Overview

A satellite is a telecommunication device that placed in space. A satellite vehicle (SV) is an object that contains communication electronics that revolves around another object of greater mass (such as the Earth). The satellite has a motion that is determined by the force of attraction (gravity) of the larger object. Satellites contain power systems, attitude (position) control systems, and communication equipment.

GPS satellites are a combination of a receivers and transmitters (transponders) that receive a signal from an Earth station (uplink) and retransmits it to GPS receiving stations (downlink). They are located at 17,700 km (approximately 11,000 miles) above the surface of the Earth and travel at approximately 7,000 kilometers per hour.

Each GPS satellite transmits two frequencies with 20 to 50 Watts of RF power. GPS satellites are assigned a space vehicle number that uniquely identifies each satellite. The satellites transmit unique reference codes.

The design life (life span) is the operational time a device or system that is expected to operate within a performance level or set of characteristics. For satellite systems, a key design life limitation is by the amount of propulsion fuel that is used to keep the satellite in its desired orbital plane. Most of the satellite attitude propulsion fuel is used to initially position the satellite into its desired orbit.

The life span of GPS satellites has increased from 4.5 years [1] on the original Block I satellites to more than 11 years on the new Block IIR satellites.

The weight of...