 Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 124 journals)
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- A review on assessment of camera sensors and data acquisitions using
satellite imaging for remote sensing-
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Authors: Shivansh Sinha, Abhishek Sharma, Sanjay Kumar Sharma, Parvin Kumar, Shraddha Tripathi, Saurabh Mishra
Pages: 209 - 226
Abstract: In this review paper, various aspects of the nano-satellite payload for satellite imagery are presented. This manuscript provides technological concepts which must be helpful for the researchers involved in the designing of payload for remote sensing. The main aim of the paper is to outline a review related to the nano-satellite payload advancement for remote sensing. This paper offers a brief insight into satellite imaging, hardware, software tools, and principles to process images obtained from the satellite. Various opportunities and domains which can be explored with the help of satellite imaging are also discussed. The manuscript includes the performance analysis and assessment of various camera modules for optical payload, to be used in nano-satellite.
Keywords: remote sensing; satellite imaging; satellite payloads; image processing; camera sensors modules; data acquisition
Citation: International Journal of Space Science and Engineering, Vol. 6, No. 3 (2021) pp. 209 - 226
PubDate: 2021-03-31T23:20:50-05:00
DOI: 10.1504/IJSPACESE.2021.113896
Issue No: Vol. 6, No. 3 (2021)
- Semi-analytical and extremal solutions for design and synthesis of powered
descent and landing trajectories-
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Authors: Minji Jo, Dilmurat Azimov
Pages: 227 - 246
Abstract: Semi-analytical solutions to the optimal control problem for 3-dimensional fuel-efficient planetary landing trajectories with constant exhaust velocity and limited mass-flow rate in a drag-existing central Newtonian field are presented. The first-order optimality conditions reduce the problem to a Hamiltonian canonical system for the design and synthesis of feasible and extremal planetary entry, descent, and landing trajectories. The proposed solutions allow us to describe the state vector and Lagrange multipliers in terms of time and switching function's characteristics to determine the number and sequence of thrust arcs. These solutions can be adjusted for manoeuvres near other celestial bodies for which a central gravitational acceleration can be dominant. The paper describes new extremal trajectories, which are based on the analysis of first- and second-order optimality conditions. The results of this work can be used to support mission design analysis and synthesis of fuel-efficient trajectories.
Keywords: entry, descent and landing; EDL; optimal control; calculus of variations; trajectory synthesis; extremal trajectories
Citation: International Journal of Space Science and Engineering, Vol. 6, No. 3 (2021) pp. 227 - 246
PubDate: 2021-03-31T23:20:50-05:00
DOI: 10.1504/IJSPACESE.2021.113892
Issue No: Vol. 6, No. 3 (2021)
- Electromagnetic-Alcubierre thruster
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Authors: Minji Jo, Dilmurat Azimov
Pages: 247 - 256
Abstract: In this manuscript we propose an electromagnetic thruster based on an analogue of the Alcubierre warp solution. The construction of such a solution can be accomplished by including a parallel plate capacitor in an electromagnetic resonating chamber. By tuning an AC voltage across the capacitor at resonance with the oscillation frequency of the electromagnetic field in the cavity one can produce a net force on the charges in the capacitor and thus on the device as a whole. The net thrust will be provided by the scattered electromagnetic waves which exit the chamber as exhaust and will depend on the resonator geometry, capacitor voltage, and power input from the electromagnetic field generator. For high energy electromagnetic field generators, 1-g of thrust can be sustained for extended periods of time on large space craft and thereby enables the possibility of robust travel within the solar system.
Keywords: advanced propulsion; warp drive; Alcubierre metric; analogue gravity; space exploration; electromagnetic thrust
Citation: International Journal of Space Science and Engineering, Vol. 6, No. 3 (2021) pp. 247 - 256
PubDate: 2021-03-31T23:20:50-05:00
DOI: 10.1504/IJSPACESE.2021.113887
Issue No: Vol. 6, No. 3 (2021)
- Fixed final time satellite attitude control with thrusters based on
dynamic programming and neural networks-
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Authors: Minji Jo, Dilmurat Azimov
Pages: 257 - 274
Abstract: This paper studies the attitude control of a satellite in three-axis using only four thrusters. The mathematical model of the attitude is represented as a switched system with 16 subsystems. Each subsystem is defined based on the thruster's on/off status. The dynamic programming is utilised to find the optimal switching between subsystems such that a cost function is optimised. Furthermore, to generalise the solution for a specific domain of interest, neural network is employed for offline training and approximating the cost function. An offline training algorithm is suggested to find the optimal weights of the neurons and determine optimal switching. It is shown that the proposed method can execute a manoeuvre within fixed final time. Moreover, the control is robust against uncertainties in the system modelling. Finally, the system modelling and control approach is suggested as a framework to design low-cost attitude control system unit, suitable for microsatellite-class.
Keywords: satellite; attitude control; thruster; dynamic programming; machine learning; neural network
Citation: International Journal of Space Science and Engineering, Vol. 6, No. 3 (2021) pp. 257 - 274
PubDate: 2021-03-31T23:20:50-05:00
DOI: 10.1504/IJSPACESE.2021.113885
Issue No: Vol. 6, No. 3 (2021)
- On the plasma density variation in the F2 region during geomagnetic storms
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Authors: Rose Chigoziri Anamezie, Kingsley Chukwudi Okpala, Obiageli Josephine Ugonabo
Pages: 275 - 291
Abstract: The features of ionospheric storm given by the percentage change in frequency (dfoF2) have been investigated for four stations. Using the international quietest days as a reference, dfoF2 was computed as the deviation of the storm day critical frequency from the quiet day diurnal variation. The main interest here was to understand the hemispheric and longitudinal differences in the ionospheric storm responses in these mid latitude locations. Clear hemispheric differences were observed in association of the ionospheric storms with geomagnetic storms. The times of significant ionospheric storms were not usually coincident with peak geomagnetic storms. It is suggested that electrodynamic changes in the high latitudes which could be linked to the geomagnetic storm may be forcing the changes in the sub aurora stations, while localized effect dominate the response in the southern hemisphere stations. These findings have important implications for our present understanding of ionospheric variation in the continent.
Keywords: ionospheric storm; plasma frequency; geomagnetic storms; F2 layer
Citation: International Journal of Space Science and Engineering, Vol. 6, No. 3 (2021) pp. 275 - 291
PubDate: 2021-03-31T23:20:50-05:00
DOI: 10.1504/IJSPACESE.2021.113867
Issue No: Vol. 6, No. 3 (2021)
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