Satellite Control Operations Research Articles

Determination of the Ground Station Locations for both Dual-Site Ranging and Site-Diversity at Q/V-band Satellite Communication for an Intersatellite System Scenario

Generally, Low Earth Orbit (LEO) satellites are used to collect image or video from earth’s surface. The collected data are stored on-board and/or transmitted to the main ground station directly or via polar ground station using terrestrial line. Today, an intersatellite link between a LEO and a GEO satellite allows transmission of the collected data to the main ground station through the GEO satellite. In this study, an approach for a continuous communication starting from LEO through GEO to ground station is proposed by determining the optimum ground station locations. In doing so, diverse ground stations help to determine the GEO orbit as well. Cross-correlation of the long term daily rainfall averages are multiplied with the logarithmic correlation of the sites to calculate the joint correlation of the diverse ground station locations. The minimum values of this joint correlation yield the optimum locations of the ground stations for Q/V-band communication and satellite control operations. Results for several case studies are listed.

Simulations of the FORMOSAT-5 Cold Gas Propulsion System by Using the Hybrid Continuum-Particle Method

Reaction control subsystem (RCS) is an onboard satellite propulsion system used to provide required thrusting for orbit raising, orbit maintenance, and attitude control etc.. High pressure flow with high temperature could be generated in a chamber by chemical reactions or other power resources then expelled through a convergent-divergent nozzle to obtain thrust. In order to optimize the thrusting performance, numerical simulation is an efficient method to study the physics and parameters in design phase. In the current study, a hybrid method coupled continuum and particle methods is proposed to simulate flows involving continuum and rarefied regions. The Navier-Stokes (NS) solver named UNIC is developed by Chen and his coworkers. It employs the cell-centered finite-volume method with a hybrid 2D/3D unstructured-grid topology. The proposed particle code named Parallel DSMC Code (PDSC) is a parallelized solver based on the well-known Direct Simulation of Monte Carlo (DSMC) method, which was proposed by Bird in 1976. The physical domain is decomposed into several regimes and each sub-domain executes the serial DSMC code at different processor for speeding up the computing. A practical cold gas thruster with different chamber pressures is simulated by using this hybrid code to study the potential malfunction of the pressure regulator. Then the curve-fitting thrusting equation can be referred to satellite control operations.

Multi-Agent Planning and Execution Approach for Controlling Multiple Satellites

Reducing the costs of space operations is an increasing demand which may be achieved by automating space operation planning and execution. Towards this aim, this work proposes a Multi-Agent Space Operation Automation architecture. Multi-Agent Space Operation Automation architecture manages ground resource allocation for multi-satellite tracking, plans the satellite control operations, and automates plan execution. For managing the sharing of ground resources, it identifies satellites with time-conflicting visibility periods and reduces the least priority satellite tracking. For the planning process, Multi-Agent Space Operation Automation architecture automatically generates planning problem descriptions and analyzes whether a satellite tracking period is sufficient to achieve all the tracking goals. If there is insufficient time, it allows the elimination of lower priority goals. The satellite control planning problem was specified in PDDL 2.2 and the satellite control plan generated according to the temporal planning paradigm.