President George Bush\u27s 1989 challenge to America to support the Space Exploration Initiative (SEI) of Back to the Moon and Manned Mission to Mars gives the space industry an opportunity to achieve effective and efficient space transportation systems (STS\u27s). This paper presents performance and requirements synthesized to support the manned Mars mission of the SEI. The information presented focuses primarily on the Mars transportation system (MTS), which uses nuclear thermal rocket (NTR) propulsion technology associated with accomplishing the manned Mars mission. Data are also shown for a propulsion system options comparison of chemical/ aerobrake and nuclear electric propulsion (NEP) systems
