The Apollo program was the third United States human spaceflight program carried out by the NASA, which accomplished landing the first humans on the Moon from 1969 to 1972.
During the Apollo 11 mission, astronauts Neil Armstrong and Buzz Aldrin landed their Apollo Lunar Module (LM) and walked on the lunar surface, while Michael Collins remained in lunar orbit in the command and service module (CSM), and all three landed safely on Earth on July 24, 1969. Five subsequent Apollo missions also landed astronauts on the Moon, the last in December 1972. In these six spaceflights, twelve men walked on the Moon.
In this multi-part series, we will discuss various details and stories from Apollo Missions. In this article, we start will Apollo Missions from Apollo 1 to Apollo 7.
Naming of the Apollo Missions.
Apollo ran from 1961 to 1972, with the first crewed flight in 1968. There is slight confusion regards to the naming and numbering of the missions, because one of the missions end up taking lives of crew in an accident and was re-named as Apollo 1 in respect of the crew who lost their lives.
The sequence of Apollo Flights in order of their launch/planned dates will be
AS-201 (Apollo 1A),
AS-203 (Apollo 3),
AS-202 (Apollo 2),
AS-204 (Apollo 1),
Apollo 5 and so on till Apollo 17.
Apollo 18, 19, 20 were planned but got cancelled.
Let’s Begin the Journey!
You can consider each of the Apollo missions as “steps” towards the milestone Apollo 11 mission which landed the astronauts on moon. With each step, all the key technologies and systems required for successfully reaching moon and coming back was tested and improved upon.
AS-201 (Apollo 1A) flown February 26, 1966, was the first uncrewed test flight in the Apollo series. Saturn 1B was the launch vehicle chosen for this mission. Also note that there were 10 missions earlier than this for which Saturn 1 rocket was used.
Key achievements – This mission proved that the engine could restart in space, a crucial part of any crewed flight to the Moon. Perfect working of stage 1, stage separations and return.
AS-202 (Apollo 2)
Another uncrewed sub-orbital test flight. The duration of flight and the number of engine burns were increased. It included the spacecraft guidance and navigation control system and fuel cells. The success of this flight enabled the judgement to be taken for carrying men into orbit on the next mission, AS-204.
AS-203 (Apollo 3)
This was an intermediate flight to ensure additional safety before going forward for a crewed flight. The purpose of the AS-203 flight was to investigate the effects of weightlessness on the liquid hydrogen fuel during flight. The tank was equipped with 88 sensors and two TV cameras to record the fuel’s behavior.
AS-204 (Apollo 1) – The first planned crewed flight scheduled to launch on February 21, 1967. The mission never flew. A cabin fire during a rehearsal test killed all the three crew members. The ignition source of the fire was determined to be electrical, and the fire spread rapidly due to combustible nylon material, and the high pressure, pure oxygen cabin atmosphere. Rescue was prevented by the plug door hatch, which could not be opened against the internal pressure of the cabin. Because the rocket was unfueled, the test had not been considered hazardous, and emergency preparedness for it was poor.
Apollo 4 – This was the first flight of Saturn V rocket. It successfully demonstrated third stage restart and tested the command module heat shield at lunar re-entry speeds.
Apollo 5 – This mission tested the lunar module in a space environment, in particular its descent and ascent engine systems, and its ability to separate the ascent and descent stages. The descent engine would become the first throttleable rocket engine fired in space.
The mission also performed a simulation of a landing abort, in which the ascent stage engine would be fired while still attached to the descent stage. This, referred to by engineers as the “fire in the hole” test, was depicted in the mission’s insignia patch.
Apollo 6 – The final uncrewed Apollo test mission. The objectives of the flight test were to demonstrate trans-lunar injection capability of the Saturn V with a simulated payload equal to about 80% of a full Apollo spacecraft, and to repeat demonstration of the command module’s (CM) heat shield capability to withstand a lunar re-entry.
Apollo 7 – The first crewed flight with Saturn 1B rocket. It went in orbit for 11 days and gave a go-ahead for the landmark – Apollo 8 mission, which will be our focus and will be covered in detail, in next article.