Science: Spacecraft: Propulsion: Light
Solar Fiber Laser   (+1, -2)  [vote for, against]
Sunlight powers an fiber optic lasers; lasers push sails.

You make a solar laser satellite out of a long fiber of pure lasing material. Surrounded by the vacuum of space, this total internal reflection will contain the beam within the fiber. One end of the fiber is coated with a mirror. The other end has a larger mirror and aiming servos to shoot the laser beam at a cloud of laser microsail particles.

The satellites orbit somewhat close to the sun, for maximum power. The long thin shape of the fibers provide lots of waste heat radiation area. Since the range of each individual laser is not so great, they accelerate multiple microsail clouds at a time using a "bucket brigade" formation.

These microsails can then accelerate an M2P2 sailship. The microsails ionize when they slam into the M2P2's plasma field, adding their own mass to the plasma field while simultaneously transfering their momentum.

For an interstellar mission, you launch a bunch of M2P2 sailship drones. These drones are little more than a large magsail. The main starship has an M2P2 plasma field also, with a more powerful magnetic field, but it's too heavy to be accelerated directly by the solar fiber laser satellites.

The drones fly through the starship's plasma field. This process strips them of much of their plasma field, transfering momentum to the starship. The drones then continue toward the destination system, slowly gathering a new plasma field as it ionizes/gathers interstellar hydrogen. The drones overshoot the destionation system, and then angle their magloops in order to "tack" against the interstellar medium. This provides sideways maneuvering capability, allowing the magloop drones to do a 180 degree turn.

Then, the starship catches up as the drones are heading straight for it. The drones with their new hydrogen plasma fields fly through the starship's M2P2 plasma field. This slows down the starship, so they arrive at the destination system.

For the starship to return, they can either set up their own solar fiber laser satellite system, or the home system can launch a bunch more drones. This will accelerate the starship back home after doing a 180, but the speed will be slower due to the speed lost while performing the 180 turn maneuver.
-- IJK, Mar 18 2007

http://science.nasa...2000/ast04oct_1.htm [the dog's breakfast, Mar 18 2007]

Don't know where lasers fit in. Solar wind (the plasma)can't be 'gathered' to be used later, and the field (around the ship)is magnetic.
-- the dog's breakfast, Mar 18 2007

The lasers accelerate clouds of sail flakes. Graphite may be a good material for this because it's cheap and naturally breaks up into tiny flakes. Flakes minimize mass, compared to spherical particles of similar diameter (you need a diameter on the order of the laser wavelength).

One problem with flakes is that they produce unwanted sideways thrust if they're reflective. This sideways thrust will divert particles out of the laser beam. Graphite flakes avoid this problem by simply absorbing photons directly. This heats them up, and the waste heat photons get radiated evenly to produce no sideways thrust.

Its these sail particles which physically slam into an M2P2 plasma field. The particles enter the magnetic field without being affected because they aren't ionized. After the impact, however, the resulting ions are constrained by the magnetic field. It's like a roach motel--particles check in, but they don't check out (or rather, they do check out eventually, because the magnetic field is somewhat leaky).

Anyway, the solar wind isn't being used. Neither the force of the solar wind nor solar light pressure is significant enough to produce the sorts of thrust required for interstellar travel. Rather, large amounts of sunlight are utilized to produce powerful narrow beam lasers. Within these beams, light pressure is high enough to accelerate clouds of dust flakes up to relativistic speeds.
-- IJK, Mar 18 2007

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