Page 6 - Apollo Moonships

4 On bOard apOllO mOOnships
THE MISSION
PROFILE
With variations in some cases, the typical lunar mission was divided into 18 main phases that began with the launch of the Apollo moonships attached to the Saturn V rocket’s third stage
and ended a few days later when the Command Module (CM) returned to Earth and splashed down in the Pacific Ocean. The only mission that followed another flight plan was Apollo 13, because an explosion inside the Service Module (SM) forced ground control to change the mission profile in order to ensure that the crew returned safely to Earth.
THE LUNAR–ORBIT RENDEZVOUS MODE
To go to the moon, NASA had three choices: first, to use a single-giant rocket to travel to the satellite and later take off home from its surface (Direct Flight mode); second, to launch two or more spacecraft to dock in Earth orbit and then travel to the moon exactly as a Direct Flight mode (Earth-Orbit Rendezvous mode); and finally, the method that was chosen, the Lunar-Orbit Rendezvous (LOR). In this mode, a single powerful rocket (Saturn V) launched a mother ship (the Command/Service Module vehicle, or CSM) and a small lunar lander (the Lunar Excursion Module, or LEM) that joined in Earth orbit and then flew together to the moon. Reaching the lunar orbit, two of the three crewmen of the Apollo mission landed on the moon using the LEM, while the third member remained in the CSM vehicle awaiting the return of his teammates. When the lunar excursion ended, the LEM came back to the lunar orbit and docked again with the mother ship. The LEM was discarded, and the astronauts returned home aboard the CSM vehicle. The SM of the mother ship was jettisoned into Earth’s orbit, and the crewmen reentered Earth and splashed down in the ocean on board the CM.
THE THIRD STAGE
The S-IVB third stage was the vessel where the lunar module was stored during the Saturn V rocket launch. This stage was powered by a single 200 000-pound rocket engine.
THE ROUTE TO THE MOON
The six Apollo missions that landed on the moon between 1969 and 1972 (Apollos 11, 12, 14, 15, 16, and 17) took off from Kennedy Space Center in Florida, U.S., and followed the same route to the moon, according to a flight plan of 18 critical phases. For all these missions, the
trip took about three days, during which time the astronauts traveled 239 000 miles (about 384 400 km). The first mission—Apollo 11— performed one extravehicular activity (EVA)
of 2:31 hours on the lunar surface. The last mission—Apollo 17—performed four EVAs and remained on the moon for more than 20 hours. The time of the trip back to Earth was different for each mission: from 2 days and 22 hours for Apollo 11 to 5 days and 3 hours for Apollo 15. The only mission that returned to Earth using a free trajectory (without propulsion, helped by Earth and moon gravity) was Apollo 11.
RENDEZVOUS IN LUNAR ORBIT
The Apollo 11 Lunar Excursion Module (LEM) was photographed by Astronaut Michael Collins from the CSM vehicle in lunar orbit. The LEM approaches from above to redock with the CSM after its crewmen have explored the moon.