The national Aeronautics an6 Space Administration's major manner program of the post-Apollo era is the development of a space transportation system (STS) based on a reusable space shuttle launch vehicle. Funded since FY71, the shuttle program is coming to fruition: the space shuttle successfully completed its series of four test flights on July 4, 1982. The first operational f1ig; fit was successfully completed in November 1982. The next shuttle flight has been delayed because of leaks in one of the orbiter's main engines. NASA hopes to be ready for launch on Apr. 4, 1963.

This issue brief discusses "killer satellites," the unofficial moniker for antisatellite (ASAT) missiles possessed by the Soviet Union in the 1970s and 1980s, as well as U.S. efforts to develop ASAT systems and simultaneously limit their development and use.

Iron dominated magnets are characterized in the limit of infinite permeability by a pole shape that is a magnetic equipotential. Deviations from this ideal because of finite permeability are associated with differences in path length, local saturation, flux concentration in slotted pole if crenellation is used, and sub surface voids. For moderate field levels the variation in flux path length throughout the iron lowers the magnetic potential on the iron surface more for the longer paths. As the excitation increases the permeability is lowered in regions of high flux density. Crenellation in this region offers some degree of control over the permeability by concentrating the flux. To a lesser degree sub surface voids can be used to control the reluctance of a flux path. The net result suggests that the shape of the effective air gap can be adjusted to be a magnetic equipotential sensibly equivalent to the ideal pole shape for infinite permeability.