Using Simulation to Evaluate On-Orbit Construction Operationsby Todd C. Parfet, Univ of Colorado, Boulder, CO, USA,
Abstract: As the NASA Space Exploration Initiative (SEI) program contemplates a permanent presence on both the Lunar and Martian soil, the necessity for On-Orbit Construction of the Earth-to-Lunar/Martian Transfer Vehicle becomes a primary concern. The Center for Space Construction at the University Of Colorado is interested in analyzing the assembly, construction, and checkout of such vehicles. Once the On-Orbit Construction requirements have been evaluated, (i.e., vehicle configuration, mass properties analysis, vehicle assembly sequence, etc.) a simulation model can be applied to estimate the Assembly Time, Tool Efficiency (by 'Tools' for orbital assembly we are referring to space cranes, docking devices, teleoperated assembly robots, astronaut maneuvering units, etc.), effect of low Mean Time between Failures, and many other operationally significant aspects of On-Orbit Construction of the interplanetary Transfer Vehicle. First, we consider Total Assembly Time. It is important to know the project assembly time i.e. the lapsed time from beginning to completion. By using SIMORB, a simulation model developed by Mark L. D'Amara, an M.S. candidate in the Aerospace Engineering Sciences Department at the University of Colorado, a time schedule for the construction of the transfer vehicle can be presented. Once the Total Assembly Time has been evaluated, orbital assembly tool efficiency can be addressed. By varying the tools used for certain assembly projects, the impact on completion time change can be evaluated. Different tool application can and will either expedite or dramatically hinder the construction process. The choice of Telerobotic Robots versus Astronaut Extra Vehicular Activity (EVA) is a another sensitive factor in the total time and reliability of the construction sequence. Due to man's vulnerability in the space environment, many feel it is a necessity to use robotics rather than EVA. How will this decision affect the construction time? This is a decision that SIMORB can evaluate and about which it can generate valuable data. Finally, one must evaluate the effect due to low Mean Time Between Failure. If a connection fails or an EVA suit malfunctions, what is the effect on the Total Assembly Time? By the use of an Orbital Assembly Simulation Model the effects of a low Mean Time Between Failures can be accurately evaluated and adjusted for in the Total Assembly Time. Then the simulation model will be used to answer specific questions of design and on-orbit assembly mission planning.
Subject Headings: Vehicles | Simulation models | Construction equipment | Orbits | Construction management | Space exploration | Failure analysis | Computer models
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