There were two kinds of clouds on Mars. Fleecy white ones which probably were water vapor, and yellowish clouds strongly suggestive of dust clouds, whipped up by violent storms. Although Mars had thin air, it could have strong winds. We could now see the two Martian moons. The furthermost of the two, Deimos, is only 15,000 miles from the surface of the planet. Its diameter is about 20 miles, and it revolves around Mars once every sixteen hours. Since the Martian day is about the same length as the earth's, being only 37 minutes longer, Deimos would rise in the west and sink in the east about three days later, being visible and moving slowly eastward through the entire time. The larger moon, Phobos, is about thirty miles in diameter, and only 6,000 miles from the surface of Mars. Even though it is extremely small it would be seen as a tiny, bright disc from the surface of Mars. Its period is six hours, therefore it rises in the west three times every Martian day. It actually circles Mars four times daily but Mars turns once so that Phobos would appear, to Martian eyes, to circle only three times. Our problem was not to hit Mars, but to score a near miss. We would come close enough to be captured by Martian gravity. Then we would spiral as a satellite, decelerating and tightening our orbit till we were as close as possible to the group of rockets that had been fired from the earth with our supplies. We would board one of these, and then, using electronic controls, would land the three rockets comparatively close together at a spot in the desert near an oasis that looked fruitful for exploration. The most interesting of these oases, of which there were many, were two oval-shaped greenish brown areas marked on Percival Lowell's maps as Solis Lacus Minor and Solis Lacus Major--generally called Solis Lacus. These were about halfway between the equator and the pole in the northern hemisphere. In 1924 Solis Lacus showed a startling expansion, growing to almost twice its size and extending northward. Undoubtedly vegetation existed in profusion in this area. Furthermore, the two areas were connected by a short canal, which frequently doubled, forming two canals. Between the oases was desert. Thus, by landing between the two Solis Lacuses we could learn a great deal about the physical characteristics of Mars. At a distance of one million miles, we had to aim carefully at Mars. The planet was speeding along its orbit at about fifteen miles per second, in comparison with our speed which was slightly more than three. If we missed we couldn't catch up because our acceleration was too slow. We'd have to go home empty-handed.