The Idea of A Space Fortress

[Chirios]

I was reading a book by George Friedman called: "The Next Hundred Years". In it he attempts to predict geopolitical and technological events using current trends in both areas for the next 100 years. It's an interesting read even if it is a bit implausible, e.g. Japan going to war with America. Again. But one thing he said really bothered me. He suggested that advances in satellite and rocket technology would lead to space based solar power(SSP) by 2050. And that America, as one of the technological centres of the world, would be at the forefront of this technology. Fine, that I can believe. He then posits that eventually SSP would provide the majority of power for industrially advanced countries in the world. Again, that I can believe. But he then suggests that to protect their SSP satellites, the US would build essentially a Space Fortress/Colony thing; which would have in it radar and spy satellite capabilities, plus a few hundred supersonic drone aircraft which they could launch at any country (from space) and a shit load of missiles etc.

That I can't believe.

The space fortress is a pretty ubiquitous idea in Sci-fi, but it's problem is that it just doesn't work. My major problem is that it's too big for one. Massive easily identifiable target than can pretty much be destroyed just by launching a missile.

But I'm not an engineer, nor an expert or even a layman in space technology. What do you guys think? Let's say there are several space elevators spread across ideal locations in North America; could a space fortress be built?

[noncredible]

Well, I'm not an engineer either (I'm 12), but personally I think it would be really useless. Why a fortress? Why not just a few satellites in strategic locations, and a couple of missile stations. The idea of having people man it is even stupider, since that requires a lot of room and technology that could break, and missiles can be controlled just fine from the ground (or by a robot).

Also, in an unrelated note, you accidentally made three threads with the same title.

[Eleas]

Since this isn't well defined as it is and I'm a complete layman, I can only speculate.</caveat>

As the old truism goes, space is the ultimate high ground. Anything launched from the Earth will be going uphill, which will tend to necessitate a large expenditure of energy. That sort of thing is going to be visible and comparatively slow. Conversely, if you have the high ground, your own down the gravity well will benefit by the same measure, both in the options you have open to you and in sheer damaging power.

Why the drone fighters would be supersonic, though, I don't really get. That sounds as if they'd be atmospheric craft, when really they should be purpose-built to strike as quickly and accurately as possible outside of the atmosphere.

That's a "space fortress" with vague capabilities, though, and if it's actually within the atmosphere, it'll probably not be nearly as impressive. Of course, if the primary purpose of the space fortress is to protect space elevators, then sure, if only because it represents the ability to annihilate whichever country just fired a cruise missile at one of your space elevators.

[Eternal_Freedom]

If you've got the ability to build one giant space fortress, why not simply build multiple smaller stations? Sure, they'd be individually weaker, but there's more of them.

Or if you've got space elevators, why not just stick some missiles on the part in orbit? You've already built the damn thing, it would be simpler to add armaments to it than build a new station. It's even easy to reload/rearm, just send some techies up with some more Space Tomahawks or whatever.

[Nephtys]

I was reading a book by George Friedman called: "The Next Hundred Years". In it he attempts to predict geopolitical and technological events using current trends in both areas for the next 100 years. It's an interesting read even if it is a bit implausible, e.g. Japan going to war with America. Again. But one thing he said really bothered me. He suggested that advances in satellite and rocket technology would lead to space based solar power(SSP) by 2050. And that America, as one of the technological centres of the world, would be at the forefront of this technology. Fine, that I can believe. He then posits that eventually SSP would provide the majority of power for industrially advanced countries in the world. Again, that I can believe. But he then suggests that to protect their SSP satellites, the US would build essentially a Space Fortress/Colony thing; which would have in it radar and spy satellite capabilities, plus a few hundred supersonic drone aircraft which they could launch at any country (from space) and a shit load of missiles etc.

That I can't believe.

The space fortress is a pretty ubiquitous idea in Sci-fi, but it's problem is that it just doesn't work. My major problem is that it's too big for one. Massive easily identifiable target than can pretty much be destroyed just by launching a missile.

But I'm not an engineer, nor an expert or even a layman in space technology. What do you guys think? Let's say there are several space elevators spread across ideal locations in North America; could a space fortress be built?

It seems like that book was written in the 1950s, where many of those predictions may have seemed sensible. Nuclear Power was not as developed as today, and the reliable, compact and economical transistor was not yet available to build capable, high-endurance satellites. The idea of orbital solar power is common, but fraught with difficulties. Transmission down to Earth would suffer extreme loss and inefficiency, in no small part due to the effects of the atmosphere. Likewise the expense of launching massive arrays of solar collectors with microwave transmission abilities. Why not, for a fraction of the price, technical difficulties, and whatnot, just construct more nuclear plants on Earth?

A 'Space Fortress' offers no advantage over satellites and other assets. For surveillance and communications, lots of satellites do the job just fine. For military applications, a large manned space station is an incredibly expensive proposition that at the same time, is a massive target. An ASAT is going to be orders of magnitude cheaper than any large manned platform, meaning it's just a sitting duck in case of actual war.

Placing weapons in space offers little if any advantage in the Cold War scenario. What advantage is gained by adding a few missiles in space, when you already have large strategic nuclear assets on Earth? It changes nothing, and adds cost for no benefit. The 'high ground' advantage is meaningless when you've already expended a lot of time, money and effort getting things up there. Not to mention it's way less concealed, given the level of accuracy in which things in orbit can be tracked from the ground. What's the difference in using an ICBM-style launch vehicle to get a nuke in orbit for future use, vs just keeping it safe earthside and launching it at the enemy in case of war?

[Lord of the Abyss]

The space fortress is a pretty ubiquitous idea in Sci-fi, but it's problem is that it just doesn't work. My major problem is that it's too big for one. Massive easily identifiable target than can pretty much be destroyed just by launching a missile.

The most obvious way of making it work is to make it tough enough that you can't destroy it "just by launching a missile". Build it into a fair sized asteroid that you've diverted into Earth orbit and mount loads of missile defenses on it, for example.

[Nephtys]

The space fortress is a pretty ubiquitous idea in Sci-fi, but it's problem is that it just doesn't work. My major problem is that it's too big for one. Massive easily identifiable target than can pretty much be destroyed just by launching a missile.

The most obvious way of making it work is to make it tough enough that you can't destroy it "just by launching a missile". Build it into a fair sized asteroid that you've diverted into Earth orbit and mount loads of missile defenses on it, for example.

If you have the capacity to move a large mass into Earth's orbit in some reasonable timeframe, and have the lift capacity to launch up lots of goodies to strap to it, you've probably also the capability to wreck anything productive on said rock.

[Lord of the Abyss]

The space fortress is a pretty ubiquitous idea in Sci-fi, but it's problem is that it just doesn't work. My major problem is that it's too big for one. Massive easily identifiable target than can pretty much be destroyed just by launching a missile.

The most obvious way of making it work is to make it tough enough that you can't destroy it "just by launching a missile". Build it into a fair sized asteroid that you've diverted into Earth orbit and mount loads of missile defenses on it, for example.

If you have the capacity to move a large mass into Earth's orbit in some reasonable timeframe, and have the lift capacity to launch up lots of goodies to strap to it, you've probably also the capability to wreck anything productive on said rock.

Presumably all the "productive" stuff would be buried deep inside and there'd be nothing but weapons on the outside. And you probably wouldn't have to lift much up to it; by the time we can build asteroid fortresses we'll probably have plenty of space industry.

[Simon_Jester]

Placing weapons in space offers little if any advantage in the Cold War scenario. What advantage is gained by adding a few missiles in space, when you already have large strategic nuclear assets on Earth? It changes nothing, and adds cost for no benefit. The 'high ground' advantage is meaningless when you've already expended a lot of time, money and effort getting things up there. Not to mention it's way less concealed, given the level of accuracy in which things in orbit can be tracked from the ground. What's the difference in using an ICBM-style launch vehicle to get a nuke in orbit for future use, vs just keeping it safe earthside and launching it at the enemy in case of war?

The big arguments for space-based weapons are-

1) Orbital ABM defense: think Reagan's SDI. This may or may not be entirely practical, but it's at least sane; my understanding is that the concept studies were done and you could set it up if you wanted to. That doesn't mean anyone will, but it would be an effective tool in the aforesaid 'cold war' situation.

2) Invulnerable second strike: you can't surprise the orbital weapons- you can attack them with ASAT weapons, but you can't take them by surprise. They'll basically always have time to fire on the enemy before being destroyed. Nuclear missile submarines have the same capability, but are potentially more vulnerable to enemy ABM defenses.

3) Global non-nuclear deterrence: thinking 'rods from God' or space-based laser arrays, this gives you an effective weapon that can be used for rapid reaction anywhere in the world that is not a nuke, and cannot be mistaken for one. Which is helpful if you're a would-be global hegemon. The US's interest in non-nuclear ICBMs suggests that having such a platform is at least somewhat desirable.

[Sarevok]

Presumably all the "productive" stuff would be buried deep inside and there'd be nothing but weapons on the outside. And you probably wouldn't have to lift much up to it; by the time we can build asteroid fortresses we'll probably have plenty of space industry.

Asteroids are very tough nuts to crack. The surface could take contact nuclear detonations while a base buried inside would be intact.

You are not destroying an asteroid base with a salvo of nuclear tipped missiles the same way as a spaceship or conventional space station. Destroying an asteroid base would be an exercise in siegecraft.

[Zaune]

Asteroids are very tough nuts to crack. The surface could take contact nuclear detonations while a base buried inside would be intact.

You are not destroying an asteroid base with a salvo of nuclear tipped missiles the same way as a spaceship or conventional space station. Destroying an asteroid base would be an exercise in siegecraft.

There's only so big an asteroid one can put in near-Earth orbit without affecting tidal conditions, and I couldn't tell you what the upper limit is but it's unlikely to be so large that even current penetrator technology couldn't trash any buried installations pretty thoroughly when paired up with a nuclear warhead.

[Sarevok]

There's only so big an asteroid one can put in near-Earth orbit without affecting tidal conditions

I am not talking about Juno or Vesta sized rocks, you don't need that much mass to shield against any nuclear weapon we can build.

The amount of energy to fragment even a 300 meter sized asteroid is ludicrous. You are talking about science fiction levels of firepower. That is why when talking NEO defense scientists don't prefer nukes, nudging them away with gravity or rockets is much more feasible. Nukes are only applicable in case of the smallest asteroids. Even then you have to send a team up there to drill through the asteroid like in the film Armageddon. A nuke left to explode in the surface would only mildly inconvenience it's occupants.

It is surprising what having a few hundred meters of rock acting as armor can shield you from.

I couldn't tell you what the upper limit is but it's unlikely to be so large that even current penetrator technology couldn't trash any buried installations pretty thoroughly when paired up with a nuclear warhead.

It is unlikely any ground penetrating nuclear will burrow through sufficient amount of rock while remaining functional. Nuclear weapons are delicate instruments. Even conventional bunker buster type munitions have reached their limit - if they try to go deeper the bomb will destroy itself before reaching desired depth.

[NoXion]

There's only so big an asteroid one can put in near-Earth orbit without affecting tidal conditions, and I couldn't tell you what the upper limit is but it's unlikely to be so large that even current penetrator technology couldn't trash any buried installations pretty thoroughly when paired up with a nuclear warhead.

What sort of thing do we have that can reliably penetrate a kilometre's thickness of an M-type asteroid, which could consist mostly of a nickel-iron mixture? It shouldn't be too hard to find one with an approximate radius of 2km, which would enable one to use the core volume for productive stuff that doesn't need to be poking out in space. Any connections between the core and the surface should be as narrow and staggered as possible. The great volume of metals and silicates will also act like a gigantic heat sink, giving the fortress an advantage over attacking ships that only have what relatively little radiators and heatsinks they have.

I don't think it would be too bad at suppressing surface targets either. Surface attackers have heat dissipation and concealment advantages, but I think that's balanced out by the fact they're fighting uphill and the fortress is fighting downhill, so to speak. The fortress could simply drop rocks on targets, or if push comes to shove, de-orbit itself in such a manner that it lands on enemy territory.

[Zaune]

What sort of thing do we have that can reliably penetrate a kilometre's thickness of an M-type asteroid, which could consist mostly of a nickel-iron mixture? It shouldn't be too hard to find one with an approximate radius of 2km, which would enable one to use the core volume for productive stuff that doesn't need to be poking out in space.

The warhead wouldn't have to penetrate all that deeply to create some considerable seismic effects in a body that size. Assuming you could contrive some level of surprise -maybe put the weapons in orbit surreptitiously beforehand?- and get a few missiles past the installation's defences, a lot could be achieved by spalling and vibration damage. I'm sure there's a theoretical possibility of hitting the critical frequency and duration of shockwaves to turn the whole asteroid into a cloud of gravel, but all one really has to do is knock the weapon systems offline for a while; if the enemy's kill-sat is unable to fire until you've advanced too close to one of their cities to use rods from God that's as good as a kill.

[Sarevok]

A good analogy for the fortified asteroid base can be found in the real world. The USAF Cheyenne Mountain Operations Center (CMOC) is quite capable of taking direct multi megaton hits. They have anticipated the sort of vibrations caused by a burrowing warhead like what you envision. A system of springs are in place that can absorb much of the energy released during a nuclear initiation. The Russians believe that the only way to destroy NORAD command center would require a prohibitive number of nuclear missiles to destroy the mountain itself; before the installations beneath it can be targeted.

[Zaune]

A nickel-iron asteroid a couple of kilometres around would present a very different set of problems to Cheyenne when it came to providing shock-absorbers, I should think. If anyone knows of a freeware program that can simulate the forces involved I'll have a go at modelling this.

[someone_else]

The point isn't "can we build a space fortress", since it's definetly doable if you sink enough money into it, and not even "could it do its task effectively?" since it will do its work, but "are we sure that ground stuff and normal satellites cannot do it much more cheaply"?

Offensive? ICBM bases already do for a fraction of the cost of redirecting asteroids or lifting billion tons of stuff to be used as anti-nuke armor.
Intelligence? You don't need a particularly big installation to make a good spysat.

And anyway, ABM don't need to reach orbital speed, but just the right height. And that means that with a much cheaper missile you reach the right height and then sum the orbital speed of the orbiting target to the Kinetic Kill Vehicle's speed when determining the damage dealt. It will have two chances to hit the target, once outbound, once inbound, and then it gets back again on Earth since it didn't have an orbital speed.
Then again, to keep any such missile from blasting your precious SSPs you can just leave a few smallish defense sats that release small KKVs that intercept the enemy's KKVs.

As a general rule of thumb, such kind of Space Fortress is useful only if you don't want (or are unable) to set a foot on the planet.
Imho, the concept comes from the old times, when computers were crappy.

[Sarevok]

A nickel-iron asteroid a couple of kilometres around would present a very different set of problems to Cheyenne when it came to providing shock-absorbers, I should think. If anyone knows of a freeware program that can simulate the forces involved I'll have a go at modelling this.

Not really. The lack of gravity infact makes it easier since the internal structure does not have to support it's own weight. There is no danger of collapse if something cracks or fails.

[eion]

Asteroid bases do offer one other advantage over smaller platforms besides meters and meters of rock armor: A massive heat-sink.

Obligatory Atomic Rockets link

During normal operations, the fortress would deploy it's fragile by efficient radiators from armored silos all over the surface. These radiators would cool the interior the asteroid as low as possible because during combat operations the radiators and anything else unarmored would be retracted, leaving the asteroid to function as both armor and heat-sink.

Then, with the benefit of their ice cold asteroid the fortress can unleash red-hot laser death from armored turrets long after other satellites, warships, and space stations have had to give up the fight and deploy their radiators for fear of being cooked alive by their own waste heat.

One Battle Moon please.

[Sarevok]

Don't forget that the asteroids massive internal volume allows you to store gazillion tons of coolant. So that the base can keep it's weapons cool much better than the painfully slow process of radiating heat to vacuum.

[erik_t]

A nickel-iron asteroid a couple of kilometres around would present a very different set of problems to Cheyenne when it came to providing shock-absorbers, I should think. If anyone knows of a freeware program that can simulate the forces involved I'll have a go at modelling this.

A 50MT detonation on a 2km-radius iron asteroid, with automagical 100% conversion of that energy to kinetic energy of the asteroid, would impart 112.7m/s of delta-V. A more sensible approach might be to scale from Project Orion. There, the exhaust velocity was on the order of 20-30 km/s. Let's assume the warhead can burrow to some degree, and will eject a 60deg-half-angle cone worth of asteroid material at 30 km/s. The mass of ejecta will thus be 2.46e4 * h^3 kg, for h penetration depth. Say 10m, for 2.46e7 kg. The momentum of the reaction mass is then about 7.4e11 kg-m/s. This implies that the velocity of the asteroid after detonation will be about 2cm/s. Suppose a duration equal to the time it takes a shock wave to go from the bomb location to the edge of the cone (speed of sound in iron is 5130m/s). The resultant 3.8ms duration, assuming a constant acceleration profile, would impart an acceleration of about half a gee. In practice, bulk compression would probably diminish this somewhat. This seems likely to be a conservative estimate - the challenges associated with a 10m iron-drilling 50MT warhead are left to the imagination.

[Feil]

Don't forget that the asteroids massive internal volume allows you to store gazillion tons of coolant. So that the base can keep it's weapons cool much better than the painfully slow process of radiating heat to vacuum.

Okay, so you've radiated your nonreclaimable waste heat into your coolant fluid. Now what? It has to go somewhere, and vacuum is still the only thing around....

[PeZook]

You know, it's great how your awesome asteroid base can take nuke hits all day long, but for the obscene amounts of money necessary to bring the damn thing to Earth, your enemy will deploy a nuclear force hundreds of times larger than yours (because you just sank hundreds of billions and a two decades into moving the asteroid to LEO) and it doesn't do shit to protect your massive solar arrays from cheap killsats, since those can fire their payloads in the opening minute of any war and ruin the solar panels with nothing more than ball bearings. It will also require regular flights for maintenance, consuming additional billions yearly.

I also presume you will want your orbital space fortress capable of doing something besides survival ; Mission killing it would be significantly easier than blowing the thing apart, as doing stuff would mean it needs silos, comms gear, docking ports etc. on the outside, which will be inherently vulnerable to nukes.

Kinda like Cheyenne mountain could technically take hits all day, but the first half dozen would collapse all entrances and cut most communications, turning it into a tomb.

[Sea Skimmer]

Protection on Cheyenne Mountain is very questionable because its an exposed peak and the tunnels inside are simply huge. The tunnels might not ‘collapse’ all day long from hits, but huge scabs are going to fall off the roof and crush the buildings anyway. A fully lined tunnel vs. the rock bolts used would help prevent that. One tunnel intersection at Cheyenne Mountain does have a concrete and steel liner because of a dangerous fault line.

Shear size can be seen here
http://www.techbastard.com/afb/co/images/BLDG1.JPG

When you build a deep underground facility a number of factors can radically effect how effective the protection actually is, and a lot of them are unique to the local geology. I’m pretty skeptical myself that you’d be able to find an iron asteroid with sufficient integrity to withstand a nuclear hit or even the extensive tunneling operations that wasn’t enormous, like 20-30km in diameter instead of just a few kilometers. Many asteroids are likely to be clumps of smaller objects in the first place and thus worthless.

[Singular Intellect]

The claim we need to deploy space based solar farms is absolutely ridiculously and absurd.

There's so much abundant solar energy hitting the surface of our planet that any endeavour to waste resources trying to put collectors into orbit while massively increasing the logistics of energy distribution suggests a level of competence bordering on retardation.

Did this author even bother doing any research into solar power production technologies and the mountains of information related to the field?