Spacecraft are vehicles or machines sent to outer space to study other planets and asteroids; for instance, Juno (for Jupiter), Mangalyaan (for Mars), etc.
So, how do we, on Earth, talk to these spacecraft so far away?
This is done using the Deep Space Network (DSN). DSN is a collection of big radio antennas.
Spacecraft sends signals with information and pictures to Earth with the help of these antennas. The farther away a spacecraft is, the larger the antenna you need to detect its signal.
While China, Russia, Europe, Japan and India also have their own DSN, NASA’s is the largest. It has twelve antennas, which are located in Madrid (Spain), Goldstone (US) and Canberra (Australia).