방법 비교

	SGP4 TLE 전파	B-Dot 제어기	TCAS
분야	항공우주공학	항공우주공학	항공우주공학
계열	Process / pipeline	Process / pipeline	Process / pipeline
기원 연도	1970s	1980s	1989
창시자	NORAD, USAF	Spacecraft attitude control engineers	FAA, ICAO
유형	Propagation method	Control law	Avionics system
원전	Vallado, D. A., Crawford, P., Hujsa, R., & Kelso, T. S. (2006). Revisiting Spacetrack Report Number 3. In AIAA/AAS Astrodynamics Specialist Conference.	Wertz, J. R. (Ed.). (2002). Spacecraft Attitude Determination and Control. Kluwer Academic.	Federal Aviation Administration (2017). Traffic Collision Avoidance System (TCAS II). Technical Standard Order TSO-C119c.
별칭	SGP4, TLE propagation, simplified perturbations	B-dot control, magnetic damping, momentum dumping	TCAS II, ACAS, traffic avoidance
관련	3	3	3
요약	SGP4 (Simplified General Perturbations 4) is a rapid orbital propagation method that predicts satellite position and velocity from Two-Line Element (TLE) sets published by NORAD. Developed in the 1970s, SGP4 accounts for atmospheric drag, gravitational perturbations, and solar radiation pressure using simplified analytical models. SGP4 is the de facto standard for space surveillance, conjunction assessment, and satellite tracking.	The B-Dot controller (magnetic B-dot control law) is a simple, robust spacecraft attitude control method that uses the rate of change of Earth's magnetic field measured onboard to generate a magnetic dipole moment. Developed in the 1980s, the B-Dot law damps spacecraft angular momentum without requiring a complex attitude estimate or external reference, making it ideal for initial momentum dumping after launch or in contingency scenarios. B-Dot is passive, simple to implement, and effective.	TCAS (Traffic Collision Avoidance System) is an airborne safety system that detects nearby aircraft using radar and mode C altitude reports, then provides traffic advisories (TAs) and recommended collision avoidance maneuvers (RAs) to flight crews. Mandated globally on commercial aircraft since 2000, TCAS is considered a last line of defense against mid-air collisions. TCAS II is the most common variant; TCAS I is a simplified advisory-only version for general aviation.