The NASA rover Curiosity, which arrived on Mars in August 2012, will reach one year spent on the planet — in local time — on Tuesday, equivalent to 687 Earth days.

NASA’s main goal for the probe was to determine whether Mars once offered environmental conditions favourable for microbial life, the US space group said Monday on its website.

One of Curiosity’s first major findings was an ancient riverbed.

Nearby, at an area known as Yellowknife Bay, the mission sampled two mudstone slabs in the Martian Gale Crater.

Analysis revealed the site was once a lake bed, with water and a type of chemical energy used by some microbes on Earth, indicating the red planet may have been able to support simple life forms, NASA concluded.