NASA spacecraft have studied Earth and the surrounding universe for more than 60 years, making ground-breaking discoveries and enabling human exploration. From hundreds, thousands and millions of miles away, these spacecraft must send their critical information back to Earth and the scientists who can use it.
That’s where NASA’s three space communications networks come in. Each of these networks covers a different portion of the sky, from just hundreds of miles from Earth’s surface to interstellar space. They also use different infrastructure and technology to enable different kinds of missions.
Earth-observing satellites provide important information about different aspects of our planet, including precipitation, ice cover, soil moisture, ozone, air quality and much more. These observations help with agriculture, climate monitoring, and natural disaster monitoring, to name just a few. Most Earth-observing spacecraft are in low-Earth orbit, meaning that they circle the Earth within about a thousand miles of the surface. Many orbit over Earth’s poles.
These missions frequently use NASA’s Near Earth Network (NEN) to communicate their data to the ground. The NEN is composed of more than 14 ground stations, comprising more than 25 antennas, worldwide. These upload and download information to and from spacecraft while they are within direct line of sight of the antenna, crossing from horizon line to horizon line.
Communications is perhaps most critical in human spaceflight, when human lives depend on being able to exchange information with mission controllers on Earth. NASA’s networks support the International Space Station, several commercial cargo vehicles, and will support commercial crew and NASA’s Orion crew vehicle in the future. NASA’s Space Network (SN) currently transmits most human spaceflight data, including astronaut communications with Mission Control and even data about the spacecraft’s health and telemetry. Data from science and technology experiments also come down to Earth through the SN.
The SN is so named because it is currently NASA’s only space communications network that employs satellites to transmit data. Tracking and Data Relay Satellites (TDRS) circle Earth in geosynchronous orbit, an orbit about 22,000 miles from Earth’s surface that allows them to remain stationary over one spot on the planet. Because of this orbit, these satellites are always within line of sight of an antenna on the ground. They are placed in key positions around Earth, meaning that one TDRS is always within line of sight of a low-Earth-orbiting spacecraft. This allows the SN to provide 24/7/365 continuous communications coverage, which is crucial to human spaceflight.
NASA is blazing a trail to take humans back to the Moon in the coming years, and then onward to Mars. Teams across the agency are working on both robotic science missions and human exploration missions and technology to make this goal possible.
Two of NASA’s space communications networks will potentially play a key role in making exploration of these distant destinations possible. Current robotic missions at the Moon, such as the Lunar Reconnaissance Orbiter, commonly use the NEN to transmit data to and from Earth. With its global network of ground-based tracking stations, the NEN can support missions from low-Earth orbit to lunar orbit and beyond.
The Deep Space Network (DSN) also plays a key role in these missions. Like the NEN, the DSN is composed of ground-based antennas and ground stations around the world. The DSN’s antennas are huge – as much as 230 feet (70 meter) in diameter – and are placed at three key locations every 120 degrees around the globe, in Madrid, Spain; Canberra, Australia; and Goldstone, California. The placement of the antennas ensures that spacecraft can reach an antenna no matter where they are located in relation to Earth. The DSN primarily supports interplanetary missions, such as the ones currently at Mars.
Beyond Mars, NASA missions explore the farther reaches of our solar system, from Jupiter all the way out to interstellar space. These missions are key to learning more about our solar system and the universe beyond, and even looking for life on other worlds.
The DSN supports these interplanetary probes through its international network of giant antennas, providing long contacts for spacecraft to send home their data over vast distances.
NASA also employs a number of spacecraft in low-Earth orbit, such as the Hubble Space Telescope, to make observations of the universe beyond our solar system. These missions rely primarily on the SN for their data coverage, allowing them to send back data at any time during their missions.
In addition to supporting spacecraft operations, SCaN develops cutting-edge technology to enable the missions of tomorrow. Currently, SCaN is exploring a wide range of new communications and navigation technologies as part of their Decade of Light initiative. In the coming years, SCaN will launch a number of optical communications missions, using infrared waves to send 10 to 100 times as much data at a time as current systems.
Additionally, SCaN is moving into the future by integrating artificial intelligence, quantum communications, pulsar navigation, X-ray communications and navigation, and more into their portfolio to support NASA missions as they collect more data and explore farther than ever before.
Space communications and navigation is an integral component of NASA’s vision to discover and expand knowledge for the benefit of humanity, serving as the conduit to transmit each mission’s important observations back to Earth.