The Union Recorder

January 29, 2014

OUR SPACE: TDRS L: Welcome to the club!

The Union-Recorder

MILLEDGEVILLE — On Thursday night NASA launched the TDRS L communications and data relay satellite. It’s another one of those infamous NASA acronyms, as you can see, but everybody pronounces it “teed-riss”.

Chances are you don’t have a clue what our pal “Teedriss” actually does. Never fear, you’re in good and plentiful company. As its name implies, TDRS satellites are communications relay satellites. They pick up signals from spacecraft out there and pass it on to a receiver on Earth. They are the all-important “middle men”. It would be lovely if every spacecraft could beam its data stream directly to a dish here on Earth. But that’s just impossible, because you don’t always have a ground station in your “line of sight”. And if you do, it’s gone again within minutes or even seconds.

And that’s where the TDRS system comes in. Since it’s a geostationary on-orbit system it has far greater access to ground stations than any deep-space or mission-specific craft, as it is always in connection with several of them, depending on where it is.

TDRS satellites are named in order of the letters of the alphabet. TDRS B was lost when the space shuttle Challenger blew up. All the others made it and hardly ever made the headlines – a fairly common fate of those utilitarian communications workhorses. As older team members drop out of service new replacements are being launched.

TDRS satellites are lifelines between the ISS and Earth, as well as many other spacecraft out there, like the Hubble space telescope. The L spacecraft is a third-generation model, able to communicate with New Mexico’s White Sands facility, bringing yet more flexibility to the network. The next member of this chatty family, TDRS M, is scheduled for launch in 2015.

Thursday’s launch had a major nail-biting moment just minutes before launch. Telemetry communication from the spacecraft on top of its rocket had suddenly become spotty and the countdown was halted as per protocol. After initiating the appropriate discussions on what might be the problem the launch team determined that the problems started when communications switched from a hard line that was directly plugged into the rocket to radio communications. Once they switched back the problem disappeared so it was decided to stay on the hard line right up to the launch, and after everything was reset the rocket lifted off with a half-hour delay but still well within its launch window.

From there on out it was a textbook launch with all the excitement of a mission going well. The weather was exceptional – clear skies and dry air, which made for fabulous viewing conditions. Ground-based cameras were able to clearly film the launch vehicle until it went out of visual range several minutes after launch.

TDRS-L then entered a preliminary highly elliptical orbit, coasted for over an hour and the re-fired its upper stage to circularize its orbit and bring it into its geostationary parking spot.

The newest member of this 30 year-old club is being welcomed with open arms by the entire space-faring community. It’s nice to know we can keep those awesome Hubble images coming!

Check out the TDRS website at


Beate Czogalla is the Professor of Theater Design in the Department of Theatre and Dance at Georgia College & State University. She has had a lifelong interest in space exploration and has been a Solar System Ambassador for the Jet Propulsion Laboratory/ NASA for many years. She can be reached at