1 Abstract The University of KansasCopyright © 2002: The University of Kansas Center for Research, Inc. 2335 Irving Hill Road, Lawrence, KS 66045-7612. All rights reserved. Technical Report Design and Implementation of Data Models and Instrument Scheduling of Satellites in a Space Based Internet Emulation System Karthik N. Thyagarajan Gary Minden ITTC-FY2003-24350-02 September 2002 Project Sponsor: NASA Glenn Research Center2Earth-observing systems (EOS) are used to study the clouds, water and energy cycles; oceans; chemistry of the atmosphere; land surface; water and ecosystem processes; glaciers and polar ice sheets; and the solid Earth. It consists of a series of polar-orbiting and low-inclination satellites for long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and oceans, which will expand our perspective of the global environment and climate. Space Based Internet (SBI) aims at applying mobile wireless network technology to satellite systems using innovative topology and routing algorithms. SBI is based on designing a prototype based on this concept and proposes to implement an emulation system to test this prototype. The emulation system shall model satellites in an actual satellite system. Satellite instruments gather data or make measurements depending on the topology or the region of the earth above which the satellite is or the portion of the earth where the satellite is. This necessitates building a realistic traffic model and scheduling the satellite instruments. Actual satellite systems are modeled to create an accurate and realistic emulation system. This thesis describes the design, implementation of the satellite data models and satellite instrument scheduling based on current satellite systems. Data models represent the region or type of data gathered by satellite instruments and scheduling represents the time duration when the data is gathered.3Table of Contents 1 INTRODUCTION ...............................................................................................................................9 1.1 EARTH OBSERVATION SYSTEMS ........................................................................................................9 1.2 SATELLITE DATA GATHERING .........................................................................................................10 1.3 SATELLITE COMMUNICATIONS ........................................................................................................10 1.4 PROBLEMS .......................................................................................................................................11 1.5 SOLUTION – THE SBI APPROACH ....................................................................................................11 1.6 MOTIVATION ...................................................................................................................................12 1.6.1 Challenges.............................................................................................................................12 1.6.2 Realistic traffic models of satellites.......................................................................................12 1.6.3 Obtaining a global topology database ..................................................................................13 1.6.4 Scheduling satellite instruments ............................................................................................13 1.7 THESIS ORGANIZATION ....................................................................................................................13 2 BACKGROUND ON SATELLITES ...............................................................................................15 2.1 EARTH OBSERVATION FROM SPACE – REMOTE SENSING.................................................................15 2.1.1 Characteristics of remote sensing by earth observation satellites ........................................16 2.2 NECESSITY OF SATELLITE DATA......................................................................................................17 2.3 REMOTE SENSING MECHANISM .......................................................................................................19 2.4 ORBITS OF EARTH OBSERVATION SATELLITES[10]..........................................................................19 2.4.1 Sun-synchronous orbit[11]....................................................................................................22 2.4.2 Sub-recurrent orbit................................................................................................................22 2.4.3 Polar Orbit ............................................................................................................................23 2.5 SATELLITE DATA GATHERING .........................................................................................................24 2.6 SATELLITE COMMUNICATIONS[13]..................................................................................................25 2.6.1 Tracking and Data Relay Satellite System (TDRSS)..............................................................27 3 SBI EMULATION SYSTEM............................................................................................................29 3.1 DRAWBACKS OF CURRENT SATELLITE COMMUNICATIONS ...............................................................29 3.2 CONCEPTS........................................................................................................................................29 3.3 EMULATION .....................................................................................................................................29 3.3.1 Reason for Emulation ............................................................................................................29 Advantages of Emulation .....................................................................................................................29 Disadvantages of emulation.................................................................................................................28 3.4 SBI SATELLITE FEATURES...............................................................................................................29 3.4.1 Orbits of SBI satellites...........................................................................................................29 3.4.2