Nuclear explosive propulsion for interplanetary travel: Extension of the MEDUSA concept for higher specific impulse
Abstract
The MEDUSA concept uses a large lightweight sail (spinnaker) driven by the pressure pulses from a series of nuclear explosions. The concept is extended to higher specific impulse by using a programmed servowinch to payout and drawnin the spinnaker tethers, thereby diluting the impulsive acceleration from higher yieldtoweight ratio explosives. The servowinch affords the crew a remarkably smooth ride and allows the use of every lightweight tethers. A Mars mission is considered and the roundtrip times for various spacecrafttofuel ratios and yieltoweight ratios are calculated. Given a total exposure constraint on the spinnaker canopy and a fuel weight only twice the spacecraft weight, the required mass of the canopy is calculated for various yieldtoweight ratios and the economy of scaling to larger spacecraft if demonstrated. Assuming a 100ton spacecraft and 200 tons of fuel consisting of 8000 bombs weighing 25 kg each, the canopy radius, mass, and thickness for a range of yieldtoweight ratios are given. Because of practical constraints on canopy thickness and weight, and concern with missions that can be accomplished only with nuclearexplosive propulsion, considerations are restricted to yieldtoweight ratios between 10 and 100 tons per kilogram. Calculations are then made on (1) specific impulse; (2) thrusttodryweight ratio; (3) pulse period; (4) required tether payout deceleration, maximum velocity, and time; (5) required tether drawnin acceleration, maximum velocity, and time; (6) length and mass of the tethers; (7) departure and arrival accelerations experienced by the crew; and (8) required energy storage for the servowinch and excess power. Radiation exposure of the space capsule and the shielding requirements for the crews are also ascertained.
 Publication:

Journal of the British Interplanetary Society
 Pub Date:
 June 1994
 Bibcode:
 1994JBIS...47..229S
 Keywords:

 Canopies;
 Interplanetary Spacecraft;
 Nuclear Propulsion;
 Sails;
 Servomechanisms;
 Winches;
 Manned Mars Missions;
 Polyethylenes;
 Radiation Shielding;
 Specific Impulse;
 Tetherlines;
 Thrust;
 Spacecraft Propulsion and Power