Space travel in a high-altitude environment: One more step in human BioSpaceForming

Abstract

BACKGROUND: Currently, space programs use sea-level pressures (760 mmHg) and normoxia (21% oxygen fraction) in space capsules. When astronauts need to go for a spacewalk, the pressure has to be reduced to 1/3 that of sea level (240 mmHg). This implies that in order to avoid decompression sickness (DCS) and acute mountain sickness (AMS), complex and time-consuming procedures need to be carried out. Furthermore, space suits have to sustain such pressure and protect them from radiation. A cooling vest is also used in order to keep the body temperature within normal values. This makes the space suits very voluminous and hence with rigid structures in order to sustain the pressure in space. Astronauts suffer, among many other complex microgravity alterations, anemia, that upon return to sea level, has to be correspondingly normalized to preflight levels. The reason that anemia presents is in part due to a lower requirement of oxygen by orthostatic muscles in microgravity. Exercise in space, reduces bone and muscle wasting. Over 200 million high-altitude residents live above 2000 m (6560 ft) of altitude and have adapted perfectly to life in the mountains. They live their life as if they were at sea level. They reproduce and practice sports, all this with a higher hematocrit. They even have proved extended longevity. METHODS: The knowledge acquired during 47 years of medical practice at high altitude, is applied to a proposal for a most efficient capsule environment for the human exploration of space. RESULTS: A cabin pressure similar to the city of La Paz, Bolivia (495 mmHg), that is, 2/3 that of sea level (760 mmHg) would not only maintain the hematocrit for reentry, but furthermore, could significantly accelerate the preparation for extravehicular activity that currently takes up several hours. High-altitude residents can tolerate lower levels of oxygen (hypoxia) providing them with an advantage of survival in oxygen poor environments. We likewise propose that a lower pressure (149 mmHg) be used in space suits, making them more flexible and thereby reducing the risks of DCS and AMS. This implies only 346 mmHg in pressure difference, from space capsule to space suit, as compared to 520 mmHg in the current methodology. CONCLUSIONS: The laws of physics in relation to pressure changes cannot be broken. However, human biology with adaptation to lower pressures and lower levels of oxygen and carbon dioxide, which is the case of high-altitude residents, can reduce the pressure gap significantly. Thereby, biology breaks the limitations of the laws of physics. Space travel will always have hypoxia as a fundamental threat, hence a hypobaric, normoxic space capsule environment results beneficial, practical, and one more step in “BioSpaceForming” of human beings.