NASA Curiosity damage
Curiosity has seen a number of issues over last few monthsNASA/JPL-Caltech/MSSS

Nasa observed breaks in the left middle wheel of Curiosity, its car-sized rover exploring the Martian surface a few months back. But, the fracture has not deterred the rover from its ambitious mission to reach and study the key regions of scientific interest on Mars' Mount Sharp.

In September, the rover, which spotted evidence of Water on the red planet and made other fascinating discoveries, started a steep ascent to examine the iron-oxide-bearing "Vera Rubin Ridge" on the northwestern flank of the mountain. The area had grabbed scientists' attention before Curiosity's landing in 2012.

The ascent to the top of the ridge is about 213ft (65m) and requires a series of drives totalling more than a third of a mile.

"The team is excited to be exploring Vera Rubin Ridge, as this hematite ridge has been a go-to target for Curiosity ever since Gale Crater was selected as the landing site," said Michael Meyer, lead scientist of NASA's Mars Exploration Program at the agency's Washington headquarters.

Curiosity has seen a number of issues over last few months. The robot has encountered software glitches here and there, including a couple of fractures in the grousers of one of its six solid-aluminium wheels.

Grousers are raised zig-zag shaped treads that extend "about a quarter inch outward from the skin of each wheel". They not only bear the weight of the rover but also provide most of the traction as well as the ability for easy movement on the uneven terrain of the planet.

Though Nasa's rover drive planners have been using enhanced methods of mapping terrains to keep the rover away from potentially hazardous routes, the image confirmed that the damage occurred sometime after the last inspection, conducted on January 27.

"All six wheels have more than enough working lifespan remaining to get the vehicle to all destinations planned for the mission," said Curiosity Project Manager Jim Erickson at Nasa's Jet Propulsion Laboratory, California. "While not unexpected, this damage is the first sign that the left middle wheel is nearing a wheel-wear milestone".