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Lunar Lasers
Two different articles about building lasers (well, lasers and a maser perhaps) on the moon. Reuters has a story about a potential lunar power plant, creating electricity with solar panels and beaming it to Earth with microwaves. Space.com has a piece about building a sort of super-sized Star Wars program on the Moon, giant lasers set up to blast incoming space debris and not, of course, anyone here on Earth.
i saw this in highlander 2 i think. it didn't work out too good.
your jesus is another mans xebu. chew on that hypocrites.
...a strange social experiment by the /. team to see how many people will come up with the same joke in a given period of time?
Hmmm...
How you see the world is how the world sees you.
Yeah, only jocks discuss lasers on the moon. Us nerds should stick to talking about football and women and beer.
(insert finger-quotes here)
These are my friends, See how they glisten. See this one shine, how he smiles in the light.
The power sent as microwaves must be focused into some reasonable area unless they propose having antennas nearly the size of the moon on earth.
1. How will they focus the beam on receptor antenas?
2. How will they keep airplanes from flying across the beams?
3. Will they coordinate with satellite operators so they can avoid the beam too?
The only way for this not to harm you would be for it not to strike you. Early radar technicians learned about microwave cooking standing in front of such beams
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Give me LIBERTY, or give me a check.
What I'm curious to know is has the cost of space missions gone down so much since then that it can now be done for the $59 billion listed in the article, rather than the >$1 trillion number cited a number of years ago, or is there some new trick (sure sounds the same), or is this guy just making up a lower number so that people will actually listen to him? Anyone out there heard of this Prof. Criswell before? I'd really like to believe that this is a viable option.
Microwaves are easy to recieve - you simply stretch out a wire between two insulated poles, and the power just flows. That's the big advantage of microwaves over other power transmission possibilities.
Granted, given the spill-over from the "concentrated" beam of microwaves, you'll probably have to use some frequency that's not very popular for communication, but it's probably do-able.
The people who are worried about power-line emissions would probably go insane over this, though - the exposure levels would be MUCH higher.
-Mark
AFAIK 20 percent is roughly the efficiency of a photovoltaic cell. So you'd need a close to 100% efficiency for a rectenna just to break even with photovoltaic cells (from a surface standpoint).
It may be cheaper to build rectennas, however I'm not convinced how it could break even in 5 years with >50 billion spent.
The Raven
The Raven
-- SIGFPE
Okay, so if this thing is so much weaker than sunlight, why wouldn't we just use terrestrial solar cells to receive existing sunlight rather than some receiving station for funky microwave power?
Come on! In order to be even slightly useful, the energy beam coming back would have to be terribly intense, which would make it terribly dangerous. Even noontime sunlight can be nasty, ask a suburban sidewalk ant or any pale-skinned swimwear-clad human.
Even antimissle lasers have a long way to go. Between power requirements, beam handling, divergence, and atmospheric interference, lasers do not make great destructive weapons.
However, they would be damned good for some nasty tricks like blinding the enemy army (or, unfortunately, civilians).
Take this scenario: a bomber/cargo style aircraft has been outfitted with a large infrared laser (similar things have been done). Fly said aircraft over the people you wish to 'zap'. Release some fireworks or other attention getting devices and when the crowd looks up turn on and start scanning the laser.
Since the laser is infrared nobody would know they are being exposed to blinding levels of light, nor would the blink/aversion reaction take place. By the time you noticed anything the permanent damage has been done. Scary huh?
Another scenario under serious consideration by police (at least here in Canada, I've participated in meetings on the subject) is the use of lasers against commercial aircraft. The idea isn't to shoot down the aircraft, but to scan at temporarily blind the pilot during final night approaches. The effect is like someone flashing a camera flash in your face when your in a dark room.
As the few moments prior to landing are the most critical, distracting and flash blinding the pilot could easily lead to the plane crashing.
Worse, new solid state lasers are available in the 3watt (plenty of power to cause permanent blindness) range and can be powered off a car with an inverter. Simply park at the end of a convenient runway at night, plug 'er in and away you go. Ok, so it's not quite that easy, but the concept is...
Doesn't that all just scare you a bit more than some silly death ray?
Note: after saying all that I want to point out that I do not support the insane regulations placed against the use of lasers in the United States by the CDRH. It's totally ridiculous and overzealous.
"They do not preach that their god will rouse them, a little before the Nuts work loose." Kipling, 'The Sons of Martha'
If you are going to do this beamed microwave thing, build it in Earth orbit, closer to the target. (distance)*(wavelength)= k*(diameter of transmitter aperture)*(diameter of beam at target), where k is a constant somewhere between 1/3 and 3. I think the moon is about 250,000 miles or 400,000 km away. So to focus a 30GHz (1 centimeter wavelength) microwave beam down to a 10 km spot on Earth takes an antenna about 400m across. Or in units the average American understands, a football-field sized antenna would put most, but not all, of the transmitted energy into a 10 mile wide spot. This whole area would have to be blanketed with receiving antennas (expensive!). And people living 20 miles away would be measuring the leaking energy and suing every time they got a cough. (Birds would be safely building nests on the antennas, but American trial lawyers never let science get in the way of a deep-pockets lawsuit.)
The best place for a solar power satellite is probably geosynchronous orbit (40,000 km). This needs a football-field sized transmitter and a mile-wide receiver; still pretty big, but maybe manageable. And the transmitter and receiver don't move relatively. A lunar array would have to keep switching between different receivers as the Earth turns. An SPS in a lower orbit would also have to keep switching receivers, but at least it would have smaller antennas.
A solar plant in orbit is in sunlight almost all the time (depending on distance from earth and orbital particulars, it might spend a few hours a year in earth-shadow). On the moon, two weeks out of every four is night.
The laser installation would also work better in a medium-height earth orbit, where it's solar panels were powered all the time and it was much closer to the targets. At least, I assume that it isn't meteroids headed for the moon that this is supposed to shoot down?
Gawd, I've seen this idea so many times before. It's something they always bring out as a gee-whiz justification of manned space exploration. Y'know, just to show that space has practical applications. The arguements against are pretty persuasive. Safety, cost, and effectiveness. I don't buy it and didn't even think much of it as a kid. I just with these people would stop insulting our intelligence. A better way to address power consumption through technology is in effeciency. A good example that works is the new compact flourescent light bulbs. I've saved my bill before and compared it to after I swithced my apartment over to them. My power bill went down by a little less than half. Pretty nifty. I figure if we can do more with less, we can satisfy our needs for more people, and we can do it without crazy crap like this. In any case, some of the new home solar products are making this thing a moot point. In the meantime, there's lots of better reasons to explore and develop space.
I have mentioned this in the other, almost identical, articles on beaming power to earth from space.
There was a proposal for the 1982 Knoxville World's Fair to do this from a satellite and have the microwave beam land on a mesh reciever.
The pesky problem had something to do with safety of birds passing through the beam, since they do not read Notices to Airmen and have no concept of "no fly zones".
The problem is compounded by basing this on the moon, since it is not geocincronious and the beam would have to continuously move to stay on target. It can only be on one target about 12 hrs/day or so too. (Yes, they CAN generate through the whole lunar cycle since the collectors can be placed all around the moon and only the transmitter has to be on the near side)
Eve Fairbanks says I drive a hybrid!LOL
you simply stretch out a wire between two insulated poles, and the power just flows
You bring up an important point: powerlines and phone lines already cover the globe. They will pick up the power too. This may not be a good thing.
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Give me LIBERTY, or give me a check.
Before you go "Bah", please understand that this has actually been tested over an atmospheric path crossing as much air as you'd need to from a typical orbit, and efficiencies around 80% were measured.
Scientists restrict study to entire physical universe; creationist
CHA!
The orbit above the equator is at a quite significant angle to the shadow cast by the earth, due to the angle of dip of the rotation of the earth. That means that the shadow only intersects the geosynchronous orbit about twice per year.
IRC geosynchronous satellites only see darkness for about 40 minutes per year.
This contrasts rather sharply with nearly all points on the lunar surface which see darkness once per month for half the month.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"Has anyone built a 100% automated large scale power plant? Even here on Earth, such a task is daunting. Saying that it can be easily done on the moon, and done cost effectively is like saying that I could build cheaper cars on the moon because my machinery will only have to cope with 1/6th of the gravity.
"But satellites and the space shuttle use solar power all the time." They also have either a 5-10 year lifespan or are serviced regularly. The article said that it could be profitable in 5 years. So when it finally becomes profitable, many of its components will be nearing the end of their lifespan. Then you have to chunk down some more money to build a replacement.
Nevermind that there will still need to be multiple ground stations in remote areas to catch the radiation. The moon is not geosynchronous. Build a station at the poles you say? There goes your costs again. Also, say what you want about safety, nobody will want to live near these things. And they will have to be in different countries which brings politics into the mix.
This is pie-in-the-sky dreaming. If you ask me, I think the money is better spent designing and running a good nuclear power plant or for some fusion research.
Remember, You are unique...just like everyone else.
Didn't you ever see/read 2001? The lunar monolith being exposed to sunrise is a critical plot element.
"The question of whether a computer can think is no more interesting than that of whether a submarine can swim" -EWD
Scientists restrict study to entire physical universe; creationist
Do you have any idea how big a 200x200 mile area is? For comparison, the State of West Virginia has an area of about 24,087 square miles. You are looking at creating a solar array that is 20,000 square miles in size. Where are you going to put this monster? How are you going to clean it? Who's going to pay for the solar cells. If you are using the normal 12% efficent cells (because they are much cheaper), then this whole array is going to cost $91,929,436,402,366US. For comparison, the current US GDP is around $10,229,700,000,000US. Oh, and those solar cells only last about 20 years, so you'll have to keep replacing them. This alos doesn't touch on the current US silicon production capacity vs. what you would need to build this.
On the other hand, my back of the evelope calculation suggests that on a bright sunny day (1000 watts/m^2 of energy hitting the surface) these solar cells could power pretty much the whole world (ignoring transmission loss of course).
I read the internet for the articles.
Since the Lunar power Station came online...
Aluminum Hats a no longer for wackos
Check out those Northern Lights (in Florida)
Forget four poster bed sleep in a faraday cage
Metal Orthadonics fall out of favor
Peeps rise up from their cellophane prisons and attack their masters
Floresencet Lights no longer need to be connected to the power grid
Just because we can does not make it a good idea.
âoeWho knew something as harmless as willful ignorance could end up having real consequences?â
Oh, I just realized how US-centric my post is. For everybody out there with a world map instead of a US map, 40000 square miles is about the size of Montenegro.
I read the internet for the articles.
"a sort of super-sized Star Wars program on the Moon, giant lasers set up to blast incoming space debris and not, of course, anyone here on Earth."
Does the phrase "tide locked" mean anything to you? The moon's rotation and revolution match each other, so anything set up on the far side of the moon to target incoming debris will never be able to hit earth-based targets, or at least not any time this eon.
X-rays cause cancer due to a higher energy and shorter wavelength. They have rather powerful penetration depths (duh, otherwise they wouldn't be used in medical research). Microwaves don't have that problem (otherwise they wouldn't use them in cell phones/telephones - what do you think a 1.2GHz phone is?)
Microwaves are perfectly safe, in normal intensities, and since they don't refract, you don't have a worry about it spreading past the area you intend it to hit. They can't affect anything smaller than their wavelength, obviously, so you don't have the danger that X-rays have.
People are bombarded with radiation every day, and this wouldn't change anything, really. You're much more at risk from that giant 4 x 10^26 watt light bulb hovering over your head every day. So if you're really worried about these microwave lasers, go hide in a cave.
Insanity is the last line of defence for the master diplomat. But you have to lay the groundwork early.
>Not to mention the fact that one side of the
;)
;)
>moon faces the sun at all times! Any solar
>collectors on Earth are subject to day/night
>cycles. The moon would rarely be impacted, when
>the lunar eclipses happen.
Doh! One side of the moon always faces the EARTH! (synchronous rotation). We had never seen the far side of the moon until we sent something "back there" to take pictures.
So: that being the case, is it really possible that one side of the moon is always bathed in the light of the sun? If so, then how did we ever get visible pictures of the OTHER SIDE of the moon? Did we use a gigantic flashbulb, or something?
Map of the entire surface including the far side
The Far Side of the Moon Consider how this picture would look if it had been taken during a "full moon:" since during a full moon the entire side of the moon that is facing the Earth is lit up, only the portion of the moon in this photograph that is said to be visible from Earth (see the pic's caption) would have any sunlight on it.
Far Side of the Moon, with animation showing the same side of the moon always toward the Earth. This doesn't show where the sun is in relation to the animation; but figure that the sun is way off the screen from the animation...the darkened part of the moon in the animation is representing the side of the moon we never see from Earth, NOT how the light hits the moon (the Earth does not illuminate the moon, although it does sometimes reflect a little of the sun's light onto the dark portion of the quarter moon...)
So, taking this into account, will it be useful to build these lasers on the moon, especially the power plant?
Apollo 11 Laser Ranging Retroreflector Experiment. "Laser beams are used because they remain tightly focused for large distances. Nevertheless, there is enough dispersion of the beam that it is about 7 kilometers in diameter when it reaches the Moon and 20 kilometers in diameter when it returns to Earth. Because of this very weak signal, observations are made for several hours at a time. By averaging the signal for this period, the distance to the Moon can be measured to an accuracy of about 3 centimeters (the average distance from the Earth to the Moon is about 385,000 kilometers)."
Add to this, the fact that the moon wobbles...
Ah yes, here's a thought...