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During periods of darkness, he flicked on the tiny flashlights that were attached to the fingers of his gloves, directed the beams on his maps. He found he could urinate easily into the "motorman's pal," which was attached to the lining of his space suit. On his second orbit, he again ran into the field of luminous particles; he turned his capsule around at a 180° angle to see them better, but most of them were eventually lost in the glare of the sun.
But Astronaut Glenn's adventure involved far more than mere sightseeing in space. He encountered difficulties that turned his journey into a nightmare of suspense. Passing within radio range of Guaymas, Mexico, on his first orbit, his attitude control system began to act up. A small jet, designed to release hydrogen peroxide steam to keep the capsule in a stable position, was not working properly. The capsule, reported Glenn, "drifts off in yaw to the right at about one degree per second. It will go to 20 degrees and hold at that."
Flying by Wire. To return the capsule to its normal position, Glenn took over the controls himself and activated other jets. For most of the rest of the flight, Glenn had to "fly" the capsule either by hand, or by using a semi-automatic "fly-by-wire" system roughly akin in its operation to the power steering on an automobile. Because of this, Glenn had no time to perform many of the planned exercises and drills to see if he would become space-sick.
As he crossed the Pacific a second time, Glenn discovered that his gyroscopes were wandering. The erratic jets were making the capsule "roll" (turn on its horizontal axis). A similar roll in November's flight of the chimp named Enos had forced the men at Cape Canaveral to bring the capsule down after two orbits. But again, John Glenn was able to overcome the trouble manually.
Worrisome as it was, the problem with the attitude control system was nothing as compared with another threat. Just as Glenn was beginning his second orbit, an instrument panel in the Project Mercury Control Center at Canaveral picked up a warning that the Fiberglas heat shield on Friendship 7 had come ajar. If the shield were to separate before or during the capsule's re-entry into the earth's atmosphere, John Glenn would perish in a flash of flame.
One by one, other tracking stations picked up the ominous signal. At the Cape, Project Mercury officials huddled tensely, trying to decide what to do. The answer might mean life or searing death to John Glenn. The final decision was made by Operations Director Walter Williams: an attempt would be made to hold the heat shield in place by changing the re-entry procedure. The retrorocket packet was supposed to be jettisoned after the rockets themselves had been fired. But the packet itself was bound to the capsule by three thin metal bands. Williams figured that the bands might be strong enough to hold the shield to the capsule during the descent. He knew that the heat would eventually burn away the straps, but he hoped that by that time the air resistance would be dense enough to hold the shield in place.