The impact on manned Mars operations of selecting a nuclear thermal propulsion (NTP) module with a relatively low total thrust, in the 222–445 kN (50–100 klbf) range, is explored. The propulsion module may consist of one or more engines. Selection of a low total thrust is robust across a wide range of payload masses provided perigee kicks are utilized for trans‐Mars insertion (TMI). The longer time taken for TMI when using a low total thrust and perigee kicks allows for extensive system evaluation before commitment to Earth escape, but will require fuels with lifetimes of at least a few hours. Longer fuel life could be obtained without using advanced fuels by operating at lower fuel temperatures later in the mission. The additional traversals through the Van Allen belts inherent with using perigee kicks for TMI does not significantly increase the radiation exposure of the crew. Negative reactivity from xenon buildup between perigee kicks can be mitigated by coasting on the intermediate orbits, by altering the selection of the intermediate orbits, by deep throttling, or by building in sufficient excess reactivity. Thrust misalignments of a realistic magnitude do not pose an Earth impact hazard. Engine crosstalk in clusters is a very manageable problem. High propulsion module reliability can be achieved with a propulsion module consisting of a cluster of three or four small engines without dropping the module thrust‐to‐weight ratio below an acceptable level. A total design thrust in the 222–445 kN range is high enough for Earth return with only one of the engines of the cluster operating.

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