On February 6, while Mars Express was flying over the area Spirit was examining, the orbiter transferred commands from Earth to the rover and relayed data from the robotic explorer back to Earth.

"This is the first time we have had an in-orbit communication between ESA and NASA spacecraft, and also the first working international communications network around another planet," said Rudolf Schmidt, ESA's project manager for Mars Express. "Both are significant achievements, two more 'firsts' for Mars Express and the Mars Exploration Rovers."

Jennifer Trosper, Spirit mission manager at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., said, "We have an international interplanetary communications network established at Mars."

ESA and NASA planned this demonstration as part of continuing efforts to cooperate in space and to enable plans to use joint communications assets to support future missions to the surface of Mars.

The commands for the rover were transferred from Spirit's operations team at JPL to ESA's European Space Operations Centre in Darmstadt, Germany, where they were translated into commands for Mars Express.

The translated commands were transmitted to Mars Express, which used them to successfully command Spirit. Spirit used its ultra-high frequency antenna to transmit telemetry information to Mars Express. The orbiter relayed the data back to JPL, via the European Space Operations Centre.

"This is excellent news," said JPL's Richard Horttor, project manager for NASA's role in Mars Express. "The communication sessions between Mars Express and Spirit were pristine. Not a single bit of data was missing or added, and there were no duplications."

This exercise demonstrated the increased flexibility and capabilities of interagency cooperation and highlighted the spirit of close support essential in undertaking international space exploration.

Spirit and its twin Mars Exploration Rover, Opportunity, frequently use two NASA orbiters, Mars Odyssey and Mars Global Surveyor, for relaying communications. The rovers also can communicate directly with the Earth-based antennas of NASA's Deep Space Network in California, Spain and Australia, another layer of international cooperation.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project and NASA participation in Mars Express for NASA's Office of Space Science, Washington.

For information about NASA and Mars programs on the Internet, visit:

http://www.nasa.gov

For images and information about the Mars Exploration Rover project on the Internet, visit:

http://marsrovers.jpl.nasa.gov

http://athena.cornell.edu

For images and information about Mars Express on the Internet, visit:

http://www.esa.int/science/marsexpress

http://marsprogram.jpl.nasa.gov/express