It was whom Houston called when they had a problem.
As the International Space Station (ISS) celebrates the 15th anniversary of the launch of its first element, the Russian Zarya module, NASA's Dryden Flight Research Center continues its vital role as an emergency communications relay for the station.
The communications relay was originally set up in support of the Mir space station, a Russian predecessor to the ISS, in 1995. The Dryden communication team developed a low-cost system consisting of modified commercial equipment to provide inexpensive communications support for the Mir when U.S. astronauts were on board. The system was then installed at two other NASA sites, the White Sands Test Facility in New Mexico and the Wallops Flight Test Facility in Virginia, to expand the ground network coverage. The three sites continue to support communications between mission control at the Johnson Space Center (JSC) and the space station today.
Michael Yettaw, Dryden's communications facility work leader, recently recalled an intense instance when Dryden provided critical communication to the station in 2002.
The positioning systems on the ISS went down putting the station in a free-drift state. The station started to slowly rotate, disabling the primary means of communications. Also, the solar arrays were no longer charging the station's power systems and the station would have gone dark if nothing was done.
During those critical moments, mission control used Dryden's Western Aeronautical Test Range's emergency communications link to transmit the instructions to the space station's crew.
With only 20 minutes notice, Justin Thomas, a communications technician, was able to set up the space communications link in 10 minutes. Dryden was able to relay the repair instructions before the other two emergency sites because of the location of the ISS.
Despite the potential danger the space station and crew were in, the calm and professional demeanor of the ISS crew and Johnson Space Center's ISS support team during the situation impressed Yettaw.
“It was like something out of the 'Right Stuff' movie,” he said. "Hours and hours of routine operations punctuated by moments of intense activity. Matter of fact, they could teach actors how to act calm under duress."
Dryden provided similar emergency support to the Mir. Yettaw recalls a time when the Russian space station lost all power after a docking crash with a Progress cargo spacecraft. The cosmonauts moved into the Soyuz spacecraft to initiate an emergency undocking and return to Earth. The Russian mission control center in Moscow was able to uplink repair instructions through Dryden to the cosmonauts to restore the Mir.
"That 10 minutes of Mir emergency support was one of the highlights of my 30-year career at NASA," Yettaw said.
In early 2007, the Dryden range communications team was again contacted to resolve an ISS issue. Astronauts were installing new cables routing communications for spacecraft dockings, and Houston needed a way to test them from the ground before the next space shuttle mission to the station.
"When the ISS chief engineer advised me that new UHF cables were being installed on-board and (they) needed a way to verify it, he asked if there was anything on the ground that could be used to verify the installation prior to the space shuttle getting in vicinity of the station or astronaut EVA (extra-vehicular activity) outside," said Joe Whitney of the Ground Control Office at Johnson Space Center's Mission Control Center in a follow-up e-mail to Larry Schilling, Dryden's Associate Center Director for Operations at that time.
"I immediately thought of DFRC. DFRC always provides top notch communications support for both the Space Shuttle Program and ISS, and I knew that if it could be done, DFRC could do it," Whitney continued. "I began a few chats with Yettaw and once it sounded doable, we proceeded with … the support."
Yettaw expanded the frequency range of the Dryden directional antennas during a routing upgrade that allowed Dryden to be uniquely qualified to support the new requirement.
The Dryden team combined the existing antennas and spectrum analyzers with a $29 TV amplifier to field a low-cost transmitter test system. Dryden successfully validated the ISS modifications during several orbital engineering support passes in time for the next space shuttle launch.
The Dryden communications support team has received numerous awards including the Exceptional Service Award, the Exceptional Engineering Award, the Manned Spaceflight Support Award, the STS Silver Snoopy and the STS Orbit and Landing Group Achievement Award.
"It's a good feeling," Yettaw said, "to be recognized for what our team does"
Sam Smith, public affairs
NASA Dryden Flight Research Center