The position of a spacecraft orbiting the Earth or travelling through interplanetary space. Both positions are expressed in angles. The position of an Earth satellite is measured by the angles of the deep-space stations (antennae) pointing at it. The location of a vehicle in distant space can be determined by precision ranging using the angular measurements of two widely separated deep-space stations or by the process of very long-baseline interferometry. The measurements are accurate to thousandths of a degree.