Hi. My name is Julia, and I am a Space Physiologist. You are probably wondering what that is! My job is to understand the impact being in space has on the human body and the systems that operate within it.
Space is associated with very little gravity exposure compared to what we experience on Earth. Our body has adapted to function in 1G (Earth’s gravity), and so all functions and processes that our bodies perform are related to that. If we come out of a 1G environment, then the body will function differently. Similarly, when we climb mountains, our physiology reacts differently because there is less atmospheric pressure than what we are used to, which changes the concentration of Oxygen we breathe in, which has numerous knock on effects. For astronauts that leave Earth for months – soon to be years at a time with pending missions to Mars – it’s important to understand how their bodies might react to their new surroundings, what consequences might be entailed, and what therefore needs to be done to prevent or minimise any deleterious effects. I’ll be posting a series of blogs that are designed to help you understand what kind of issues might be faced by astronauts, and also the analogies to Earth-based populations. I’ll start with a generic overview of the primary issues faced in space.
Gravity plays a fundamental role in shaping how the human body works. In particular, the musculoskeletal (muscles and bones), cardiovascular (the heart and blood vessels) and neuro-vestibular (brain and balance) systems are all highly dependent on gravity for normal function. Therefore, in reduced gravity environments, changes arise in each of these systems.
Within the first two days of being in space, blood moves from the lower body to the upper body. Normally, the heart has to work hard to get blood that usually sits lower down up towards the head to make sure that we don’t faint! In space, because the blood is already upwards, the heart doesn’t have to work as hard anymore, making it slightly weaker. Upon return to Earth, astronauts find it hard to stand up again because the heart isn’t used to having to pump blood from the legs up to the head again!
Our muscles stay healthy by being used; our bones stay healthy by being in contact with something. Every day on Earth we use muscles and bones to stand and walk around, and they are constantly working against the floor to enable us to do so. In space, astronauts float, meaning that those muscles and bones are not required as much. As a result, both get smaller and weaker.
The organs in the inner ear responsible for balance are disturbed. There is also no sense of direction. There is no up, down, left and right; any direction could be any direction! This combination can cause disorientation and something called space motion sickness.
Space radiation is also a major risk factor for astronauts, as they do not have the protective shield that Earth’s atmosphere provides us with.
The good news is that there are plenty of countermeasures – an action taken to prevent something bad from happening – in place, both during and after space missions to help with these issues.
Stay tuned for the next snippet!