How do deep-space probes keep sending data back from billions of kilometers away?

Signals from deep-space probes are incredibly weak by the time they reach Earth, so spacecraft use carefully aimed antennas and efficient transmitters. On Earth, agencies such as NASA rely on the Deep Space Network, a set of giant radio dishes in California, Spain, and Australia spaced around the globe. These antennas can track spacecraft continuously as Earth rotates and can receive extremely faint signals. The result is that probes like Voyager, New Horizons, and Mars orbiters can keep transmitting scientific data across enormous distances.