The 24 GPS satellites carry atomic clocks to accurately measure and transmit time information to GPS receivers on Earth. This is essential for determining precise location and navigation information.
Atomic clocks use the natural oscillations of atoms as a timekeeping mechanism, making them much more accurate than regular clocks which rely on mechanical movements. They are also able to maintain their accuracy over long periods of time.
Each GPS satellite carries four atomic clocks, two rubidium and two cesium, to ensure redundancy and accuracy in timekeeping. This means there are a total of 96 atomic clocks on the 24 GPS satellites.
The GPS system uses the time information transmitted from the atomic clocks on the satellites to calculate the distance between the receiver and each satellite. By using the distance from at least four satellites, the GPS receiver can determine its exact location on Earth.
The accuracy of the timekeeping on GPS satellites is crucial for the functioning of the entire GPS system. Even a small error in time can result in a significant error in location calculation, making precise navigation impossible. Therefore, the atomic clocks on the satellites are constantly monitored and corrected to ensure accuracy.