NASA's Curiosity rover is celebrating its eighth (Earth) year on Mars. The car-sized rover's sibling, the newly launched Perseverance rover, took flight merely a week ago.

Curiosity was launched into space in November 2011 and landed on Mars on Aug. 5, 2012. The probe touched down inside Gale Crater and kicked off a surface mission that was supposed to last about 687 Earth days or approximately one Martian year.

Curiosity's main mission was to discover whether Gale Crater could ever have supported Earth-like life. The rover eventually delivered the news that the crater millions of years ago was once had a lake-and-stream system that had the potential to be habitable.

The space robot also detected complex organic chemicals in rocks found in Gale Crater rocks. Perhaps its most exciting discovery is the presence of methane, which on Earth is a sign of life. Although abiotic processes are able to produce the gas as well, it is unclear what the source within the crater is.

Curiosity reached the base of Mount Sharp in September 2014, which rises about 5.5 kilometers into the sky from Gale's center. The rover has been treading the mountain's foothills since, looking for clues about the crater's habitable environments in Mars' ancient life and how the planet transformed into a cold and dry desert world we know today.

Since Curiosity landed on the Red Planet eight years ago, its odometer had read over 23 km and the rover itself had so far collected six soil samples and drilled 27 rock samples. Another NASA rover holds the surface distance record, Opportunity, which had covered approximately 46 km in its active years from 2004 through 2018.

Perseverance's $2.7 billion mission, called Mars 2020, aims to extend Curiosity's findings. The newly launched rover will search for signs of past life on Mars in the planet's Jezero Crater, which billions of years ago was a lake and river delta.

Aside from collecting samples and saving them for a future return to our home planet, Perseverance will also test out new exploration technologies, including an innovative space helicopter called Ingenuity and MOXIE, a tool that produces a small amount of pure oxygen from Martian atmospheric carbon dioxide.

Perseverance will land on Mars on Feb. 18, 2021, but Curiosity will continue on with its mission. Their sibling, Opportunity, was declared dead on Feb. 13, 2019, more than eight months after the solar-powered robot went silent during a raging dust storm on the Red Planet.