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To wash his blood free of nitrogen that might bubble up and give him a fatal case of the bends, Leonov breathed pure oxygen for a while before he entered the lock. Now, enclosed in his space suit, he was still getting pure oxygen at just about the pressure that he would breathe it on earth. As air escaped from the lock, the vacuum of space reached into it like a monster's claw. The oxygen in Leonov's suit tried to expand, and the suit inflated like a balloon. The cosmonaut must have listened anxiously for the hissing of tiny leaks. But all went well; he flung open the outer door and was the first human to look the deadly vacuum full in the face.
Air locks are simple, straightforward devices; their relatives have been used for more than a century in underwater excavating. But to resist pressure, they must be bulky and fairly heavy. The cramped cabin of a U.S. Gemini has no room for them, and when the first U.S. astronaut ventures into emptiness, he will open a single hatch and expose the whole cabin to vacuum.
Autonomous or Umbilical. Much more interesting than the air lock, though, was Leonov's space suit. One Russian commentator called it "autonomous," which means that it is independent of the spaceship except for a simple tether. The pictures do show cylinders on Leonov's back that probably held oxygen, but the cable attaching him to the spaceship was thick enough to contain a good-sized oxygen tube. It may be an umbilical cord supplying oxygen from the spaceship's tanks, besides carrying wires for communication and telemetering. The tube could also carry away carbon dioxide from Leonov's breathing, water vapor from his perspiration and excess heat. The oxygen cylinders on his back may have been for emergency use.
Whether autonomous or not, the suit was well-insulated and covered with a white material to reflect all possible sunlight, for maintaining tolerable temperatures is one of the major problems in the design of space suits. Because sunlight in space is twice as strong as at the bottom of the atmosphere, and contains ultraviolet rays that quickly weaken many materials, the outer layer of a space suit must not only ward off light and heal, but must be proof against ultraviolet.
Almost as dangerous as radiant heat is the fearful cold of space, which strikes wherever an object is shadowed from the sun. If an astronaut stays long out of sunlight, as may be necessary on future space missions, his body heat will tend to leak away. Thus the outer layer must be made of material that does not radiate too much heat. The Russians have not told what they use for a space-suit coating, only that it is white.
Another serious space-suit problem is flexibility. Contrast between the pressure inside and the vacuum outside tends to make the suit as tight as a drumhead. To move at all, arms and legs must be fitted with accordion-like joints. To judge by his motions, Leonov could move his arms fairly freely, but his legs and torso seemed stiff and straight most of the time.