Fear is a primal instinct; it is the reason why man, such a defenseless being, without sharp teeth and nails, without great size or power, has survived and has been prevalent for so many thousands of years. It is, the characteristic that we have to be vigilant at all times, to live the moment. Yet another characteristic of the human is that, unlike most beings, s/he has been disobedient for years. Whether this is the disobedience towards the gods, the laws of nature, or even the mocking of gravity, limitations, the atmosphere. This disobedience, creates new limits, new conditions, allows the human to explore, to discover the unknown, to learn. It allows the development of ideas, of knowledge, of perceptions. It creates an urge to understand the inexplicable, to create, to record. And suddenly, s/he forgets the existence of fear, starts to mock it, and as another Odysseus wanders fearless towards Ithaca.
So while up there, the astronaut realizes that everything is a matter of perception, and of data processing. Fear becomes a driving force and limits are mere points of reference, because each one is able to overcome and redefine them.
A wonderful excerpt from White Fang by Jack London (1906) adapted for astronauts titled “THE WALL OF THE WORLD”