When Mars rovers phone home, their calls are routed through NASA's Deep Space Network (DSN), which has been operating for 40 years.

The network includes three stations: California; Canberra, Australia; and Madrid, Spain. The worldwide positions allow round-the-clock communications with spacecraft as Earth rotates.

This 230-foot-wide (70-meter) antenna is the largest and most sensitive in the system. It sits in California's Mojave Desert at the Goldstone complex. It can track a spacecraft that's more than 10 billion miles (16 billion kilometers) away. The network is used to track all NASA spacecraft and some missions of other countries, too, including the current European Mars Express orbiter.