<h2>AAS 99-103</h2>
<h2>Departure Energies, Trip Times and Entry Speeds for Human Mars Missions                                                                          </h2>
<h4>M. Munk                                                                                                                                                                             </h4>
NASA- Langley Research Center, Hampton, VA                                                                                                                                
<h2> Abstract </h2>
The study examines how the mission design variables departure energy, entry speed, and trip time vary for round trip conjunction class Mars missions. These three parameters must be balanced in order to produce a mission that is acceptable in terms of mass, cost, and risk. For the analysis, a simple, massless planet trajectory program was employed. The premise to this work is that if the trans-Mars and trans-Earth injection stages are designed for the most stringent opportunity in the energy cycle, then there is extra energy capability in the "easier" opportunities which can be used to decrease the planetary entry speed, or short the trip time. Both of these effects are desirable for human mission design.