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back to article Enormous orbiting solar raygun power plants touted

Many years ago, in Galaxy magazine, Jerry Pournelle devoted his A Step Farther Out column to describing how satellites could be used to harvest solar energy on a scale impossible underneath Earth’s atmosphere. The idea never really went away, but it’s been mostly out of the spotlight. Now, Reuters is reporting a study by the …

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Silver badge
Happy

I support this!

But wasn't there a story by Asimov about a robot who went religious nutcase while in control of such a station, with everyone fearing that it/he/she may no longer be able to align the beam during solar disturbances, thus possibly causing large-area fritzy-frutzy earthside?

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Anonymous Coward

Ziwzih Ziwzih oo-oo-oo

It was called The Prophet.

http://www.youtube.com/watch?v=AMWV1ZzE6KY

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Bronze badge

That was "I, robot", god that book was so much better than the awful film.

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Yes.

"Reason", one of a series featuring Powell and Donovan.

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Anonymous Coward

Yep

There was, pretty sure it was iRobot, not to be confusd with the film about a man and his love affair with his shoes.

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Devil

The robot is the least of your problems

The whole thing is one HUGE tangle of problems.

Unless the solar batteries are positioned on top of something really really really heavy like let's say the moon they will be pushed by the solar wind out of their orbital positions. In addition to that all the "easy" positions in stationary orbit are already occupied so there will be some very entertaining logistics in terms of jumping from one receiving station to another and doing something with the surplus energy while the jump takes place (OK, that can be solved by multiple antennas but this means more weight, complexity, etc). Add to that that the energy beam will ionize the atmosphere and generate enough ozone and nitrous oxides to kill anyone for miles downwind...

Why do I suddenly think that nuclear is such a good idea...

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Gold badge

The plan I saw had the beam hitting the earth with about 1kW/M², which is about the same as the power from the sun (in countries other than the UK where it is cloudy instead). The advantage over pure solar power on the ground was 24hour power, except for 70 minutes eclipses during the equinoxes, and better efficiency of the beam receiving equipment.

The orbital slots were on the GEO belt. The gaps between sats up there is still big enough that we could fit a few of these in there. Plus it hasn't been said anywhere, but taking a miserly 4-16kW of the juice to run a few bent-pipe TV relays won't really hurt the power generation of the satellite. In fact, selling payload space might help pay for the things.

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Anonymous Coward

>"they will be pushed by the solar wind out of their orbital positions"

Well, that's a big problem. If only this orbital power station had... I dunno... some source of power, that it could use to drive engines to maintain its orbit with?

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Boffin

So...

just how 'heavy' is the moon, then-?

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Anonymous Coward

All the technical problems are soluable at a cost...

Gyros could be used to stabilse the Position in space.

Geostationary slots are available and if not then something will get bumped to make way for them.

I understood, but will be corrected, that the solar energy energy flux was 10kW/M2. this turns into about 200W at the surface at the equator with the losses being absorbed/re-emitted.

The biggest issue is that such a device would be considered to be a space based weapon and would need to be controlled by one of the responsible superpowers wish space access - now who could that be......

Wait for the energy prices to rise and no other options and we might consider this as a solution if we are not back in the stone age... Or we all become a bit more mature about this sort of technology?

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A few corrections

Gyros can't, strictly speaking, position you in space; all they can do is control your attitude. Which is also critically important.

You don't need to put a solar power station in geostationary. You would almost certainly put it in a MEO orbit. Not much atmospheric drag, lots of space, and little shadowing from Earth.

Solar flux above the atmosphere is about 1.3kW/m^2

You could quite easily show that such a space facility is not a weapon as the design would have to be considerably different. Plus they would be fragile, vulnerable targets if used as weapons. Nukes are far cheaper, easier and destructive...!

I'm a big fan of solar power in space, but the economics demand a much cheaper launch mechanism. Roll on the Skylon!

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fch

Since you ask to be corrected ...

... just use the omniscient garbage pile that is Google to find out about what's called the "solar constant". No, I'm not going to gtfy.

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Joke

About 1/6th the weight it would be on Earth - why do you ask?

ttfn

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Ru
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FAIL

Re: "The whole thing is one HUGE tangle of problems"

Your understanding of engineering and physics is atrocious.,

I'll deal with your two most obvious errors.

1. Station keeping will be nice and easy; just fit a brace of VASIMRs. There'll be more than enough juice to go round. You significantly overestimate the strength of the solar wind within Earth's magnetosphere too.

2. Any beam that is ionising the atmosphere is wasting a colossal portion of its energy... so much, in fact, that it could not possibly be economic. The transmission beams will be tuned for minimal absorbtion by the atmosphere.

I wonder what the cause of Pathological Internet Omniscience is. You clearly know nothing about the issues, yet rant as if you're informed.

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Terminator

Pedant Alert!

Isaac Asimov never wrote a story called "I, Robot".

The book with the same title is a collection of short stories by Asimov which he originally intended to be called something entirely different, but was over-ruled by his publisher. None of the stories in the collection are called "I, Robot", although the "Three Laws of Robotics" do feature heavily throughout.

The publisher obtained the title for the collection from another writer entirely (Eando Binder), who HAD written a (pretty bad) story called "I, Robot".

The film bears no resemblance whatsoever to either Binder or Asimovs work.

The story in which a robot "gets religion" is, I think, part of the Caves of Steel series which partly inspired the film.

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Energy yes

Reaction mass not so much. Unless the probably frequent maintenance visits also provide something to be spat out of said engines, or a reactionless drive is also invented. In which case I'm gonna get myself one of those first!

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Mushroom

Surplus energy...

... point the massive microwave cannon sideways and blast space debris out of the way. One stone, two birds.

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Rockets?

TBH I don't know why a giantic magnetic rail gun / catapult into space to shoot things up there hasnt been built yet. It would make such things (after the initial and horrendous building costs of the darned catapult) somewhat cheaper than sticking things into orbit now,

Anyway such stories are common place in Sci FI, in gundam 0083 they had the Solar System II mirror array. This was used in an attempt to stop a colony drop though.

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Boffin

Rail guns?

| "TBH I don't know why a giantic magnetic rail gun / catapult

| into space to shoot things up there hasnt been built yet."

To get into (and stay in) LEO, an object needs to be traveling at about 17,500 mph when it reaches its orbital slot.

A rocket gets there by starting off traveling slowly down where the air resistance (and hence friction) is heaviest and accelerates as it rises into less dense/less compressible/less friction-inducing atmosphere.

On the other hand, atmospheric friction and compression is used when decelerating out of orbit. This generates thousands of degrees of heat which needs to be dissipated/shielded against.

Now take your rail gun. Assuming as a starting point that it is long enough -- some number of miles maybe* -- that the acceleration to escape velocity doesn't pancake every structure in your launch vehicle and payload, there is still the issue that being at the bottom of a gravity well requires that your projectile be going at well OVER orbital speed when it leaves the muzzle.** Otherwise,just as with a thrown rock, gravity will start slowing it down as soon as the driving force is off. If it doesn't reach orbital height at orbital velocity -- just like that rock -- back to earth it falls.

So your railgun launcher has to -- slowly enough not to destroy the projectile -- accelerate it to something in the 20,000 mph range... at sea level... in order to still be at orbital velocity when it finally reaches its intended altitude... And once fired into flight, the projectile has to be sufficiently heat-resistant that it isn't instantly immolated by friction/compression-heated atmospheric values above anything that humankind has ever built. (Bear in mind that -- while, granted, its thermal protection had been compromised -- the temperatures and stresses that destroyed the shuttle Columbia happened when it was decelerating from the arbitrary "edge" of the atmosphere at 75 miles above sea level down to final breakup at about 40 miles up.)

...And you want to shoot your payload out of a cannon at HIGHER speeds than the Columbia was traveling, in atmosphere that is DENSER by a couple of orders of magnitude than she was traveling through, and hope to get it to orbit intact...?

Good luck with that.

A long-enough catapult might POSSIBLY be useful for accelerating something akin to a SCRAMjet to operational speed, which could then accelerate through much of the atmosphere before handing off to a rocket engine for orbital insertion, but a catapult to orbit setup without any other motive force...? SO not happening. And I see no way that a catapult/scramjet/rocket combination isn't going to be MORE complex and expensive than what we have now,

No, I'm afraid that (absent any completely new science like antigravity) until we get the first beanstalk built, rockets are pretty much going to be the only way into orbit.

--------------------

* The difficulty of building a miles-long, precision-engineered railgun in an utterly straight line tangent to your starting point on the surface of the earth (You can't just put a ski-jump at the end if you're launching something at Mach 27 or so) is left as an exercise for the reader.

** Ditto the effects of a Mach 27 sonic boom on surrounding organisms and structures (including your miles-long, precision-engineered etc. etc.).

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Mushroom

Nice post

@Mike,

There are just a few extra ideas around the subject which I've heard for helping to make it slightly more feasible.

Namely building it up the side of a mountain, the bigger the better. Though land rights (Everest would be lovely) will be an issue and there is still a large technical challenge there. However it would be a lot easier than trying to build a 7Km tall building...

The launcher itself of course would have to be vacuum sealed so as to not destroy itself with super sonic speeds and the like. However as for the exit from the tunnel I have heard some people talk about the possibility of either firing a sacrificial leading shot to help disperse the air opening up a vacuum ahead of the tunnel for the actual payload or accelerating the air to nearly the same speed as the payload (massive leaf blower :p) to try and cushion its launch.

These are still far from perfect and well beyond out technology but the idea isn't without merit. Perhaps for lugging very large solid masses (ores, minerals, etc) which are to be later picked up by another conventional rocket powered vessel.

(Icon? Mostly likely result from that hydrogen/uranium shipment they were sending to the moon...)

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Himalaya's

Could you build it on the side of a very high mountain?

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Silver badge

Rail launch

I've always wondered why (outside of the movies) no consideration seems to have been given to a launch where the first stage of aceleration uses external electric power to drive the rocket up a ramp. I'd have thought that there are considerable advantages to firing the rocket when it's already travelling at (say) 300mph along a ramp up the side of a mountain.

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Coat

7km Building

Phineas & Ferb did it in a morning....

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Gold badge

The Russian Depnr rockets are ejected out of an underground silo using steam and then the rocket motor is ignited once it's above ground (I kid you not!). You are not allowed to know too much about this, and not even look in the direction of the silo when you are there, but this website from one of the suppliers shows it nicely:

http://www.arkos.kharkov.ua/sumbr_e.php

Although maybe this isn't exactly what you meant :)

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Thumb Up

Beanstalk +1

Meantime, what about shooting rockets from very high altitude balloons? (idea shamelessly pilfered from Red star, Winter orbit by Gibson & Sterling)

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just deliver it in

milk bottles

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Thumb Up

What goes around comes around?

NASA did studies on this back in the late 60's or early 70's. The main problem is, of course, the Green folks.

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Anonymous Coward

Aren't they always when progress is involved?

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Alien

Green Folks

They're just pissed that Capt. Kirk kept loving and leaving them :S

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Anonymous Coward

FUND FUND FUND FUND

Good idea, except for the Microwave oops! disaster scenario.

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Ru
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Boffin

Yay sim city

The risks of frazzling the target site are smaller than you might expect. There's probably an optimum surface power density value that depends on how efficienr your microwave photovoltaics are, and how big a receiver array you can build. You certainly don't want to be transmitting power on a microwave frequency easily absorbed by water, which would of course by the optimum frazzling mechanism.

Being irradiated by a strong RF emitter isn't going to be very good for anything, but these aren't going to be orbital death beams.

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Mushroom

>"but these aren't going to be orbital death beams"

Orbital death beams? What orbital death beams? Nobody mentioned orbital death beams. What aren't you telling us?

<-- Dooomed, I tell ye.

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Alert

space sharks would need those wouldn't they? Dibs on the space shark idea btw.

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Didn't the Xindi try this already and it ended badly for Florida, or am I getting Star Trek and reality mixed up again?

Seriously though, this could end badly in so many ways if the wrong people were in control. You wouldn't want the downlinks anywhere near populated areas, air routes, bird migration routes, etc. Presumably as well, the downlink stations would need to be in the equatorial region which doesn't leave too many bits of land in stable countries to choose from.

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Big Brother

You can put the downlinks almost anywhere you want

"Presumably as well, the downlink stations would need to be in the equatorial region which doesn't leave too many bits of land in stable countries to choose from."

No, you don't have to put them near the equator, it's just that you get the most concentrated beam that way because the farther away from the equator you get, the more the beam spreads, just like sunlight.

And, there's a real nice advantage to this that nobody's mentioned: once you get a country dependant on your beamed electricity, all you have to do is shut it off if they do anything you don't like, and there's not one damned thing they can do about it. Kind of like OPEC, only more so.

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Pint

Not to mention ...

... being able to recalibrate to destroy all of those those nasty incoming comets!

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Terminator

Pournelle had plenty of "good" ideas back in the day, and was worth listening to if you could handle the rather hectoring style and right wing ranting that sometimes accompanied his utterances. Wasn't he part of the "Rods from the Gods" brigade?

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Silver badge

Yes, there was a chapter called the "The Jayhawk War" or something in "Footfall" where aliens rod a whole tank division from orbit.

In five minutes it was all over.

I have never heard anyone explain how one actually *deorbits* those rods without huge boosters and keeps them on target for the pretty chaotic ride down. One cannot just drop them.

A the joys of americocentric warjerking.

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Off the top of my head

a rail-gun (see Moon is a Harsh Mistress for lunar based prior art).

Of course the proper way to build this stuff is with a suitable rock boosted in from the asteroid belt. Would take years but it's entirely do-able. Requires real long term investment though, so it'll be a long time before we see it.

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I've read enough Eagle comics to know where this is going...

The Tower King

http://www.thoseweleftbehind.co.uk/2008/05/post-apocalypse-vi-tower-king-1982.html

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Terminator

http://en.wikipedia.org/wiki/Reason_(Asimov) is the story you are thinking of. There is also a spooky Delia Derbyshire track from the BBC tv adaptation that is worth checking out: http://www.youtube.com/watch?v=dulk_GfkcDA

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Megaphone

What about the poles?

Instead of trying to hit a spot on the Earth rotating at over a thousand miles-per-hour with a high-energy beam of microwaves, would it be possible to place the collector (s) at the poles so that the target doesn't move so much? From the poles we could build a distribution grid to carry the power down to the lower latitudes. Less of a chance of zapping someone by mistake that way.

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Stop

Aiming high power microwave at ice... Ask Belgians how they feel about this idea.

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Re :"What about the poles? "

The apparent rotation of the earth would be zero as the satellite is intended for geostationary orbit.

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Anonymous Coward

Someone explain why you would want to spend (tens of) billions of pounds lifting heavy solar panels into orbit, along with all the consquent problems with maintenance, control, power transmission, array degradation, non-negligible chance of catastrophic mission failure, when you could just build twice as many dirt cheap panels on the ground to make up for the fact that you get 12 hours of sun rather than 24? Unless 'much more sun' is many multiple orders of magnitude greater, an admittely untrained idiot like me cannot see the economic case as to why solar panels in orbit (at costs thousands of times higher than building terrestrial arrays) are even being considered.

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Why in orbit?

Because there's no pesky atmosphere to get in the way of the solar energy.

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Try 5-6 times as much energy from space solar(generally you only get 5 peak hours of sun). But costs for space solar are a lot more then 5-6 times then terrestrial solar.

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Boffin

Because earth based solar array can produce electricity for about 10% of time averaged over a year.

Add the energy stopped by atmosphere and you have a system that is at least 100 times as effective.

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Anonymous Coward

Someone actually gave you a thumbs up for this? Utter bullshit. The equator gets 12 hours of sunlight a day (not 2.4, as your 10% figure estimates) and If the 'energy stopped by the atmosphere' was indeed 90% of the suns total power, then where does that energy go? As heat? Since we still -have- an atmosphere, I can only surmise that 90% absorption figure is bullshit too. And even if it wasn't, and an orbital array was actually 100x more efficient than a land based one.. then you're still only another order of magnitude or two away from it being as cost effective as a ground based one. Oh wait... except you have to beam that energy back to earth, through that incredibly opaque atmosphere that inexplicably causes 90% transmission losses... bwuahhaha....

At best a solar panel in orbit is going to give 5 times the power of a land based one. Not 100 times. And it'll cost thousands of times more to get it up there. So I'll let you do the simple maths (1000 >>> 5)

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It doesn't seem to add up

As above. The Desertec project to produce 15% of Europe's energy from solar power in the Sahara is much less challenging and would produce cheaper power more quickly.

http://www.guardian.co.uk/business/2009/nov/01/solar-power-sahara-europe-desertec

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