The US space agency said it is giving up on trying to contact its Spirit Rover on Mars, saying the robot explorer likely froze to death in the Red Planet’s harsh winter.

“Nasa is ending attempts to regain contact with the long-lived Mars Exploration Rover Spirit, which last communicated on March 22, 2010,” it said in a statement.

Spirit was only supposed to endure for three months but carried on a bountiful career that lasted more than six years after it first landed on Mars in January 2004.

Last year, Nasa said the tireless, 180-kilos, six-wheel robot had broken through a crusty surface layer and hit sand at one edge of the Troy crater, west of the Home Plate plateau, in the Martian southern hemisphere.

All attempts to extricate it failed. Spirit was unable to shake off the Martian dust that has been slowly accumulating on its solar panels, preventing its batteries from recharging.

Scientists held out some hope that after the Mars winter passed, the Spirit would get enough light from the sun to be able to recharge, but it was not to be.

“With inadequate energy to run its survival heaters, the rover likely experienced colder internal temperatures last year than in any of its prior six years on Mars,” Nasa said.

“Many critical components and connections would have been susceptible to damage from the cold.”

The US space agency is turning its attention to the launch of its next-generation Mars rover, named Curiosity, later this year but will keep an ear out for the Spirit from time to time.

“We’re now transitioning assets to support the November launch of our next generation Mars rover, Curiosity,” said Dave Lavery, programme executive officer for solar system exploration.

“However, while we no longer believe there is a realistic probability of hearing from Spirit, the Deep Space Network may occasionally listen for any faint signals when the schedule permits.”