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Water Droplets In Orbit On the International Space Station
BuzzSkyline writes "Astronaut Don Pettit, who is aboard the International Space Station right now, puts charged water droplets into wild orbits around a knitting needle in the microgravity environment of the ISS. A video he made of the droplets is the first in a series of freefall physics experiments that he will be posting in coming months."
This is the kind of news that saddens me. The grand endeavor to explore the universe that I knew as a kid has turned into, well, basically nothing at all, and the astronauts that once went where no one had gone before have turned into Mr. Wizards doing Newtonian physics demonstrations for ten-year-olds. I mean, the off-the-cuff demonstrations of floating pencils one saw in the Apollo program videos, in between doing stuff like developing space rendezvous techniques and going to the moon, have turned into the raison d'etre of the space program.
I am depressed.
Could be worse I guess; ridged potato chips, for instance.
It's worth remembering that the V2 effort helped Germany lose WW2 - the energy needed to produce the fuel meant shortages of fuel for aviation and transport. The private space initiatives are relying on the custom of a few billionaires - and once they start getting sued for environmental damage, and the price of their fuel is driven up by the inexorable laws of supply and demand, I doubt they will have a future.
The sources of energy that are rapidly declining in price - solar and wind - or are already economic - nuclear and gas - are not suitable for space vehicles. On the other hand, the attempt to produce low cost, low power universal communication tools has been successful beyond the imaginations of people even thirty years ago, and fundamental physics research would simply awe the likes of Feynman and Dirac if they were around to see it. There has been great endeavour in science and engineering, it just turned out that space exploration wasn't it.
From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
I don't care what you say, that is pretty cool, On his free time he is making great videos that, potentially for hundreds of years, will be available for future generations of k-12 science classes.
Is it really that inspirational, though?
I mean, think of what really inspired generation X. I don't think it was just the prospect of having a chance to sit in a cramped capsule in orbit for two days, and even that chance being lower than being hit by lightning.
I think it was more like the extrapolation of where it's going. SF told us stories of it becoming a mass thing, every other guy being at least a space freighter pilot, and the cool ones like us would be space FIGHTER pilots, exploration, whole colonies on other planet and in orbit, meeting horny green alien babes, and going bald where nobody had gone before. Oh wait, the last one was the porn ;) And not just space travel. It told us tales of robots, lasers, near-infinite sources of energy, etc.
It was an age of very rapid progress in a whole bunch of domains, and a naive linear extrapolation ahead promised to soon take us where we can't even imagine. Now it was the moon, tomorrow it will be colonies on Mars, and the day after tomorrow probably meeting the Vulcans.
It was that imaginary destination, not the current state that got us SF nerds dreaming.
Nowadays, it seems to have pretty much become a horizontal asymptote. Or near enough. Within your lifetime, or even your kids' lifetime, we'll probably still have half a dozen people in orbit. Your grandkids' chances of being an astronaut will still be lower than winning the jackpot and retiring to a tropical resort.
And even if they won that lottery, what will they do in orbit? Where does that extrapolation lead nowadays? They'll maybe levitate droplets of oil instead of water? Study the growth of mold on a petri dish in zero gravity?
Even robots are not what we dreamed they would be. Instead of cool HK-47 style androids at the bank teller, we have the more logical thing of a box with a screen and a keypad. Instead of robotic vendors, we have the more logical vending machines. And instead of having a robot copilot, you just have an autopilot AI, because it would be stupid to build a humanoid frame where just a few chips will do the same job better. And instead of C3PO style protocol droids, we have cell phones with translator apps, or just a browser to point to Google translation. Again, because it makes no frikken sense to actually build a dedicated humanoid frame for just one application, when an app on a general purpose gadget will do the same thing.
And you can forget the whole space fighter thing, since not only it turns out that blowing enough shit up in orbit would nix all our access to space, but pilots are being replaced by remote controlled drones even on Earth. And in space probably even more so, since you can do much tighter turns and accelerations if you don't have to worry about squishing the human inside.
So, you know, inspire kids to aspire to... what?
But even forgetting the extrapolation, the thing about the human brain is that it works with differences more than with absolutes. To be interesting enough, something must be different enough. You wouldn't think for example that a new LCD TV is new and interesting if it just has the buttons in a different position than yours.
At some point there was enough change per time unit to be interesting. Yay, we went to the moon. Yay, we have a space shuttle that promises to make space travel cheap and often (yeah, right.) Yay, we have a space station.
Now it's, what? Yay, we're stuck in the same orbit, but we can do another elementary-school level science experiments in space? :p
A polar bear is a cartesian bear after a coordinate transform.
Space should not be just for the 'elite'! It should be able to pay a few thousand and go spin water droplets for a few hours, we should all be so lucky! I'm sure past elitists such as Christopher Columbus felt the same way hundreds of years ago.... "Damn those bourgeois traders and colonists ruining the New World for the REAL explorers!.... bah!
High school was 20 some years ago and I didn't pass physics anyways.
To me it LOOKS like gravity. But I am having a lot of trouble imagining that a knitting needle has enough mass to orbit water droplets. The description talks about another needle off camera which sounds like he is trying to keep a charge on the needle.
So my best guess is that the water droplets are negatively charged, the needles positively charged.
The only thing missing is the orbit. I wasn't aware you could get an orbit out of something like this.
Can someone here expand on this?
WTFV. It's electricity, as stated numerous times during the video.
Zero g as in dropping the 'g' off 'knitting' . It was interesting that he kept the g for orbiting, always dropped it for knittin, but there was one other word that I heard him say where he dropped the g. Is this an indication of when and where he first learnt these words? Or is it just lazy pronunciation, and he can get away with saying knittin, but not orbitin?
I am Slashdot. Are you Slashdot as well?
I don't think they'll have a choice, though. The problems are that:
1. As Douglas Adams put it, "Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space." So you'll need incredible speeds to get anywhere interesting even within one lifetime.
2. In that domain, Albert Einstein is the biggest mofo. He'll be a bigger pain in your dreams of space domination than Mace Windu.
Everyone has some half-baked solution like "well, just keep accelerating at 1g for a few years, and you'll be at 0.9c". What they don't think about is what kind of energy you need to keep doing that. Even fusion won't cut it.
At 0.9c, every gram of your ship packs enough kinetic energy as a 29 kiloton atom bomb. By comparison, the bomb dropped on Hiroshima was 15 kilotons. Even at near perfect efficiency, you'd need two of those to accelerate just one gram of matter to 0.9c.
If you want to do a round trip, you have to accelerate then decelerate in one direction, then accelerate and decelerate again in the other direction. So multiply by 4.
And that's with a cannon kind of a setup, so you only accelerate that one gram of matter, not also the rocket and fuel and whatnot. If you carry your own fuel and engines, you'll have to accelerate those too.
Doing it slowly or doing it fast, won't change anything. At the end of the acceleration period, each gram of your ship will still pack that much kinetic energy, so still that much energy will have gone into accelerating it.
Take your choice of realistic engine. Orion? If you took all the atom bombs ever made, they still wouldn't be enough to push even a modest capsule for a one way trip to a good habitable planet. Engine with uranium salts in water? Ditto, plus you now have to accelerate the water and the moderator bars too. Ion thrusters? Well, you still need that much energy piped into accelerating the ions. You'll still need a reactor that produces that much energy, and there just ain't enough uranium produced in the world for that.
The point is that even the next generation still ain't going anywhere. It doesn't matter if they want to push space travel or not, they're still not going to put a guy farther than maybe Mars. Unless some miraculous new source of energy is found -- note that even Star Trek essentially has infinite energy and stored as densely as antimatter -- the next generation is just tied to this rock as we are.
A polar bear is a cartesian bear after a coordinate transform.
Orbit is usually associated with gravity but it can happen with any attractive force.
I am deaf. I can't hear the sound in the video.
Like I said, didn't pass High School physics.
Strange how the things that interest me change as I get older.
I mean, this stuff is genuinely interesting to me now. It wasn't then.
I had the time to learn it then, I don't now.
life is funny that way.
"Water Droplets In Orbit On the International Space Station" is a misleading headline. It made me think of a space station plumbing failure.
Of course electricity can make things orbit. Anything that pushes stuff toghether can make things orbit.
Also, if that something pushes with a force that doesn't change with the 1/r^2 that gravity and electricity do, you can create some quite interesting orbits. Try a string sometime.
Rethinking email
Any attractive force can cause orbit. The water droplets were forced out of a syringe and have a velocity pointing away from the syringe .. when the droplets get attracted to the knitting needle they still retain that velocity/momentum .. the attraction of the needle can't erase the droplet's pre-existing velocity .. this causes the droplet to orbit .. it slowly spirals inwards because air resistance that slows down it's velocity.
You didn't think to mention that the first time around?
This is the internet. You claimed to have watched a video and not understand something that was patently obvious if you had watched it.
What did you expect people to assume? The internet is filled with morons. Including the ones who don't mention their relevant disabilities when asking for clarification.
Your best guess was the right one. Also that second needle was of a different material. I think part of his little experiments was using different charged materials. Teflon, nylon, and so on.
http://soylentnews.org/~tibman
And just to add one thing about interstellar travel at relativistic speeds: that energy per gram works both ways. If you're going at 0.9c and hit a grain of mater (e.g., ice) just half a gram in weight, that's pretty much stationary compared to your own speed, the energy in that impact is going to be equivalent to having the Hiroshima bomb strapped to your ship and detonated.
When you're moving at relativistic speeds, every single spec of dust or ice is a relativistic weapon, packing energies measured in kilotons.
We're not talking something that will crack your windshield, but something that will vapourize even battleship-class armour and send chunks of it doing a mega shotgun blast through the rest of the ship.
So, you know, even if we figured out the engines, then we'd have to figure out some kind of Star Trek or Star Wars energy shield before we can actually make like an exorcist and get the hell out of here ;)
A polar bear is a cartesian bear after a coordinate transform.
Let me chime in with a zoom-out perspective.
Physics is using math to predict what matter will do in certain circumstances. (I find that pretty mind-blowing - that you can *calculate* what will happen to *stuff* if the system is simple enough. Too bad the calculation approach didn't work out for me so well in the girlfriend department in high school - another story.)
Anyway, the math behind how positive and negative charges attract is the same as the math behind how masses attract: they're both "inverse square laws." Three times the distance, one-ninth the force, since 3 squared is nine.
That means that the motion of a charged water droplet around the needle will be the same type of motion as orbiting, which is why it looks just like gravity. The math is the same, so the motion is the same.
Expected time to finish is 1 hour and 60 minutes.
What's wrong with the solar system to get ourselves experienced with space? Interstellar travel is out until we solve the issues you mention but the solar system is most definitely within reach - the limitations there are technology not basic physics. I think most people would think that mining Helium-3 on the surface of the moon, watching a sulphur volcano erupt on Io or sailing the methane oceans on Titan would count as exciting.
"Don use the faucet."
So remind me again why this EM effect is unworkable when scaled to the size of planets, moons, and suns? Simply because these astronomical bodies don't maintain charge?
ok, im on board
LOLWUT?
Exactly where did you see anything about refusing to grow up, or using fiction as proof, or not being able to tell the difference between reality and fantasy, in the actual message you answer to? Please do address what was actually said, not what imaginary faults of other people you need to postulate to feel good about yourself.
First of all, the whole point there was about inspiring future generations of very young schoolboys. That was the gist of the message exchange you butted into. Which of course didn't grow up yet. Yes, I realize that a certain kind of loser needs to hear himself say "grow up", and thinks it makes hims sound so superior, but it's a pretty stupid thing to say when the topic is actually inspiring elementary school students. Of course those didn't grow up.
And of course a certain amount of unrealism will be involved. You don't actually think that little girls dreaming of being princesses and having a pony actually thought through such aspects as "and be some piece of property to pawn off or give as a reward" like real princesses were, or about having to shovel the crap a pony produces, do you?
Second, I dare say that being able to distinguish between reality and those future scenario is kinda a pre-requisite for their being something to dream about in the first place. Nobody grows up dreaming to be a garbage truck driver. Dreaming of growing up to be a cool spaceship pilot was only cool and inspirational because we knew it's not something from the reality of here and now. If anyone actually thought that space cities and space freighters are real in the here and now, they'd have been mundane things for them.
Using fiction as proof? Where the fuck did you actually see me say or do that? Again, kindly address what's actually written, not what kind of strawmen would let you sound smart.
You'll notice that I hadn't used the word "disappointed" in what you quoted there, or really in the whole message you answer to. So, again, please do address what's actually written, not what strawmen make you feel better.
It has nothing to do with being disappointed that translation apps are small. The point is what looks cool if you want to inspire kids, because that's what we were talking about. Functionalism is certainly good and fine, but you're not going to get a school-kid interested in science so they can design an own logo and catchy name for cell phones designed by Google and manufactured in China.
A talking robot is "cool" enough to be an inspiration. Using a browser to access Google translations is not. You can grow up dreaming to have a cool talking robot like Luke Skywalker. You don't grow up dreaming of having a cell phone with a browser. (Or if anyone does, well, they probably need help.)
A polar bear is a cartesian bear after a coordinate transform.
in fact, electricity and gravity are identical, except that for gravity there is only one kind of "charge", and the force is only attractive. in electricity, there are two kinds of charges, and there is attraction only between opposed charges.
in practice, if the moon was positively charged and the earth negatively charged, and there was no gravity, you could still obtain the same trajectory of the moon around the earth (provided that you have the correct charges).
the force for gravity is (m1*m2)/(r^2), where "r" is the distance between the masses m1 and m2, and the force for electricity is (c1*c2)/(r^2) for the charges c1 and c2 (note that there are some other constant factors there, but they don't matter for the shape of the orbits).
anyway, the second (important) difference between electricity and gravity is the coupling constant. i.e. it turns out that the gravitational force between objects on our scale is negligible. in practice, this means that you could, in theory, see the same video where the gravitational force acts instead of the electric force, but it would take a much longer time to generate the video.
the two forces are identical in the sense that an identical experiment can be made with gravity, but you would have to rescale the time to reproduce the exact video.
in the same way wind tunnels are used to find the drag coefficient for cars: you just have to rescale the force according to the size of the model, and you get it for the real thing.
if you write down the equations for the objects in the video, it doesn't really matter if you say it's electricity or gravity, the result is identical (as long as you ignore the drag --- by the way, you can't really ignore the drag since after a few orbits the droplets "fall" on the needle).
new sig
Can someone hear expand on this?
FTFY
Well, that was of course about space TRAVEL. Which usually is understood as involving at least one human, but basically the problems are the same even for sending a robotic probe to bring back samples.
If what you want to do is just blow the shit out of some alien planet, then, yeah, things are a lot simpler. A ton worth of solid warhead coming at you at 0.9c will pack 29 gigatons of TNT worth of kinetic energy, i.e., will hit like 600 Tsar Bombas.
Though it will still fall short of, say, the Yucatan impact that killed the dinosaurs. That's estimated at 100 million megatons, while we just reached 29,000 megatons here. We'll have to do about 3000 times more energy into ours to do the same kind of destruction.
Hmm... A bit over 220 tons at 0.999c should do the trick :p
A polar bear is a cartesian bear after a coordinate transform.
Isn't it the same thing, though? Of course, basic physics doesn't technically get into the way of getting to Alpha Centauri either. It's economics and technology that put the kibosh on it.
Going anywhere in the solar system is, of course, going to be an easier proposition, and you can get some of that energy by slingshot fly-bys of planets. It's still going to involve a lot of time, a lot of shielding, and ultimately a lot of energy. I don't think technology and economics will make that a realistic goal for most people in any foreseeable future.
Helium 3 mining on the moon for example sounds the most feasible, but the economics just aren't there yet. If you need to get a 50 ton truck to moon and back (chosen as close enough to the total weight of the orbiter and lander for Apollo 11), exactly how much Helium 3 can you get back to even pay for the costs?
Or let's think big. Let's say we have a space truck roughly about the size of the late Space Shuttle. Let's also say that technology evolves so, adjusted for inflation, it costs as much to get it to moon and back as it costs currently to get it to LEO. Let's also say that on that cost, it can haul as much payload to moon and back as it currently can haul to LEO.
Not exceedingly SF scenarios, I think you'll agree. I mean, we're not talking warp engines and antimatter there, but the kind of better engines you'd expect to happen somewhere in the near-ish future.
Well, the Space Shuttle cost per mission according to NASA, as of 2011, was about 450 million dollars. So in my scenario, we'll pay that for a trip to the moon and back, so it's not that huge. It can haul 24,400 kg to LEO, let's say our space truck can do 25 tons to the moon and back. (Probably 25 tons of supplies in one direction, and 25 tons of He3 on the return route, not counting the weight of the tanks and such, which would probably be a part of the cosmic tanker truck as the cheapest solution.) It's a fair amount actually, since Helium is lightweight.
Well, now we have 450 million dollars / 25t = 18 million dollars per ton. That's how much you'd have to sell that He3 for, to just break even.
In fact, even if the cost of that round trip dropped by an order of magnitude (hey, technology progresses), it still has to be worth nearly 2 million dollars a ton to be worth just the trip alone, never mind the costs of the moon base.
So I still think that even that won't happen any time soon. Sorry. Adam Smith's invisible hand is flipping us SF nerds the bird :p
A polar bear is a cartesian bear after a coordinate transform.
Does anyone have any insight into these electro-static orbits.
I'm curious if the orbit would decay naturally if this was done in a vacuum. Is the air friction the only thing stealing the droplets velocity or is there a change in the droplet (and needle) charge, resulting in a electromagnetic force against the droplet?
This is the internet. You claimed to have watched a video and not understand something that was patently obvious if you had watched it.
Obviously that's not true. I can't blame you for your assumptions, since most of us aren't accustomed to dealing with deaf people very often. But even after it's pointed out that it's an incorrect assumption, you still state something based on that incorrect assumption
The internet is filled with morons.
As you've so clearly demonstrated.
And it's not like he said "I'm deaf, you jackass". He simply replied back as a matter of fact "I'm deaf" just to clear up the misunderstanding. He replied back very civilly. Can't say the same for you. So I'd like to ammend your previous statement: The internet is filled with morons and assholes.
I used to hate and have no interest in math or history and now I seek related materials out on my free time for my own edification. You are not alone. Science rules.
I think it's a pretty jerky thing to post asking questions about a video without saying you didn't listen to it. It wastes everyone's time. Also, the blurb clearly uses the word "charged", so maybe I should be assuming he might be illiterate too? Anyway, I see lots of asshats on this thread, so I figured I'd join in.
1. I'm not sure you're right about the efficiency of the system.
2. Which planet are you thinking? I'm thinking to simply get to the next system - forget planets for a second, Orion may be the way to go.
I believe if you rub the nylon knittin' needle against the teflon one, one will become positively charged and the other negatively charged. I'm not sure which one is shedding the electrons and which is picking them up, but that's the reason. I'm guessing that the nylon one gains electrons, and teflon donates them.
He's transferring the charge from the needle to the droplets, then they're orbiting the oppositely charged needle due to electrostatic attraction. (the needle wants its electrons back, basically).
I used to have a sig, but I set it free and it never came back.
When I first read it, I took it to mean they had found water droplets orbitting the station itself.
When our name is on the back of your car, we're behind you all the way!
Oh, don't get me wrong, I'm not saying that that energy is why it can't EVENTUALLY be done. I'm just saying it's why it won't be done during the lifetime of generation Y either. Since, really, that's what I was answering to: whether it will inspire the next generation to not fail to move on with space travel.
I'm just saying that, yeah, focusing on the here and now, I wouldn't bet on the next generation getting a guy out of the solar system.
Further in the future... who knows? We've only had even cities for like 10,000 years, and existed as a species for 200,000 years. It would be presumptuous of me to state what can't be done in the next 4-5 billion years we can exist on this planet. (Past which point if it's not done yet, it effectively means "never.") I'm perfectly willing to say I have no bloody clue what will happen that far in the future.
A polar bear is a cartesian bear after a coordinate transform.
My initial thought is that his explanation is incorrect. My reasoning is:
Orbits are "a 1/r^2 phenomenon". He says that the force is coming from a charged droplet orbiting an oppositely charged rod. But, a rod (1-d object) doesn't have a 1/r^2 field -- it has a 1/r field. So I think that a charged droplet would NOT orbit a rod (it would orbit a charged sphere- or point- like object).
However ... water is a good dipole. And (if i remember right), a dipole in a field feels a force that is reduced by an extra 1/r. i.e. a dipole in a 1/r field would have a force that is like 1/r^2 - i.e. it is capable of orbiting, when it is NOT charged.
(for instance, if you comb your hair with one of those crappy plastic combs, and then turn your faucet on such that it's the weakest stream it can have without being turbulent, and then put the comb near the stream, the stream will bend toward the comb. Dipole force.)
With that said ... I am pretty rusty. What do you guys think? Am I wrong? if so, why?
Thanks!
Isn't it the same thing, though? Of course, basic physics doesn't technically get into the way of getting to Alpha Centauri either.
Ok, I suppose technically it is basic physics and biology. Given basic physics there is no way to make the trip short enough that anyone setting off will live long enough to get to Alpha Centauri. Until you solve that there is no economic problem because, even with infinite money, nobody can make it there.
For the solar system I agree that there is an economic hurdle to overcome but, as launches keep getting cheaper, it is just a matter of time before we find something valuable enough to be worth the cost to recover. Once we get there and build infrastructure off the Earth things will tend to get cheaper because something constructed on the moon has a far smaller energy cost to launch.
This is much the same thing which happened during the colonization of North America - initially everything was imported from Europe and then gradually local manufacturing took over because it saved the (then expensive) transport costs from Europe.
I just couldn't get past the thought that he was able to get knitting needles onto the space station but would never have been able to get them onto a commercial airline flight.