This book presents fundmentals of orbit determination--from weighted least squares approaches Gauss to today's high-speed computer algorithms that provide accuracy within a few centimeters. Numerous examples and problems are provided to enhance readers' understanding of the material. *Covers such topics as coordinate and time systems, square root filters, process noise techniques, and the use of fictitious parameters for absorbing un-modeled and incorrectly modeled forces acting on a satellite. *Examples and exercises serve to illustrate the principles throughout each chapter. *Detailed solutions to end-of-chapter exercises available to instructors.