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John Butler

Publications and source records attributed to John Butler.

Mission and space vehicle sizing data for a chemical propulsion/aerobraking option

This paper presents sizing data for various combinations of Mars missions and chemical-propulsion/aerobraking vehicles. Data is compared for vehicles utilizing opposition (2-year mission) and conjunction (3-year mission) trajectories for 1999 and 2001 opportunities, for various sizes of vehicles. Payload capabilities for manned and unmanned missions vehicles and for propulsive-braking and aerobraking cases are shown. The effect of scaling up a reference vehicle Is compared to the case of utilizing two identical vehicles, for growth In payload capability. The rate of cumulative build up of weight on the surface of Mars is examined for various mission/vehicle combinations, and is compared to the landed-weight requirements for sortie missions, moving-base missions, and fixed-base missions. Also, the required buildup of weight in low Earth orbit (LEO) for various mission/vehicle combinations Is presented and discussed.

John Butler↗

Mission and space vehicle concepts

This paper discusses a number of top-level considerations which affect Mars and vehicle selection. Indications are provided of the nature and severity of the impact of these considerations on missions and vehicles. The paper identifies and discusses various types of missions, such as Mars fly-bys, Mars orbiting and landing missions, and missions to the moons of Mars. Mission trajectories and opportunities are discussed briefly. The paper also discusses the different types of vehicles required in a Mars program. Discussion includes several potential Earth-to-Orbit (ETO) vehicles, Mars surface vehicles, and 2 types of Orbit-to-Orbit (OTO) vehicles. Indications are provided as to preference for some of the concepts discussed.

John Butler↗