Is there life on Mars? This is a question which scientists and others have been asking for a long time because Mars is more similar to Earth than any other planet in the solar system. There is also evidence that liquid water flowed on Mars in the past and that there is frozen water beneath the poles of Mars. Spacecraft have been sent to Mars to either orbit or land on the planet since the 1960's. In 1976, NASA's two Viking landers touched down on the surface of Mars. Part of their mission was to collect soil with a robotic arm and study it to see if there were any signs of life, such as bacteria. Thousands of images were taken of the surface of Mars as well, but so far no evidence of life has been found. Future missions are being planned to continue the search for life on Mars. These missions will land at different locations and dig deeper into the soil to look for signs of life.