Ignoring relativity, the physical interpretation is the velocity at which you can throw fuel mass "overboard." If it is some kind of "ion drive" I suppose you can't ignore relativity.
The photons from the sun also act with direct force on the solar panels. Past studies have looked at solar sails, etc. Converting some of the energy to an ion drive could be a way to "vector" the thrust from the light pressure and provide more control. ________________________________ From: "[email protected]" <[email protected]> To: U.S. Metric Association <[email protected]> Sent: Mon, June 20, 2011 9:50:32 AM Subject: [USMA:50686] Solar Electric Propulsion The NASA John Glenn Center in Cleveland, Ohio is requesting Proposals for a demonstration of Solar Electric Propulsion, a method of slowly thrusting probes along spiral trajectories into the outer regions of our solar system. The "specific impulse" (m/s) required for such missions can only be achieved by electric propulsion (not by chemical rockets) fueled by solar or nuclear energy. Specific Impulse (thrust times time; divided by the mass ejected by the rocket motor) (newtons x seconds per kilogram) i.e. (kg x m/s^2) x s per kg = m/s. In outdated studies, some engineers equated mass with weight and got the less acceptable result that pounds times seconds divided by pounds equals seconds. Let's see if the winning proposal(s) can correctly distinguish mass and weight? Gene Mechtly
