Space Exploration: Side Effects May Include…

Astronauts Bob Behnken and Doug Hurley arrive at the International Space Station in May 2020. Img Source:

Around the world, people of all ages dream of what it would be like to step into an astronaut’s shoes — or boots, rather. Well, it would be shaky, nauseating, rocky, heavy then weightless, and full of pressure (both mentally and physically). And that’s all just during the launch.

Astronauts’ bodies go through so much in a short period of time, with missions ranging from three to six months on the average. The crazy part is most of the time, they don’t even know their bodies are changing. These are the side effects of space exploration.

Launching to Space

Launching into space on top of a powerful rocket sounds fun to many people. It’s definitely exhilarating for the astronauts (whom I think are all adrenaline junkies), but has its rocky downsides.


G-force is a force that acts on something due to acceleration. Not the 2009 Disney movie. It acts on us all the time. On Earth, the g-force is 1g. As you get farther from Earth’s surface, the acceleration due to gravity changes. When an astronaut is strapped in and launches, the g-force is 3x that of a stationary object on Earth. Astronauts have described that feeling as though their crew mates are standing on their chest and won’t get off. They can still breathe normally, but the pressure is immense. To put this into perspective, average humans can withstand about 5g’s before blacking out, though this number can depend on how physically healthy the person is and other factors like alcohol intake.

Another part of launch is when the astronauts go from 3g’s to 0g’s in a matter of seconds. A popular way for astronauts to indicate when they hit 0g’s is releasing a toy to float around the craft.

During the SpaceX Crew Dragon Demo-2 mission, the astronauts released a sequined blue and pink dinosaur named Tremor to indicate 0g’s. Img Source:

Living in Space

Humans were meant to live on Earth. We were born in Earth’s gravity and our bodies developed in it, too. We are protected by our atmosphere from radiation which can cause cancer. When astronauts leave the planet, their bodies immediately start changing.

Astronauts sleeping on a 2002 Space Shuttle mission. Img Source:


The International Space Station (ISS) and spacecrafts are usually equipped to block radiation coming from the sun, but astronauts are still exposed to it. In fact, they are exposed to ten times the amount of radiation than what they are exposed to on Earth. This exposure puts them at risk for cancer, degenerative tissues diseases, and radiation sickness.

Change in Gravity

During an astronaut’s trip, they will experience different amounts of gravity in two to three different environments. On a mission to the ISS, they will experience Earth’s gravity and microgravity (0g). Other missions could be to Mars or the moon, where they would experience Earth’s gravity, microgravity, and the gravity of Mars (1/3 of Earth) or the Moon (1/6 of Earth).

The rapid changes in gravity affect spacial awareness, coordination, and balance. Their spines lengthen causing them to get taller. These changes also affect internal body systems. Because bones are not subject to gravity, they start losing mass. That is why astronauts have to be in peak physical condition and have to do specialized exercises during their trip.

Space Adaptation Syndrome (SAS)

Space Adaptation Syndrome, or Space Motion Sickness (SMS), affects 60–80% of astronauts during their first few days in microgravity. You know that awful tummy-turning feeling you get on boats, airplanes, or rollercoasters? Well, SAS is very similar to those yucky feelings of motion sickness. Just imagine traveling on a rocket seven miles a second. Similar symptoms include nausea (vomiting), fatigue, and loss of appetite. Other, more specific to space, symptoms include facial stiffness from pressure, back pain, and headaches.

Muscle Atrophy

While living in a weightless environment, astronauts don’t need to use as many muscles to function as they did on Earth. These muscles are called anti-gravity muscles and include muscles in the neck and back, quadriceps, and calf muscles. The process of muscles weakening and deteriorating is called atrophy. Astronauts can lose up to 20% of muscle mass in just five to eleven days in space. This is why astronauts have to spend two and a half hours intensively exercising every day in space.

Space Blindness

Space blindness isn’t just a convienient subplot in Netflix’s Away. It’s a real issue that affects about two-thirds of all astronauts. On Earth, gravity naturally pulls bodily fluids down towards the feet. But in microgravity, bodily fluids flow upwards towards the head. This puts pressure on the eyes and causes them to swell and inflames the optic nerves. A study done by the University of Miami also found that there was a significantly larger amount of cerebrospinal fluid (CBF) in astronauts’ brains that was putting pressure around their eyes. While CBF is completely normal for the brain, it is more easily regulated on Earth. In space, the body becomes confused from a lack of posture-related pressure changes.

Confined Spaces & Isolation

This can depend on the astronaut, but ultimately, humans don’t particularly like being locked in small spaces for long periods of time. Especially with other people. Behavioral issues are almost inevitable when three to four people are sent up to live with each other for six months. That is why space companies like NASA select and train astronauts together carefully so that the possibility of issues between them is minimal.

Astronauts are still affected mentally. They can get depression, or symptoms like fatigue, mood swings, decline in morale, and boredom. Sleep loss can affect astronauts when their circadian rhythm is disrupted from all whirring and hum of machines and the changes their body is going through. The monotony of the mission can have a large impact too. No fresh food, no new clothes, no new people.

Inside of an ISS lab. Img Source:

Hostile Environments

Believe it or not, inside the spaceships and the ISS, there is a whole ecosystem. Microbes and microorganisms living on you and your crew mates affect each other. An astronaut’s immune system is altered from the new conditions and therefore can have negative impacts. For example, they could become more susceptible to allergies and other illnesses.

Because missions are high-intensity and full of pressure, stress hormone levels often rise. To help this, the spaceships and the ISS are designed and crafted to comfort the astronaut. Things like room temperature, noise level, and air quality are carefully adjusted so that the astronauts can feel the most comfortable. This sounds a little pretentious, but you would not be a productive and healthy person if your house and workplace were too cold or too loud.

Returning to Earth

Coming home sounds like the easy part. The astronauts have already done all the work to get up to space, stayed there for six months working hard and exerting their bodies. Now they get to relax and go home. Well… not quite.

The Ride Home

Returning home is the bumpiest part of the trip. They are basically plummeting back towards Earth’s surface. Again, they feel the pressure of the g-force, but this time in reverse. Depending on the space craft, landing can be rough. The NASA Space Shuttle glided down and landed like an airplane does. The SpaceX Crew Dragon splashed down in the ocean. The Russian Soyuz Capsule parachutes down to the ground.

Adjusting to Life Back on Earth

The process for adjusting to Earth and Earth’s gravity is different for every astronaut, depending on how long they were in space and how much previous experience they’ve had in space. But no matter what, they have to get their Earth legs back.

When astronauts are retrieved from their capsules, attendants usually lift them from the capsule so that they don’t have to walk yet. The astronauts are immediately evaluated by medical staff to make sure they are doing okay. Astronauts usually feel tired, heavy, and hungry. In extreme cases, like Scott Kelly who returned from a whole one-year mission to the ISS, they can’t walk at all and require lots of recovery and physical therapy to adjust their bodies to Earth. But once astronauts are all good and normal again, they can begin training for their next mission!

American astronaut Tim Kopra being carried from the Russian Soyuz after returning home from the ISS in 2016. Img Source:

Space travel is not as glamourous as it seems and requires lots of mental and physical resilience. The side effects can be pretty extreme and take a toll on the body. So why is this important to anyone besides astronauts?

The future of interplanetary exploration and commercial space travel depends on solving this problem.

What’s the point of going to Mars if we’re weak and half-blind by the time we get there? Currently, NASA is working with Translational Research Institute for Space Health (TRISH) to study problems that could occur during long missions to Mars. I am interested to see how the commercial space travel industry goes about this since civilians won’t have the same type of training and exercise regimens in space as astronauts do.

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Welcome! My name is Allison. I’m a 17 year old high school student with a passion for biotech and space science!