Читать книгу Foundations of Space Dynamics - Ashish Tewari - Страница 17

Space flight requires a definite background of objects to measure distances, as well as to orient the spacecraft in specific directions. Since fixed objects are hard to come by in practice, navigation and attitude determination are non‐trivial problems in space flight. Such a problem does not exist for the motion taking place on, or very close to, a solid surface, where ground‐fixed objects can serve as useful references for both navigation and orientation of the vehicles.

Figure 1.3 The equinoctial sidereal frame , the ecliptic synodic frame , and Earth centred celestial meridian.