Why is Mars so different from Earth?

Did Mars ever support life of any sort?  Why is Mars so different from Earth? Can we deduce its history from current conditions?NASA's Curiosity rover is using a new experiment to better understand the history of the Martian atmosphere by analyzing xenon. While NASA's Curiosity rover concluded its detailed examination of the rock layers of the "Pahrump Hills" in Gale Crater on Mars this winter, some members of the rover team were busy analyzing the Martian atmosphere for xenon, a heavy noble gas. Curiosity's Sample Analysis at Mars (SAM) experiment analyzed xenon in the planet's atmosphere. Since noble gases are chemically inert and do not react with other substances in the air or on the ground, they are excellent tracers of the history of the atmosphere. Xenon is present in the Martian atmosphere at a challengingly low quantity and can be directly measured only with on-site experiments such as SAM.