Looks like they're missing an ATH in there.... Sneaky way of getting funding!
The largest recorded asteroid to enter Earth's elbow-room has passed by safely, with 2012 DA14 skimming through the geostationary orbit of our satellites at 17,450 miles per hour without leaving a scratch. The asteroid was observable with binoculars as it reached its closest point to Earth at 11:25am PST (7:25pm UTC) over …
Looks like they're missing an ATH in there.... Sneaky way of getting funding!
Surely mirrors are cheaper than solar cells. If you can get enough solar panels into orbit to drive a powerfull enough laser to fullfil the requirement, surely a buch of mirrrors with independent targeting would be cheaper and more effective. OK, so coherent light is more effective at delivering a lot of punch at a concentrated point, but I remain to be convinced that after all the conversion losses that it can be more effecting than using the sunlight directly.
A quick look at http://en.wikipedia.org/wiki/Solar_furnace shows what can be achieved with a relatively small array whith the much diminished light that arrives at the earths surface. A visit to the smaller prototype (now a museum) at Mont-Louis-Font-Romeu has demonstrations of rocks, bricks and steel bursting into flames after several seconds in concentrated sunlight.
They would need to focus the light over millions of km. I would think they would need coherent (LASER) light to do that.
Although I think a lot of their experiments are far fetched this is actually an area which the Mythbusters covered quite excellently (in my humble opinion that is).
Because you see; in ancient history there is a tale that a village which got under the attack of an invading army gathered together holding nothing but mirrors and in the very dry heat of the day all pointed those mirrors at the invading fleet of ships thus causing it all to go up in smoke.
The Mythbusters gathered a schoolclass or two (so plenty of people) and gave them all mirrors; I forgot the numbers but I'd say they had at least 60 or 80 mirrors. All full sized ones mind you; even somewhat bend to reflect the light a little better even though the legend spoke of regular mirrors.
One of the Busters was hauled in a fire resistant suit; put on the self-build wooden "ship" and then the "attack" began. Oh; obviously in the mid of day where the sun was at its best and hottest.
The end result ? While (iirc) Jamie mentioned that he felt that the temperatures were rising and that the bright light was distracting, there was no way that this could have stopped an invading army. They didn't manage to set fire to the boat, they didn't manage to hurt Jamie in any way nor did they even manage to set fire to the sails (which were mere cloth).
That myth got busted. And although I'm often a little bit sceptic about some of their experiments its my full believe that they couldn't have carried this one out any better.
Now; I know that the Sun is most likely to have more power outside of the atmosphere than inside. But given prior examples I think they're not that dumb to ignore this option. Simply because chances are much higher that it'll fail. And then we're not talking about saving money but wasting it.
I have worked this out - how the coherance works, that no one else has ever factored in.
Sun = HUGE and far away, Diameter - down to a tiny mirror, reflection from tiny mirror, back into space, same distance away = same image size of sun..... although much weaker in intensity.
Coherence is an issue, but the simple beam spread, to reflect the original image is a part of the real problem with mirrors over LONG ranges.
"Although I think a lot of their experiments are far fetched this is actually an area which the Mythbusters covered quite excellently (in my humble opinion that is)."
I think JassMan has already pointed out above that a number of solar furnaces/power stations using mirror arrays are already established. So Mythbusters or legend means nothing.
See also http://en.wikipedia.org/wiki/Solar_power_tower
A magnifying glass a mere 8cm across will focus sunlight and set a variety of things alights. So I'm pretty sure if Mythbusters had focused all their mirrors then the result would have been very different.
Does something lead you to believe that a laser beam doesn't diverge?
Would a series of Fresnel lenses do the trick?
The mirrors used in solar power towers are _precisely_ curved to match the ideal focal point at a given distance. The legend, and Mythbuster attempt, did not come anywhere close to the level of tuning for a given focal point, nor did they have the reflectivity of the highly-polished solar power mirrors.
in ancient history there is a tale that a village which got under the attack of an invading army gathered together holding nothing but mirrors and in the very dry heat of the day all pointed those mirrors at the invading fleet of ships thus causing it all to go up in smoke
"in ancient history"? "a village"? That story is about Archimedes, one of the great Classical thinkers, and it takes place in Syracuse a couple of centuries BCE. "Ancient", though imprecise, is hardly the term of choice, and Syracuse was not "a village". And the "tale" comes from various Classical historians, who, while they were hardly rigorous, at least attached their names to their accounts; it's not like this is a bit of folklore.
Honestly, what do they teach kids these days?
The Mythbusters experiment has been criticized in a number of quarters, as a quick web search would show you. One of MIT's 2.009 classes had more success in reproducing the effect, for example. Probably more importantly, it's quite plausible the accounts omitted key details; for example, the "heat ray" could have been used in concert with flammables flung onto the attacking vessels with siege engines - another of Archimedes' research areas.
That picture is not to scale...
Maybe the merkins have to propose a high tech answer to a simple problem so they can patent it. Obviously any attempt to patent a mirror solution would fail with prior art, because Archimedes aleady did the same thing in 214–212 BC at Syracuse ( http://en.wikipedia.org/wiki/Archimedes#Heat_ray )
And as usual in bloody Britain, the weather was cloudy as hell.
Was good out west. The ISS was brighter than an aeroplane at about 7pm to the naked eye, but didn't have any binoculars with me to see anything else :-(
I'd love to get paid to think up stuff like this. No worries about the financials, no international political concerns, just fun ideas.
Please...let's stop the small thinking here!!
I hereby propose the that Earth build the Directed Energy Assuring Terran Habitability Solar Targeting And Reconnaissance satellite.
As a gesture of international goodwill and a harbinger of the project being run with proper unemotional judgment, DEATHSTAR would be run by a rather icy Brit with an Oxbridge accent.....
"2012 DA14 is too small an asteroid to provide a good demonstration of this space station's firepower. But don't worry, we shall deal with your rebel friends soon enough."
"could send 1.4 megatons of energy per day"
Megatons of energy? If that's megatons times c squared you'd do a lot more than just melt the asteroid.
But isn't it fortunate that this giant space-based laser will be run by those nice americans, who can be trusted not to use it for anything nasty like blowing away third-world countries that don't grovel enough?
Beat me to it.
... a megaton of energy is a fairly well-established amount of about 4.2PJ, as it refers to the energetic content ---- by combustion, rather than antimatter annihilation --- of a million tons of TNT.
So just under 6 PJ/day or about 70GW. (1 GW is very roughly the output of a decent size power station.)
Yeah, once all the Death Star giggles are out of the way, an objective look at any such frikkin' laser will reveal it to be indisinguishable from a weapons system, which is banned from space by treaty. Unless humanity can come up with a governance structure for it that everyone trusts, then it isn't going to happen. Any one sovereign nation having control would be unacceptable, any of the current national blocs, ditto. The United Nations? That would just play into the hands of the conspiracy theorists who believe that the purpose of the UN is to disarm them.
@ Johnathan Richards 1
Where will we find a shark large enough to wear the anti-asteroid laser on it's head, how do we get the shark into orbit and how do we keep it alive once it's up there??
Maybe this could be a new ScyFy channel movie--"Megashark vs. Asteroid"!!
Good point, however I'm not a physicist and even I know never to let the word "amount" anywhere near a discussion involving verifiable units and values.
"I have changed our treaty... pray I do not change it further."
"Unless humanity can come up with a governance structure for it that everyone trusts, then it isn't going to happen."
"Any one sovereign nation having control would ..." impose a new governance structure.
All hail our new space laser wielding over lords.
Because a major nation having the power to wipe out whole countries with wweapons of mass destruction would be a major change too the balance of power?
No, it's from Starship Troopers. :-b
"Right now we're looking at the very tiny possibility that it could hit the Earth in 2080, but I suspect that will go away and we'll know we're safe from this asteroid for a long time."
I like that optimism!
Been there, done that (usually in pubs)
IS2R we used to call this kind of thing a "DOOM" --- a riDiculously cOntrived acrOnyM.
I came up with one in a few seconds and it only needed a little thought, of which I'm sometimes capable. Directed Energy Solar Targeting of Asteroids and Remnants. Of course I could go for the Mass Effect link with Directed Energy Solar Targeting of Asteroids and Reapers but if this would take a year to kill an asteroid I don't want to think how long it would take to scratch a reaper :/
Genuine question: in the morning we were told it would miss the earth by a margin of 28,000 miles. In the evening it got as close as 17,000. Do we really know the trajectory, or was the problem a reporting cock-up?
Unit cock up. 28000km, or 17000 miles.
Anyone who thinks a 130,000 ton rock flying at 17,000 mph is going to be deflected by a laser is in urgent need of some basic physics. I suggest starting with a kick up the arse.
But it's one big fuck-off laser on the back of an even bigger space-going shark
Space is big. This means orbital trajectories are long. This means you have quite some time to apply your lasers to the target, and even a modest continuous force applied over a large enough period of time could deflect an asteroid's orbit enough to avoid the Earth.
The problem here is that you'd actually have to understand a modicum of astrophysics and orbital mechanics rather than hoping that your school-level basic physics has equipped you well enough to trash the ideas of people who actually understand what they're talking about.
It's a laser pointer to attract the giant, interstellar cat to deal with the problem.
If that cat is anything like my Loki, black pound domestic cat, we'd be better off letting the asteroid hit us. Bastard attacks dogs, printers, toes, xboxen, anything that moves. Not conducive to the survival of the human race, to be sure.
If you can harness the energy to do something like that, it seems like a waste pointing it out to space. It should be pointed the other direction so we can get rid of all the fossil fuel and nuclear plants throughout the entire world.
If we had a year's notice, we'd probably be able to aim that thing at one side of the asteroid and the jets of material ejecting from the blast would steer the asteroid out of a collision course with Earth in a few minutes, or few hours at most. Vaporizing the asteroid only happens in Hollywood.
The most dangerous thing about asteroids is how vulnerable they are to human curiosity.
The solar system is One Interdependent Web of orbital paths and objects, stabilized over billions of years.
It is computationally impossible to model that system in hi fidelity, the effects of any changes we make are completely unpredictable on long timelines.
Changes that seem innocuous at first could have unmanageable after-effects decades/centuries later.
Asteroid mining is an activity in which the entire human race can win a Darwin Award.
Stop flapping your mouth already, you are disturbing finely tuned trajectories! Who knows what could happen!! Quick, where's the number of Greenpeace??
When it is not in use saving the planet could they point them at a receptor on Earth to harness the energy?
"the size of 2012 DA14 puts the asteroid's dollar-value in the twelve-figure range, with lots of valuable metals and liquids that could be harvested automatically and fired back to orbit around our planet to be used in orbiting manufacturing facilities."
Manufacturing would be stupid in Low Earth Orbit. There are enough hazardous bits in orbit now without putting a factory up there to spread out even more bits of paint, bolts, hammers, etc.
A far better place for the space lasers and space manufacturing would be at the Lagrange Points. Specifically at L2 solar wind would help push any debris out into the solar system and away from Earth. Shielding, its necessity and its weight, becomes the real issue because outside of LEO, and Earth's protective magnetic field, the full radiative brunt of the Sun requires such to keep people alive long term.
And, until methods less costly than $10,000 plus per Kg of payload to LEO or beyond come into play, all of this talk of factories and lasers in space is quite frankly just that, talk.
<grabs sides of walker with June 1978 copy of Popular Science tucked under arm and shuffles away from keyboard muttering bitterly about Solar Stirling Engine Generators, gravity wells and whippersnappers>
"Shielding, its necessity and its weight, becomes the real issue because outside of LEO, and Earth's protective magnetic field"
Water is an ideal shield and there's an awful lot of it out there. It just needs to be appropriately shaped, positioned and warned (needs to be liquid - but any shade of paint other than "reflective silver" would do the trick)
L2 isn't really a position so much as an arc and there is already some junk there which needs to be cleaned up first.
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