Skip to main content
Move the World.

When an audience member asked Elon Musk what he could do to prepare for an eventual trip to Mars, Musk answered the man’s question with another question: “Are you prepared to die? If that's okay, then you're a candidate for going.”

We’re experiencing a level of space enthusiasm we haven’t seen since the Apollo era. But we also know way more now than we did then about what space travel does to the human body. Some of it’s strange, some of it’s awful, some of it is just speculation. So if the idea of going to Mars fills you with glee, here’s what you should know about what happens to the human body in space.

Going into deep space may increase the risk of cardiovascular disease (and probably cancer)

Research published earlier this year suggests that the unusually high rate of heart disease experienced by the 24 astronauts who traveled to the moon as part of the Apollo program was the result of cosmic radiation, which drastically increases as we travel away from the Earth’s protective magnetosphere, ozone layer, and atmosphere.   

Chart via Nature.com

The sample size is small, probably too small to say for sure that going into deep space (the moon, Mars) is significantly more harmful than extended periods in Low-Earth Orbit (the International Space Station, Space Shuttle flights). But the study’s authors suspect that the difference between lunar astronauts and other astronauts is too significant to rule out the effect of cosmic radiation.

Then again: Of the 12 astronauts who walked on the moon, seven are still alive. An additional 12 astronauts orbited the moon without going to the surface, and nine of those guys are still alive. Which means that of the 24 human beings who have traveled the deepest into space--where there’s no protection from cosmic radiation--16 have lived well into their 80s.

The amount of cosmic radiation travelers would endure on a two-year-long trip to Mars would be 300 times what an average person would be exposed to during a year on Earth.

That said, finding a way to shield space travelers from cosmic radiation is absolutely necessary, if not because of heart disease, then because of cancer. The amount of cosmic radiation travelers would endure on a two-year-long trip to Mars would be 300 times what an average person would be exposed to during a year on Earth. NASA isn’t quite sure how we’ll do that, while Bigelow Aerospace is working on an inflatable habitat that would provide some protection from cosmic radiation.

While I have no idea how Buzz Aldrin’s ticker is doing today, I do know that at age 72, his heart was strong enough for him to slug a moon-landing conspiracy theorist after the guy got in his face.

Being exposed to space won’t cook you alive, but it will suck all the air out of your body

Every good space movie and sci fi novel features a character dying in space. But what really happens to an unprotected human body isn’t quite as morbid as you might think. Basically, you just suffocate, as Hank from SciShow explains here:

**Traveling to space makes you taller, but shrinks your heart **

If the Earth’s gravitational pull compresses our spines and forces our heart to pull blood away from our lower extremities, it stands to reason that removing gravity would elongate our spines and reduce the heart’s workload. It can also change your vision and weaken your bones, as astronaut Leland Melvin explains here:

Fitness routines keep ISS crewmembers from completely losing their Earth physiques (exercising starts at around the 9:20 mark):

But coming back to Earth still hits them like a wall of bricks. When astronaut Chris Hadfield returned to Earth after five months aboard the ISS, he had to relearn how to talk. "Right after I landed, I could feel the weight of my lips and tongue and I had to change how I was talking," Hadfield said at a press conference in 2013. "I hadn't realized that I learned to talk with a weightless tongue."

Related: We could be grappling with these questions sooner than many think. Some even envision a near future where humans are taking flights to space everyday. Watch the video below for more:

*Home and feature image from NASA*

Explore More Stories

Science
Scientists Grew a Mini Brain in a Lab. It Has Human-Like Brain Waves. What Does...
Scientists Grew a Mini Brain in a Lab. It Has Human-Like Brain Waves. What Does That Mean for Research?
Science
Scientists Grew a Mini Brain in a Lab. It Has Human-Like Brain Waves. What Does...
For the first time, a lab-grown mini brain has brain waves. Researchers can now launch new ways to study brain disorders. But the question of consciousness in the brain-like organoid could raise concern.
By Teresa Carey

For the first time, a lab-grown mini brain has brain waves. Researchers can now launch new ways to study brain disorders. But the question of consciousness in the brain-like organoid could raise concern.

Dispatches
Training the Body to Fight Off Drug-Resistant Bacteria
Training the Body to Fight Off Drug-Resistant Bacteria
Dispatches
Training the Body to Fight Off Drug-Resistant Bacteria
A new strategy, called host-targeted defense, could help solve antibiotic resistance by upgrading the immune system.
By Zahidul Alam

A new strategy, called host-targeted defense, could help solve antibiotic resistance by upgrading the immune system.

Science
Growing Food with Seawater
Growing Food with Seawater
Watch Now
Science
Growing Food with Seawater
This designer invented a greenhouse that lets you grow food with seawater.
Watch Now

Water is in short supply in much of the world — but what if we use seawater? It’s been a dream for years, but now technology is making it possible. This new seawater greenhouse uses a clever cardboard design to distill fresh water from salt water cheaply and efficiently. It’s helping grow crops in Somaliland, and could help stop the water crisis in Africa and other parts of the world that are susceptible to drought. The...

Intel
The Future of Cancer Research
The Future of Cancer Research
Watch Now
Intel
The Future of Cancer Research
Intel's Bryce Olson used genomic sequencing to help fight his cancer. Now he’s helping researchers use artificial intelligence to discover entirely new cancer treatments.
Watch Now

Intel employee Bryce Olson was diagnosed with stage 4 prostate cancer. When the standard of care didn’t work, Bryce turned to genomic sequencing which allowed his doctors to identify specific genetic drivers of his disease and specific treatments and clinical trials that were a fit for his cancer. This precision medicine approach helped send his cancer into remission for several years. Now that his cancer has returned,...

Sponsored
Can Science Make People Live Healthier for Longer?
Can Science Make People Live Healthier for Longer?
Watch Now
Sponsored
Can Science Make People Live Healthier for Longer?
An MIT researcher has turned 30 years of aging research into something you can use right now.
Watch Now

Most of medical science focuses on combating disease and managing the impact of aging. But one MIT researcher wants to tackle aging head on. Through decades of research, Dr. Leonard Guarente has uncovered a basic mechanism to regulate aging and co-founded Elysium to turn his research into a product. Elysium’s mission is to help people live healthier for longer. Freethink is proud to present this story in partnership with...

Dispatches
A Prosthetic Memory Can Help You Remember
A Prosthetic Memory Can Help You Remember
Dispatches
A Prosthetic Memory Can Help You Remember
Scientists have figured out how to hack the brain's memory.

Scientists have figured out how to hack the brain's memory.

Technology
eSight Lets the Legally Blind See
eSight Lets the Legally Blind See
Watch Now
Technology
eSight Lets the Legally Blind See
This legally blind man is seeing his wedding for the first time. 15 years after he got married.
Watch Now

Some people who are legally blind can still see, but images can be blurry and in low contrast. eSight has created a headset that can give sight to the blind through three technologies. First, an HD camera captures video. Second, a built in computer increases contrast and clarity. Third and finally, the image is projected on displays in real time. 15 years after marrying his wife, eSight helped a legally blind man...

Coded
Meet the Digital Bodyguard for Investigative Journalists
Meet the Digital Bodyguard for Investigative Journalists
Coded
Meet the Digital Bodyguard for Investigative Journalists
Smári McCarthy discusses his job protecting the work of journalists investigating organized crime and corruption
By Mike Riggs

Smári McCarthy discusses his job protecting the work of journalists investigating organized crime and corruption

Coded
Meet the Programmer Who Defied the FBI
Meet the Programmer Who Defied the FBI
Coded
Meet the Programmer Who Defied the FBI
Ladar Levison spent 10 years building his business, then destroyed it all in one night when the FBI came knocking.
By Mike Riggs

Ladar Levison spent 10 years building his business, then destroyed it all in one night when the FBI came knocking.