<P> All Apollo lunar missions had a third crew member who remained on board the Command Module . The last three missions had a rover for increased mobility . </P> <P> In order to go to the Moon, a spacecraft must first leave the gravity well of the Earth . The only practical way of accomplishing this currently is with a rocket . Unlike other airborne vehicles such as balloons or jets, a rocket is the only known form of propulsion which can continue to increase its speed at high altitudes in the vacuum outside the Earth's atmosphere . </P> <P> Upon approach of the target moon, a spacecraft will be drawn ever closer to its surface at increasing speeds due to gravity . In order to land intact it must decelerate to less than about 160 kilometres per hour (99 mph) and be ruggedized to withstand a "hard landing" impact, or it must decelerate to negligible speed at contact for a "soft landing" (which is the only viable option with human occupants). The first three attempts by the U.S. to perform a successful hard moon landing with a ruggedized seismometer package in 1962 all failed . The Soviets first achieved the milestone of a hard lunar landing with a ruggedized camera in 1966, followed only months later by the first unmanned soft lunar landing by the U.S. </P> <P> The speed of a crash landing on its surface is typically between 70 and 100% of the escape velocity of the target moon, and thus this is the total velocity which must be shed from the target moon's gravitational attraction for a soft landing to occur . For Earth's Moon, the escape velocity is 2.38 kilometres per second (1.48 mi / s). The change in velocity (referred to as a delta - v) is usually provided by a landing rocket, which must be carried into space by the original launch vehicle as part of the overall spacecraft . An exception is the soft moon landing on Titan carried out by the Huygens probe in 2005 . As the moon with the thickest atmosphere, landings on Titan may be accomplished by using atmospheric entry techniques that are generally lighter in weight than a rocket with equivalent capability . </P>

How many landings on the moon have there been