effective sail area determined for the magsail by Zubrin from equation with the 3.1 correction factor from Freeland applied and using the same velocity value (resolving the discrepancy noted by Gros) as follows: The figure shows the normalized effective sail area normalized by the coil area for the MKM case from Gros of equation and for Zubrin from equation for , =100 km, and =0.1 cm−3 for the G-cloud on approach to Alpha Centauri corresponding to ISM density (kg/m3) consistent with that from Freeland plotted versus the spacecraft velocity relative to the speed of light . A good fit occurs for these parameters, but for different values of and the fit can vary significantly. Also plotted is the MHD applicability test of ion gyroradius divided by magnetopause radius <1 from equation on the secondary axis. Note that MHD applicability occurs at < 1%. For comparison, the 2004 Fujita as a function of from the MHD applicability test section is also plotted. Note that the Gros model predicts a more rapid decrease in effective area than this model at higher velocities. The normalized values of and track closely until 10% after which point the Zubrin magsail model of Equation becomes increasingly optimistic and equation is applicable instead. Since the models track closely up to 10%, with the kinematic model underestimating effective sail area for smaller values of (hence underestimating force), equation is an approximation for both the MHD and kinematic region. The Gros model is pessimistic for < 0.1%. Gros used the analytic expression for the effective reflection area from equation for explicit solution for the required distance to decelerate to final velocity from equation (10) given an initial velocity (m/s) for a spacecraft mass (kg) as follows: where . When =0 the above equation is defined in equation (11) as , which enabled a closed form solution of the velocity at a distance in equation (12) with numerical integration required to compute the time required to decelerate in equation (14). Equation (16) used this result to compute and optimal current that minimized as where . In 2017 Crowl optimized coil current for the ratio of effective area over total mass and derived the result in equation (15). That paper used results from Gros for the stopping distance and time to decelerate. The figure plots the distance traveled while decelerating (ly) and time required to decelerate (yr) given a starting relative