" Perhaps the most dangerous Symptom is impairment to cognitive function-we have to be able to perform tasks that require a high degree of concentration and attention to detail at a moment's notice, and in an emergency, which can happen anytime, we need to be able to do those tasks right at the first time. Losing just a fraction of our ability to focus, make calculations, or solve problems could cost our lives"

Scott Kelly: Endurance-A Year in Space, a Lifetime Discovery. Alfred A. Knopf, New York, 2017. pp 86-87.