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NSSO on Space Based Solar Power
Posted by
samzenpus
on Wed Oct 10, 2007 07:12 PM
from the it-is-always-sunny-50-miles-up dept.
from the it-is-always-sunny-50-miles-up dept.
apsmith writes "About a year ago some of the people at the US National Security Space Office began looking into space-based solar power (SBSP) as a technology in the near-term strategic interests of the United States. At first the participants were skeptical, and the "phase 0 study" went along with no official funding. In a rather innovative move, they organized the study as a series of internet-based (bulletin-board and email) discussions, with the wordpress site open to the public, and a closed experts-only discussion using Google Groups. Initially expecting only a dozen or so interested parties, the discussion grew to include over 170 people with past expertise and interest in the issues. The final report was released Wednesday morning; it provides an excellent broad-brush review of the status of SBSP, showing immense potential, but also a number of challenges that appear only surmountable with a strong government commitment to the project. The big question is where it goes from here — NASA? DARPA? The new ARPA-E? Or something new? I was able to attend the press conference, which included Buzz Aldrin in an announcement of a new alliance to push for implementing the recommendations of the report."
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cool (Score:3, Insightful)
Ok, someone explain it to me (Score:5, Insightful)
Don't get me wrong, I'm all for finding ways to utilize space, but I don't see how this is even remotely economical, especially at our current technology levels.
Convince me.
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Re:Ok, someone explain it to me (Score:4, Informative)
So that problem's solved...leaving only the original problem of manufacturing enough defect-free tubes in enough industrially-significant quantities to make the skyhook in the first place...
Parent
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heh
Re:Ok, someone explain it to me (Score:4, Funny)
Parent
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No weather, and a clear view (no atmosphere at all in the way).
That gives you a factor between 5 and 10 over on-the-ground systems to start with.
If you really lose 50% in transmission *and* 50% in receiving the case is harder to make - most estimates seem to have higher numbers for overall system end-to-end efficiency, but of course nobody's buit one yet.
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Of course, I'm more of the belief that solar power satellites will not be practical until we have off earth resources to build them from and, as such, low tech heat exchange designs are a better s
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Obviously it's no
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how do you propose we maintain them from that distance? yes, solar cells aren't this eternal source of power people think they are. expect to need to do rolling replacments every 10 years atleast, if not more under those conditions.
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Robot equipment would perform the maintenance, powered by the array itself.
...and how will the robots create a new solar panel if a panel is damaged?
Think of them as an army of advanced Roombas.
Are they able to repair themselves, and if so, where do they get spare parts?
As far as the idea is concerned, I'd not mind if they can do it cleanly. The S-G power delivery methods I'd heard of so far have been microwave-based; anyone think there'd be any impact to global warming?
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Interesting hard SF treatment of this in a fairly old set of novels. They were talking of communications, but the same rules apply. I recommend "The Complete Venus Equilateral" by George O. Smith.
Re:Ok, someone explain it to me (Score:4, Interesting)
And how exactly do you keep the power beam locked onto the target, when the target is on a sphere rotating once per day?
Putting them in equatorial geostationary orbits is *much* simpler. You'll lose a small amount of generating time each day (while the station is in Earth's shadow), but if you schedule as much of your maintenance as possible during this time, the effect is minimal.
And maintenance *will* be required, for the foreseeable future. Someday we may be able to build solar cells that don't need to be periodically replaced, but not today.
Furthermore, it's been noted that Earth orbit is "halfway to anywhere in the solar system" (attributed to Heinlein). So we'll need serious orbital capability to build these things, regardless of where we put them.
Parent
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No. An equatorial orbit only goes into Earth's shadow during two short periods a year, near the Equinoxes. Off the cuff, I think the sats will be able to enter Earth's shadow once daily for about three weeks every Equinox.
The rest of the time,
we will indeed need serious orbital capability (Score:3, Informative)
Because you don't need batteries... (Score:5, Informative)
I'm skeptical too, but it's not quite as crazy as it sounds.
Parent
The difference between... cannot go wrong (Score:3, Interesting)
Lets build in some redundancy shall we? (Just in case.)
I think you covered the list pretty well but corrosion is also a factor that space should mitigate. Well, mostly aside from the wandering bit of space debris.
I haven't RTFA, probably won't, but I'd
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Re:Ok, someone explain it to me (Score:5, Informative)
Portability:
By using an orbital energy collection system, you can simply re-route the beam to any place on the planet within the system's FOV...done right, you can get full 4*pi sr coverage of the Earth 24/7. Design a portable ground station, and you can provide power to a disaster area that has been removed from the rest of the power grid (paraphrased directly FTA).
Extensibility:
If, once in place and a standard orbital collection platform design has been established, more power is required, simply launch the spare unit. Proper formation flying techniques (something currently at about the cutting edge of orbital design) should allow the new unit to 'hook in' to the system to boost the amount of available power. This may be in the article, I have not finished reading it yet.
The LISA mission provides a pretty good overview of how I see the entire system distributing power from the collectors to the emitters (the things that will transmit the power down to the surface), though I may be totally off base from what the authors have in mind. The LISA mission will consist of three satellites forming an equilateral triangle with leg lengths of 5 million Km shooting lasers at each other. Last time I checked, anyway.
It is currently not economical, nor is it really achievable yet. I encourage you to at least browse through the article as it does discuss some of your questions in a more cogent manner than I have.
Parent
Re:Ok, someone explain it to me (Score:5, Informative)
The second number, however is totally wrong. If you're going to talk about what "the sun provides", i.e., the theoretical 100% efficiency solar panel, then you get a figure of about 1000W/m^2 on the Earth's surface. You could say it is more like 800W/m^2 when you take cloud cover into consideration.. and then there's the fact that you only get that during daylight hours, so halve it to get 400W/m^2 but that's still a lot more than 250W/m^2. It *feels* like someone is downplaying the possible efficiency of solar panels on the Earth's surface vs the same solar panel in space in order to make their argument stronger. As you took that figure straight from the article, I'll give you the benefit of the doubt, but that's what it sounds like.
It's still a heck of a lot of difference though. You're talking nearly 3.5 advantage to putting your solar panels in space over leaving them on the ground.. but there *are* losses to transmitting the power as microwaves through the atmosphere, and there is the astronomical cost of launching anything into space.
Whenever I hear people talk about solar power satellites I'm reminded of the episode of Seinfeld where they stock the mail truck with bottles to collect the 5c deposit in the adjacent state. If you can get a free ride you might be able to make solar satellites work, but you've still gotta crunch a lot of numbers first, and no-one has done that successfully.
Parent
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It's space, dude.
The orbit is 264,869 km around.
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Thank you, but it's not original.
Let's put the receivers and transmitters right next to the gigawatt microwave antenna! That will surely fix all those problems!
Yep. Unless you're trying to watch satellite TV in the middle of a rectenna farm, of course -- although even there they'd likely have the transponders for that particular region mounted on a different satellite. It's not like everything on the powersat has to point in the same direction, you know, or operate at the same frequency.
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Another advantage is that the array could be pointed directly at the sun permanently, whereas on Earth, you need to keep swiveling it.
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Re:Ok, someone explain it to me (Score:5, Insightful)
Parent
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The infrastructure developed to implement this project is pretty much the infrastructure needed to leave earth and visit other places on a regular basis.
You get the Electricity, and Access to the Universe is gravy.
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Actually, that part is simplicity itself. All that is needed is an array of radiator fins, positioned behind the collector mirror. In the perpetual shadow behind the collector, things are going to get very cold, and any waste heat can easily be bled off there.
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That depends on what your definition of the word "cold" is
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Basically, if you're using a steam-engine type of generator to produce your power, you're tapping into the energy of a temperature differential you're creating. Using the occluded space behind the mirror as your low point increases that differential considerably. Also, even though the only mechanism a radiator fin can lose heat by is radiation, that difficulty can be surmounted by simply increasing the surface ar
Beyond the Orange-Bellied Parrot (Score:3, Interesting)
I like the idea of a separate organisation dedicated to this technology, as it's clear none of the existing organisations can do it. Set it in motion, get it done before the bloat sets in. Also like the idea of the solar-electric HEO ferry -- anyone have a link to an artist's perception of it (a real one I mean)?
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Ryan Fenton
bring in Zaph Brannigan (Score:2)
By "something new", I'm sure you mean the formation of D.O.O.P.
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I would say the same. (Score:2)
If I needed funding for my project I would say the exact same thing, especially if I had 170 other highly skilled fanboys to back up my idea..
more intense sunlight? (Score:2)
solar cells here now aren't capable of extracting more then 35% of the light that makes it to earth now, so they won't do any better in space.
the only type of solar generation that will produce more power in space due to the more intense soalr rays will be some form of mirror heating, and that present a whole bunch of other problems.
i'm also curious as to how they will keep the solar a
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The main proposed orbit is geo-stationary; these are very rarely shaded (for about 1 month of the year a satellite there gets about an hour's worth of shade every day, the rest of the year it's clear).
Inexpensive space launch is definitely one of the technical challenges. The report calls for large-scale development and deploy
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On earth, you get ~250w/m^2, is space, you get 4-5 times as much. So, a solar cell in orbit at the same efficiency will produce 4-5 times as much power. It's not that they are more efficient, it's that they are getting more sunlight->more po
Gerard K. O'Neill (Score:2, Informative)
It is a gun, a really big gigawatt class gun. (Score:2, Insightful)
Won't happen until one world, united. (Score:3, Insightful)
We're certainly not going to rely on a very fragile orbiting setup which is a sitting duck to anyone with a decent missile/launch vehicle.
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Nope.
These things will be high up - in GSO, which takes it right out of the range of any ICBM based launcher. Unless you can figure out how to pack propulsion, power, guidance, and a Dangerous Payload into a five to ten pounds or so... (And no, the classic 'handful of sand' or 'paint chip' or 'styrofoam cup' won't cut it here - the interception geometry is diff
Jimmy Carter must be laughing his ass off (Score:5, Insightful)
So, here we are today, some 27 years later, and the same proposal gets floated.
Imagine if laziness hadn't dropped the issue back then. Iran, Iraq and the whole business of 9/11 would have been less critical than they now are.
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forget LEO (Score:2)
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if it's geosynchronous, you still have night time to deal with, since *shock* the earth will block the sun on you.
what makes you think your power production will double out in space suddenly. solar panels are operating at their limits under the measley solar rays we get here on earth.