Tend orbiting satellites. These satellites are emplaced by and are under the control of the main station. They fulfill a single major purpose or a related series of purposes such as Earth sensing, plant growth experiments, or optical astronomy. The use of tended free-fliers solves the problem of conflicting priorities (e.g., pointing a telescope at a star and a sensor at the ground simultaneously). It enables scientific experiments or other tasks to be performed without con tinuous human supervision but which do require very low movement or very low containment levels. The satellite module can be resupplied, repaired, or given new tasks and then left undisturbed. The satellites should them selves be designed on the modular principle, and tending them will drive development of technologies required to repair satellites in LEO and GEO, to assemble large satellites and space probes, and to provide flight support for missions conducted farther from the Earth. Build, test, and transfer to orbit large complex space stations. This capability derives from Shuttle beam building experiments and the assembly of modular structures and produces many of the products of this stage of development. These products include: • SPS proof-of-concept and prototype devices • Communications platforms • Large antennas and antenna forms • Clustered satellites and multipurpose platforms The ability to construct very large space structures such as the solar power station depends heavily on automated construction and assembly techniques developed at this stage. Reduce station dependence on Earth for control and supply. Solar and nuclear power modules, modules for atmospheric recycling and renewal, food production and waste recycling capabilities, and the ability to assemble platforms and station sections from supplied parts and then to make those parts from supplied raw materials, all contribute to the growing independence of the space industrial complex. Increasing independence demands progressively increasing capacity to generate electricity (energy self sufficiency), to recycle air and water in an increasingly closed ecosystem, to monitor crew and station health (life sustaining independence), to process materials and fabricate products in space (economic and manufacturing independence), and finally to acquire and utilize nonterrestrial esources (material independence). The stages of independence may be pursued in parallel, and the progress toward self-sufficiency is quite gradual. There is no requirement that a facility be fully or even mostly self-sufficient at the outset. Automate space operations to support in-space human activity. Automation will not eliminate human activity in space. Human-built machines are not people and space in the long run will have little meaning for humanity unless people are living in space. The purpose of automation is to make human tasks easier and less hazardous, to remove tedious and repetitive tasks from human responsibility, and to enable each individual to accomplish more. The term "automation" is loosely used to encompass the full range of autonomous or semiautonomous systems including robots and free satellites that perform a set of tasks and exercise judgment when faced with unforeseen developments, automatic processing machines with little or no judgment, and teleoperators controlled entirely by humans who provide the required judgment. Prime candidates for early automation are the assembly of stations and OTV modules, satellite assembly, emplacement, replacement and repair, and space processing techniques. Advance deep space exploration. Advanced future deep space probes can build on the experience of earlier probes such as Voyager and Viking, but tile new generation of machines may be larger and considerably more autonomous. They can be greater in size because of modular construction in LEO. On-board artificial intelligence will enable the probes to perform largely autonomous scheduling, sequencing, and contingency planning. Automation may also include on-board analysis, data correlation, and perhaps, even mechanized, hypothesis-formation development of models describing a remote planet. All of these capabilities, along with robotic systems, are required for the ambitious Titan mission described in chapter 3. In the shorter term, space probes will serve as the automated prospectors of the utilization-oriented space age. Asteroid rendezvous missions currently being considered will only be the first of many missions to seek out possible extraterrestrial resources for in-space materials processing. Multiple asteroid prospecting in the asteroid belt, comet rendezvous and sample return, Mars rover and sample return, planetary and satellite lander/rover/sample return missions are believed credible but are not yet in mainstream space mission planning.
7.2. 2 Recommended NASA Space Systems Technology Model Updates The NASA/OAST Space Systems Technology Model (OAST, 1980) is intended to serve as a reference for planning technology programs and options, identifying technologies required for planning and potential future missions, assessing ongoing technical programs, and providing a technology reference source for mission planning. Ascertaining requirements for planned and future missions ensures that the focus of technology programs is coupled to tile overall goals and missions of NASA The three volumes of the Model treat systems, programs, and technology from the present to the reasonable limits of projection. Volume I describes those systems and programs which the NASA program offices endorse as being within their
