Two NASA radios aboard the European Space Agency's Mars mission are engineered to provide communication relay service for rovers and landers on Mars. ESA's ExoMars 2016 mission, combining the Trace Gas Orbiter (TGO) with the Schiaparelli landing demonstrator, began a seven-month journey to Mars. The twin Electra UHF (ultra-high frequency) radios from NASA are slated for a first in-flight test in about six weeks.

"This partnership with Europe will strengthen and extend the existing infrastructure at the Red Planet for orbiters to support assets on the surface," said Phillip Barela of NASA's Jet Propulsion Laboratory, Pasadena, California, project manager for NASA's participation in ExoMars.

NASA is on an ambitious journey to Mars that will include sending humans to the Red Planet. Current and future robotic spacecraft are leading the way and will prepare an infrastructure in advance for human missions.

TGO's Electra radios use a design from JPL with special features for relaying data from a rover or stationary lander to an orbiter passing overhead. Relay of information from Mars-surface craft to Mars orbiters, then from Mars orbit to Earth, enables receiving much more data from the surface missions than would otherwise be possible.

As an example of Electra capabilities, during a relay session between an Electra on the surface and one on an orbiter, the radios can maximize data volume by actively adjusting the data rate to be slower when the orbiter is near the horizon from the surface robot's perspective, faster when it is overhead.

NASA's Curiosity Mars rover and Mars Reconnaissance Orbiter (MRO) already use Electra technology for relay of data. NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, in orbit since 2014, also carries an Electra radio.

Due to improvements in the newest Electra radios and reduced interference levels compared with MRO, TGO's relay radios are expected to have a relay signal about twice as strong as MRO's. Compared to MAVEN's highly elongated orbit, TGO has a planned orbit similar to MRO's relay-favorable orbit at about 250 miles (400 kilometers) in altitude and nearly circular in shape.

TGO's main X-band radio will use a dish antenna 87 inches (2.2 meters) in diameter to communicate with Earth-based antenna networks operated by ESA, NASA and Russia.