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Space Science

Spacecraft May Surf Magnetic Fields 98

Posted by kdawson
from the radioactive-space-stocking dept.
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.'"
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Spacecraft May Surf Magnetic Fields

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  • 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?
    • Re:Last I Checked (Score:5, Informative)

      by headkase (533448) on Wednesday March 14, 2007 @01:15AM (#18343939)
      The Sun's magnetospere is bigger than the orbit of Pluto if I remember correctly. And it doesn't have to be exclusive, you could use the magnetic "sock" for a stage of the journey and maybe propellents in another stage of the same voyage and then you short range teleport for the last 5000km ;). It's just another useful tool to employ from a mission planning perspective.
      • by headkase (533448)
        magnetospere == magnetosphere.
        One of these days I'll actually learn to spell or /. will integrate a checker and there will be much rejoicing.
        • Re: (Score:1, Offtopic)

          by omeomi (675045)
          One of these days I'll actually learn to spell or /. will integrate a checker and there will be much rejoicing.

          Just use Firefox 2, it has a spell checker built in...
      • Ah okay, I was not aware of the effect of the Sun's magnetic field.
        • Re: (Score:2, Troll)

          by cluckshot (658931)

          The magnetic field of the sun is pretty strong but of course is highly variable. At one point in 2005 (about the time we got the strong hurricanes) there were several Coronal Mass Ejections that left the sun riding its field at extreme speeds. By the time one of them passed earth (29 minutes after ejection) the matter was going 15% of the speed of light. By the time the same CME passed Saturn, the matter was going 30% of the speed of light.

          People get this right! The solar system is electrical. The who

          • "I am sure some one of the old guys will declare me Troll rather than accept the obvious reality." Well, I'm not that old a guy, but statements like "obvious reality" do need to be backed up with some hard proof and proper theory, and last I heard, most folks were happy with the sun being powered by nuclear fusion rather than "electrically". By all means, let's see your theories and proof, and then we can all decide for ourselves.
            • by Gilmoure (18428)
              Electrically straightened my teeth, rebuilt the transmission in my '72 Nova and made my wife's breasts larger. I love it!
          • It is not your theories which make you a troll, it's your lack of substantiation for same. Provide some research and evidence past simple assertions, and I'll pay attention. Until then, you're just another crackpot who's probably trying to get me to invest in his perpetual motion machine.
          • Now, see what you've done. You've made Steven Hawking cry.
          • by eno2001 (527078)
            Jesus K-Riste. This guy is NOT a troll. I was one of the guys deployed by Halliburton to rebuild the sun when it imploded and went black hole back in 1906. Of course, it wasn't called Halliburton then and that whole Tunguska thing was just a cover up. Fortunately, we already had a backup sun in place because we'd been anticipating this stuff since Leonardo (DaVinci) first noticed the magnetic fluctuations back in the day. The backup sun was one gigantic halogen lamp matrix and was being powered by a ma
      • Re: (Score:2, Funny)

        by WingedEarth (958581)
        Don't you mean, "The Non-Planet Formerly Known As Pluto"?
        • by ultranova (717540)

          Don't you mean, "The Non-Planet Formerly Known As Pluto"?

          Even if Pluto was downgraded from "planet" into "big rock", wouldn't it still be called Pluto ? It is Pluto's status that is in question, not name.

    • by Yvanhoe (564877)
      Mybe would it be useful to get a boost while still in earth's vicinity or maybe it would be really useful for satellite that would not have to embark a limited quantity of fuel anymore.
      • by Mr2cents (323101)
        I think navigating such a thing could prove to be very difficult.. If they want to change the capacitance, then they'll have to roll it up or something like that.. adding extra weight. I wish them good luck, but I'm a bit sceptical.

        Sidenote: did they use an image of MRO with an extra 'sock' attached to it in the article? It really looks like MRO.
    • Mercury has no magnetic field

      Wikipedia [wikipedia.org]: Despite its slow rotation, Mercury has a relatively strong magnetic field, with a magnetic field strength 1% as strong as the Earth's.

      Perhaps you mean it's not strong enough?

    • 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 [jhuapl.edu] is currently on its way to Mercury to study the planet's magnetosphere. Venus [ucla.edu], on the

  • not spacecraft. (Score:2, Interesting)

    by YenTheFirst (1056960)
    with the power involved here, it wouldn't be propelling any manned missions.

    After reaching orbit, his present design would be off to a slow start, taking about a year to escape the Earth's gravity.
    this seems like it would only be useful for satellites and probes and such.
    • by Nyeerrmm (940927)
      It's still a spacecraft, just not a manned spacecraft. And I don't know much about the technology, but if its anything like acceleration from ion drives, it may take a while to get going but it could still be fastest method in the long term for a long trip (longer than one to Mars I would guess.)
    • by simm1701 (835424)
      Um why not a manned space craft?

      Any manned mission would need a huge amount of support equipment and probably a very large ship. Putting enough fuel in orbit to speed it up would be expensive. Speeding it up this way and then shuttling the human personel in using a much smaller ship (eg a shuttle) that could catch up to that speed ansd rendevous without needing anywhere near as much fuel would certainly be possible

      If its just going in a circle while it speeds up it doesn't mean its out of range for us.
      • RTFA. It says in the article, that the acceleration from this thing would be on the slow and steady side, and that it might take a spacecraft propelled by this technology "as much as a year" to break out of Earth's magnetic well.

        We'd start having huge astronaut endurance issues before they got anywhere cool.
        • by CmdrGravy (645153)
          The obvious solution to this is to not climb aboard the craft until it's reached a decent speed. Launch it a decade or so before you wish to fly anywhere and have it do trips around the sun and back building up it's speed. When it's going fast enough build a very fast short range rocket to match it's speed and allow the astronauts to board.
          • Then what would be the point? If you could match the speed once it got past the snail-crawl, why wouldn't you just use that technology instead?

            So assuming this craft would use the same technique for deceleration, once this thing got to its destination would it have to boomerang around the local star a few times before it could slow to a speed more conducive to deboarding? Or can we just expect that by the time this thing would even have accelerated enough to be useful in the first place, all human passeng
            • by CmdrGravy (645153)
              If you already have most of the spaceship in space flying along and the only thing you need to add to it are some pilots you will be able to build a rocket capable of getting the rocket and the few passengers to the same speed as your mothership. The rocket would then stop accelerating and carry on at the same speed whilst the mothership would continue to accelerate.

              You wouldn't be able to attach the rockets to the mothership and accelerate it to the same speed it is able to reach on it's own after 10 years
        • by simm1701 (835424)
          RTFP - I was suggesting letting it get up to speed and THEN putting people on board

          I also rather like the other comment here of speeding it up even further by doing solar orbits before you actually put people on board - that might start to challenge how quickly we can accellerate a small ship to rendevous... but it would be very interesting!!
          • by 2short (466733)

            If you can catch up to it, why climb on board? You're going to have the same issues decelerating at the other end too. Even as an unmanned cargo drone, sent ahead with supplies it doesn't work. The reason it's slow is itdoesn't push very hard; give it lots of mass to push and it's not slow but glacial.

            This sounds great for a lightweight unmanned probe that just keeps steadily accelerating forever. Other than that I can't see it.
  • oh great (Score:2, Funny)

    by User 956 (568564)
    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.
  • Gotta get me some freaky space stockings

  • by Alex Belits (437) * on Wednesday March 14, 2007 @01:48AM (#18344069) Homepage

    But the amount of charge held by a sphere at a given voltage, a quantity known as its capacitance, is not very large. Long, thin filaments, on the other hand, have a lot of charge-holding surface area, so one possible design involves many filaments attached to the spacecraft. The setup would have a rather comical look - because of the static charge, the filaments would stick out in all directions, like newly brushed dry hair.


    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.
    • ...in vacuum it won't discharge like it would in the air, where those spheres have to be smooth.

      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.

      • by Alex Belits (437) * on Wednesday March 14, 2007 @03:06AM (#18344405) Homepage
        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.
        • 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...
          • Re: (Score:3, Insightful)

            by Alex Belits (437) *
            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
            • Re: (Score:3, Insightful)

              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.

              • by pclminion (145572)

                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, bu

                • 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.
    • Where did those people study Physics? It doesn't work that way.

      Carl Sagan said that the ship would look like a dandelion, so it's going to look like a dandelion, physics be damned!

    • Unless the material is non-conductive and the charge is fixed into the material...
      • by Alex Belits (437) *
        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.
    • 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 Electromagne [nasa.gov]

  • Fixed it for you (Score:2, Informative)

    by TheTopher (879626)
    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 f
  • by viking80 (697716) on Wednesday March 14, 2007 @02:58AM (#18344355) Journal
    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.

    • by Jesrad (716567)
      Why would this craft not just use a long current carrying wire instead.

      Actually, this is exactly the principle of the magsail: magnetic solar sail. You deploy a long wire loop on every side of the spacecraft, circulate a current in it, and it catches the Earth's or Sun's magnetic field to propel the spacecraft.

      A spacecraft using this method of propulsion could even launch in complete silence from either Pole, if it had a sufficiently large coil and current. An alternative to the wire is to use ionized gas i
    • by pbaer (833011)
      "Why would this craft not just use a long current carrying wire instead?"

      This is actually answered directly in TFA. The short anwser is that this has the potential to be much smaller.

      Other methods of propellantless space travel have been suggested before, including solar sails and electrodynamic tethers. Like Peck's proposal, tethers are also designed to get a grip on planetary magnetic fields, but in a slightly different way, by sending an electrical current along a wire.

      Tethers may prove hard to control

      • by viking80 (697716)
        My point was how can this work? I can suggest to use a 300m sombrero made of nanotubes, that would give better performance than the 3 km carbon tether.

        But unless I gave a clue on why it would be better it would not be worth very much.
  • WTF? Really, WTF?
    • by aldo.gs (985038)
      Come on, not every geek/nerd likes anime. I know I do.

      Unless by "Eureka Seven" you mean "Linux" or "Beowulf Cluster", or something like that.
  • 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 [venganza.org] will know the high inner circle secret that it is HE who travels by the spaceship and not that HE is the spaceship.
  • Just be sure not to touch it when it lands - at least not without Earthing (or Marsing or Mercurying) it first!
    • not without Earthing (or Marsing or Mercurying) it first!

      Harry Harrison has suggested that humans in the distant future will wonder why we named our home world "Dirt". But anyway I can't imagine that in a future mars colony the three wire AC will come as Active (brown), Neutral (blue) and Mars (striped green/yellow). I think we will all just quietly ignore the inconsistency and call it Earth.

  • by Ancient_Hacker (751168) on Wednesday March 14, 2007 @05:52AM (#18345059)
    A few glitches in this idea:

    • Building up and keeping a substantial charge may be difficult-- the solar wind will tend to get in the way.
    • "Steering" is a bit misleading. Assuming you can only shoot out electrons, you're limited to one polarity of charge, so you can only turn in one direction, normal to the magnetic field.
    • Most planets have a bit of inclination, so you're going to be turning into an angle to the ecliptic-- not very useful if you want to aim at another planet.
    • A sudden solar flare is likely to really mess up the charge, leading to unexpected twists and turns.

    • Most planets have a bit of inclination, so you're going to be turning into an angle to the ecliptic-- not very useful if you want to aim at another planet.

      Niven and Pournelle made the point in The Mote in Gods Eye that if you build a laser boosted solar sail to travel to another star then you could use the galactic magnetic field to do a 180 degree turn, approach the target star from the opposite direction, and then use your laser boost to slow down.

      In the story that wasn't used because the people running

  • 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 [slashdot.org] system [wikipedia.org]?
    • 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'd think that they'd be able to adjust the shape of the generated magnetosphere. It might not turn on a dime, but it should be steerable.
  • first they say:

    would not need rockets or propellant of any kind
    and then immediately after, say:

    fire a beam of charged particles into space
    ..how is this not a propellant?
    "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. :))
  • 'Tis the last of the old Dick Tracy comic strip technologies to be realized.
  • by jovius (974690) on Wednesday March 14, 2007 @12:21PM (#18349809)
    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 [electric-sailing.fi]
  • a black hole
  • So, does noone here remember M2P2 from a few years back?

    http://www.ess.washington.edu/Space/propulsion.htm l [washington.edu]

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