build the Perseverance Rover . But why is NASA investigating Mars so closely , and how are they doing it ? In truth , the chance of life existing on Mars today is extremely slim , and scientists are more focused on finding evidence of life that existed long ago . Mars wasn ’ t always the barren wasteland that it is now . It once had a much denser atmosphere that could allow liquid water to exist on its surface . Today , there are even areas that resemble riverbeds , shorelines , and islands , indicating that rivers and seas once existed on Mars . If the planet did have this much liquid water on its surface , there ’ s a real possibility that life once existed there . So NASA does have a good reason to be interested in searching for life on Mars , but how have they been doing it ?
The two most recent rovers that NASA has sent to Mars are called Perseverance and Curiosity . The Curiosity Rover launched in November 2011 and landed in the Gale Crater , where there was once much liquid water flowing over its surface . The evidence for this water was found in rounded pebbles that , similar to pebbles on Earth , most likely became round after they rubbed against other rocks while traveling downstream . In June 2018 , the Curiosity Rover found organic molecules on Mars within sedimentary rocks that are billions of years old . Every living thing on Earth is made of organic molecules , from single cell organisms to human beings . Although this is promising for astrobiologists , organic molecules can form by non-biological processes , and it is not necessarily a sign of life .
There ’ s more than one way to search for signs of life , though . On Earth , we know that fossils in sedimentary rocks can hold evidence of past life . We also know that sedimentary rocks most often form in watery environments , such as lakes or streams . That is why the Perseverance Rover , the most advanced rover to ever land on the surface of Mars , has been exploring a sediment-rich delta since April 2022 . It has been hard at work drilling samples of sedimentary rocks . There is a slight problem , though . Perseverance doesn ’ t
16