About: Triad method

The Triad method is one of the earliest and simplest solutions to the spacecraft attitude determination problem. Given the knowledge of two vectors in the reference and body coordinates of a satellite, the Triad algorithm obtains the direction cosine matrix relating to both frames. Harold Black played a key role in the development of the guidance, navigation, and control of the U.S. Navy's Transit satellite system at Johns Hopkins Applied Physics Laboratories. Triad represented the state of practice in spacecraft attitude determination before the advent of Wahba's problem and its several optimal solutions. Covariance analysis for Black's solution was subsequently provided by Markley.