9.3.3 Schedule Issues for Deployable and Assembled Structures Certainly, our ability to assemble and deploy large structures will be a driver in the very large satellites envisioned for a space solar power program. This program is not the only one in which construction methods will be required, though. The assembly of Spacecraft to be used in Mars missions and the installation of a lunar outpost are two mega-projects in their own right which will be enabled by the use of these technologies. Deployable structures (to date usually antennae, solar panels, and booms) have gotten larger as space missions have gotten more ambitious. One can see, then, that the development of these technologies has a schedule of its own which interacts with many programs. Milestones in any one of these programs can be considered advances for all of them. Figure 9.12 diagrams these milestones in a logical possible order. Programs and milestones which are important for assembly techniques of large structures include: • Reliable techniques for GN&C of expanding structures during the construction phase. This is especially important during the very dynamic periods when vibrations are occuring and mass properties change continuously or in large steps. This will be demonstrated during the assembly of Space Station Freedom. • Assembly and construction of a Spacecraft with high pointing accuracy (as might be required for beamed energy transfer.) A test article in -2005 is suggested. • Operation and control of large, flexible Spacecraft with vibration modes which could interfere with its mission. Operation of Space Station Freedom will be a major milestone in this regard. This might be especially important for those Spacecraft which have a high requirement for pointing accuracy. • Trades should be performed for each project where the optimum point of EVA vs robotic assembly lies. This will change based on the structures themselves as well as the capability of space robotics at that time. • Trades must also be performed on the assembly of many small parts, which can be densely packaged in a launch vehicle, vs the launch of volume inefficient, preassembled structures. Programs and milestones which might be important for deployable structures and methods include: • Increased reliability of advanced deployable structures. • Development of deployable high-precision elements. This might include the demonstration of a deployable solar dynamic generator with both high pointing accuracy and high precision reflector requirements. This could, perhaps, be the same test as one suggested for in-space manufacturing (9.5.3, below) wherein chemical vapor deposition to produce a reflector is suggested. • The assembly and deployment of the many structures at a Lunar Outpost will provide skill in assembly in general as well as the infrastructure on the Moon for the use of nonterrestrial resources. Figure 9.12 Construction, Assembly, and Deployment Task Schedule
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