John Glenn--Aging Astronaut Flies Again
(Neuroscience in Space)

By Ellen Kuwana
Neuroscience for Kids Staff Writer
November 6, 1998

Some nights you're so tired you don't even want to brush your teeth before hitting the sack. Imagine having to attach 23 sensors to your body before bed. Then imagine you're in zero-gravity, where wires and sensors float--and you're floating too!

This has been the nightly routine for John Glenn, the 77-year-old astronaut on the space shuttle Discovery. When he and his crewmates--most are half his age-- returned to Earth on Saturday (November 7, 1998) after nine days in space, they will have completed sleep and other science experiments that will provide valuable scientific data about aging.

Glenn is not the only one doing experiments. There are more than 80 experiments on the shuttle. Some astronauts are researching how balance is affected in zero-gravity; research with fish also will help shed light on this topic. Your sense of balance and knowing where you body is in relation to the floor (imagine yourself on a boat that is rocking in the water...your body senses the motion and your brain sends signals to your muscles to adjust so that you do not fall) is a cooperative effort of your inner ear, which senses motion; your brain, which processes the information; and your muscles, which contract to keep you upright.

Another experiment uses an "electronic nose" to take samples from the air in the shuttle to make sure there are no contaminants such as harmful gases that could make the astronauts sick. This "e-nose," like our nose, detects and identifies organic and inorganic molecules at very small levels.

Glenn's research will focus on several topics. The first is bone-loss. When a people age, their bones actually lose mass (volume or bulk). This also happens to astronauts in space. By studying the astronauts, scientists and doctors may be able to help aging people on Earth slow the process of losing bone density. One disease of bone loss is called osteoporosis. This disease affects middle-aged and elderly people, particularly white females.

A second area of research is muscle atrophy. Atrophy means deterioration or wasting--literally, "lack of food." This occurs when people age or are immobile, such as being bedridden or paralyzed. Glenn has been taking amino acids (one is ingested, or swallowed, and one is injected by a shot), which are the basic units from which proteins are formed. Scientists want to see how the amino acids, alanine and histidine, are incorporated in his muscle and how fast they break down.

In a third research project, Glenn and crewmate Chiaki Mukai have had their sleep monitored each night. It takes them about an hour to put on all the equipment that records their body movements during sleep. Sensors on their bodies monitor breathing, snoring, eye and chin muscle movements, and brain waves. In order to record their brain waves during sleep, they wear special head gear that has electrodes (sensors that detect electric current).

Brain cells generate electrical activity that indicate the brain's state of activity. The electrodes detect the brain waves. A record of the brain waves is called an electroencephalogram (EEG). The pattern of brain waves can indicate when a person is awake, stressed, thinking, or sleeping. One pattern of waves produced during sleep is called delta waves.

Astronauts typically have trouble sleeping in space, because the sun rises and sets every 90 minutes, about the time it takes the shuttle to orbit the Earth. The astronauts will have orbited the Earth 144 times on the 3.6 million mile trip. Trouble sleeping is another trait astronauts in space and elderly people on Earth share.

Glenn said that he is eager to provide data to help "lessen the frailties of old age," which will help the aging population of the world.

While Glenn is providing important scientific data by being the oldest person in space, and his medical records from the past 50 years give a written record to compare with his present physical state, it must be noted that he only provides one data point. What does this mean?

Basically, Glenn is only one person, and one cannot draw strong conclusions from data obtained from only one person. For instance, if the doctors find something unusual with how Glenn absorbs the amino acids in his muscles, that could be because of his space travel, or it could be something unique to Glenn, or unique to men. It is not until you have several people to compare that you can make a general conclusion and apply it to a wider population.

That is why the space experiments try to involve as many astronauts as possible--so there will be more people to provide data for comparisons; a few of the astronauts will not participate in certain studies so that they are the control group. A control group does everything the same except for the experimental part, the variable. So if a few people take amino acids, a few people will not, yet they are spending the same time in space, eating the same food, doing the same activities, so that everything is the same except for the variable, which is taking amino acids. That way, if there is a difference between the groups, you should be able to conclude that it is a result of the amino acids, not anything else.

The shuttle returned to Earth at 12:04 pm EST at Kennedy Space Center's Runway 15 on Saturday, November 7, 1998.

For more information on this space shuttle flight (STS-95) and John Glenn, see:
  1. John Glenn - Then and Now
  2. John Glenn's Excellent Adventure - Scientific American (Jan. 1999)
  3. NASA Home Page

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