the theoretical viability of a Magsail and described common mistakes. Equation (2) states that the magnetic field of electrons rotating in the large coil was greater than and opposed the magnetic field generated by the current in the coil and hence no thrust would result. In 2014 Vulpetti published a rebuttal that summarized plasma properties, in particular the fact that plasma is quasi-neutral and noted in equation (B1) that the Bolonkin paper equation (2) assumed that the plasma had a large net negative electrical charge. The plasma charge varies statistically over short intervals and the maximum value has negligible impact on Magsail performance. Furthermore, he argued that observations by many spacecraft have observed compression of a magnetic field by dynamic (or ram) pressure that did not depend on particle charges. In 2017, Gros published results that differed from prior magsail work. A major result was the Magsail kinetic model of equation that is a curve fit to numerical analysis of proton trajectories impacted by a large current carrying superconducting coil. The curve fit scaling relation for the effective sail area was logarithmic cubed with argument with the loop current, the curve fit parameter, the ship velocity and the speed of light. This differed from the power law scaling of prior work. The Gros paper could not trace back this difference to underlying physical arguments and noted that the results are inconsistent, stating that the source for these discrepancies was unclear. Appendix B questioned whether a bow shock will form if the initial spacecraft velocity is large, for example for deceleration after interstellar travel, since the predicted effective sail area is small in this case. One difference is that this analysis used the coil radius for computation of the ion gyroradius as compared with prior work use of the magnetopause radius Advantages and disadvantages One advantage of magnetic or solar sails over (chemical or ion) reaction thrusters is that little to no reaction mass is depleted or carried in the craft. Acceleration or deceleration against a planetary magnetosphere is possible. A disadvantage for interplanetary travel is that acceleration is only in the direction of a plasma wind away from the Sun or a star or deceleration in only in the direction opposite to the plasma wind from the Sun or a star. Only deceleration is possible in the interstellar medium. Fictional uses in popular culture Magnetic sails have become a popular