weight ratio is much better than aluminum.  But, it's also known to be sensitive to stress raisers IIRC.  I forget if they use titanium, or superalloys (or what else) in jet compressors...

Then there is the lifetime cost analysis. A cubic meter of monocrystalline aluminium is relatively expensive, but overall worth it in the pumping costs; I bet titanium would be simply r

Ah, so you were involved in surface chemistry research on this stuff?

Not surface chemistry; more like the transition layer between bulk and surface, and specifically for FeCr (of 10%-20% Cr).

It is not that hard to get surface properties right in a computational simulation; it's just that bulk properties then tend to be off, and vice versa. The transition zone is harder to model. And due to the large number of atoms involved, you can't use ab initio methods (simulators like vasp).  Yet, a large fraction of the interesting effects (corrosion resistance, ion implantation, gamma radiation effects) happen in that zone.

Gradient alloy maybe?

I was thinking of doping (with high-energy ion bombardment) with cylindrical radial distribution prior to machining. Or after. Defects do tend to cluster, but we already have amorphous materials that actually diffuse them instead (self-healing solar panels); getting the same to happen in a metal alloy lattice would be a breakthrough.

I mean, that makes even less sense, because pure aluminum is almost as soft as sodium.

I am not sure which aluminium alloy is actually used. I do know it is monocrystalline, in the sense of being grainless, as close to a perfect lattice as one can get, without any macroscopic defects.

If I was unclear, let me clarify: I've worked with the simulations on FeCr, not on Al. The info I got was directly from guys who make those pump turbines, as they explained the requirements, and we discussed how similar the requirements are, fundamentally, to high-energy plasma container materials.

The acceleration at the blade tip is something ferocious. Aluminium is light, about 2.7 g/cm³; Inconel is what, 8+ g/cm³? Just to keep the blades intact, you need triple the tensile strength to account for the higher density.

Well, there you go, it's easily 3 times stronger than any aluminum alloys I know of.   Unless there's something crazy going on with the single crystal structure.

Plastic deformation characteristics, maybe? Or yield too low due to grain boundaries in such large chunks, causing early structural failures? Cost? I dunno.

What I do know, is that if we could cast those metals (and generally create the billets) in microgravity, we'd get a huge step forward in what we can actually consider viable as manufacturing materials. The vacuum helps too; the purities possible are something totally different.

If you ask me, I think we should definitely risk occasionally dropping a small hill-sized metallic asteroids on our heads, just to get some experimental foundry work going in orbit. The potential discoveries and possibilities it might open are definitely worth it.  It's not like we avoid traffic, even if it kills something like 1.25 million people worldwide each year (20 to 50 million injured).

(I forgot to mention earlier, but one really interesting way of shedding delta-V when tugging back metallic asteroid fragments from the belt to Earth, is solar sails, using low-thrust trajectories.  Slow, but nothing happens too fast, and keeps Earth impact risks low.  It is a bit surprising, but volatiles (snowballs) are much harder to handle; their unpredictable outgassing when getting closer to the Sun poses severe difficulties.)

[Nominal Animal]

How would a space elevator work, the bob at the end of the string would have to be above geo-stationary to keep the string taut, but then the bob wouldn't be geo-stationary.

You first tug a metallic asteroid to a geostationary orbit. This is your counterweight. The string is attached to the asteroid, not to Earth. (It is possible that to get the necessary purity, or tube length if carbon nanotubes are used, manufacturing the material in orbit is cheaper than on Earth.)

The center of mass of the counterweight + string system is kept at geostationary orbit, about 36 000 km above equator. This means that when you spool the string out, the counterweight drifts a bit outwards.

If the counterweight is large enough, you can use a mass driver (essentially a railgun) that shoots small slugs tangentially to the orbit, to speed up or slow down the counterweight, as a backup for chemical or ion thrusters.  But you do need to continuously control its orbit.  Safety-wise, you'd design the system so that if neglected, the string would fall down to Earth (and possibly make a lot of damage on the equator, if it does not burn up in the atmosphere), and the counterweight just drift to a higher orbit.  It's not nearly as dangerous as traffic, but it ain't perfectly safe either.

It is a wonderful idea, but I personally would prefer more practical efforts in developing better rocket engines, like aerospike engines.  We need to get a pretty heavy presence in orbit before we can build a space elevator, so getting better at chemical rocketry seems a prerequisite to me.

[T3sl4co1l]

It is not that hard to get surface properties right in a computational simulation; it's just that bulk properties then tend to be off, and vice versa. The transition zone is harder to model. And due to the large number of atoms involved, you can't use ab initio methods (simulators like vasp).  Yet, a large fraction of the interesting effects (corrosion resistance, ion implantation, gamma radiation effects) happen in that zone.

I had "surface-ish" in my mind, but didn't say so.  Yeah, near-surface effects and mobilities must be... interesting.

Coincidentally (or perhaps not), "surface" in E&M terms is ca. 100nm, because of the effective e_r of a metal at optical frequencies.  Which is, roughly speaking, the high frequency (quantum) extension to classical skin effect, but not really because of plasmon effects and other weirdness that I know very little about.

That's, for example, why you can see blue through a CD's foil layer, dimly but definitely nonzero.

If you ask me, I think we should definitely risk occasionally dropping a small hill-sized metallic asteroids on our heads, just to get some experimental foundry work going in orbit. The potential discoveries and possibilities it might open are definitely worth it.  It's not like we avoid traffic, even if it kills something like 1.25 million people worldwide each year (20 to 50 million injured).

People are fundamentally bad at statistics when E[event] < 0.01 or so.

Education would probably help, but that's probably a pipe dream.  Just critical thinking would be nice.  Alas...

(I forgot to mention earlier, but one really interesting way of shedding delta-V when tugging back metallic asteroid fragments from the belt to Earth, is solar sails, using low-thrust trajectories.  Slow, but nothing happens too fast, and keeps Earth impact risks low.  It is a bit surprising, but volatiles (snowballs) are much harder to handle; their unpredictable outgassing when getting closer to the Sun poses severe difficulties.)

Yeah, I would expect you'd want to manage an icy asteroid with some mirrors and/or sails.  It's going to evaporate, but you can control where and how much, and use that to steer it, very slowly.  Some instrumentation (a small satellite swarm?) monitoring outgassing and dV would be able to manage the unpredictability.

Also, a volatile NEO is probably heavily caked in insulating dust already, wouldn't expect putting it in orbit would be much difference.  That probably helps.

Tim

[StillTrying]

Space elevators aren't really practical on earth, you could have one on the moon though.

I think there's only 2 stable places a moon space elevator could be, directly inline between moon and earth, or directly behind on the dark side, and around 95,000kms high. That doesn't seem very practical either.
https://www.quora.com/Does-the-Moon-have-a-geostationary-orbit-If-so-what-is-its-altitude

[apis]

I think I would prefer mining the moon, safer and gives more options to do other things. You can send many smaller packets of minerals back to earth instead of one large mountain.

Space elevators aren't really practical on earth, you could have one on the moon though.

I think there's only 2 stable places a moon space elevator could be, directly inline between moon and earth, or directly behind on the dark side, and around 95,000kms high. That doesn't seem very practical either.
https://www.quora.com/Does-the-Moon-have-a-geostationary-orbit-If-so-what-is-its-altitude

What makes it at least feasible on the moon is that the moon has lower gravity, so the stresses on the cable will be lower, and there is no atmosphere to worry about.

It would be very valuable to reduce the cost of transferring cargo between the moon and earth.

[Nominal Animal]

I had "surface-ish" in my mind, but didn't say so.

Yup; I just wanted to make sure I'm not accidentally misleading anyone.

In computational materials physics, it is usually not easy to state the exact depth; it is much easier to say it is the region between the surface (that can be modeled pretty easily with results corresponding to real-world measurements) and the bulk (that can also be modeled easily with results corresponding to the real world) that is the interesting-but-problematic zone.  For ferrochrome, it is a few hundred nanometers; if I recall correctly, on the order of 400 nm or so.

Yeah, near-surface effects and mobilities must be... interesting.

Especially so for chrome and other metals with interacting electrons in different orbitals. One way to describe those interactions is analogous to magnetic interactions.

Multiband EAM models for chromium essentially treat the 4s electron and the 3d electrons separately.  In complexity, it is an interatomic potential (so not that complex, although the two bands make it technically challenging, regarding cache behaviour and such); nowhere near as some of the force field models chemists use.  There is an underlying physical model, but the actual parameters are obtained by fitting to real world results. If you were a chemist, things would be even harder: water molecules, for example, are fiendish to model correctly (correctly representing its solvent properties, clathrates, and similar phenomena) in molecular dynamics.

Just critical thinking would be nice.

I'd give my left pinky if it made even a tiny, but statistically measurable increase in critical thinking among humans. Not kidding.

For example: Who you listen to, does not matter.  Who you do not listen to, matters.  This is because you cannot form an informed opinion on something you do not know about.  So, when someone refuses to consider a message because it is from a source they dislike, they are doing so for ideological reasons, not because they are critical or sceptical.  It is just reverse *argumentum ab auctoritate*.  Sure, philosophers cannot agree whether argument from authority is a fallacy or valid argument; but in science, argument from authority is worthless.  I trust science more than I trust philosphers opinions.

Yeah, I would expect you'd want to manage an icy asteroid with some mirrors and/or sails.  It's going to evaporate, but you can control where and how much, and use that to steer it, very slowly.  Some instrumentation (a small satellite swarm?) monitoring outgassing and dV would be able to manage the unpredictability.

Definitely agreed.  Doing it at low thrust (trajectories several years, perhaps on the order of a decade), means the technical risks would be very small.

It's not like Earth isn't bombarded with rocks all the time.  There is another Chixculub impactor out there.  Considering typical human behaviour, robotic tracking won't cut it, because humans will lose interest in a few decades (á la "we haven't found a significantly dangerous impactor yet, so why do we spend all that money on robotic tracking? we could use it to make our nests so much more comfortable instead!"). The only long-term hope is to have some permanent human presence in orbit, up to and including at least the asteroid belt.  The further out, the likelier early detection would be, and thus more time to react to dangers.  Some of the asteroids are too dark (low albedo) to be detectable from Earth orbit, too.

I think I would prefer mining the moon, safer and gives more options to do other things. You can send many smaller packets of minerals back to earth instead of one large mountain.

Very true.  Especially something like "cannonballs" or elongated "pills" made mostly of volatiles, with a thickish metal shell, shot into orbit using solar-powered mass drivers.  Having access to low-cost volatiles in orbit (hydrogen, oxygen, nitrogen) and carbon and iron would be akin to industrial revolution in Earth orbit capabilities.

That isn't "science fiction", either. The escape velocity on the moon is about 2.4 km/s, and railguns that shoot 2 kg projectiles at 3 km/s already exist here on Earth.

(I just realized that that would work for ³He mining just as well.)

[raptor1956]

How would a space elevator work on the Moon?  The Moon has a very slow 29 day rotation rate so where is the elevator to be anchored in space?  Beyond that problem how would it be useful?  If it were supposed to make accessing the Moon easier from Earth how would that work.  I mean, we'd have to reach it and that means leaving Earth at very high speed, and then coming to a near dead stop -- you'd waste about as much on deltaV as landing on the Moon.


Brian

[T3sl4co1l]

How would a space elevator work on the Moon?

It doesn't...



Stop trying to make elevators / beanstalks happen... they're not going to happen.

The racetrack thing looks neat, https://en.wikipedia.org/wiki/Launch_loop but it's probably never going to happen given the massive cost and risk in building and operating such a structure.  Not this century at least.

Tim

[apis]

I don't think it's going to happen on earth, but on the moon it's a possibility.

How would a space elevator work on the Moon?  The Moon has a very slow 29 day rotation rate so where is the elevator to be anchored in space?  Beyond that problem how would it be useful?  If it were supposed to make accessing the Moon easier from Earth how would that work.  I mean, we'd have to reach it and that means leaving Earth at very high speed, and then coming to a near dead stop -- you'd waste about as much on deltaV as landing on the Moon.

That's why it only would work at two places on the moon. You can put one between the earth and the moon, just far enough out from the moon that earths gravity becomes stronger and pulls the cable taut (L₁), or you could put it on the dark side of the moon, and use the centrifugal force it gets from rotating around the earth (together with the moon) to counteract gravity (L₂).

On the earth side you get nearer earth and you also get out of the moons gravity well, that makes it cheaper to travel to/from earth.
On the dark side you get out of both the earth and moon gravity well into the solar system, that makes it cheaper to travel into the solar system.

Otherwise you'd have to use something else, like rockets, to get off the moon. But on the moon there are other options, like a mass driver.

[apis]

Actually, having played around with this for a while, the potential energy for an object at the moon - earth L₁ point would correspond to the energy of an object in low earth orbit.

So basically you can launch LEO and higher orbit  satellites from the moon using only a mass driver. If you want to send cargo to the surface of the earth you can just "drop" them and use the atmosphere for braking (with a suitable shield).

So to send something to some point at LEO and below cost no more energy than it takes to get away from the moon's gravity. Since you can use a mass driver or elevator for that, it's very cheap.

It gets even better if you use momentum exchange tethers (skyhooks). Then you can slow down cargo when dropping it from the moon, and use the stored energy to bring cargo up again from LEO to the moon. So for every kg you transfer to the earth you could send a kg cargo up to the moon!

Building an orbital ring might not be so expensive after all, if you build modules on the moon and then shoot them into LEO.

Almost sounds too god good to be true.

[Nominal Animal]

Almost sounds too god to be true.

Funny slip of the tongue there    The technical hurdles are not that big; it is true.

But then you start thinking about the political implications.  Our current countries can barely agree on a single shared space station.  A facility that could (at least in theory) bombard any place on Earth with near pinpoint accuracy at basically zero cost, is not something the warmongers will allow (to be in someone elses hands).  Heck, if someone started building that alone, it might be enough to spark the next world war.

I do not see governments coming together on something as complex as this: their internal goals differ too much to allow this to happen.  A commercial company might get away with it, if it was profitable enough to sweeten the deals with politicians so much they handle the warmongers (out of their self-interest).  Or a breakaway group of people doing it in "secret", that is, not telling the general population on Earth anything about it; the few politicians that would know would likely keep quiet about it, again purely out of self-interest.

[Mr. Scram]

Funny slip of the tongue there    The technical hurdles are not that big; it is true.

But then you start thinking about the political implications.  Our current countries can barely agree on a single shared space station.  A facility that could (at least in theory) bombard any place on Earth with near pinpoint accuracy at basically zero cost, is not something the warmongers will allow (to be in someone elses hands).  Heck, if someone started building that alone, it might be enough to spark the next world war.

I do not see governments coming together on something as complex as this: their internal goals differ too much to allow this to happen.  A commercial company might get away with it, if it was profitable enough to sweeten the deals with politicians so much they handle the warmongers (out of their self-interest).  Or a breakaway group of people doing it in "secret", that is, not telling the general population on Earth anything about it; the few politicians that would know would likely keep quiet about it, again purely out of self-interest.

Orbital bombardments aren't as ideal as people seem to think. Due to the distances involved, it's often easier or less predictable to just use a traditional ballistic missile. Not to mention the soft target such a station would be.