The NASA Office of Exploration (OXEP) was established in June 1987 to provide recommendations and viable alternatives for an early 1990's national decision on a focused program for human exploration of the solar system, particularly of the Moon and Mars. 1 Missions beyond the low earth orbit Space Station Freedom poise new and different challenges for crew life support systems (LSS). Case study missions under consideration will demand careful selection of reliable and efficient LSS technology by the mission planners. This paper describes a study currently underway to develop a Mission Planners LSS Guidebook for providing tabular data, such as weight, volume, and power for comparing various LSS approaches against key drivers derived from mission case studies. These quanitative data facilitate LSS approach selection for any mission of interest bounded by the current OXEP case studies. Also included is a preliminary summary of high leverage technologies for achieving LSS beyond those baselined from Space Station Freedom.