The Mars Global Surveyor, which concluded its the primary mission on Wednesday, will stay aloft one more year to continue its observations of the red planet, the US space agency NASA said.

"By any conceivable measure the scientific impact of the Mars Global Surveyor has been extraordinary," project scientist Arden Albee said in a statement issued by the California Institute of Technology in Pasadena, California.

"In many ways we now know Mars to be a different planet than when the spacecraft arrived in 1997, and our perspective continues to evolve as the data keep flowing," he said.