Advanced propulsion systems and technologies today to 2020 Introduction Advanced solid rocket motors Advanced cryogenic engines Advanced LOX HC engines for boosters and upper stages LOX hydrocarbon engines in Russia Green propellants Green propellants in Russia Miniaturized propulsion Solar thermal propulsion for upper stages Electric propulsion systems Superconductivity The case for nuclear propulsion : the Rubbias engine VASIMR prefeasibility analysis Laser propulsion systems Mass accelerators : Maglev and Railguns Solar sails : propellantless propulsion for near and medium term deep space missions In situ resource utilization