Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-3 Summary Vacuumsolar UV degradation contamination Neutral:Mechanical effects (aerodynamic drag, physical sputtering) chemical effects (atomic oxygen attack, spacecraft glow) Plasma:Spacecraft charging (shift in ground potential) Electrostatic charging (dielectric breakdown, gaseous arc discharges Radiation:Total dose effect (solar cell, sensor, electronics degradation) single event effects (upsets, etc….) Micro-meteorites and Debris:Mechanical damage EnvironmentEffects

Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-3 Orbit Types Geosynchronous Orbit (GEO): ~35,800 km Mid-Earth Orbit (HOE): km Low Earth Orbit (LOE):less that 1000 km Earth Sun

Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-3 Spacecraft Subsystems Attitude determination and control: Vehicle Stability and pointing control Avionics:Data and command relay to payloads subsystems Electrical Power: Power generation and distribution Propulsion:Maneuver vehicle into desired orbit Structure:Integrity during launch and maneuver Telemetry, tracking and communication: Command and data handling with the ground Thermal control: Maintain temperature balance

Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-3 Example: A typical Geostationary communication satellite Station-keeping:Contains thrust and stabilization subsystems (control of orbital altitude, position, and direction) Power sub-system:contains electronics to convert solar power to electrical and supply power the vehicle Command and telemetry:transmits data to Earth receives commands from earth Antenna:serves to transmit and receive data Transponder:receive signals, amplify, change frequencies, and re-sent the signal to Earth

Gamma ray observatoryX-ray observatoryExtreme UV UVVisibleIRMicro-wave Some Satellites on Orbit September 30,2003 H. Kirkici Istanbul Technical University Lecture-3 Space Environment

September 30,2003 H. Kirkici Istanbul Technical University Lecture-3 A typical satellite orbit in LOE (Speed: ~ 8km/s) Day and night time line on Earth

Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-3 HW-1 Due Date:October 1, Give names of at lest for 4 orbital satellite subsystems in a typical communication satellite. 2.Describe the functions of these subsystems listed above in few sentences. 3.When was the last solar storm observed (give the month and year), and what effects were observed by scientism due to this storm on Earth or on satellites?

Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-3 QUESTIONS?