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| SPACE AGING | |
 October 29, 1998 
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TOM BEARDEN: The early years of manned space flight were truly journeys into the unknown. If John Glenn and the other early astronauts were to survive, they had to have a viable spacecraft, and engineering had the highest priority. Biomedical research was a stepchild, mostly limited to collecting samples and listing heart rates and the like. Even that was tricky. Joan Vernikos, the present head of life sciences at NASA, remembers the Gemini missions.
TOM BEARDEN: A lot has changed in 36 years. As a 77-year-old John Glenn returns to space, life sciences research is finally getting more attention. One big reason for that is space science and aging science are being to converge.
And I'm looking at my role in this -- I just hope we can bring back -- I can bring back very good information in this area so that there won't be any doubt about going ahead with continued experiments in this area. |
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Space and aging |
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TOM BEARDEN: About 10 years ago, scientists began to realize how much the human body's reaction to space resembled the aging process on Earth. Muscles, for example, gradually atrophy in space. Nobody knows
exactly why. One theory has to do with the way that proteins are built up and broken down in muscle tissue. In space, with no weight to provide constant resistance, muscle protein breaks down more rapidly than it is replaced. With no work to do, bone chemistry also subtly changes. In normal adults, bone matter is constantly being created -- a process called modeling -- and constantly being destroyed -- resorption. On Earth the two processes are roughly in balance. But in space the bone loss gradually gains the upper hand. Bone mass gradually diminishes -- up to 1 percent per month for some weight-bearing bones. Astronauts can fight that with exercise, but only up to a point. When they return, some of their bone mass is believed to be gone forever. Sound familiar? Bone loss in space has struck many researchers as similar to the bone loss that happens to the elderly in osteoporosis. Space science and geriatric science recently began to collaborate to try to find out if the underlying causes of that bone loss are the same. It's just one of the new possibilities that's opening as science begins to understand how life functions in the absence of gravity.
Microgravity also affects the subtle interplay of sensory stimuli, from the eye, the touch, and the inner ear, that give a sense of where we are in space and where our body parts are. John Glenn's Japanese colleague on the shuttle mission had that experience on her last flight.
TOM BEARDEN: The space agency began to study that process in earnest when it sent up Neurolab, the first mission dedicated to studying the nervous system. That was just last April -- a measure of how recently life sciences research has come to the forefront. JOAN VERNIKOS: There is value of microgravity of space flight as a tool in understanding physiology because we have here normal physiology in abnormal environment where we can delete one of the presumably prime sensory inputs that we receive here on earth. TOM BEARDEN: One experiment on Neurolab placed astronauts in a rotating chair. When they spun around, centrifugal force made the inner ear feel some, but not all, of the forces it would feel on earth. A TV camera focused on eye movements to see how the balance system would respond in the new environment. Another experiment ejected a spring-loaded ball from overhead toward the astronaut's hand to test how eye-hand coordination changes in the absence of gravitational cues. Neurolab also investigated sleep disruption -- it's a longstanding problem in space and among older people on earth. Glenn and his crew will continue that investigation. |
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What about sleep? |
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TOM BEARDEN: Dr. Charles Czeisler has studied sleep disorders for more than 20 years. At his lab at Brigham and Women's Hospital in Boston, he keeps volunteer subjects in isolation for months at a time. On earth, the body follows a daily pattern of change in temperature and chemical balance that both follows and governs our sleep-wake cycle. In isolation the so-called Circadian Rhythm begins to lose its connection with the cycle of day and night. That is similar to what happens in space. DR. CHARLES CZEISLER: The sun rises and sets every 90 minutes in the space environment, instead of every 24 hours as it does here on earth. And that sends a signal to the pacemaker in the brain that controls the biological clock in the brain that normally cycles every 24 hours. That sends a signal that it really can't interpret. TOM BEARDEN: Research on earth has shown that during the sleep period the pineal gland in the brain produces more of the hormone melatonin. It plays an important but not fully understood role in the sleep-wake cycle. On Neurolab, astronauts wore special apparatus that measured eye movement, breathing, body temperature and brain activity while they slept. They took melatonin pills one day and a placebo the next, without knowing which was which. Sleep patterns were compared in hopes of developing something to help astronauts sleep normally in space. Glenn and Chiaki Mukai were scheduled to repeat the experiment on this week's shuttle mission. But in the weeks before the flight, Czeisler discovered Glenn did not meet one of the 200-odd criteria he had established for his study. So Glenn will not take melatonin -- but his sleep patterns will still be measured. TOM BEARDEN: Does it hurt the experiment that he's not taking melatonin? DR. CHARLES CZEISLER: I don't think it will decrease the science yield on his experiment because we'll get a very fine look at how his sleep on the ground compares with his sleep in space. TOM BEARDEN: There's never been a 77-year-old astronaut before and not likely to be another one anytime soon. How valuable is the information you're going to get from him? DR. CHARLES CZEISLER: As Senator Glenn put it, there always for every experiment, there has to be a first subject. |
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One more data point? |
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TOM BEARDEN: One of the major unanswered questions about the Glenn mission is how much science can you get with just one man and one data point? Critics of the senator's participation argue he is scientifically superfluous Dr. Mary Osborn headed a panel that recently studied the future of biomedical research in space for the National Research Council.
TOM BEARDEN: Just one more data point? DR. MARY OSBORN: Perhaps. I think it will be very interesting but also not terribly likely that there will be anything beyond a very careful and well-designed set of data points as a matter of fact. TOM BEARDEN: Glenn himself said his presence would be justified only if it was scientifically useful. SEN. JOHN GLENN: This has to make sense from a science standpoint, or we can't even consider it. And I said it has to make sense from a science standpoint or I don't think I should go either. TOM BEARDEN: He said in his press conference he only wants to go on this mission if he actually contributes to the science itself.
But it's not every day that John Glenn presents himself, and I don't think he'd wait five years, or we might be willing to wait for him to go five years from now. And in space, we've learned to take advantage of our opportunities when they present themselves. |
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Repeat performance?
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JOAN VERNIKOS: In an experimental science, as you well know, no one in their right mind would publish the results of one experiment, which is the situation we have found ourselves in. You have to repeat it at least, to make sure that what you saw the first time is real. And so far, we have had 40 years of NASA and less than a year of space, life sciences research. So when people say well what have you done in 40 years, it's all, you know, yeah, we've flown humans and they survived. But that's hardly science. TOM BEARDEN: The Research Council generally endorsed NASA's goals in astro biology but had concerns about the small numbers -- made even smaller by the fact that astronauts can withhold medical data from researchers for reasons of privacy. The council also is worried about the lack of research opportunities.
This will be the last life sciences mission until the international
space station is MISSION CONTROL: Three, 2, 1 -- booster ignition and liftoff of Discovery. TOM BEARDEN: The experiments that Glenn and the other astronauts now in orbit will be performing are among the first steps toward solving those formidable biomedical problems. |
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JOAN
VERNIKOS: Gemini, for instance, we had Gemini 7. That was fabulous --
14 days of actual first time in-flight urine collection. I mean, when
I go and look at that spacecraft in the Smithsonian, I wonder how on
earth l4 days of urine collection could have happened. 
SEN.
JOHN GLENN: We have 34 million Americans over 65 right now. That figure
is supposed to go up to -- according to the demographers -- is supposed
to go up to about l00 million by the year 2050. And this graying of
nations, as it's been called, is going on all over the world. 
Until
space flight, no terrestrial organism had ever experienced a lack of
gravity. Every life form -- from the smallest one-celled animal to the
largest -- evolved in ways that allowed it to function in the presence
of gravity. On Earth everything in an organism is pulled downward. In
humans, muscles and bones work against gravity to keep us upright. A
whole complex of systems work together to keep us from toppling over.
The heart has to work against gravity to pump blood to the upper reaches
of the body and the brain. All of that is gone in the weightless environment
of space. Fluids begin to shift away from the lower body and toward
the head. The face and neck swell up. Most astronauts report a feeling
similar to a head cold. 
CHIAKI
MUKAI: When I went to space, I couldn't tell which is ceiling and which
is the floor. It was so neat -- and wonderful experience because my
eye says, Chiaki, that should be your ceiling, but my body didn't feel
it was the ceiling. Sometimes I felt the wall is my ceiling and floor
is my ceiling and I thought, oh, gee, that's a wonderful experience.
DR.
CHARLES CZEISLER: Many crew members take some form of sleeping pill
to help them sleep while they're in space, which gives, you know, some
measure of the difficulty that the crew members have sleeping in the
space environment. They lose about one to three hours of sleep per night
when they're in space, as compared to when they're here on earth. 
DR.
MARY OSBORN: My own personal opinion would be that one person is not
going to make or be the source of major new insights any more than one
woman astronaut would be considered a source of major new insights.
JOAN
VERNIKOS: And he is. Would we be flying an older astronaut now if we
were developing the program in a systematic fashion? Probably not. Probably
in five years we might be at the point where we'd want to fly an older
individual, or older individuals, maybe. 
TOM
BEARDEN: Taking advantage of the opportunities has been a way of life
in astro biology -- that's changing as the science matures. But there
is still the problem of doing good science with small numbers. 
operational.
That's at least five years away. And in that time scientists and funding
could drift away. And yet, unless countermeasures to the physical problems
of space travel are developed, there's no way astronauts can go to Mars
-- a trip that should take place within the next 20 years. 
