The Dunes Of Mars . ... Credit Copyright: Mars Global Surveyor Project , MSSS , JPL , NASA Explanation: The North Pole of Mars is ringed by a "sea of sand dunes". For Mars' Northern Hemisphere, Spring began in mid July and increased sunlight is now shrinking the polar cap revealing the wind-swept dunes to the cameras onboard the Mars Global Surveyor spacecraft. ... Near the end of January 1999 Summer will begin and offer even clearer views of Northern dunes of Mars . ... NASA Official: Jay Norris. ...