Amodified output error method developed by the authors are presented, and an example of its application on the YF16 aircraft is shown. The method is originally developed for the purpose of analyzing an air accident. As the method has been proven to be quite effective, we hoped to apply it to the other aircraft's flight data for estimating the aerodynamic cnaracteristics and the input control histories. As there were no data available at hand, we first produced the flight data by simulations, then applied the method whether we can reproduce the aerodynamic characteristics and input control histories. The employed aircraft is YF16 about which the fairly detailed data are published. The result shows that the method is very effective to this purpose.

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A concept on automatic construction of space structures by shape memory alloy is proposed. Basic equations of motion of multibody system with shape memory alloy hinge elements are derived from Lagrange equations by considering potential energy of the hinge elements. The possibility of this concept is clarified through the experiment and simulation of free-flying rigid multibody systems. Flexible multibody systems are also examined, and their results are compared with those of rigid multibody systems through numerical simulations. Order of heating of many hinge elements is also studied using genetic algorithms.

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We have been investigating a modular antenna reflector to reduce the cost and time for designing, fabricating and testing. In this modular antenna, the displacement errors at the connecting points cause the shape distortion including the alignment error. In this study, we propose an error estimation method which calculates the variance of the displacements. By using this method, we calculate the error variance for a modular structure when we change the number of modules and the way of connecting modules. Considering the result, it is represented quantitatively that the shape distortion is reducing by mutual two dimensional constraints and elasticity.

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The program GEO-EVOL is now being updated at Kyushu University. The purpose of GEO-EVOL is to estimate population in geostationary orbit and its vicinity in the future based on the present situation and projected space activities. Among the model parameters that appear in GEO-EVOL, we examine the ratia that describes how many fragments cross GEO altitude among the total number created. The fragment migration ratio was kept constant in GEO-EVOL but must be a function of breakup energy and altitude. The code that can treat the fragment migration ratio as the functian of breakup energy and altitude was named GEODEEM (GEO space Debris Environment Evolution Model). Breakup numbers can be estimated in each altitude bins with known population, but breakup energy can vary. Then, we can describe the population growth with respect to the associated energy level. The current result of our simulation will be presented.

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