The White Sands Complex in Las Cruces, New Mexico, comprises several antennas that provide communications to spacecraft as part of NASA’s Space Network. Credit: NASA
SGSS, SN, ACCESS, NSN 

NASA Modernizing Ground Stations to Ensure Longevity

Upgrades Make Communications Services More Robust

By Matthew D. Peters

October 16, 2020

This blog post was written prior to a reorganization of ESC’s projects and networks in support of the agency’s commercialization effort. Though accurate at the time of publication, it is no longer being updated and may contain broken links or outdated information. For more information about the reorganization, click here.

NASA is comprehensively modernizing Space Network ground stations to enable continued radio frequency communications services to science and exploration missions in low-Earth orbit. This upgrade effort, known as the Space Network Ground Segment Sustainment (SGSS) project, will secure the Space Network’s longevity, and meet the changing needs of user missions.

Through the Tracking and Data Relay Satellite (TDRS) constellation’s unique geometry in geosynchronous orbit, 22,000 miles above Earth’s equator, the Space Network transmits data using radio frequency, which NASA has utilized since the earliest days of space exploration. The TDRS’ orbit is the same as the speed as Earth’s rotation, allowing a direct line of sight from a TDRS to a ground antenna at all times. Missions transmit their data to a TDRS, then the TDRS relays the signal to the ground antennas. This data is then forwarded on to scientists and researchers who make key discoveries about our world and the solar system.

Thirteen ground antennas at the White Sands Complex in Las Cruces, New Mexico, are receiving upgrades. SGSS recently enhanced antennas to be able to transmit and receive using both the Ku- and S- radio frequency bands. These are areas of the radio frequency spectrum suitable for communications in different scenarios. Ku-band is used to carry user data to and from the mission. The addition of S-band capabilities improves TDRS tracking, telemetry, and command by allowing communications to the TDRS in the event Ku-band becomes unavailable. These recent enhancements allowed SGSS to begin testing the upgrades with user missions, to ensure the enhancements are working correctly and that impact to missions are minimized.

As part of the upgrade, previously analog signals will be converted to digital which will eliminate data degradation as the signals travel through the system, so that more data reaches its destination intact. Data rates and volumes will be increased so that the system can send more data in less time than through the legacy system, enabling support to future missions with high data requirements. User coverage will also be improved so that the network will be available to individual users more frequently, increasing the possibilities for more discoveries.

SGSS’s extensive upgrades are being completed while the Space Network remains operational so as not to affect user support. An upgrade effort of this size has never been attempted without interrupting operations. This is like trying to upgrade your home computer for a faster internet connection while on a video call.

Performing this extensive upgrade without interruption is essential. The Space Network supports over 40 missions, including the Hubble Space Telescope and the International Space Station, satellites that gather climate data, and missions that expand our understanding of our solar system. Without the Space Network, missions could not get their data back to Earth.

As a result of the advancements, the Space Network’s new system will be simpler to maintain and operate. Many of the new components are commercially available, as opposed to the custom made components of the legacy system which will lower future upgrade costs. The improvements will also raise system security, and provide more robust training resources for engineers who operate the network. All of this is in service of ensuring the Space Network’s important communications services will be available to science and exploration missions for many more years to come.

The SGSS project is based at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Goddard’s Exploration and Space Communications projects division manages both SGSS and NASA’s Space Network with NASA’s Space Communications and Navigation program office providing programmatic oversight. To learn more about SGSS, visit: https://sgss.gsfc.nasa.gov.