Scientists have not yet proven that Mars can currently support life as we know it on Earth. Based on data from the NASA Exploration Rover, Mars may have been able to support life approximately 4 billion years ago.
Mars is the closest planet to Earth, but it has different conditions. Mars is very cold, by Earth's standards. It has an average surface temperature of -67 degrees Fahrenheit, and a range of -207 degrees F on the winter pole, to 80 degrees F during the day at the summer pole.
Scientist know from analyzing data from the Hubble Space Telescope, Viking Landers and Mars Global Surveyor that Mars has polar ice caps, but the frozen water is highly acidic. There is no fresh water on Mars. Additionally, Mars has a thin atmosphere with only trace amounts of oxygen.