This Is What Happens To The Body During Space Travel

Space travel is not for the faint-hearted—literally; it involves significant mental, emotional and physical stressors, many of which can become prohibitive to the majority of the population. Fortunately, the rapid advancement of space sciences in recent decades has significantly promoted the medical research that examines the impact of space travel on human physiology. As the demand for both space research and tourism increases, more emphasis is being placed on how humans can successfully travel in “cosmic conditions,” and perhaps one day, foster sustainable life for elongated periods of time in space.

A groundbreaking paper published in the journal Cells in December of 2022 explains the numerous changes that the human body undergoes during space travel. For example, due to the effects of microgravity, the cardiovascular system reduces circulatory blood volume, diastolic blood pressure, and cardiac contractility—- all of which can alter peak exercise performance and even potentially cause orthostatic hypotension post-flight. Another example is the GI system; studies have found that exposure to gamma radiation that is commonly found in long-duration spaceflight is a risk factor for colorectal cancer. Immune systems have also been found to be relatively compromised in astronauts upon returning to Earth. Neurovascular systems are also altered slightly, resulting in astronauts frequently experiencing deterioration in postural and locomotor control that can elevate the risk for falls. The list is endless.

This is a primary reason why the pre-requisites for space travel are incredibly nuanced and onerous, and why astronauts often have to undergo rigorous training before spending time in space. Astronaut training programs entail some of the most competitive selection criteria globally; just 6 years ago when there was a nationwide search for the next class of astronauts, nearly 18,000 people applied for approximately 8 to 14 spots, indicating a ~.0007% chance of acceptance. Being selected seems like the easy part; once acceptance is finalized, astronauts must undergo rigorous training programs for years, often entailing intense physical, mental and emotional exercises and tests. Examples include completing water survival training, prolonged exposure to microgravity to acclimate the body, complex flight simulations and tactical response training, and numerous team-building exercises and tasks.

Although the formal astronaut training curriculum has been prevalent for decades since the dawn of the space program in the United States, a new challenge has emerged with the recent growth of and interest in space tourism for civilians. Reports indicate that the space tourism market is expected to reach nearly $5.19 billion in value by 2034. However, standards and protocols for how civilian tourists will visit space have not yet been established. Independent bodies will have to determine whether civilians will have to undergo similar types of rigorous training programs—and if so, what the selection criteria for travel will be. Especially as the space tourism industry continues to proliferate in the private sector, the appropriate levels of checks and balances required will have to be established.

Nonetheless, society has been fortunate to witness incredible feats in both space travel generally as well as the medical research and advancements to support it. Assuredly, this will continue to be an emerging field in the coming decades.