Question

Why are there 30 GPS satellites orbiting the Earth?

a) To provide the power necessary to send out high-amplitude waves to GPS devices.
b) If there were fewer, they'd be overloaded with information from all the GPS devices on Earth.
c) So that four satellites are above the horizon everywhere on Earth at all times.
d) 15 provide coverage for all the GPS devices on Earth; the other 15 provide backup in case the main ones break down.

Answer 1

The 30 GPS satellites orbiting the Earth provide global coverage and ensure at least four satellites are visible from any spot on Earth. A precise atomic clock on each satellite allows GPS receivers to calculate positions based on the time it takes signals to reach them.

Step-by-step explanation:

The 30 GPS satellites orbiting the Earth are there to provide global coverage and ensure that at least four satellites are above the horizon everywhere on Earth at all times.

Each satellite carries a precise atomic clock, and your GPS receiver detects the signals from those satellites that are overhead and calculates your position based on the time it has taken those signals to reach you.

The synchronization of the atomic clocks on the satellites is essential for the accuracy of GPS, as relativistic effects need to be taken into account. If the clocks were not synchronized with high accuracy, GPS units would lose their accuracy in a matter of minutes.