Experts at a NASA lab say that the rover Opportunity has just reached an impressive milestone on the Red Planet. It reached the halfway point of its new mission, which is to reach Endeavor Crater.

It's currently unknown whether the robot will ever get to that landscape feature, given the fact that it is located miles away from its current position.

The robot itself is very old, and its solar panels are covered in dust. But it also has some advantages from its sister rover Spirit, which is currently in hibernation mode, and also trapped in a patch of loose soil called Troy.

Opportunity can function around the year, as it roams Mars at a latitude that allows it to get sufficient sunlight ever during the harsh winters. It has been driving for more than 6 and a half years.

This month marks the two year anniversary since the rover left its previous major target, the Victoria Crater, which it investigated closely for a long time.

Since then, it has been on the road, heading towards Endeavor, and stopping to analyze various interesting rocks along the way. Victoria is separated from Endeavor by around 11.8 miles.

Thus far, the rover has navigated more than 22,640 meters (or roughly 14.07 miles). In order to cover the remaining distance, it would have to endure for another 5 to 7 years on Mars.

While this is unlikely to happen, given the extreme conditions it needs to face, experts are not deterred from trying. They say that, in the offset chance that Opportunity does make it to the crater, the amount of scientific return will be well worth the effort.

The robot completed its primary, three-month mission in April 2004, and has been putting in “overtime” ever since. Like Spirit, it is operated by experts at the Jet Propulsion Laboratory (JPL), in Pasadena, California.

As a geology explorer, it has conducted numerous studies of the ground, of exposed geological layers, and also of various meteorites it stumbled upon on the Red Planet.

It is also now the longest-surviving mission on Mars, having exceeded the endurance record set by the Viking 1 lander a few months back.

If and when Spirit awakes from its hibernation, it will take this record away from Opportunity, given that it arrived on Mars earlier that its sister robot.

This year, Opportunity received an important update, which is meant to allow it to discover objects of interest all on its own. This reduces its dependency on its JPL drivers and mission planners.

The moves also make the entire navigation process easier, by saving time.