The Idea of A Space Fortress

[Sky Captain]

The problem with ground based solar power is it is horribly inefficient. For example German solar plants get avarage capacity factor of about 10 - 12 %. Their total installed capacity is ~9 GW with average output of 710 MW. During winter when the electricity is needed the most they get barely any power at all from solar. Without massive government subsidies costing ~billion of euros per month comercial solar power wouldn't even exist in Germany because conventional coal and nuclear plants generate electricity much more cheaper. For that money one could buy 3 - 4 AP1000 reactors per year and in return get reliable 24/7 3 - 4 GW of electricity without the need for additional expensive energy storage schemes. If goal is to get away from fossil fueled generation then nuclear is among the most cost effective options.

[PeZook]

Actually, the topaz solar farm is said to be able to deliver 1100 gigawatt hours of energy annually, so yeah it is a bit less than its stated power (about 1/3, if I got my math right)

Second-generation nukes are actually a bit more costly than that farm (you pay 2 billion per gigawatt of reactor power, plus the plant facilities itself) but work 24/7.

Both solutions are of course vastly superior to a 15 000 tonne solar satellite

[Sky Captain]

Yeah in a desert capacity factor would be better hovewer people usually don't live in desert so the electricity has to be transported hundreds of kilometers with high voltage lines to where it is needed which add aditional costs.
Probably the most cost effective use of solar energy is to simply provide hot water and heat. The hardware is simple and inexpesive, basically a black metal plate with coolant pipes welded to it in a glass enclosure and a big water tank to store the heat.

[PeZook]

The infrastructure to distribute energy across hundreds of miles is already mostly there: at worst you need a build some additional lines (which isn't exactly some new and exotic tech...).

Power flows across the US all the time, saying "well it's gonna be far away from anybody" is not an argument ; It's a common ocurrence for power companies to buy additional power when their own generation can't keep up. Of course it's preferable to have a plant near the receivers (duh) but it's not a deal breaker ; Transmission losses over long power lines are not that significant.

EDIT:

Check this out - in many states, most pepole already live hundreds of miles away from the nearest power plant.

Beaming it down across 32 000 kilometres changes nothing ; The receivers would by themselves be as large as a power plant, and still have to be located outside significant population centers, so you'd still get transmission losses over power lines.

[Sarevok]

Sorry about derailing the discussion on solar power (even though it derailed the thread itself :p),

But I just had a thought about the idea of using burrowing nuclear warheads to destroy defended asteroids. It probably is not going to work. Why ? Because the warheads will have to slow down before impact. No realistic warhead's is going to be intact after smacking into solid space rock at thousands of meters per second. But slowing down makes the warhead a most excellent target for defensive weapons. For weapons designed to engage objects moving in space a warhead at typical bunker buster bomb like velocities would be like shooting fish in a barrel.

[Purple]

Just a question. If that solar station thing will cost like 10 or 20 times that of a nuclear power station and produce about as much power as one why not just build something like 15 nuclear reactors and use the remaining money to pay for shooting the radioactive waste into space to the moon or something?

[PeZook]

All satellites have that. It's a solved problem.

Really, dude?

So if somebody proposed to build a submersible aircraft carrier, and I say that it's a stupid idea because, unlike surface carriers, the ship will need to be absurdly huge and expensive and need to accomodate systems which make it a submarine in addition to the flight deck and other equipment, you can then say "All submarines have that, it's a solved problem"?

Here's a newsflash: it's not a solved problem when you want to put up a 15 000 tonne space station up there. It provides new exciting and radical engineering problems to solve merely because of its weight, and costs literally orders of magnitude more per megawatt of power produced than ground based power plants due to launch costs alone.

You know how satellites "solve" the problem of degrading solar panel output? They are deorbited/moved to a parking orbit and replaced with fresh ones. You can't do that with a massive station like that solar power satellite for obvious reasons: so you'll need periodic flights with lots of spacewalks to replace damaged panels, and of course refuelling flights for the attitude and station-keeping thrusters (even in geosynchronous orbit you need periodic adjustments ; and boy, adjusting that station by 1 m/s is gonna take some propellant ). Each such flight is a hundred million at the very least (if it brings nothing but three astronauts and some hand tools), a billion and more if you want stuff like a robotic arm and a goodly amount of spare parts.

Which means that for every maintenance flight to this monstrosity, you could build another brand new 500 megawatt power plant on Earth

[bz249]

Each such flight is a hundred million at the very least (if it brings nothing but three astronauts and some hand tools), a billion and more if you want stuff like a robotic arm and a goodly amount of spare parts.

Which means that for every maintenance flight to this monstrosity, you could build another brand new 500 megawatt power plant on Earth

Oh maybe if some handwavium tech works we can reduce the cost of lobing something to geosynchronous orbit by a factor of 2. So than it needs two repair mission to build a brand new 500 MW power plant.

Anyway I really do not know that 24/7 availibility really compensates for the cost of adding two inherently inefficient system (producing maser/laser radiation, and converting laser/maser radiation into a useful form of energy) so anything more complex than a giant mirror might kill the entire goal.

[PeZook]

This is more like someone saying "I want to build a submarine" and you countering with "but the designers didn't mention that it'd have to function under water, which is not a minor problem!"

Except the very articles posted give rough specifications for the installation and it's pretty clear that the SPS is not going to be merely a satellite, but an unprecedently massive one, which suddenly turns a solved problem into an unsolved one, as you can't just discard it and launch a new one for less than 100 million: you have to fly maintenance crews with spares (and every single kilogram of consumables for the crew...) to replace parts of the gigantic panel in situ.

Which is not a problem on Earth, as you just drive a truck out for 600$ and pay a couple dudes for a day's work and you're done: In essence, you can replace hundreds of panels on a ground based solar plant for the price of replacing one in space, so even if the wear and tear in atmosphere is greater, it still doesn't pose as much of a problem as the one in space.

On the propellant issue, it is non-insignificant: if the thing needs to do three adjustments a year of 10 m/s each, it will burn 5000 kilograms of propellant each year (and even then, only if it uses ion thrusters ; If it depends on chemical rockets, it will require 50 tonnes of propellant)

So add another 100 million or so per year just to refuel the satellite (provided you have a fully automated ship that can actually do that and need no crew to handle it. Otherwise, add R&D for something new and manned and its launch vehicle).

All these issues are probably why the JAXA guys commented the technology to build one of these things does not exist yet. It may never exist, in fact: what's missing might just be the space industry capable of producing the components outside the gravity well.


EDIT:

Which means that for every maintenance flight to this monstrosity, you could build another brand new 500 megawatt power plant on Earth

This is, of course, why many people put them hand in hand with space colonies, so the maintenance and construction crews and materials don't have to be launched from Earth every time...

(Let's be honest here, space solar isn't just about power. It's an excuse to get big shit groundwork done to open the door for other things...)

Except if it's ever built as the first step, and it inevitably goes bankrupt/requires tremendous subsidies to operate, it may have the opposite effect of burning off all the political will to undertake grand projects in space, since it's such a gargantuan and expensive project.

Most likely, small "technology demonstrators" will be deployed to get people excited, but not actual proposed 15 000 tonne full-sized stations: since, well, we could resurrect and run the entire Constellation program for the cost of one of those things and get ourselves a lunar base with some ability to use local resources

[PeZook]

Right, and I'm sure any of the 10 zillion white papers and spacecraft proposals promising grandoise things by 1970 1980 1990 2010 were also totally accurate and perfectly feasible and accounted for all variables when they were first published and disseminated by the media.

Even the JAXA guys themselves went "Yeah the tech to do that doesn't really exist so we don't know exactly how much it will cost", implying it's nothing more than a simple white paper at this point. NASA does those all the time, too, in the hopes that maybe one day they can dust one off, see the tech they needed is available now and convert it into actual hardware.

...which will probably look nothing like the initial concept anyway.

To summarize my ramblings: I'm sure JAXA experts know of the problems with launch costs ; It's just that some people apparently can't consider the obvious unless the experts cover all angles in a short interview.

EDIT: Same goes for the space junk issue ; For all we know, they're still discussing the possibilities of handling the problem without launching handymen to geostationary orbit.

[bz249]

To clarify what I'm saying here: rocket scientists and other space engineers aren't stupid. They know what's going on in the space environment and know how to work with it. They have the smarts, the education, and the data to account for the bleeding obvious.

On the other hand, members of this forum are stupid (myself excluded, of course ). We're all lifeless retards, most drop outs or maybe students with, at best, a bunch of news articles or Wikipedia pages written by other ignorant retards as our data sources.

If a bbs.stardestroyer.net member can think up a problem or a solution, I guarantee you that someone on the engineering team thought of it too. After all, they have Google at JAXA and NASA and ESA, etc. too.


Now, if the source was another intertard or some daydreaming inventor or something like that; someone writing about stuff where he isn't an expert, there might be obvious mistakes in their writings. But when it's a full team of engineers allegedly missing a basic engineering fact? Give me a fucking break. Extraordinary claim needs some extraordinary evidence (from primary sources!)

Should someone emphasize that exactly no research was done in the field how to build such a thing? And even less was carried out to demonstrate that such a thing might work. Other than perhaps producing a bit of paperwork which make some small group of engineers occupied. So this project has seen a similar level of investment like the 1000 ton Nazi supertanks. Of course that might change in the future, but observing the foreseable tendencies none of those things will ever be built.

[someone_else]

As much as I love how Japan is interested in the Sun (solar sails, HINODE and solar energy on the ground), I think this claim is totally idiotic.
No less than Zubrin's wankings about going to Mars.

And I'll show you.

I'd love to know how in the hell they are going to lift a twenty-fucking-thousand metric tonnes station to GEO.
I'd like to challenge anyone to find any other article claiming a smaller mass (newer ones keep silent on that detail, but hint at the fact that "Transportation of the solar panels into space is too expensive at the moment to be commercially viable, so Japan has to figure out a way to lower costs".
Will be obviusly split in smaller pieces and thrown up with rockets, but what are those costs they are talking about?

If they use their H-IIB rockets, that will take what, 2500 launches? But that's just to GTO, so that's around double that to bring the stuff actually up to GEO. Let's say around 5000 launches of 4 metric ton sections.
There are no cost figures around about that rocket. Nor a decent reliability has been shown (there have been a couple launches, both successes).

They can use proven and reliable Protons from the Russians, that have similar (and thankfully already stated) payloads to GEO.
With around 4 tons to GEO per launch it's what, 5000 Protons?

I mean five-thousand-motherfucking-Protons?

They have built and launched only 334 of them since the times of Soviet Union.
And here they claim it is 110 millions a pop. So let's say they can build and launch 50 of them per year (feel free to laugh at this), and it will take 100 fucking years.
With a total cost of 550 billion dollars. Only to launch crap up to GEO.

And you say it is a good idea? Kidding me or what?

Realize how the entire concept relies on the hope that a cheaper and faster way to get in orbit is found by 2030 or 2040.
And stop campainging about this madness already.

[Sky Captain]

Well, obviously such project is not economical with current launch costs. For the same money that prototype SPS would cost we probably could develop reliable mass producible thorium reactor and forget worrying about where to get energy for next few million years.

To make SPS a cost effective option we would have to drastically reduce launch costs and preferably also develop industrial base in space capable to make most of SPS from resources gathered in space since even if it would cost only 100$/kg to place stuff in GEO an SPS would still be vastly more expensive than comparable nuclear plant (since the goal is to get rid of fossil fueled generation nuclear would be direct competitor to SPS).

[Skgoa]

[...] so even if the wear and tear in atmosphere is greater [...]

It isn't.

[Singular Intellect]

[...] so even if the wear and tear in atmosphere is greater [...]

It isn't.

Solar panels are actually quite low on maintenance requirements, aside from cleaning them off regularily. And even that is being addressed with self cleaning mechanisms and designs, like here.

[Skgoa]

While you are right, there are much cheaper/less complex ways than what you linked to.

[krakonfour]

Okay...here's an easy way out of the flame war.

Today's nuclear raectors can easily put out 500MW.
Solid state lasers are said to be able to have efficiencies of up to 0.6 ie 500MW in, 300MW out in beam power.
Set the beam wavelength to green light, as it goes through the atmosphere the easiest. Say 20% (wild guess) of the beam energy is lost going through 100km of air.
In orbit, we can use our space elevators to place 6 20m-wide mirrors. They are in LEO, and there's 6 of them so that we can shoot at any target in the sky 24/24.

The beam produced can go through several tens of m/s of rock, and km/s drilling rates can be achieved against a comet (made of ice).

Nothing unarmored can survive such a relatively cheap beam, powered by a single reactor, staring at them for the whole day. IF you decide to armor your fortress, I hook up ten, twenty nuclear reactors for a TW beam able to go through a few km/s of ANYTHING for much cheaper (I can sue the civilian use nuclear reactors. Hook the beam of death to the power grid).

Fortress? NO!

[Simon_Jester]

At what spot size can you drill "tens of meters per second" through rock with a hundred-megawatt laser? What will vapor plumes do?

How much power is being transferred into your mirror and staying there, heating it?

What happens to your emitter arrays when there are clouds overhead?

Is that 20% figure for atmospheric losses realistic, or are you being wildly overoptimistic? I'd like to see some figures, since atmosphere blooming and related problems are a huge issue for laser weapons in atmosphere in general.

Can you align the mirrors in such a way as to focus a beam from a groundside solid state laser array into a relatively small spot size on the target?

[PeZook]

Here's another easy way out of the flamewar ; Do not necro month-old threads.

Locked.