Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Named after the Roman god of war, Mars is the fourth planet in our Solar System. Sometimes referred to as the “Red Planet” due to its iron oxide rich soil, which gives it red appearance, it is slightly more than half the size of Earth. Mars observation dates back to ancient Egyptian astronomers and is still an important part of space exploration programs today, aimed at answering questions about the planet's history and whether it has, is or ever will be able to sustain life. Learn more about the major milestone missions to Mars in this book.