NASA’s Curiosity Rover photographs round ball-like object on the surface of Mars

NASA’S Curiosity rover has photographed a perfectly round ball-shaped object on the surface of Mars. What is it?

Anyone for tennis on a red clay surface? ... the ball shaped object snapped by NASA’s Curiosity rover. Picture: NASA

NASA’S Curiosity Rover has sent back many puzzling images in its two-year exploration of the Martian surface — but this must rate as one of the most unexpected.

Is it a soccer ball on the surface of the red planet? Or a remnant of a meteorite, rounded to spherical perfection by the Martian winds?

Apparently it’s neither of those things.

RECENT: Indian spacecraft reaches Mars

Say cheese ... a self-portrait taken by the NASA rover Curiosity in Gale Crater on Mars. Picture: AP Photo/NASA

As yet, no balls exist on the surface of the red planet. (Although as a side note, there are in fact two golf balls on the surface of the moon — struck by NASA astronaut Alan Shepard on the Apollo 14 mission in February 1971.)

NASA experts have deduced that the sphere in this photo — taken in the Gale Crater and uploaded to their website on September 11 — is tiny, probably just 1cm wide.

It’s an example of a geological process called concretion that occurs when minerals separate from water and become hard masses inside sedimentary blocks which eventually erode.

Discovery.com reports that the evidence of concretion on Mars helped scientists deduce that water once flowed on the surface of the planet.

It’s not the first time that spherical objects have been found on the planet.

NASA’s Opportunity rover photographed a series of blueberry sized “spherules” not long after it first landed in 2004.

Evidence of concretion ... the ‘blueberries’ helped scientists deduce that Mars once contained water.

2004 discovery ... the microscopic balls of iron hematite nicknamed ‘blueberries’ by NASA. Picture: from the Olivier Goursac book ‘Visions of Mars’.

And in 2012, Opportunity photographed more spherules — this time from an area called the Endeavour Crater — which were embedded within a rocky outcrop.

Those spherules were about 3mm in diameter and were found to be different in structure, composition and distribution than those discovered in 2004.

“It’s going to take a while to work this out, so the thing to do now is keep an open mind and let the rocks do the talking,” Opportunity’s principal investigator Steve Squyres said at the time.

2012 discovery ... spherules embedded in an outcrop called Kirkwood photographed by Opportunity. Picture: AFP / NASA