Bioastronautics: The Influence of Microgravity on Astronaut Health

Abstract

For thousands of years different cultures around the world have assigned their own meaning to the Universe. Through research and technology, we have begun to understand the nature and mysteries of the Cosmos. Last year marked the 40(th) anniversary of our first steps on the Moon, and within two decades it is hoped that humankind will have established a settlement on Mars. Space is a harsh environment, and technological advancements in material science, robotics, power generation, and medical equipment will be required to ensure that astronauts survive interplanetary journeys and settlements. The innovative field of bioastronautics aims to address some of the medical issues astronauts encounter during space travel. Astronauts are faced with several health risks during both short- and long-duration spaceflight due to the hostile environment presented in space. Some of these health problems include bone loss, muscle atrophy, cardiac dysrhythmias, and altered orientation. This review discusses the effects of spaceflight on living organisms, in particular, the specific effects of microgravity on the human body and possible countermeasures to these effects.

Modulation of gene expression in endothelial cells in response to high LET nickel ion irradiation

“…In the context of space exploration, high linear energy transfer (LET) radiation found in space produces high values of relative biological effectiveness (RBE), as compared to low LET radiation, such as X-rays or gamma-rays, which can increase the health risks to astronauts (2). Indeed, during long-term missions, such as a journey to Mars, astronauts are bound to be exposed to cumulative doses between 0.3 and 4 Sv, depending on the spacecraft shielding and on the intensity of solar particle events (3).…”

Osteoporosis in Microgravity Environments

“…Actin filaments, intermediate filaments, and microtubules are the key elements and they serve as a highly organized dynamic scaffold on which intracellular processes take place. In microgravity, cellular structure, intracellular organization, and micro-fluid dynamics are altered [1]. Disruption of normal biochemical and physiological processes follows.…”

“…Clearly the best strategy is to conduct experimental in-vivo human studies in space, but limited access to spaceflights and limited time during flight available to dedicate to these studies renders extensive (but necessary) study unachievable [1]. Accordingly, microgravity simulation has been the primary source of basic biological scientific information including most of what has been discussed thus far in this chapter.…”

“…Accordingly, microgravity simulation has been the primary source of basic biological scientific information including most of what has been discussed thus far in this chapter. On the celular level, simulation can be carried out within the rotating-wall vessel (RWV); a NASA-designed tissue culture bioreactor which simulates microgravity [1]. The bioreactor rotates horizontally such that, at an ideal speed, the contents achieve relative suspension simulating microgravity via dynamic equalibrium of forces---the contained cells / tissues remain in a state of long-term, suspended free-fall.…”

“…Additionally, comparison with studies performed in space will be required to validate the model and to ensure that changes noted are not unique to the system itself---in-vitro cellular behavior does not always mirror real life. On the system / organism level, research has focused on animal models; most commonly hind-limb unloading and head-down bed rest (which has also been used in human volunteer subjects) [1]. While such models provide some insight into rapid bone loss, they are not fully satisfactory given that they fail to incite the noted cellular changes associated with microgravity and gravitational forces still compress bodily tissues whereas, in true microgravity, there is negative pressure experienced by tissues.…”