Astronaut on space walk

Space Tourism and Your Body: What You Should Know Before Takeoff 

BY Marie Hasty (Archive July 2021)

On a clear night in May 2019, my boyfriend and I watched the stars wheel overhead at a campsite in the North Carolina Mountains. The black vacuum of space gaped indifferently back at us. From the darkness, a shooting star sailed across the periphery and we pointed up, ooh-ing and ah-ing as it disintegrated.

Minutes passed. Our campfire turned cold. Crickets murmured in the grass.

From the blackness, another flash. We pointed and exclaimed again, but this one was different. Instead of winking out, it trailed across the sky. A pearly chain of blinking beads, pulsing overhead as it crossed the heavens. We looked at each other, wide-eyed and questioning, not believing what we were seeing. For minutes, the conga-line of dots continued, then disappeared into the southern sky. We went to sleep in our tent that evening with one conclusion: aliens.

Of course, the next day a Google search gave us the terrestrial truth: the SpaceX Starlink satellite. Evidence of what some scholars are calling the “Corporate Occupation of the Final Frontier”, it represents one of several private companies in the new space race of bringing business to the cosmos. 

“Starlink satellite train as seen from M.B Gonnet, Buenos Aires, Argentina” BugWarp, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

Speaking of race, the United States and Russia are once again fighting to be the first to achieve stardom amongst the stars. In 2020, Russian space agency Roscosmos announced plans to film a new movie, Challenge, at the International Space Station (ISS). News also broke last year of a collaboration between Tom Cruise, SpaceX, and NASA to produce a feature-film aboard the ISS. One of them will be the first non-astronauts to step foot onto the Space Station after NASA announced plans to allow private citizens aboard the station in 2019.

Several companies have aspirations of sending regular folks into the final frontier, not as movie stars but as tourists. SpaceX plans to fly 3 people to the ISS in late 2021 on a 10-day trip that will reportedly cost nearly £40 million ($55 million)  a head. A similar but lagging project, Blue Origin by Jeff Bezos, plans to send six tourists just beyond Earth’s atmosphere into microgravity. This shorter trip will be minutes long, and at the most recent press leakage was reported to cost £140-210k ($200-300k) per person. Virgin Galactic, a British company with 8,000 requested reservations, aims to take wealthy tourists on 90-minute space flights that will also cost about £177k ($250k) per ticket. Other companies vying for their place in the tourism industry continue to crop up. Two space hotel concepts are in the works, with a presumed “if we build it, they will come” philosophy. 

Still, NASA has more ambitious plans. While currently gathering data from unmanned robots, they plan to send humans to Mars in the 2030s. This trip will take a minimum of 3 years, encompassing the most ambitious human exploration of the cosmos yet. 

These projects captivate our imaginations. After a year of feeling hemmed-in by the pandemic, gazing up into the glittering vacuum of the night sky and pondering the possibilities of space travel gives one a swelling feeling in the chest. A chance to see Earth not as an inhabitant, but as a “pale blue dot” in the grand dance of the universe. 

It’s difficult to comprehend the scope of this ambition, to leap into worlds beyond our own. These businesses make space travel for people like you and me more possible than ever (give or take a few million dollars/pounds). But make no mistake; space travel is far from routine. By going “boldly where no man has gone before”, we’re taking ourselves out of the systems we evolved for. 

To date, only 553 people have gone into space, and only 12 have left footprints on the moon. 18 people have died in the pursuit of space travel. We have little understanding of what being in space means for our terrestrial bodies, as NASA and countries outside the US continue to discover new effects with every mission. While Hollywood loves to explore the creatures and phenomena that could hurt us in space, we should be thinking about what being in space is doing to us in itself. What we do know for sure is that space does funny things to our bodies. 

What does space do to us?

Several of the known health consequences of space travel come from something we don’t think about a lot: gravity, or G-force. The amount of gravity we’ve evolved for on earth is 1G, and we don’t notice it unless we drop our phone or stumble over a coffee table. Astronauts and jet pilots routinely experience gravitational pressure of six to eight times Earth’s gravitational pull, or 8Gs. But the average person can lose consciousness at 3Gs, an effect scientists call G-LOC (Gravity-Induced Loss of Consciousness). 

Dental examination in space
“Dental examination in space” NASA, Public domain, via Wikimedia Commons

This happens for a few reasons. Our blood pressure is precisely calibrated for 1G, pushing blood to our brain without blasting our vessels open like a firehose. But under intense pressure, our heart can’t push hard enough to get blood to our brain and other organs. At the same time, blood is pulled down to our extremities where it can’t get back to the heart. Your brain cells keep enough reserve oxygen to keep the lights on for about 4 seconds, but after that the brain protects itself by shutting down. This is G-LOC, and it can be preceded by motion sickness, vision loss, and tunnel vision.

You don’t have to hop into a fighter jet or a rocket to experience high G-force. According to the Rollercoaster Wiki Coasterpedia, the Shock Wave roller coaster at Six Flags in Texas catapults riders to 5.9Gs. If you’re willing to go abroad, the Tower of Terror in Johannesburg, South Africa, subjects its participants to 6.3Gs of force

Pilots and astronauts go through rigorous training and simulation before experiencing multiple Gs to ensure they won’t pass out mid-flight. We can only assume that space tourists will receive some training under gravitational pressures before being launched. But it’s important to be aware of the consequences of these high pressures before you board your rocket to the heavens, and some people may be more susceptible to G-LOC. Smokers have lower oxygen reserves and lower tolerance for high altitudes and G-forces. Other health-related behaviours like sedentary lifestyle, alcohol intake, and cardiovascular disease make people more vulnerable.

But peak physical condition isn’t a necessity for space travel. Dr. Benjamin Levine, NASA’s lead cardiologist, said:,”At some point, we may well send people who are less healthy than astronauts to space, but we’re not going to send them any time soon for six-month trips. So, if you were a betting person, you would say that almost anybody would be at low risk for a two-week activity, whether that be on a cruise ship or a spaceship,” While good physical shape might make space travel more comfortable, the size of your wallet might matter more than the size of your belly. 

On the other end of the gravity spectrum, microgravity exists at the outer reaches of earth, as well as on the moon, and has its own effects on the body. Some of the bodily changes from microgravity have to do with the fact that over half of the mass in our bodies is fluid. We evolved with gravity in mind, and some of our circulation depends on that downward pull. In lower gravity and weightless conditions, fluid accumulates in unexpected places and changes blood flow. One study published in the Journal of Physiology estimates that space travel causes an immediate shift in two litres of blood

Microgravity also causes the position and shape of organs to change, including the eyeballs, heart, and brain. Sans gravity, the eyeball flattens, and post-flight assessments of astronauts have found swollen optic nerves. More than half of astronauts on long-haul voyages in space report vision problems on return. These are typically attributed to intracranial pressure, which is higher in space without gravity pulling fluid down from the head. Astronauts had more cerebrospinal fluid, a circulating fluid in the brain, after spaceflight. Their white matter, or deep brain tissue, was also increased compared to pre-flight. These greater volumes within the skull could also contribute to higher intracranial pressures, and remained elevated for a year after their return. Pituitary glands, an important part of the hormone system, also changed shape consistent with increased intracranial pressure. 

Almost immediately after blast-off, the cardiovascular system changes. Astronauts’ faces feel “puffy” due to fluid shifts, and their lower extremities look like “chicken legs”. The heart rounds in microgravity, losing its oblong shape because blood isn’t pooling in the coronary arteries. After only two weeks, the heart becomes nearly 10% more spherical

A 2020 article in the American College of Cardiology asks the question, Does the Heart Love Space? The evidence is mixed. Dr. Levine found that after a six-month stint in space, astronauts had increased the volume of blood passing through the left atrium, which can preclude arrhythmias and atrial fibrillation. These are unusual rhythm changes for the heart, and increase risk for stroke and heart attack. Dr. Levine noted that astronauts tend to develop atrial fibrillation about a decade earlier than average people. But he says the changes he finds in astronaut cardiology don’t worry him: “It’s just a gravity effect that has no consequence”, he said about changes in shape and flow. The jury may be out on whether or not the heart loves space, but future space tourists should know that they’ll be contributing to space research as much as capitalising on it. 

The sinuses and inner ears are also disturbed in space travel. Astronauts report feeling stuffy almost immediately after launch. Our internal compass, the inner ear gives us our sense of place and position. Without gravity, the delicate vestibular system that helps us balance can’t interpret stimuli. Astronauts often experience dizziness and motion sickness, as well as difficulty performing some tasks.  Some medications have been used to counteract these effects of microgravity, but their side effects often create other problems. One medication that has shown promise for preventing microgravity sickness, scopolamine, causes drowsiness and can inhibit decision-making for astronauts. In the blank void of space, side effects such as these could lead to dangerous or even deadly outcomes. 

While some organs change their shape, position, or function, others just waste away in space. Muscle loss happens surprisingly quickly without the latent strengthening effects of gravity. Astronauts undergo intense exercise regimens to avoid this. According to NASA, astronauts can lose nearly a quarter of their muscle mass in only 11 days. To prevent this, they spend over 2 hours a day exercising.

NASA reports a 20% loss of bone mass after long stays in space, with degradation at about 1% per month. However, a systematic review found that some bones actually gained mass. Cranial bones grew by a little over 2%, perhaps to combat the increase in intracranial pressure. Still, bones in the lower back and pelvis lost an average of more than 6%. This loss makes astronauts more prone to fractures on return, and the degradation of bone leeches calcium into the blood. Astronauts gain most bone mass back in the first few months back on earth, but not all of it

Bones are the site of immune cell growth, and because of bone loss, their immune cell genesis and function changes. Microgravity causes the thymus, a critical part of the immune system, to shrink. Post-flight blood counts of immune cells are consistently wacky, with some counts higher than normal and others low. Some people experience allergies and skin rashes in space flight. Astronauts returning from space are more likely to get sick than they were pre-flight. Luckily, it’s impossible for astronauts to catch a cold in space since contact with other people is limited. Last year, astronauts on the ISS watched in horror as the world below them was enveloped by COVID. They were the only humans totally safe from the virus.

We know one thing for sure: every mission to the cosmos helps us learn more about life, science, and what lies beyond Earth’s blue glow. Research in cosmic physiology has led to breakthroughs for disease processes here on earth. A 2020 NASA publication 20 Breakthroughs from 20 Years of science aboard The International Space Station details several of these innovations. These include research for Alzheimer’s and Parkinson’s Disease, as well as cancer and asthma. Astronauts have created advanced water filtration aboard the ISS, which benefits people in areas with little drinking water access. The station also supports natural disaster response worldwide, and has had breakthroughs in physics and chemistry.

The Red Planet

As NASA looks ahead to Mars exploration, they’re considering the health implications of extended space travel.  Scott Kelly holds the NASA record for longest single mission at 340 days, not even a third of the length of a trip to Mars. We’re unsure what effects this odyssey will have on the human body, but we know that astronauts bound for the red planet face several possible health consequences. 

One study published in 2016 by the University of California at Irvine asks a frightening question: if astronauts make it to Mars, will they remember it? Exposure to radiation levels has caused brain damage to rodents in the past, and researchers worry that humans could experience the same. This study notes, alarmingly, that important decisions under normal or emergency circumstances could be compromised by this mental degradation. In rodent studies, these changes persisted for months after exposure ceased, with little evidence of ever returning to normal. After enough time in space, will astronauts’ decision-making and functioning become so impaired that they are unable to perform important tasks, or even return to Earth? This is one of the questions that NASA continues to ask in their research towards Mars exploration. 

Cancer is also a significant risk for astronauts who embark on longer-term space travel. In 2018, researchers at Georgetown found evidence that radiation in deep space could lead to gastrointestinal damage as well as cancer of the colon and stomach. This risk comes from constant regeneration of the mucosal lining in the gut, a process that could be disrupted and hijacked by radiation. Damage to gastrointestinal cells prevented nutrient absorption in mice, and cells did not recover after exposure was over. This study notes that these effects could occur across other vital organs, with devastating effects on human life.


Artist rendition of astronauts living on Mars
“First Humans on Mars (Artist Concept)” NASA, Public domain, via Wikimedia Commons

As stated earlier, astronauts undergo cardiovascular changes that put them at increased risk for arrhythmias. “Increasing evidence has also elucidated conduction problems that are unique to long-term spaceflight”, states a 2020 study published by Precision Clinical Medicine. The same study also points out that the radiation exposure of space can preclude heart disease, even in healthy people. Changes in blood flow also pose risks. Upon return from longer missions, a few astronauts have had clots found in their neck veins, which could point to an increased risk for stroke or heart attack. Changes in blood volume pose a risk for astronauts returning from longer missions; they can have up to 20% decreases in plasma volume compared to pre-flight.

Still, some studies yield less concerning conclusions. One 2019 NASA study used twins, one who embarked on a 340-day space mission, and one who stayed on Earth. They found that the majority of health effects from space came back to baseline upon return to Earth. This study concluded, “human health can be mostly sustained over this duration of spaceflight.” 

We have more information about the body’s response to space than ever before. With each mission, we learn more about ourselves and the great beyond. But when evidence conflicts, as it often does, astronauts and NASA will have to decide what they are willing to risk by embarking on long-term missions. The first trip to Mars will be a grand experiment for Earth, and especially for the humans who choose to go where none have gone before. 

Regulating Space Tourism

Expanding space travel represents a new opportunity for businesses, and regulatory agencies are trying to keep up. In 2004, the Commercial Space Launch Amendments Act created a grace period as private companies developed space tourism programs. This “learning period” released them from government safety regulations, and was upheld by the Federal Aviation Administration (FAA) in 2019. In 2022, the FAA will reassess whether to continue this unregulated period, or crack down on safety precautions in the industry. But to create regulation, industry standards need to be in place, and the field of space tourism is still perhaps too new. In August of 2020, the Congressional Research Service released The Future of Space Tourism, a document giving background on space regulations and how they could be implemented to enhance safety amongst the stars. In it, the Service states; “at present, the U.S. government has no procedures for certifying the safety of launch vehicles for tourist passengers.”

Currently, the FAA requires passengers to sign an acknowledgement of the risks of spaceflight. But these risks are still being investigated. The Research Service notes that “aerospace medical experts recognise many health risks associated with spaceflight are still not well understood, and very little research has been done on medical consequences of such flights on the health of untrained participants.” Essentially: launch at your own risk. These waivers absolve the government and launch company of liability, but families of space tourism participants could still sue the launch company after a tragic accident.

The FAA and NASA do have recommendations for the training of commercial spaceflight participants. In 2021, they partnered with medical experts to release screening standards for space tourism. For participants on orbiting flights, they recommended a barrage of drug tests, chest x-rays, pregnancy tests, pulmonary function testing, and exercise stress testing. 

As early as this year, SpaceX plans to begin training tourists for space travel. They’ll partner with Axiom, a company with the ambition to put the first private space station in low earth orbit by 2024. Training for space tourists will include medical examinations, but it’s unclear if participants will be barred from flights due to health concerns. On their website, SpaceX announces its goal to “make life multiplanetary”, and each day we move closer to routine space flight. 

But as we look to the future and the stars, it’s worth wondering whether our terrestrial bodies are ready for space. When we think of danger in the cosmos, we think of alien contact, black holes, and treacherous planets. The large-scale dramas of the untamed universe. But the greatest risk to people in the cosmos might not be what’s “out there”, but what is in ourselves. The greatest danger to humans in space might just be our own humanity. 

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