نشریه علوم و فناوری فضایی
سال شانزدهم شماره 3 (پیاپی 57، پاییز 1402)

Aeronautical-ESIM (A-ESIM) provides a satellite broadband service for aircraft occupants. Due to the frequency sharing of Aeronautical-ESIM (A-ESIM) satellite broadband service with previous ones, there is a possibility of its frequency interference on them. According to the resolution WRC 2019, the A-ESIM frequency interference on co-frequency ground stations must be prevented by observing the Power Flux Density (PFD) mask . However, the approval of the PFD condition fulfillment method has been postponed to the World Radio Communication Conference 2023. In this regard, some countries have simulated and determined the minimum allowable height of A-ESIM from the ground, so that the PFD reached the ground does not exceed the specified mask. In many cases, only limited positions of unauthorized heights will cause the PFD to override the mask. Therefore, in this paper, with a new solution, the authorized and unauthorized positions of A-ESIM are determined at any height less than the minimum allowable height, relative to a fixed ground station. In addition, the unauthorized positions of the A-ESIM in both take-off and landing positions are simulated and determined depending on the slope of the A-ESIM

This paper deals with form-finding and free vibration analysis of a pre-stressed class-one triplex tensegrity structure. The form-finding is performed via a two-step procedure, the nodal coordinates connectivity matrix, and structural element force density determination. Accordingly, the possible states for the nodal coordinates and the structural force density of the triplex prism have been determined by trial and error (based on topology and member type knowledge) to satisfy the force density, and equilibrium matrices rank requirements. Based on different structural topologies, the equation of the motion in the frequency domain for free vibration analysis of the system is derived using the spectral element approach and dynamic shape functions. Simulations are provided for different system heights and the top-bottom aria ratios and compared with the FEM. The numerical simulations in the form of a comparative study of the natural frequencies of triplex tensegrity prism with different heights and cross-sections represent the system’s robustness with different topologies for single or multi-stage applications.

Aerospace systems and subsystems are subjected to impulsive loads due to several reasons like engine start and burnout, separation, and so on. These loads may make temporary or permanent failures in some sensitive components or subsystems. To avoid these failures some constraints should be consider in design mechanical process. Another approach can be reducing the load level in transmission path without any change in the source of load and without adding any new component and only with design optimization of available components i.e, structural joints destructive effects of impulsive loads. This paper uses analytical results of joints behavior to present practical solution for minimizing load transmission through the joint

This paper presents a solution for detecting and recovery for the spoof error of GPS receiver signals, in order to increase the accuracy of the navigation system integrating inertial systems with GPS signals. integrated inertial navigation and GPS data has many advantages. However, due to the weakness of satellite signals against jamming and spoof attacks of providing analytical solutions, they have a special place in improving Kalman filter estimation compared to hardware solutions. In this paper, a new method for loosely coupled of INS/GPS is presented, in which the steady state of Kalman gain parameters is used during deception detection and recovery. With the gain parameters of the Kalman filter tending to constant values, with the aim of correcting and predicting the error of state variables, it can be used to detection GPS spoofed data. It can be detected by spoof in the GPS receiver signal when couple with inertial waves through the amount of Kalman gain fluctuations. In the case of closed loop, the Kalman gain matrix denominators tend to a constant value, and in case of deception, this function is associated with many fluctuations. By using dynamic weighting, the effect of errors caused by these attacks is recovered.

This paper investigates solar activities and its phenomena from the perspective of risks to the earth's environment, human health, and space weather risks to space systems. In this article, in addition to a brief explanation about the physics of the sun and space weather phenomena, the effects of these phenomena on human health have been investigated. moreover the results of international researches have been studied and analyzed to determine the relationship between heart diseases, brain diseases, cancer, birth rates, health of astronauts, and animal life with space weather phenomena. The results of this article help to predict these events during the occurrence of solar events and by taking the correct actions in addition to preserving biological health, possible damages can also be minimized.

Light is a vital factor for plant cultivation. LED lamps in different spectra have some advantages such as low heat production and energy requirement, and long lifespan, which was used for the first time to design plant growth chambers in closed culture systems and space research. In this research, impact of light spectrums was studied on the growth mechanisms through chlorophyll pigments, enzyme defense system, and antioxidant metabolite analyses. Seeds were cultivated in Murashige and Skoog medium and exposed to different light spectrums of white, red, blue, and red-blue. Then, the seedlings were harvested for growth and biochemical analyses after 4 weeks. Results showed that red-blue and blue lights induced the fresh weight, dry weight, root length, adventitious roots, chlorophyll content, protein, flavonoids and antioxidant enzymes of superoxide dismutase and catalase. Blue spectrum significantly decreased stem length and increased the relative water content. Moreover, the highest amount of hydrogen peroxide was observed in seedlings treated with red light. It seems that light spectra by changing the hydrogen peroxide level can regulate antioxidant enzyme activity and enhance antioxidant metabolites, and red-blue light may use as a suitable lighting spectrum for the design of M. chamomilla cultivation chamber in space research.

In this article, a new approach has been presented in the design of a satellite's status controller using reaction wheels. First, a non-linear controller whose gains depend on the state variables at any moment is proposed. In the first step, the process of extracting control coefficients using the GA optimizer is described. Then, using the results of a number of tests, sufficient data for meta-modeling of the system is extracted and the relevant control gain functions are optimized using the data bank. The input of the mentioned function is the system states and its output is the control coefficients. Finally, a simulator platform was used to determine and control the position of the satellite based on the air bearing to evaluate the proposed approach. Laboratory test results show that the performance of the proposed method is up to 30% better than the classical PID controller with fixed coefficients.