Mars – rises as expected in the east but slowly. Despite the 30-hour orbit of Deimos, 2.7 days elapse between its rise and set for an equatorial observer, as it slowly falls behind the rotation of Mars. Because the orbit of Phobos is below synchronous altitude, the tidal forces from the planet Mars are gradually lowering its orbit. In about 50 million years, it could either crash into Mars's surface or break up into a ring structure around the planet. The origin of the two moons is not well understood. Their low albedo and carbonaceous chondrite composition have been regarded as
Exploration of Mars one of the proponents of such missions. Various asteroids, moons, and places on Mars can be mined while crops are initially being planted. This method will save lives on Earth, add potentially trillions of dollars to the world economy annually, and provide a stable colony on Mars. Some have also stated that persons should stay on Earth, but get food and resources from Mars and surrounding asteroids, moons, greenhouses in space and other structures. Some critics contend unmanned robots can perform better than humans at a fraction of the expense. If life exists on Mars, a human mission could contaminate