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Several research programs which have applied thermal scale modeling to a radiation-conduction heat transfer system (unmanned spacecraft) and to a radiation-conduction-convection heat transfer system (manned spacecraft) are reviewed and evaluated. ...The utilization of scaled models in the development of spacecraft thermal control systems is discussed. The criteria necessary to establish thermal similitude are developed as well as techniques for designing scaled thermal models.

Because of the capability of extended accuracy, digital systems are indicated for guidance and control of spacecraft. Furthermore, by implementing these systems with integrated microelectronic components, substantial improvement in reliability can be expected. ...A study and experimental evaluation program was performed to apply such digital techniques to the spacecraft stabilization and control problem. Of major consideration were the selection of appropriate mathematical techniques for system analysis and the development of suitable fabrication methods for hardware implementation. ...A discrete state model of a spacecraft reaction wheel and jet attitude control system was developed and computer simulations were performed.

The MUSES-B spacecraft will be launched in 1996 by the Institute of Space and Astronautical Science (ISAS). ...The thermal design and verification has been performed separately for the major modules of the spacecraft; a main structure, a deployable antenna and Reaction Control System (RCS). Special attention is paid to the exposed RCS whose solar input varies significantly depending on the sun angle.

The results of computer simulation of a typical spacecraft pumped two-phase thermal control system are presented. The two-phase thermal control system transients under effect of the typical disturbances are obtained.

., Apollo Support Dept. for the National Aeronautics and Space Administration, Manned Spacecraft Center. This model simulates the entire spacecraft structure and the four closed fluid loops of the Environmental Control System.

Analysis has been performed for the overall spacecraft, the subsystems and some selected units. The thermal control system of the RADARSAT-1 has been examined for cases of both normal orbital conditions and abnormal thermal environments and operations.

New thermal control systems like evaporator heat sinks are integrated into the Active Thermal Control System and into the Flight Control System of Space Planes. The development of these new systems is performed through mathematical process analyses and tests. This paper concerns the establishment of a Thermal Mathematical Model (TMM) for the analyses. The design of the HERMES Water Evaporator Assembly (WEA) is presented. The thermodynamics and numerical requirements upon a TMM for heat exchangers are derived and explained in detail. As an example the WEA TMM is depicted and results of transient analyses are discussed.

Several areas for improvement in the thermal and mechanical properties of the passive thermal control optical solar reflectors (OSRs) have been identified and discussed in a previous paper (1). These include the use of specialised optical coatings to optimise the emittance and absorptance of OSRs and also chemical treatments to provide greater resistance to handling and better conductivity where necessary. Each of the proposed techniques have been demonstrated and the most promising have been incorporated into development programmes leading to production. In parallel with this activity, examination of aspects of the whole passive thermal control system, in terms of optimal construction and assembly, and thermal and conductive properties is expected to commence shortly. It is anticipated that these will result in the specification and use of optimal thermal control systems for future satellites.

A passive thermal control system (TCS) augmented with manual and auto heaters are provided. The spacecraft completed four years of operation since 28th Dec'95. The TCS of the spacecraft has been very good. ...Temperature variation of the spacecraft is presented and discussed here. A nominal rise in temperature of the spacecraft observed is found to fit linear equation, and the same could be used to predict a conservative value of the temperature for the next few years. ...IRS-1C spacecraft is the most advanced civilian remote sensing satellite built in India with a steering panchromatic camera having a ground resolution of 5.8 m.

The system is comprised of a manipulator whose end-effector rigidly grasps a functional spacecraft, a six-axis force/moment (F/M) sensor placed at the interface of the spacecraft and the manipulator, and a control system. ...The controller takes the values of the force/moment as well as the manipulator's joint angles and velocities and issues torque command to drive the manipulator so that the motion of the spacecraft model in the presence of external forces replicates 0-g motion dynamics of a flight spacecraft. The control system can also modify the inertial properties of the spacecraft so as to match those of an actual spacecraft, even if the latter is flexible and the former is rigid. ...A system emulation that can be used for testing a spacecraft control system with all of its hardware in place, in a 1-g laboratory environment, is presented.

A design study of pumped two-phase and capillary-pumped thermal control systems (TCS) was conducted on a typical, advanced earth-orbiting spacecraft (AEOS). NASA's Upper Atmosphere Research Satellite (UARS) size and baseline design were chosen as the configuration for AEOS; however, the power requirements were increased and the allowable temperature range was decreased to represent the requirements of a more advanced spacecraft. ...NASA's Upper Atmosphere Research Satellite (UARS) size and baseline design were chosen as the configuration for AEOS; however, the power requirements were increased and the allowable temperature range was decreased to represent the requirements of a more advanced spacecraft. For peak-power dissipations of 1 or 2 kW, the capillary-pumped system was lightest. ...In addition to the weight advantage, the more nearly isothermal spacecraft obtainable with the two-phase system permits less compensation for thermal distortion; a simpler, less costly structure results.

A passive thermal control system is provided for the temperature control of the panchromatic camera of IRS-1C spacecraft. The camera with a spatial resolution of better than 10m and a revisiting capability requires a stringent thermal control system.

The Mars Pathfinder (MPF) Spacecraft, scheduled for a December 1996 launch to Mars, uses a mechanically pumped loop to transfer dissipated heat from the insulated lander electronics to an external radiator. ...Finally, some thoughts on the development of mechanically pumped loops for future spacecraft are presented.

Solar electric propulsion (SEP) provides a unique capability for interplanetary missions, although spacecraft designs based on solar power, developed by large flexible arrays, lead to formidable vehicle interactions with attitude control. ...It is concluded that the state-of-the-art of control system design is mature enough to support an SEP spacecraft for such heliocentric missions as rendezvous or slow flyby of the comet Encke or out-of-the ecliptic missions in the 1980s.

A computer-based design system has been developed for conceptual design of spacecraft active thermal control systems (ATCS). Its purpose is to aid the thermal systems engineer in selection of a working fluid and thermal cycle for a given set of requirements. ...It is found that reductions in power system weight penalty result in considerable weight savings for vapor-compression systems, making them more attractive for future spacecraft. The advantage of the present approach lies in the capability to accomodate quantitative technical information as well as environmental and safety considerations in a single model.

The properties of the prepared nanofluids will allow for lighter, smaller, and higher efficiency spacecraft thermal control systems to be developed. Nanofluids with spherical or rod-shaped metal nanoparticles were investigated.

This paper deals with review of the issues associated with modelling the dynamic processes in the spacecraft two-phase thermal control systems. The work presents the results of modelling the nonstationary conditions of the evaporative and condensation heat exchangers functioning, investigates their response to the characteristic external influences.

Such metal nanoparticle-fluid composite materials are referred to as nanofluids and their use as coolants has the potential to reduce the weight and power requirements of spacecraft thermal control systems. The thermal conductivity of nanofluids is dependent on the concentration, size, shape, surface chemistry, and aggregation state of the constituent nanoparticles.

This paper describes a model-based approach to diagnosing electrical faults in electrical power systems. Until recently, model-based reasoning has only been applied to physical systems with static, persistent states, and with parts whose behavior can be expressed combinatorially, such as digital circuits. Our research is one of a handful of recent efforts to apply model-based reasoning to more complex systems, those whose behavior is difficult or impossible to express combinatorially, and whose states change continuously over time. The chosen approach to representation is loosely based on the idea of the equation network proposed in [6]. This requires a more complex component and behavior model than for simpler physical devices. The resulting system is being tested on fault data from the SSM/PMAD power system breadboard being developed at NASA-MSFC [9].

This paper outlines some of the parameters considered in the design of stabilization and control systems dynamic test facility of the Grumman Aircraft Engineering Corp. The facility is described and initial test results discussed. The need for additional studies of this three axis, air bearing simulator is indicated.