Different Coverage Patterns Different Coverage Patterns for a Single Satellite and for a Single Satellite and

Constellation of Satellites in Constellation of Satellites in Real Time with the STKReal Time with the STK

Pedro A. Capó-LugoPedro A. Capó-LugoGraduate Student Graduate Student

Dr. Peter Bainum (HU)Dr. Peter Bainum (HU)Master’s Thesis AdvisorMaster’s Thesis Advisor

Department of Mechanical EngineeringDepartment of Mechanical EngineeringHoward UniversityHoward University

IntroductionIntroduction

Define the Classical Orbital Elements Define the Classical Orbital Elements and the Laws of Kepler and Newton.and the Laws of Kepler and Newton.

Introduction and simulation with the Introduction and simulation with the Satellite Tool Kit (STK) Software.Satellite Tool Kit (STK) Software.

Show different coverage patterns Show different coverage patterns and communication architectures and communication architectures with the use of the STKwith the use of the STK..

Classical Orbital Classical Orbital ElementsElements

•Kepler’s Laws of Planetary Motion

•Newton’s Law of Motion

c

a

ce

Satellite OrbitsSatellite Orbits

Polar Orbit

Low Earth Equatorial Orbit

Geostationary Orbit

Molniya Orbit

Single Satellite vs. ConstellationSingle Satellite vs. Constellation One Power SystemOne Power System One Attitude Control One Attitude Control

SystemSystem One Telemetry One Telemetry

SystemSystem Single Launch VehicleSingle Launch Vehicle Carry Larger and Carry Larger and

more complex more complex instruments.instruments.

Minimized CostsMinimized Costs

Provide Better and Provide Better and Continuous Coverage Continuous Coverage over all or part of the over all or part of the EarthEarth

High reliability if a High reliability if a satellite is lostsatellite is lost

More survivabilityMore survivability Vary geometries or Vary geometries or

configuration.configuration. Smaller and simpler Smaller and simpler

satellites satellites High costsHigh costs

Communications ArchitectureCommunications Architecture

Arrangement and configuration of different Arrangement and configuration of different subsystems (antenna, receiver, subsystems (antenna, receiver, transponder,etc.) communicating from the transponder,etc.) communicating from the Earth to the Satellite.Earth to the Satellite.

Architecture depends on Three Basic and Architecture depends on Three Basic and Important Objectives: Mission Objectives, Important Objectives: Mission Objectives, Data Rates, Uplink and DownlinkData Rates, Uplink and Downlink

Know the different subsystems to Know the different subsystems to complete the communication complete the communication requierments with the satellite.requierments with the satellite.

STK SoftwareSTK Software

Used to simulate satellite orbits in Used to simulate satellite orbits in real time.real time.

Synthesize the positioning of the Synthesize the positioning of the ground antenna once the orbit has ground antenna once the orbit has been defined.been defined.

Used to establish communication Used to establish communication time intervals with the satellite.time intervals with the satellite.

Have a three dimensional window to Have a three dimensional window to visualize the satellite orbit.visualize the satellite orbit.

Molniya OrbitMolniya Orbit

Has a period of 12 hours.Has a period of 12 hours. Has an altitude of 40,000 km at Has an altitude of 40,000 km at

apogee and an altitude of 500 km at apogee and an altitude of 500 km at perigee.perigee.

Covers the north polar areas for a Covers the north polar areas for a period of 8 hours. period of 8 hours.

Has an inclination angle of 63.14 Has an inclination angle of 63.14 degrees.degrees.

Iridium ConstellationIridium Constellation

Has an altitude of 700 km.Has an altitude of 700 km. Has 6 orbital planes with 11 satellites Has 6 orbital planes with 11 satellites

per orbital plane.per orbital plane. Used for phone satellite Used for phone satellite

communication.communication. Can communicate to any place on Can communicate to any place on

the Earth. the Earth.

Tetrahedron ConfigurationTetrahedron ConfigurationNASA GSFC Proposed Benchmark NASA GSFC Proposed Benchmark

Configuration Configuration Has an altitude of 12 times the radius of Has an altitude of 12 times the radius of

the Earth at apogee.the Earth at apogee. Has the same configuration at apogee.Has the same configuration at apogee. Generate multiple measurements of the Generate multiple measurements of the

magnetic field of the Earth.magnetic field of the Earth.

Molniya OrbitMolniya Orbit

Iridium ConstellationIridium Constellation

Tetrahedron ConfigurationTetrahedron Configuration

ConclusionConclusion

Knowledge of the Classical Orbital Knowledge of the Classical Orbital Elements.Elements.

Understand how to design a Understand how to design a communication architecture for a communication architecture for a satellite or group of satellites.satellite or group of satellites.

Know the difference between a Know the difference between a constellation and a single satellite.constellation and a single satellite.

Simulations with the STK software Simulations with the STK software are very accurate.are very accurate.