Opportunity is on the move. The NASA Mars Exploration Rover has begun wheeling itself toward a rock outcrop that should double as a geological time capsule.

On Thursday, rover engineers took Opportunity out for a spin, tracking across the pebble-strewn floor of crater in which the rover landed in Meridiani Planum.

On Friday, operators at the Jet Propulsion Laboratory (JPL) in Pasadena, California plan to edge the rover another 3.6 feet (1.1 meter), steering the robot closer to the exposed rock outcrop.

From that vantage point, Opportunitys Panoramic Camera and a Mini-Thermal Emission Spectrometer (Mini-TES) are to begin a systematic campaign of studying the outcrop area. Mini-TES identifies rock types from a distance.

Put on hold for the time being is using one of the rovers six wheels to trench into the martian soil. One front wheel would spin to dig the hole while the other five wheels remain stationary.

A decision has been made to proceed to an area with a higher intensity of hematite before trenching.

Also of keen scientific interest is more examination of tiny spheres seen by Opportunity.

The spherical pebbles are among the mix of particles spread across the crater floor. How these rounded pebbles formed remains a puzzler, but they could be the result of accretion under water. The objects upon microscopic study, however, show apparent pores suggestive of other alternatives, like meteor impacts or volcanic eruptions.

Hap McSween, a rover science team member from the University of Tennessee, Knoxville told SPACE.com that the tiny spherical objects might turn out to be "microtektites".

Tektites are found in different locations on Earth, determined to be blobs of glass. Yet they remain unexplained as to their formation.

A popular view is that tektites are a byproduct of a meteors impact, whereby high temperatures and pressures are provoked and interact with layers of rock on Earths surface. During that process fused glass is formed.

Microtektites, McSween said, could be "one of the possible origins of these intriguing objects." If they are microtektites they ought to be glass, he said, although whether or not thats the case is not known at the moment.

"I guess that glass beads could have devitrified (crystallized) over a long period of timeso maybe thats not a good constraint. But if they are glass, they are either tektites or droplets from a lava fountain," McSween concluded.

Using science instruments mounted on Opportunitys robotic arm, extensive scrutiny of the curious objects is on the rovers agenda.

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