Worldwide ground-based tracking stations comprise NASA's Near Earth Network, which connects scientists and mission controllers to critical spacecraft data. More than 20 tracking sites around the globe provide the communications link that allows more than 40 missions to transfer their data to Earth.

Missions using the Near Earth Network may require daily or even hourly contacts with NEN resources, and the network rises to the challenge, averaging between 120 and 150 spacecraft contacts a day to bring data securely to mission operations centers on Earth. The NEN supports not only robotic missions, but also human exploration through their Launch Communications Segment in Florida.

The NEN provides space communications support to spacecraft in multiple orbits, including low-Earth orbit, highly elliptical orbits, lunar orbit and even orbits around the sun-Earth libration points, up to a million miles from Earth.

The NEN provides science data transfer, but also support for important functions like telemetry, tracking and command. Telemetry, tracking and command assist with the “housekeeping” functions of a spacecraft that enable optimal operation for long periods of time. These services allow operators on the ground to do things like track a spacecraft's location, adjust its orbit, perform a system back-up and more.

The NEN provides these services across multiple radio frequency bands: VHF, S-band, X-band and Ka-band, depending on the data rates needed by each mission for various functions. For more information about the NEN's services, see Our Services.

The Near Earth Network continually develops and constructs new antennas and ground-based resources to support the increasing demands of new missions. For future spaceflight missions, the NEN is currently adding construction of new antennas in Alaska, South America and Africa that would provide data rates as much as 10 times better than previous systems, a huge leap in data transfer capability.

Additionally, the NEN is developing and incorporating numerous next-generation technologies into the network, including Ka-band arraying, disruption-tolerant networking (DTN), CubeSat accommodations, and more.

Ka-band arraying enables two or more NEN antennas to function as one larger antenna, capable of receiving science data at higher data rates than either could alone.

The NEN will adopt DTN technology, which will allow the network to store and forward data if there are any interruptions in network availability along the path back to Earth.

The NEN is exploring concepts to become more accommodating for CubeSat missions, which could become numerous, with constrained budgets, and limited spacecraft size, weight and power (SWaP) available for communication and navigation.

Ground-based communications networks formed the cornerstones of NASA's Goddard Space Flight Center, where the NEN is headquartered, in the 1950s and 1960s. Over 50 years, these networks have provided critical space communications support to hundreds of NASA spacecraft, allowing them to "phone home" The NEN evolved from this storied history. The network has existed in its current incarnation since the 1990s and has evolved over time, particularly incorporating more commercial ground stations, to meet the changing needs of its many customers.

Today's NEN is a trusted provider of reliable services for many science missions.