New NASA Communications Satellite Bridges Legacy, Future Technologies

NASA’s new TDRS-K communications satellite, built by Boeing, features new electronics and better power management to serve future space missions.

The TDRS constellation adds to its lifetime, but NASA planners already are looking at revolutionary technologies for the subsequent generation of orbiters.

The latest generation Tracking and Data Relay Satellite, known as TDRS-K, updates existing technology with an eye to the future. New electronics and better power management will help extend the TDRS constellation for at least another decade, but NASA already is looking ahead to major changes in the system’s capabilities that would define the next-generation TDRS.

The new TDRS-K, which launched last week, comes at a time of transition for NASA and manned spaceflight. The constellation originally was orbited to provide connectivity between Mission Control and space shuttle missions. It later served to communicate with the International Space Station, and this continues with ongoing station operations. But shuttle operations ended nearly two years ago, and NASA has ceded future low-earth-orbit human space missions to the commercial sector.

Jeffrey Gramling, TDRS project manager, says that future commercial human launches should be able to interoperate with TDRS. NASA currently supports many existing commercial launch vehicles, and the agency is working with prospective manned launch companies on their programs. “We expect that, whatever direction we go with manned spaceflight, there certainly will be a role for TDRS in the mix,” he states.

Gramling explains that TDRS-K takes advantage of technology advances that have occurred since the previous generation of TDRS orbiters—TDRS H, I and J—were built. These advances include new payload electronics and better solar panels. In some cases, entirely new electronics suites needed to be designed because the electronics built for the previous generation of satellites had become obsolete and no longer were available.

Many older TDRS satellites lasted well beyond their design lifetime, but the remaining orbiters were pushing the limit. The new TDRS K-M series of satellites are designed to continue constellation functions and serve whatever future missions may emerge over the next decade.

NASA planners already are looking at what may lie ahead for the next TDRS generation, Gramling allows. These orbiters may employ advanced technologies such as optical communications. Given development and procurement timetables, these futuristic satellites probably would be launched no earlier than 2022, especially given their prospective technology advances. “I expect the next generation to make leaps into newer and different communications domains,” Gramling states.

While TDRS-K represents an improvement over its immediate progenitors, it also returns to a data-processing approach that characterized the first seven TDRS orbiters. Where the three most-recent TDRS satellites formed multiple access return beams onboard, for TDRS-K those beams are formed on the ground station at White Sands, New Mexico, as was done with the early TDRS satellites. This saved spacecraft weight and power, Gramling notes, but it also arose from changes since the last TDRS satellites were built.

TDRS-K continues the H-J function of providing S-, Ku- and Ka-band service to the satellite’s two single access antennas. But, when personnel at the White Sands ground station added demand access service, that permitted a user to put a beam former at White Sands for generating a full-time signal. Doing that mandated ground beam forming, Gramling explains, so that function was returned to Earth.