scholarly journals Optimisation problems and resolution methods in satellite scheduling and space-craft operation: a survey

2019 ◽  
pp. 1-24 ◽  
Author(s):  
Fatos Xhafa ◽  
Andrew W.H. Ip
Keyword(s):  
Space Craft ◽  
Satellite Scheduling

Stellar Evolution

1962 ◽  
Vol 11 (02) ◽  
pp. 137-143
Author(s):  
M. Schwarzschild
Keyword(s):  
Solar System ◽  
Stellar Evolution ◽  
Space Craft ◽  
New Techniques ◽  
Substantial Body ◽  
Individual Stars ◽  
The Past ◽  
Evolution Of Galaxies ◽  
History Of ◽  
Fast Flow

It is perhaps one of the most important characteristics of the past decade in astronomy that the evolution of some major classes of astronomical objects has become accessible to detailed research. The theory of the evolution of individual stars has developed into a substantial body of quantitative investigations. The evolution of galaxies, particularly of our own, has clearly become a subject for serious research. Even the history of the solar system, this close-by intriguing puzzle, may soon make the transition from being a subject of speculation to being a subject of detailed study in view of the fast flow of new data obtained with new techniques, including space-craft.

Analysis of Hybrid Programming Simulation Based on the Variable Stiffness Ring With Expanding Loop SMA Actuator

2017 ◽  
Author(s):  
Lei Wang ◽  
Zong-quan Deng ◽  
Hao-di Wang ◽  
Hong-hao Yue
Keyword(s):  
Thermal Stress ◽  
Elastic Modulus ◽  
Active Control ◽  
Driving Force ◽  
Structure Design ◽  
Smart Structure ◽  
Space Craft ◽  
Stiffness Variation ◽  
Sma Actuator ◽  
Driving Source

In the development of space craft design index, the requirements of hypersonic space craft control accuracy has been increasingly rigorous. Thin-walled structure is often employed in hypersonic craft to reduce the weight of the load and to save the room. During the flight of the craft, temperature field is produced along the surface and the dynamic properties of the craft structure are obviously changed. The decreasing elastic modulus of the structure material and the appearance of thermal stress lead to the decrease of integral rigidity and stability of the structure, then the thermal flutter appears and control difficulties increase. Shape Memory Alloy (SMA) has the advantages of the considerable driving force in the compact volume and the simple driving method. By the combination of actuator structure design and stiffness control, the smart structure is able to make active control to the thermal stiffness variation. In this paper, the apex high-temperature area is equivalent to a ring structure. Finite difference method is employed firstly to transform the governing partial differential equation into discrete finite difference equations. Then the elastic modulus change, thermal stress and tension along the circumference are considered comprehensively to propose the calculation formulas of equivalent young’s modulus. The discrete dynamic matrix model is obtained containing the control terms of SMA. To solve the big-matrix calculation and multiple iterated large data problem, hybrid program is developed with C++ and MATLAB. Finite element software is employed to make optimization analysis to design an expanding loop actuator containing SMA as driving source, variable thickness loops of spring steel as expanding units, and universal-ball pre-loading units. On the basis of that, the thermal stiffness variation active control system with smart structure is developed based on expanding loop SMA actuator. After the analysis of examples, the variation law of the needed SMA driving force is obtained. The distribution position and quantity of the driving source is optimized. This research provides reference for the Theoretical Analysis and Simulation of structure stiffness active control and adaptive control of the aircraft employing smart material. The research results have guiding significance for the smart structure design of hypersonic aircraft in the future.

BepiColombo – Mercury Swing-Bys

2021 ◽  
Author(s):  
Joe Zender ◽  
Johannes Benkhoff ◽  
Go Murakami ◽  
Elsa Montagnon
Keyword(s):  
Remote Sensing ◽  
Space Exploration ◽  
Terrestrial Planet ◽  
Field Of View ◽  
Space Craft ◽  
Joint Project ◽  
The Earth ◽  
Space Agency ◽  
Euro Pean ◽  
French Guyana

<p><strong>Abstract</strong></p> <p>The BepiColombo spacecraft was launched on 20 October 2018 from the European spaceport in French Guyana and is currently on its way to Mercury. On its way, the spacecraft will swing-by Mercury six times in its stacked configuration, before releasing the Mercury Magnetospheric Orbiter (MMO) and the Mercury Planetary Orbiter (MPO) in their corresponding orbits around the target planet.</p> <p><strong>Introduction</strong></p> <p>Mercury is in many ways a very different planet from what we were expecting. On 20 October 2018 the BepiColombo spacecraft [1] started its 7 year journey to the innermost terrestrial planet to investigate on the fundamental questions about its evolution, composition, interior, magnetosphere, and exosphere.</p> <p>BepiColombo is a joint project between the Euro- pean Space Agency (ESA) and the Japanese Aero- space Exploration Agency (JAXA). The Mission con- sists of two orbiters, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO). From their dedicated orbits the two space- craft will be studying the planet and its environment.</p> <p>The mission has been named in honor of Giuseppe (Bepi) Colombo (1920–1984), who was a brilliant Italian mathematician, who made many significant contributions to planetary research and celestial mechanics.</p> <p>During the cruise phase, the spacecraft flies in a stacked configuration: the MMO and MPO are mounted ontop of the Mercury Transfer Module (MTM). As a consequence, most remote sensing instruments onboard the MPO are mounted towards the MTM and have a fully obstructed field-of-view. The MMO instrumentation is shielded by a protection shield (MOSIF) and several instruments still await the deployment on measurement booms.</p> <p>Despite the reduced instrument availability, scientific and engineering operations will be scheduled during the cruise phase, especially during the swing-bys.</p> <p><strong>Mercury Swing-bys</strong></p> <p>Following the Earth and two Venus swing-bys, six Mercury swing-bys are foreseen from October 2021 until 9 January 2025. The poster will discuss the flyby geometries and potential operation opportunities, in comparison with the three MESSENGER Mercury swing-bys from 2008 and 2009 [2][3].</p> <p><strong>References: </strong>[1] Benkhoff, J., et al. (2010) <em>Planet. Space Sci. </em>58, 2-20. [2] Baker, D.N. et al. (2011) Planet. Space Sci 59, 2066-2074. [3] McNutt, R.L. et al. (2010), Acta Astronautica V67, Iss 7-8, p 681-687</p>

scholarly journals Stochastic Trajectories of Space Vehicles with Gravitational Manoeuvres

1993 ◽  
Vol 132 ◽  
pp. 123-130
Author(s):  
A.V. Krivov ◽  
L.I. Sokolov ◽  
V.B. Titov
Keyword(s):  
Theoretical Aspect ◽  
Random Motion ◽  
Space Vehicles ◽  
Space Craft ◽  
Routing Scheme

AbstractThe theoretical aspect of close flybies of space-crafts near planets-gravitational manoeuvres have been studied. It is proved that the space-craft motion with gravitational manoeuvres admits the existence of routing scheme and, consequently shows the existence of quasi-random motion.

scholarly journals Application of a Multi-Satellite Dynamic Mission Scheduling Model Based on Mission Priority in Emergency Response

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1430 ◽  
Author(s):  
Jintian Cui ◽  
Xin Zhang
Keyword(s):  
Dynamic Scheduling ◽  
Search Algorithm ◽  
Earth Observation ◽  
Impact Factors ◽  
Scheduling Problem ◽  
Model Based ◽  
Scheduling Model ◽  
Earth Observation Satellites ◽  
Scheduling Plan ◽  
Satellite Scheduling

Emergency observations are missions executed by Earth observation satellites to support urgent ground operations. Emergency observations become more important for meeting the requirements of highly dynamic and highly time-sensitive observation missions, such as disaster monitoring and early warning. Considering the complex scheduling problem of Earth observation satellites under emergency conditions, a multi-satellite dynamic mission scheduling model based on mission priority is proposed in this paper. A calculation model of mission priority is designed for emergency missions based on seven impact factors. In the satellite mission scheduling, the resource constraints of scheduling are analyzed in detail, and the optimization objective function is built to maximize the observation mission priority and mission revenues, and minimize the waiting time for missions that require urgency for execution time. Then, the hybrid genetic tabu search algorithm is used to obtain the initial satellite scheduling plan. In case of the dynamic arrival of new emergency missions before scheduling plan releases, a dynamic scheduling algorithm based on mission priority is proposed to solve the scheduling problem caused by newly arrived missions and to obtain the scheduling plan of newly arrived missions. A simulation experiment was conducted for different numbers of initial missions and newly arrived missions, and the scheduling results were evaluated with a model performance evaluation function. The results show that the execution probability of high-priority missions increased because the mission priority was taken into account in the model. In the case of more satellite resources, when new missions dynamically arrived, the satellite resources can be reasonably allocated to these missions based on the mission priority. Overall, this approach reduces the complexity of the dynamic adjustment and maintains the stability of the initial scheduling plan.

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