The Plasma Magnet work sponsored by NIAC in 2004-2005 developed a means of producing drag against the interplanetary solar wind or interstellar medium with high drag-to-mass ratio.
A new class of reaction drive is discussed, in which reaction mass is expelled from a vehicle using power extracted from the relative motion of the vehicle and the surrounding medium, such as the solar wind. The physics of this type of drive are reviewed and shown to permit high-velocity
changes with modest mass ratio while conserving energy and momentum according to well-established physical principles. A comparison to past propulsion methods and propulsion classification studies suggests new mission possibilities for this type of drive. An example of how this principle might be embodied in hardware suggests accelerations sufficient for outer solar system missions, with shorter trip times and lower mass ratios than chemical rockets.
A detailed design would be required to estimate mass but a sizing study, based on peak currents in superconducting MgB2 tapes at 20K of 2.5 x108 A/m2, suggests that accelerations in the 0.025-0.05 m/s2 range may be feasible using this approach. The long tether, carrying oscillating currents in the 1 kHz range from end to end, modulated by a reciprocating frequency in the 20 Hz range, is admirably suited to form a Wideröe style ion accelerator, thus providing an integrated method for converting the resulting electric power to thrust.
SOURCES- Tau Zero Foundation, Interstellar Research Group
Written by Brian Wang, Nextbigfuture.com
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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