Copyright © 2004 by Edward N. Brown. Published by The Mars Society with permission.
CHALLENGES IN HUMAN-RATING THE CREW EXPLORATION VEHICLE
WHY HUMAN SPACEFLIGHT IS SO DAMNED EXPENSIVE
Edward N. Brown
Senior Principal Engineer, Mars Society Member
Lakewood, CA 90713
The Orbital Space Plane (OSP) project was conceptualized to be a safe, reliable, robust, responsive, and low cost means to provide crew rescue, crew transport, and small cargo delivery from Earth to the International Space Station (ISS) for 20 years. Although the mission needs may have changed, there was value in undertaking that initiative since a crewed space transport vehicle had not been designed in over 25 years and there was danger that valuable technological and intellectual expertise was being lost by attrition. Human spaceflight is not a task to be left to the penny-pincher, tinkerer, experimenter, or inexperienced newcomer regardless of his or her sincerity. To keep established processes, frameworks, and procedures fresh and applicable to modern needs, as well as maintaining and invigorating the intellectual capital base, such a project is invaluable. This is especially true in the area of flight safety. A number of important design analyses and trade studies required to assure the safety and mission effectiveness of astronauts in the complex OSP flight system had been started (and were making considerable progress) when the program was terminated at the end of February. This work was required, in NASA parlance, to human-rate the space flight system if the system is to accommodate astronauts. High-level human-rating requirements have been provided by NASA (for general spaceflight as well as for the OSP) but decomposition of these requirements into lower level design specifications is the responsibility of the industrial design contractors. Many of these requirements were directly applicable to the Crew Rescue Vehicle (CRV) and Crew Transfer Vehicle (CTV) missions to support the ISS but many other requirements are applicable to human spaceflight in general.