Aboard the U.S. submarine Haddock, tied up beside a barge in Connecticut's Thames River, a watertight, airtight door was opened for a few moments each morning last week—just long enough to let five scientists into the sub's inner compartments. Then the door was shut and dogged down again. The scientists found that half of the 22 enlisted men on board, instead of going to breakfast, were lolling in their bunks. Far from committing a flagrant breach of discipline, they were performing a valuable duty for which the Navy had invited volunteers. They, and one officer, were guinea pigs in a test which has a vital bearing on the design and operation of tomorrow's atomic-powered submarines.
The purpose of the test is to find out how the human system will react to long confinement in a cramped, enclosed space, with no natural light, no normal exercise and no fresh air. In fact, one of the biggest elements in the Navy's problem is to decide how fresh the air has to be. It is not enough to add oxygen for the crews to breathe; the carbon dioxide which they exhale must also be removed. (Continuing to breathe a 3% concentration would eventually cause death.)
In conventional diesel-electric submarines, which cannot stay down for more than 72 hours at most, the problem was solved by carrying tanks of oxygen and using lithium hydroxide to soak up the excess carbon dioxide. But in an atomic-powered sub that might stay submerged for 72 days, the air-freshening gear could grow to monstrous size. So the Navy wants to know how much CO<sub>2</sub> it can safely leave in the air.
In the Haddock, the carbon-dioxide level in the air has been kept higher than normal—just how high is a Navy secret. The scientists, who have been going aboard each morning since the test started on Jan. 19, took blood samples from the bedfast half of the crew. They checked the men's lungs to make sure their breathing had not become impaired, and recorded their brain waves with an electroencephalograph.
As the day wore on, all the men were tested for ordinary vision, night vision, hearing, hand steadiness and ability to do mental problems. After lunch the Haddock got the traditional "clean sweep down, fore 'n' aft," and then the psychologists took over. They checked the men's moods, how they were getting along with one another, what new likes & dislikes they were forming.
So far, reported Commander Gerald J. Duffner of the Navy's Medical Corps, boss of the $30,000 test, few changes have shown up. A minor, temporary effect in the blood is believed due to absorption of carbon dioxide. The men started out by eating voraciously, but only one has gained (7 lbs.). They still like steak best. One thing Commander Duffner cannot explain: why so many seem to have developed a craving for cottage cheese. And one thing the Navy will not tell, even after the test is over, is how much carbon dioxide the men can withstand for a long period.