Since 1957, when it was launched into space the first artificial satellite In the past, hundreds of millions of people have at one time or another watched the development of a space mission. In the vast majority of cases, the public perceives them as great spectacles that involve a certain amount of risk. Because the truth is that these are missions in which many of the parameters involved are not the usual ones on Earth, and each situation involves a certain degree of complexity.
The transposition, docking and extraction manoeuvre of the Apollo programme was an example of planning by the engineers who designed the flight.
This is where the following come into play science and engineering. The challenge posed in each of the processes or actions carried out in the development of any space mission is immense. It is necessary in each case to foresee the participation of a multitude of parameters that condition each of the situations that will occur until its completion. The expertise of the engineers who design each stage of the journey must be extraordinary and we, here on Earth, should be aware of the difficulties and the magnitude involved.
Take, for example, one of the most exciting episodes of the Apollo XI space mission, which is celebrating its fiftieth anniversary: the manoeuvre of reorganisation of the lunar module and the command and service modules in mid-flight.
At liftoff, the configuration of the Apollo spacecraft, from top to bottom, was as follows: Command Module, CM (where the crew members travel), the Service ModuleSM (engine, fuel, life support, communications and other components) and the Lunar ModuleLM (amorphous spider-shaped spacecraft, which is the one that landed on the surface of the Moon).
The Lunar Module, LM, was protected by a fairing and was located just below the Command and Service Modules (together called CSM) and above the second stage of the Saturn rocket (the space shuttle).
In mid-flight, on the way to the Moon and with almost no gravity, a complex manoeuvre was carried out consisting of separating and rotating the CSM 180º so that it could connect to the LM in a position of that would allow astronauts to move from one spacecraft to the other. through an 80-centimetre hatch. The challenge was not only to carry out this manoeuvre (known as the "transposition, coupling and extraction".), but to do it at a speed of over 30,000 km/h and in a hostile environment to which we humans were not accustomed.
Let us bear in mind, moreover, that in the mid-1960s the the programming and data processing capacity was very limited if we take the current era as a reference. The astronauts usually made most of the calculations manually, relying on calculation tables. The Apollo spacecraft's navigation computer had a ROM memory of 32 kB and RAM memory of 2 kB, and was responsible for helping to perform some of the calculations needed to orientate the spacecraft or to operate the automatic guidance system of the Command module itself. Most of these calculations were aimed at guiding the spacecraft, while many others were intended to provide information to the astronauts for carrying out certain manoeuvres or operational actions, as in the case of this mid-flight module reorganisation procedure.
Why risk such a delicate move? Wouldn't it have been simpler to have the same configuration from take-off?
This was actually a design problem for the engineers in terms of how each stage of the flight was to be executed. The problem was that, in its launch configuration, the command module had to be located at the highest point of the flight. in order to be able to attach it to the exhaust tower (or rescue rocket). In the event of an emergency situation at liftoff, this "small" rescue rocket is responsible for extracting the command module and moving it away from the rest of the shuttle in order to save the crew.
If the Lunar Module had been in its final location (with which it was to reach lunar orbit), the escape rocket would have had to be much larger to carry the additional 15,060 kilograms of mass of the LM. Faced with this dilemma, and after months of calculations, it was assumed that the most feasible and potentially less risky option was for the LM to be positioned at the bottom and to perform the aforementioned reorganisation procedure in mid-flight.
The manoeuvre was performed by CM pilot Michael Collins, although Armstrong and Aldrin had also been trained to perform the manoeuvre if necessary. According to the flight programme, the astronauts required approximately one hour for full execution, although time was not critical in this case, given that they had just over two days from just after the translunar injection (a propulsion manoeuvre performed from a low circular parking orbit around the Earth to place a spacecraft on a trajectory towards the Moon) to perform it.
Let us take into account all the parameters that had to be involved in carrying out each of these manoeuvres. We are talking in terms of calculations involving time, space, mass, many laws of physics and which have to be foreseen to be carried out thousands of kilometres away and in an environment with which we humans are unfamiliar. In fact, quite a feat of engineering.
Approximately 400,000 people worked directly or indirectly to get the Apollo spacecraft to the Moon and bring the astronauts safely back to Earth. Many of the solutions they provided to the problems that such a mission required had not been done before. The engineering, data analysis, calculation, design, programming and planning work was enormous because it was not only a question of being the first, but also of successfully completing the mission. It was a matter of state.
