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Spacecraft May Surf Magnetic Fields
Maggie McKee writes "Future spacecraft may surf the magnetic fields of Earth and other planets, taking previously unfeasible routes around the solar system, according to a proposal funded by NASA's Institute for Advanced Concepts. The electrically charged craft would not need rockets or propellant of any kind. To get charged up, the spacecraft could either fire a beam of charged particles into space or simply allow a radioactive isotope to emit charged particles. Because long, thin filaments have large surface areas for holding charge, the spacecraft might look like Einstein's head — with wiry filaments sticking out at all angles — or a weird space 'stocking.'"
Mercury has no magnetic field and the one around Mars is patchy and not nearly as strong as the on here on Earth.
Does that mean this would be better suited for terrestrial travel?
09:F9:11:02 - 9D:74:E3:5B - D8:41:56:C5 - 63:56:88:C0
It's not stupid. It's Advanced.
We probably could have done without the last sentence in the summary, but thanks anyway.
Future spacecraft may surf the magnetic fields of Earth and other planets, taking previously unfeasible routes around the solar system
I'm not sure this "surfing the galaxy" technology is a good idea. It'll just be used to lead Galactus here to consume our planet.
The theory of relativity doesn't work right in Arkansas.
Gotta get me some freaky space stockings
I don't therefore I'm not.
what I wanna know is, where's my damn FLYING CAR?!
Where did those people study Physics? It doesn't work that way.
The only surface area that matters is an equipotential surface, so in the case of "filaments sticking in all directions" it will be a roughly spherical surface formed by the ends of filaments. Within this sphere there is almost no electric field -- filaments can be seen as a kind of lightning rods, except there is no lightning because they are in vacuum. So at best they will have a larger sphere, at worst a cigar or other shape with less surface area. If one has to build a large but light sphere, he can make it out of the wire mesh -- in vacuum it won't discharge like it would in the air, where those spheres have to be smooth. Filaments or spikes can be useful for acceleration of charged particles.
As for usefulness of the whole thing, I guess, you can use this for steering the spaceship, however the analogy to surfing is very poor. Surfboards can accelerate by absorbing the energy of waves moving from deep to shallow water. This thing flies through a stable magnetic field, steering by changing its electric charge. A better analogy would be a sailboat changing tacks, with gravity acting as a wind and magnetic field as water resistance.
Contrary to the popular belief, there indeed is no God.
Will they be able to identify Klingons?
I couldn't help getting Zardoz flashbacks only the head looks like Einstein.
Mason Peck of Cornell University in Ithaca, New York, US, has received a grant to study the idea, which is based on the fact that magnetic fields exert forces on electrically charged objects with a velocity that is not parallel with the field lines.
I'm guessing this system will work by having an orbit that travels over the magnetic poles, as the magnetic field lines are much closer there, and reversing the charge between poles so that it doesn't end up at the same altitude as it started. One problem, the further you get from Earth, the further apart the lines and therefore, less force. It seems as if it's going to take a very long time to get anything close to an escape velocity (if even possible). Who knows, it may even be more efficient to just shoot those charges out the back, aka ion drives.
It would discharge in vacuum aswell, but the body is capable of holding on to a lot more charge without doing so. Lots more.
The geometry of the body still matters too, since equal charges push each other away. A corner would have a lot more electrons pushed into it, eventually causing them to "squirt" off the sharp edge or corner. This is called "corona discharge", and is what makes Tesla coils look pretty.
All rites reversed 2010
That space-stocking looks suspiciously like Atlas' Crystal Castle from Astroboy. New Scientist hiring ex-manga artists perhaps...
I don't believe this would be the case. To use Gauss's law to calculate the charge at a surface, you have to have an actual closed physical surface along the equipotential surface. Consider a charged metal ball with a metal spike on the end of it. The charges would not congregate at the tip of the spike, but would distribute non-uniformly across the entire surface of the conducting object. Now consider a ball with two spikes. Now four, etc.
The charges would therefore distribute along the entire physical surface of the object, including the surfaces along the length of the filaments.
Observe a graphical representation
Equipotential surface does not need a conductor along it. Drill a hole in a metal sphere on a Van de Graaf generator, and it will make no difference except for immediate edges, the potential in the center of the hole will be approximately the same as it was when there was metal in it.
Contrary to the popular belief, there indeed is no God.
Anyone who remember physics 101 will recall the following:
A magnetic field will create a force normal to the velocity of a charged object. So
1. The force on any charge will be normal to the velocity, so it will move around in circles. This includes the charged spacecraft. (The field here is not homogeneous, but still, no gain in energy)
2. A current loop(i.e. a moving charge) can change the energy or be accelerated in a magnetic field.
(2) is and has been used since the first satellites were orbited to do orbital corrections, and are well understood and used. It can allow the life of the satellite to be expanded by many years.
Why would this craft not just use a long current carrying wire instead.
don't cut it off www.mgmbill.org
Corona in a gas is easy to produce because gas can be ionized by strong electric field along the spike or fiber, giving you a lot of charged particles to carry your discharge current. In vacuum you have nothing but those electrons that are already in metal -- you can emit them if you are negatively charged, and can't emit anything if you are positively charged (think of it as a giant diode tube). Even if you emit electrons, you have to move very fast so magnetic field will divert them away from you, and once you are sufficiently positively charged, emission will stop.
Most likely at best this will produce a cloud of electrons following a positively charged spaceship, so forces that magnetic field applies to both will almost completely compensate each other. With radioactive source of charged particles (positively or negatively charged), or electron cannon you can produce more charge on the spacecraft, and probably it can be combined with ion engine that produces charged particles anyway.
Contrary to the popular belief, there indeed is no God.
Sigs are too short to say anything truly profound so read the above post instead.
...and to make it even more clear -- no, charges do not get evenly distributed along the surface. They repel each other to the end of the filaments, and ends of the filaments repel from each other, forming a sphere.
Contrary to the popular belief, there indeed is no God.
Oh, right! I didn't think about a positive charge. - Though that would limit the greatest possible charge to the number of electrons you can do without. I'm not sure how that works out into real numbers...
All rites reversed 2010
WTF? Really, WTF?
Contrary to the popular belief, there indeed is no God.
Because long, thin filaments have large surface areas for holding charge, the spacecraft might look like Einstein's head -- with wiry filaments sticking out at all angles -- or a weird space 'stocking.'
Oh no! The Pastafarians secret spaceship design has leaked out. Now all the acolytes of The Flying Spagetti Monster will know the high inner circle secret that it is HE who travels by the spaceship and not that HE is the spaceship.
- Tjp
I am in wallow with my inner money grubbing capitalistic pig. ... Oink!
It will be the same as in vacuum tubes and CRTs -- spikes themselves won't do much, but you can heat up the cathode, and create some electric field with anode -- electrons will be emitted, some of them will be captured by anode, the rest will escape the device, leaving it positively charged. As long as anode is positive relative to cathode, electron cannon will work. You can lose electrons until the point when you are so positively charged that all electrons that left the cannon have less energy that it is necessary to leave the spaceship.
Or you can make a source of positively or negatively charged ions -- they can be accelerated in a similar way. Again, this probably can be much easier achieved by messing with an ion engine, under/over compensating the positively charged ions that leave the engine.
Contrary to the popular belief, there indeed is no God.
Just be sure not to touch it when it lands - at least not without Earthing (or Marsing or Mercurying) it first!
Only three things are certain; death, taxes, and apocryphal quotations - Ben Franklin.
With a radioactive source emitting alpha and beta radiation it might be possible to use two ion drives; one ejecting the positively charged alpha particles and the other ejecting the negatively charged beta particles. That way you won't build up a total charge in the craft. Plus, there won't be any charged cloud tracing the craft since the sum total charge of the ejecta is zero.
Though apparently, the NASA people WANT to build up a charge... Meh.
All rites reversed 2010
I'm guessing that all of those filaments are going to add a LOT of launch mass. Why not just make use of an M2P2 system?
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And they really WILL make a spaceship modeled on Einstein's head.
t he_palm_islands.php
They have a little fetish for cute stuff like that.
http://guide.theemiratesnetwork.com/living/dubai/
Carl Sagan said that the ship would look like a dandelion, so it's going to look like a dandelion, physics be damned!
Censorship is telling a man he can't have a steak just because a baby can't chew it. --Mark Twain
Unless the material is non-conductive and the charge is fixed into the material...
The Code Master
>>>A better analogy would be a sailboat changing tacks, with gravity acting as a wind and magnetic field as water resistance.
Sure, then when we have a gay space ship.
If the charges can't distribute themselves to the lowest-energy configuration, it means that higher potential difference corresponds to the same charge, what means your capacitance is lower. Same happens when you pull the capacitor's conductors to put thicker dielectric between them -- charge is the same, energy is added therefore capacitance is lower.
Contrary to the popular belief, there indeed is no God.
I don't doubt that this will produce thrust. But I don't see how they will be able to direct the thrust in a specific controllable direction.
I have one question. If the Japanese Ministry of Agriculture is not in charge of Gundam, then who is?
What does Stephin Merritt think of all this?
I mean, come on. Why are we developing all these "space-sails"? I've read in the last couple months a few stories about different kinds of sails.
Why are we trying to make devices that ride solar wind, or magnetic fields, when we should be developing REAL space engines and such?
It's just plain tacky, inefficient and slow. Sure it's kind of fun, but why are we making devices that take SO long to get places? Humans only live so long...
Here's an illustration of the spacecraft running Linux! I can't get Netcraft to confirm it, though. All I get from them is "In Soviet Russia, spacecraft launches YOU!" But imagine a beowolf... sorry, never mind. I'll go take my meds and be quiet now.
"in this house we obey the laws of thermodynamics!"
Everybody knows that a hitchhiker's best friend (other than a babelfish) is a towel ... not a sock. :))
"Happy families are all alike; every unhappy family is unhappy in its own way." -- Anna Karenina by Leo Tolstoy
'Tis the last of the old Dick Tracy comic strip technologies to be realized.
Lets just hope they get to test this before the poles swap or the earth's core solidifies.
This is eminent, I have seen it on TV yesterday.
With a radioactive source emitting alpha and beta radiation it might be possible to use two ion drives; one ejecting the positively charged alpha particles and the other ejecting the negatively charged beta particles.
For that to work, the two materials would have to emit charge at exactly the same rate (more accurate, the beta rate would have to be twice the alpha rate, because alpha has twice the charge of beta). You could place just the right amount of two materials to INITIALLY have the same rate, but because no two materials (unless they are identical) have the same half-life, the rates would eventually not be matched and a charge would start building up.
Unless you had a way to actively manage the particles and control how many of them actually left the spacecraft (which I think would be difficult) I don't see how it could work, except momentarily.
The breakdown doesn't have to occur simultaneously. When the alpha particle radiates, two electrons will be freed. A single electric field could direct the differently charged particles in opposite directions, then down to the awaiting ion engines.
All rites reversed 2010
There exists another interesting invention around about the same principles. This one however uses solar wind, not magnetic fields, is steerable and able to work itself against the solar wind by adjusting the polarity and charge of the individual wires. They are apparently doing practical research on this right now. A short english description can be found at http://www.electric-sailing.fi/index.html
Mercury has no magnetic field and the one around Mars is patchy and not nearly as strong as the on here on Earth. Does that mean this would be better suited for terrestrial travel?
You are correct that Mars has a very weak, patchy magnetic field. However, Mercury does have a rather strong magnetic field. Mercury even has a magnetosphere, even though it does not have an atmosphere. In fact, the MESSENGER spacecraft is currently on its way to Mercury to study the planet's magnetosphere. Venus, on the other hand, does not have a magnetic field.
Within this sphere there is almost no electric field -- filaments can be seen as a kind of lightning rods, except there is no lightning because they are in vacuum.
Space is not as empty as people think. The near-Earth space environment, and the space environments of any planet with a magnetosphere, are full of plasma. As a result, spacecraft charging and electrical discharges (think lightning) are a problem for spacecraft. This problem has been studied by a lot of people, including NASA's Electromagnetic Effects & Spacecraft Charging Working Group.
As for usefulness of the whole thing, I guess, you can use this for steering the spaceship, however the analogy to surfing is very poor.
I admit that I didn't really understand this article or how this spacecraft design is supposed to work. The people working on this have probably published something a bit more technical that would do a better job of explaining it. However, the idea of using magnetic fields in space to "steer" spacecraft is not new. Interactions between the Earth's magnetic field and magnetic torquer coils are already being used for attitude control and spin rate control on satellites.
a black hole
http://www.ess.washington.edu/Space/propulsion.htm l
I always get the shakes before a drop.
Adam Roberts would be proud. This sounds like his latest novel, "Gradisil", where the spacecraft 'push' against Earth's magnetic field to lift up to orbit.
Awesome book. Read it! http://en.wikipedia.org/wiki/Gradisil
This was covered in fiction by Gradisil written by Adam Roberts a book I enjoyed http://www.amazon.co.uk/Gradisil-Gollancz-SF-Adam- Roberts/dp/0575078170/ref=pd_ka_1/203-9719250-2991 164?ie=UTF8&s=books&qid=1173987235&sr=8-1