On July 20, America commemorated the 50th anniversary of the Apollo 11 moon landing. Not only was the mission arguably one of the greatest human achievements of all time, it set the course for discoveries on how the body ages in space, and back on earth.
Neil Armstrong and Michael Collins were 38 years old and Buzz Aldrin was 39 during the first moon landing. Since then, astronauts on active missions have been considerably older. Moreover, their missions are considerably longer — weeks and months, compared to the early missions that lasted several days.
Among the older scientists who have spent more time in space, Peggy Whitson celebrated her 57th birthday there and performed two space walks at that age. She is only the seventh oldest person to spend time in space. The record holder, of course, was the late astronaut and former Senator John Glenn, who, at 77, orbited the earth 134 times in a 10-day mission in 1998. Glenn, who for a time served on AFAR’s board of directors, is known for being the first American to orbit the earth, in 1962.
During Glenn’s 1998 mission, he participated in a series of tests on the aging process. Later, the aging population was one focus of his work as a U.S. senator, and he vigorously promoted the relationship between healthy aging and physical exercise, balanced nutrition and social engagement.
Space travel has taught us what accelerates the aging process, and what can slow it.
Older astronauts exemplify how we are living longer, in general, and how social and professional engagement are key factors in staying healthier for longer. Still, space travel poses health hazards to astronauts at any age, and these hazards parallel the aging process.
Health Hazards of Space Travel
The first health hazard associated with space flight is weightlessness. Our bodies are designed to thrive with the downward pull of earth’s gravity. When it’s not there, muscles (including our most important muscle, the heart) and bone quickly lose strength, spinal columns become unstable (back pain is a particular problem faced by astronauts), and the distribution of fluids in our bodies goes quickly out of whack leading to problems with balance, eyesight, arteries and the immune system.
Second, our body’s important 24-hour light-dark cycles are disrupted. Astronauts orbiting the earth experience our normal 24-hour day every 90 minutes. Consequently, they sleep less with worse sleep quality than they do on Earth. In fact, sleep medications are the second most common medications (after anti-nausea drugs) taken by astronauts on board the International Space Station.
Third, astronauts are exposed to higher levels of damaging radiation than those of us on the ground, having lost most shielding of the earth’s atmosphere.
Astronaut Scott Kelly, who recently spent a year aboard the Space Station at 50 years of age, experienced the radiation-equivalent of 50 years of exposure on Earth, which led to increased damaged to his DNA.
DNA damage, of course, can lead to cancer as well as other health problems. Several studies have also reported reduced speed of mental acuity among astronauts in space, although what this is due to is not clear.
If all this sounds familiar — weakening muscles, bones and heart, compromised vision, balance and immune function, increasing DNA damage, reduced speed of mental function — it should. These are the very signature of aging.
Exercise, Once Again, Turns Out to Be Key
Space travel has taught us about what accelerates the aging process, and what can slow it. Through these space studies with older astronauts, we’ve learned that much, although not all, of the accelerated aging effects of space flight return to normal after the return to Earth.
Some of the same therapies that help us resist aging on Earth, also appear to work in space. Specifically, much (but not all) of the muscle and bone decay involved in space flight can be prevented by exercise.
American astronauts on the International Space Station exercise at least two hours per day. (Whether this amount of exercise also preserves brain function as it does on Earth isn’t yet known.) And because of the similarities between aging and the rigors of space flight, our rapid recent progress in discovering new ways to slow aging is likely to help preserve astronaut health on longer space flights as well.
So, as our thoughts turn from the glorious remembrance of Apollo 11 to the prospects of future permanent settlements on the moon and landings on Mars, it is comforting to know that the same research that will prolong the health of the aging Earth-bound population may also preserve the health of our new pioneers in space.
It’s inspiring to see how NASA continues its commitment to studying how aging faster in space can help us age better on Earth, helping advance the biomedical research that’s working to help us all live healthier for longer.