PASADENA, Jan 17: The Mars rover, Spirit, began its scientific mission in earnest on Friday, stretching out its robotic arm for the first microscopic look at the surface of another planet.

A separate picture of the six-wheeled rover's tire tracks from its first drive onto the red, dusty surface of Mars a day earlier showed tantalizing signs of fine soil and a thin crust of dirt that might - or might not - be evidence the rover landed in an ancient lake bed, scientists said.

Spirit's clearly-etched tracks showing the outline of the tires like a handprint left in sand, relieving scientists who said the ground looked good for driving.

"Today Spirit began its mission," Mission Manager Mark Adler told a briefing.

"About seven hours ago, we made our first use of the arm. We put the arm out in front of the rover, down hovering over the soil with the microscopic imager, and we took the first microscopic images of the surface of another planet."

Scientists want to search for clues that would explain the planet's geological history, including the question of whether water ever flowed on the surface.-Reuters