Space Propulsion comprises the propulsion technology required to reach space, as well as that which can be used to maneuver in space. The first category (space access) remains confined to chemical rocketry, although some attempts continue to be made at electromagnetic or other alternative means of high-g propulsion. The in-space category, by contrast, has evolved towards the use of more mass-effective types of thruster, such as Electric Propulsion rockets, solar sails, or electrodynamic tethers. The key difference, in this case, is the possibility of accumulating momentum for a long time, at the very low rate allowed by the limited supply of power available in space. Electric Propulsion (EP) has had a long laboratory maturation period, going back to the early 1960s, and has now reached the practical application stage, to the point that essentially all new satellites, commercial as well as scientific or military, now feature some form of EP as their nominal propulsion system. An intermediate category, Nuclear Thermal propulsion, exists in principle, although environmental, economical and sometimes political obstacles have prevented its application so far.<br><br>The educational goal of the MIT graduate program in Space Propulsion Engineering is to provide students with a foundational understanding and a working knowledge of the many technical issues surrounding the design, operation and integration of the propulsion systems used in space. This includes both, chemical and non-chemical types of propulsion systems, although the latter category is emphasized for its closer ties to research conducted at MIT.