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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.
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.
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.
That is a LOL moment. If you're going to rewrite engineering history as part of tiresome environmental guilt trip prattle, don't do it on a website populated with engineers. Wrong both at the microscale in that A4/V2 didn't burn avgas or diesel or petrochemicals at all, wrong at the macroscale that every A4/V2 ever launched added together adds up to frankly not very much fuel. Those were relatively tiny SRBMs roughly similar performance to a modern MLRS not a thundering herd of saturn-5s.
fundamental physics research would simply awe the likes of Feynman ... if they were around to see it.
He didn't die that long ago, you know. Yes he chilled out with the manhatten project dudes as an extremely young man hanging with middle aged and old men. You may have missed he was on the Challenger loss commission in the 80s, etc. Even Dirac didn't die until the early 80s. If you want to surprise a physicist, find someone who croaked before WWII not a recently deceased.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
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.
Nuclear energy isn't suitable for space vehicles? I'm sure the voyager program would beg to differ.
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.
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.
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.
You are kidding, right?
Feynman and Dirac are responsible for the most successful scientific theory in all of the history of mankind thus far.
Its Quantum Electrodynamics and the theory fits experiment to such a great degree that they were able to predict the value of a fundamental constant verified in their lifetimes to billionths of a percentage point. You talk of modern communication tools but you dont seem to realize that they all owe their existence to the very men you wish to brush off.
Richard Feynman was hands down the greatest scientist the world has ever known, as it was not just QED that he was essentially involved with pioneering. He was essential in developing the mathematics of quantum mechanics, essential in superfluidity, and pioneered the quark model of particle physics. He even invented quantum computing and was first to suggest nano-technology for christ sakes!
"His name was James Damore."
You answered the parents question correctly, but if you have not seen it you should have a look at http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation.
For a rocket to get into orbit, most common propellents end up requiring 80% or more of the mass of the rocket be propellent. Now, if we had a big cannon we could do it with the energy you are mentioning.
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
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?
Pretty much. Because each type of charge (positive and negative) repels like types of charges and attracts opposite types of charge, in order to get this type of attraction between two objects you need to cram a bunch of positives onto one object, and negatives onto the other. But those positives do not "want" to stay crammed onto the object - they don't "like" each other. Similarly for the negatives. If you get significant numbers of them together, they have a tendency to fly apart.
In contrast, "gravitational charges" (called "mass") are all the same type, and they all attract each other, so they easily clump together forming planets and suns, and continue to attract each other. Thus even though the electric force is in many ways "stronger" than the gravitational force (by something like 10^20), most of the time we don't even notice the electric force, while we do notice the force of gravity all the time - the earth is so huge.
Yes!. You just got the charges backwards. If you look up triboelectric series (example here http://www.siliconfareast.com/tribo_series.htm) you'll see that nylon is half way up the positive scale where as Teflon is the second from the bottom on the negative side of the scale. Positive means that it tends to donate electrons and negative means it wants to accept or 'steal' electrons.
They key though, is the induction created to the water droplets which you can read about it here (http://www.eskimo.com/~billb/emotor/kelvin.html)
What is happening (my guess) is that the nylon when rubbed is positively charged (lost electrons) when placed near the tip of the syringe, the water is positively charged because its electrons are given to the nylon needle, creating a positive charge in the water. The Teflon needle, on the other hand, is a very negatively charged material (gained a lot of electrons through rubbing it with paper) and thus the positively charged water is attracted to the negatively charged teflon needle and the orbit through these opposing fields is achieved in microgravity!
A black cat crossing your path signifies that the animal is going somewhere. -- Groucho Marx