Did life really arise on Mars? For years, NASA’s Mars Exploration Program has been systematically trying to find out. NASA’s Spirit and Opportunity rovers showed that liquid water once existed on the surface. Building on that discovery, NASA's Curiosity rover found conditions on Mars around 4 billion years ago that could have supported life as we know it. Now, Perseverance will directly search for signs of past life.

Perseverance launched on 30 July 2020 amidst the added challenge of the global COVID-19 pandemic. On 18 February 2021, it landed in Jezero crater, the site of an ancient lake and river delta. There, the rover will search for microbial fossils in rocks that formed in Mars’ warm, wet past. It will also look for carbon-containing molecules called organics that form the building blocks of life on Earth. Not since 1976 has NASA directly searched for life on Mars when the dual Viking landers performed long-shot chemistry experiments that turned up inconclusive results.

Perseverance is collecting soil and rock samples as it travels, and storing them in tubes that future missions by NASA and the European Space Agency will collect. Despite technological advances in making small, low-power science instruments for space missions, many types of laboratory analyses still can’t be performed in space or can’t be done very precisely. Additionally, science is all about being able to reproduce results; getting Perseverance’s samples back to Earth means we could run the same science experiments in multiple laboratories.