this has led to the assumption that it was once a lake. it was a lake, it was a lake that was about 40 kilometers across. we are not looking for things that would have been growing in the sea. the other important aspect of this is that we are looking very, very far back in the history of the solar system. what that means is that life would not have had much of a chance to advance very far, and that s why we always say that we are looking for evidence of potential microbial life. reporter: the rover s robotic arm will dig out samples and store them in tubes and analyze them. the front of the rover then has another sample handling arm which manages those tubes and the samples inside of them to do imaging and measure the volume, and then we will seal those and store those for planned future return to earth. reporter: although it s still unclear if perseverance will be back, it s possible its collections of rock samples could be back on earth in a decade.