How do we communicate with spacecraft

Radio Communication:
Radio waves have been the workhorse of spacecraft communication for decades. The process involves transmitting and receiving radio signals between a spacecraft and Earth-based antennas. The spacecraft is equipped with a communication system that includes an antenna for transmitting and receiving radio signals. Ground-based antennas, often part of large networks like NASA's Deep Space Network (DSN), are strategically positioned around the globe to ensure continuous coverage.

The spacecraft sends signals encoded with data, such as images, telemetry, scientific measurements, and commands, using specific radio frequencies. These signals travel through space and are picked up by the ground antennas. The ground stations use high-sensitive receivers to capture the weak signals from far-off spacecraft.

Data Modulation:
To transmit data effectively, various modulation techniques are used to encode information onto the radio waves. Modulation methods include phase-shift keying (PSK), frequency-shift keying (FSK), and more advanced methods like quadrature phase-shift keying (QPSK) and binary phase-shift keying (BPSK). These methods help to transmit more data within a limited frequency bandwidth.

Deep Space Network (DSN):
The Deep Space Network is a global network of ground-based antennas operated by various space agencies, including NASA. These antennas are positioned at locations around the world to ensure continuous communication with spacecraft throughout their journeys, even when they're on the far side of planets or deep in space. The DSN provides the necessary infrastructure to communicate with spacecraft in deep space.