Today, Mars would be a dry desert with just a small amount of ice in the pole regions and no water on the surface over much of the planet.
The appearance of Mars was significantly different millions of years ago. It may have even resembled Earth since it formerly had plenty of liquid water on its surface in the shape of rivers and lakes.
Because of this, scientists believe that although there is probably no life on Mars at the moment, there may have once been microbial life there.
As part of the rover's second science mission, a total of 12 samples have been taken, four of which were from the river delta, a particularly exciting region in Jezero.
An great place to look for signs of life is in this region, which was formerly a delta where material was dumped by a river.
According to Thomas Zurbuchen, assistant administrator for science at NASA, "We chose the Jezero Crater for Perseverance to investigate