Nasa's "veteran" Opportunity rover has achieved a major milestone as it completes 5,000 days (sols) on Mars.

The rover, which landed on the Red Planet in 2004, saw its 5,000th Martian dawn on Saturday, 17 February. Over last 14 years, the tiny robotic machine has come a long way and is still making surprising discoveries on the planet.

Nasa had originally planned a 90-sol mission for Opportunity. The agency never thought that the rover would survive fierce Martian winters, but it did, and not just one but eight seasons.

"Five thousand sols after the start of our 90-sol mission, this amazing rover is still showing us surprises on Mars," said Nasa's Opportunity Project Manager John Callas. The agency even shared the rover's first full selfie in a tweet.

The photograph is a combination of several images taken by the microscopic imager positioned at the rover's robotic arm.

Though Opportunity's sibling Spirit died way back in 2010 due to power loss, the cute little chunk of technology continued. Occasional Martian winds cleared dust from its solar panels and kept the whole thing up and running, Gizmodo reported.

So far, the rover has driven 45km from its landing site and is currently looking at Perseverance Valley – a shallow channel at the western rim of the planet's Endeavour Crater. Just a few weeks back, it spotted mysterious Earth-like rock stripes in the same valley.

But that's just one of the several secrets Opportunity has uncovered throughout the unexpectedly long life.

It found that the planet had water in the past. It also drilled into rocks and sent back more than 200,000 images and loads of scientific data to help Nasa understand the chemistry of Martian surface and environment.