On Nov. 22, 2016, a NASA radio aboard the European Space Agency's (ESA's) Trace Gas Orbiter, which arrived at Mars the previous month, succeeded in its first test of receiving data transmitted from NASA Mars rovers, both Opportunity and Curiosity.

This graphic depicts the geometry of Opportunity transmitting data to the orbiter, using the ultra-high frequency (UHF) band of radio wavelengths. The orbiter received that data using one of its twin Electra UHF-band radios. Data that the orbiter's Electra received from the two rovers was subsequently transmitted from the orbiter to Earth, using the orbiter's main X-band radio.

The Trace Gas Orbiter is part of ESA's ExoMars program. During the initial months after its Oct. 19, 2016, arrival, it is flying in a highly elliptical orbit. Each loop takes 4.2 days to complete, with distances between the orbiter and the planet's surface ranging from about 60,000 miles (about 100,000 kilometers) to less than 200 miles (less than 310 kilometers). Later, the mission will reshape the orbit to a near-circular path about 250 miles (400 kilometers) above the surface of Mars.

Three NASA orbiters and one other ESA orbiter currently at Mars also have relayed data from Mars rovers to Earth. This strategy enables receiving much more data from the surface missions than would be possible with a direct-to-Earth radio link from rovers or stationary landers. Successful demonstration of the capability added by the Trace Gas Orbiter strengthens and extends the telecommunications network at Mars for supporting future missions to the surface of the Red Planet.

NASA's Jet Propulsion Laboratory, Pasadena, California, designed Electra radios to include several features valuable for such data relay. Curiosity and two NASA orbiters already use Electra radios. The Electra radios on Trace Gas Orbiter (the one used for this test and an onboard spare) have improvements to enhance performance compared with the Electra capability on NASA's Mars Reconnaissance Orbiter, which has been in service at Mars since 2006.

For more about ESA's ExoMars program, including TGO, visit http://exploration.esa.int/mars/. For more information about NASA's journey to Mars, visit http://www.nasa.gov/topics/journeytomars.