One Twin Lives In Space For A Year, Then They Notice Something Different About Him When He Returns

One Twin Lives In Space For A Year, Then They Notice Something Different About Him When He Returns

Back in the 1960s, brothers Scott and Mark Kelly shared two very important things: a nearly-identical genetic makeup and a desire to boldly go where no one had gone before. They had no idea that, a few decades later, they’d be the subjects of a history-making experiment in space that would leave one brother permanently changed, and scientists everywhere scrambling for answers. Finally, the truth of what really happened up there is coming out—and it’s more unsettling than we ever could have imagined.

Scott and Mark Kelly

Identical twin brothers Scott and Mark Kelly had both achieved their life-long dream of becoming astronauts for NASA. This wasn’t only a once-in-a-lifetime opportunity for the twins, but for NASA: it’s not every day that you see a pair of twins who are both capable of space travel. 

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Twin Experiments

“Early on in our astronaut career, my brother and I had kind of wondered about it — hey, I wonder if they’ll ever do an experiment with the two of us, being genetically nearly identical,” Scott Kelly explained. It took years, but then NASA approached the brothers with a proposition.

Kelly Sullivan / Getty Images

Worlds Apart

With Mark as the “control” on Earth and Scott as the “experimental” on the International Space Station, the twins spent almost a whole year on different worlds. They had no idea how doing so would shed light on the effects of space travel on the human body.

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Mark’s Carefree Life

Mark’s life on Earth didn’t change much, except for how little he saw of his twin brother. He ate whatever he wanted, drank whatever he wanted, traveled wherever he wanted, and did whatever he wanted. Life was not so carefree for Scott.

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Scott on the International Space Station

Life on the ISS followed a strict schedule. Scott carefully tracked when he ate, when he went to the bathroom, when he did blood tests, and so on. He was confined to the walls of the station, away from the sights, smells, and sounds of Earth.

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High-Stress Job

Most of all, Scott’s days were spent doing the high-caliber, high-stakes work of an experienced astronaut — he wasn’t exactly on vacation. Throughout the year, both Scott and Mark dutifully collected body samples to send to NASA for monitoring.

Bill Ingalls / NASA / Getty Images

The Twin Study

When Scott and Mark finally reunited on Earth, it took months for Scott’s body to get used to gravity again. During this time, the results of the Twin Study were finally analyzed…and what scientists discovered about space and human genetics was astonishing.

Bill Ingalls / NASA / Getty Images

Internal Changes

As it turned out, Scott’s body went through things Mark’s body back on earth did not: On the ISS, fluids swelled around his upper body and head, his immune system worked overtime, and his metabolism was altered…and those were just the internal changes.

Public Domain / NASA

Damaged DNA

When Scott finally reunited with Mark, what Mark saw was different from the familiar face he’d known all his life. You see, what had changed the most in space wasn’t Scott’s body chemistry, but his genetic makeup. His DNA had been damaged.


Most Comprehensive Research

According to Mike Snyder, a co-author of the Twins Study, “This is…probably the most in-depth study, certainly at the biochemical level, that’s ever been done in people in space.” It’s a good thing, too: Scott’s unusual genetic changes told a bizarre story.  

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Scott’s Chromosomes Changed

While in space, there was Instability in Scott’s genome. This caused the protective structures at the ends of Scott’s chromosomes to get longer for a short period of time. However, they didn’t go back to normal as one might expect.

Ed Reschke / Getty Images

Learning About Telomeres

Instead, when the protective structures on Scott’s chromosomes “shrunk” back, they ended up being shorter than they once were. This may not sound like a big deal, but these protective structures, called “telomeres,” actually play a huge role in our lives.

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Telomeres Indicate Age

Internally, telomeres indicate what stage in the aging process a person is at. The longer the telomere, the younger the person. The shorter the telomere, the older the person…and the more at-risk they are for age-related illnesses.

NASA / Getty Images | NASA Johnson / Flickr

Long Telomeres = Longer Youth

This brings two main questions to mind: Has NASA discovered the secret to youth, and has Scott’s body aged more quickly than Mark’s? In terms of the secret to youth, NASA doesn’t want people to get too excited — at least not yet.


No “Fountain of Youth”

As Twin Study co-author Susan Bailey said, “I don’t think that [the elongation] can…be viewed as the fountain of youth and that people might expect to live longer because they’re in space.” In fact, NASA points to Scott’s shortened telomeres to prove otherwise.

Photo by NASA via Getty Images

Age-Related Illnesses

The fact that Scott’s telomeres were only temporarily lengthened and are now permanently shorter than they were proves how space flight can actually put the body at risk for age-related conditions, like heart disease and cancer, earlier in life than before.

Jose Luis Pelaez Inc / Getty Images

Are They Still Identical?

Of course, that leaves us with one question: Did Scott age in space as much as his genetic expression implies? When Scott and Mark were once again face to face, everyone wanted to see if the twins still looked identical…

Photo by Bill Ingalls/NASA via Getty Images

Double Trouble

Weirdly, it wasn’t Scott who looked different, but Mark. Despite being the control subject, it was Mark, who had lived normally on Earth, who had higher levels of DNA changes, probably because of his “carefree” life. Still, there were some bizarre physical changes in Scott. 

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Decrease in Cognitive Speed

Not only had Scott’s eye shape changed, but his body seemed to have aged a bit, too. His vision was weaker, he had a decrease in cognitive speed, and despite being the same age as Mark, he’s at a somewhat higher risk for heart disease.


Not Enough Twins

You might think that these findings would transform space travel, but that’s not the case. There’s no way that NASA will ever have enough twin astronauts to study to turn their findings into anything more than interesting observations. Still, there may be hope yet.

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“Genomic era of space travel”

The Twin Study proves that scientists can monitor an astronaut’s genetics from space. The study could even have “inaugurated the genomic era of space travel,” according to Professor Andrew Feinberg, which could lead the way to one long-anticipated achievement. 

NASA / Getty Images

Going to Mars

Scott and Mark’s participation in the Twin Study will help future scientists understand how the human body relates to space flight, and if it will ever be possible for humans to explore new worlds at all — worlds, as Feinberg suggests, like Mars. Scientists have been working for years to actually get humans to Mars and with recent technological advances, this mission is now very much a reality.

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Fellow Martian

NASA is aiming to send people to Mars by the 2030s. While Scott and Mark aren’t on their shortlist of candidates at this time, one of NASA’s most unexpected prospects is a child. Alyssa Carson doesn’t have a twin sister to aid in NASA research, but there is definitely something special about her.

Above And Beyond

In some ways, 17-year-old Alyssa Carson is just like any teenager. She plays soccer with her friends and chess with her dad. But even she wouldn’t go so far as to say she’s a regular teen. While kids her age fill out college applications, Alyssa has her eyes on another kind of application—one with a chance to change not just her life, but the world itself.

Fast Track To Space

The second she turned 18 in 2019, Alyssa filled out the application for NASA’s astronaut training program. Her hope wasn’t to study on the International Space Station or leap on the moon like Neil Armstrong. Her ambitions go even further.

Extreme Dedication

If everything goes according to Alyssa’s plan, she’ll be the first human being ever to step foot on Mars! And this isn’t some silly teenage dream: her dedication to this goal makes even the most committed workaholics’ head spin.

Early Interest

Her interest in space started at just three years old. Little Alyssa watched an episode of the kids’ cartoon Backyardigans where barnyard animals, below, went on a trip to Mars. After the episode, the curious little girl went to her father, Bert.

Mars Generation

She asked him if human beings have ever been to Mars. “I explained to her that we’d been to the moon, but not Mars,” Bert said. “But it would be her generation to become the Mars generation.” From that moment on, the Red Planet fascinated her.

A Breakthrough

“I started watching videos of rovers landing on Mars,” Alyssa says. “I had a gigantic map of Mars in my room I would look at. We started getting telescopes so we could look at space.” At age seven, she had a career breakthrough…

Dream Camp

It was then her dad took her to NASA’s space camp in Huntsville, Alabama. “That was the weekend of my life,” she recalls. “I got to learn everything I had been wanting to know and more…I got to see a life-size rocket.” But one trip to space camp wasn’t enough.

Breaking Records

Over the years, she returned to NASA’s camps a whopping 18 times. By age 12 she became the first person in history to attend all of NASA’s space camps located throughout the world in Alabama; Quebec, Canada; and Izmir, Turkey. She was only getting started.

Photo by © Richard T. Nowitz/CORBIS/Corbis via Getty Images

License To Rocket

Alyssa undertakes any space-related activity she can get within a finger’s length of. “She’s the youngest to ever graduate from Advanced Space Academy,” her father noted. “She got her rocket license before getting a [driver’s] permit.”

Advanced Training

The teenager also regularly participates in simulated space missions and physical preparedness training; she builds robots and rockets and regularly takes weeks off from her college-level coursework—which she performs in four different languages—for additional training.

What’s The Payoff?

“Sometimes coming back to high school can be boring compared to this,” says the girl who’s earning certificates in diving to “build [her] resumé.” But when will her passion and drive actually see the payoff? Are humans even close to going to Mars?

Five-Phase Plan

Well, on March 21st, 2017, United States President Donald Trump gave NASA a mission: get human beings to Mars by the year 2033. Just one week later, the agency released a five-phase plan to make it happen…

Vying For A Spot

Phases zero through three will see rocket testing—which is already underway, below—deep space transportation, and study of deep space living. By 2033, NASA plans on sending humans on the nine-month trip to Mars—hopefully with a then-32-year-old Alyssa included.

Photo by Bill Ingalls/NASA via Getty Images

Big Sacrifices

With her eyes on such a far-off prize, Alyssa understands the sacrifices she must make in her modern day life. “The idea of having a family,” Alyssa says, “is something NASA would want you to consider once you come back from Mars.” In other words…

No Romance

“It’s a place we’ve never been to, and it’s a dangerous mission,” she says. “Having someone you love on earth, that’s a distraction.” Romance, then, is off the table for another 15 years. But potential relationships aren’t the only ones affected by Alyssa’s plans.

Difficult Parting

“Every time Alyssa talks about having to go to space,” Camille Taylor, left, Alyssa’s best friend, says, “it makes me sad because I’m saying, ‘oh she’s going to leave me one day.'” Her father echoes that sadness.

The Next Generation

Bert recognizes the dangers of space travel. As former International Space Station commander Chris Hadfield, below, explained in a 2018 interview, right now, “the majority of the astronauts that we [would send on Mars] missions wouldn’t make it.”

Risky Mission

Space travel in cramped quarters could drive a person crazy. Deep-space radiation would bring incredibly high cancer risks. Not to mention, more than one cleared-to-launch rocket has just straight up exploded. Bert, however, considers another factor, too.

Three Years On Mars

If all goes according to NASA’s plan, Alyssa would spend three years on the Red Planet, growing food and performing experiments, essentially making it livable for colonizing humans. The idea is practically unbearable to the loving dad.

Letting Go

“I still have to look at it as a father,” he said, fighting back tears, “that I’ll have my child for 20 more years and then I may not ever see her again. And that’s hard. But for what she’s wanting to do I have to support her.” Indeed, her mission might be crucial to the survival of mankind.

For The Future

Alyssa believes that a “single-planet species will become extinct. Just going to Mars will show people that we can move on from planet Earth”—a planet humans have inarguably done damage to over the millennia.

Photo by Kevin Frayer/Getty Images

Bigger Rewards

“Even though there’s a lot of risk in going to Mars, I believe that the rewards are so much greater,” Alyssa says. And her father, sad as the idea of losing his daughter makes him, couldn’t agree more. “This is bigger than the two of us,” he says.

Alyssa Carson/Facebook

Relentless Pursuit

And that’s why Alyssa’s relentless in her pursuit of getting to Mars. NASA is even “more precise about who they want for [the Mars] mission,” Alyssa says. It “motivates me to put in the hard work now to…help me stand out.”

Youngest PoSSUM

And in 2015, she added another impressive line on her resume. She was the youngest person ever accepted into PoSSUM Academy—a program “preparing people for space flight.”

Super Achiever

Amazingly—though maybe not so surprisingly by this point—the teenager already has aspirations for her time after Mars: she wants to be a teacher—which she’s already done a bit of!—or president of the United States. No doubt, she shoots far beyond the moon.

Focus Is Everything

So what is Alyssa Carson’s secret to success? “I don’t think there’s anything specifically that makes it easier for me or that others can’t do,” she says. “It’s just something I’ve really focused myself on.”