By: Jefferson Morris

A group of industry and government researchers are working to improve communications to and from the International Space Station (ISS).

The current ISS communications systems are not substantially different from those that have been flying on the space shuttle for 20 years, according to David Beering, principal partner at Infinite Global Infrastructure, LLC (IGI), who is part of the modernization effort.

Speaking at a satellite Internet conference in Arlington, Va. June 13, Beering said he and his partners hope to improve three things.

"One is the quality of life for the astronauts and cosmonauts and crewmembers on the International Space Station," he said. Another is "to improve the quality of science on that platform. And then finally, to improve our usage and NASA's usage of national assets, and improve the efficiency of these assets."

Current systems

The current ISS communication system design dates back 10 to 15 years, Beering estimates, when it was conceived as part of the Space Station Freedom program.

The primary communication system is an S-band system that handles critical commands and telemetry.

Beering and his colleagues are working to upgrade the payload communication system, which operates in the Ku-band through NASA's Tracking and Data Relay Satellite System (TDRSS).

Right now, the ISS payload communication system sends data through TDRSS satellites to a ground station in White Sands, N.M.

TDRSS is a highly asymmetrical "bent pipe" system, capable of relaying data to the Earth (the "return" link) at a rate of 50 megabits per second (Mbps), and uplinking data to the station (the "forward" link) at a rate of 3 Mbps.

Once they reach the ground, the signals are relayed from White Sands to the DOMSAT satellite, which beams them back down to various NASA centers.

The improvements

Despite its vintage, the ISS system is fairly robust in its capability, featuring a Ku-band transponder that is 225 MHz wide. "For anybody who works in commercial satcom ... that's a big, fat transponder," said Beering.

The key is to take better advantage of this capability, which mostly involves upgrading and reconfiguring ground equipment, according to Beering.

"What we're hoping to do, in our design, is basically to get rid of that second satellite link, because it adds a lot of delay," he said.

The proposed new system would have a return link of 155 Mbps and a forward link of 6 Mbps. Data would be relayed terrestrially from White Sands directly to the NASA centers, without having to use any other satellite links.

In addition to streamlining and generally speeding things up, this higher forward link speed will allow astronauts to send high-quality video to Earth - a capability the station doesn't currently have.

"This is a really important capability for us to bring to this environment," Beering said.

Beering says making the station HDTV-friendly will not only enable a variety of educational programs, but more importantly, could "provide scientists a very, very high definition view of their science," said Beering.

Demo at NAB

The architecture of the improved system was demonstrated at the National Association of Broadcasters (NAB) convention in Las Vegas, Nev. in April, with the Naval Research Laboratory (NRL) in Washington, D.C. standing in for the ISS.

The team relayed distribution-quality HDTV (about 20 Mbps) from NRL to White Sands, NM, via TDRSS. The signal was then sent via wide area network (WAN) to a satellite uplink facility and re-broadcast for wide distribution via Boeing's Telstar 6 satellite.

Contribution-quality HDTV (about 45 Mbps) was sent from NRL to White Sands, and then directly to Las Vegas via WAN.

Money trouble

The modernization work has so far been funded under the Consolidated Space Operations Contract (CSOC) - a 10-year, $ 3.5 billion Lockheed Martin contract for the management of NASA's data collection, telemetry, and communication operations. IGI is a sub-contractor for CSOC, under prime contractor Lockheed Martin.

Unfortunately, station funding overruns have left little money aside for communication modernization. "When you get into that kind of environment, the mindset focuses on the safety, and the actual structure, rather than on optimization and science missions and trying to make the comm system better," said Beering.

He said IGI is negotiating with a number of commercial companies in an attempt to bring in some commercial funding so his team can "actually build the thing."