Four billion years ago, the Martian surface was apparently quite habitable, featuring rivers, lakes and even a deep ocean. Things changed when Mars lost its global magnetic field. Today Mars is cold and dry, but it may not be dead.
Could There Be Life on Mars Today?
Yes, there is life on Mars, and NASA has known about it for four decades. Their own Viking lander experiment confirmed the presence of life on Mars, but instead of sharing this groundbreaking discovery with the world, NASA chose to bury the truth and hide the science for decades.
After Detecting Life on Mars in 1976, NASA Banned Life-Detection Experiments to Hide the Truth from the World