How Scientists Communicate With Satellites In Space

How does an earth station talk to and steer a satellite?

- Rekha Dixit

HOW DO SCIENTISTS sitting in their control centres on earth talk to a satellite in deep space? How do they “drive” the satellite to its destination, on a surface several thousand kilometres away?

Once a satellite separates itself from its rocket, the first step in establishing communication is to know its location. For that, a simple radar is good enough. The radar sends a pulse, much like a torch illuminating a dark section of the room. The satellite reflects back that pulse, and thus, becomes “visible” on the radar. Scientists can track the movement of the satellite by adjusting the radar. The distance between the satellite and earth can be calculated from the time taken by the signal to hit the satellite and return.