This past August, a NASA rover named Curiosity touched down inside Mars’ Gale crater, carrying 10 new instruments to advance the quest for signs that Mars might once have been suitable for life. With inside access to the massive team of scientists and engineers responsible for Curiosity’s on-the-ground experiments, NOVA was there for the exhilarating moments after the rover’s landing—and for the spectacular discoveries to come. As NOVA reveals the dynamic new picture of Mars that these explorers are painting, we will consider the deep questions raised by 40 years of roving Mars: How do we define life? How does life begin, and what does it need to survive? Are we alone in the universe?