How To Build Star Wars-Style Deflector Shields Right Now
    By News Staff | May 1st 2014 03:01 AM | 1 comment | Print | E-mail | Track Comments
    Star Wars Day is May 4th so you are probably wondering how you would build deflector shields in case the US government is worried about turtles on its former nuclear testing grounds and thinks your cows will harm the ecosystem and sends a Death Star after you.

    You're in luck; not only are they scientifically feasible, the principle behind them is already used here on Earth.

    If you're too young to have seen the original, and missed the flawed prequels, you needn't feel left out - in almost every science-fiction scenario, spaceships are protected by a shield defense system that deflects enemy laser fire. 

    Death Star. Source: Wikipedia.
    Link: University of Leicester.

    How would you build one of those? You'd need a surrounding field of super-hot plasma, held in place by a magnetic field around the ship. The denser the plasma, the higher the frequency of electromagnetic wave - laser radiation - deflected.

    The principle is already used in ‘over-the-horizon’ radio communications, used for decades in early warning RADAR systems and for long distance communications where satellite communications are not feasible.

    Three fourth-year physics students from the University of Leicester tackled the problem of how to create this kind of deflector shield.  They also discovered one limitation.

    They calculated that the magnet strength required is achievable, but would need a large power source that would restrict space in your ship. One major restriction would be that a shield designed to deflect light radiation would prevent any light reaching the pilot, leaving them effectively blind.

    That's solvable, though. Set phasers for fun!

    Citation: Joseph McGuire, Alexander Toohie, Alexandra Pohl, 'P6_11 Shields Up! The Physics of Star Wars', Physics Special Topics, North America, 12 8 12 2013.


    "They calculated that the magnet strength required is achievable, but would need a large power source that would restrict space in your ship."

    Then don't use a plasma as the shield. Use nanoparticle Iron dust, coated with black Iron Oxide. The fields used, whether electrostatic, if you charge the particles, or magnetic using just the particles, will require far lower field strengths. The field lines would run from a dust emitter at the bow of the vessel to a collector at the stern, from which they get sent back to the emitter. The particles will follow the field lines. The nanoparticles will have a *huge* total area per kilo. They will absorb laser light, and re-emit it immediately as infrared light, with high efficiency. The shield need only be thick enough that it is opaque through its total depth.

    The lasers won't burn through the nanoparticle shield until they can not only vaporize the Iron in their path, but do so fast enough that other particles flowing in from the bow do not re-occupy the volume of the vaporized particles before sufficient energy is delivered to the hull to damage it. Indeed, the shield should have a low enough density that vaporized nanoparticles cannot provide enough of a shockwave that it would push particles coming from the emitters away from the laser's path. That increases the needed depth of the shield to meet opacity requirements. The shield can be low mass, but even so some particle leakage from the field lines will occur. Therefore, the shield will not be deployed at all times. It is good that native nickel/iron is common in asteroids, because that will allow the vessel to "top up" at each stop.

    It is likely that instead of a crisp "shields up!" you would hear, "Captain, the enemy ship is 45 seconds from G2's estimate of their effective laser range, ...emitters are deploying the shield now, forward section shielded in 15 seconds, ... 30 seconds to completed shield".

    If nanoparticle losses can be got low enough, this scheme could also work as a "dynamic radiator" for near-term interplanetary vessels that need to keep radiator mass low.
    Tom Billings