Chapter 15: To return in flames
Theme: September 1961 to February 1962. After months of frustration due to weather and equipment problems, Project Mercury reaches its goal, but not without some tight moments that test the mettle of those on the ground as well as the man in space.
10:50 A.M. Tuesday, February 20. John Glenn is passing overhead at the beginning of his second orbit around the earth. In the control center the deliberately paced communications procedure covers the growing elation. After two months of frustrating delay for weather and equipment, the flight is proceeding with amazing smoothness.
John is experiencing a slight problem with the manual control system. It is obviously nothing serious, but it gives the ground controllers an opportunity to participate in the flight by helping the astronaut to analyze the problem. Word has been passed that the President himself will speak to John over a special radio telephone circuit. But some technical problem keeps the President’s voice from going out over the radio. Well, never mind. Perhaps next time around.
Throughout the world, thousands of engineers and technical specialists are manning communications stations and recovery facilities. The wall charts in the control center and in the recovery room indicate that everyone is on station. In another three hours the spacecraft will land and Project Mercury will have accomplished its goal of manned orbital flight and safe recovery.
In the main room of the control center the flight monitors eye their instruments carefully, watching for any sign of trouble. But everything is within tolerance. In the back room, communications experts are watching their oscillographs, making sure that the information flows to the flight controllers. From time to time they also check the more than fifty indications which are not normally displayed in the main room.
Huddled over one instrument, a technician notices that segment 21 is not normal. It is probably unimportant, but the rules say report all unusual indications. So he hands a note to one of the runners who move about the control room dropping messages into the baskets on the flight controllers’ desks. A few moments later, Chris Kraft, sorting rapidly through his papers, comes across the note, “Segment 21 indicates landing bag deployed.”
But the deployment of the landing bag should be the final operation prior to landing. This bag protects the spacecraft against a jarring landing impact and is normally lowered at the last moment, just before touchdown. The vital heat shield, which must be in place to protect the spacecraft from the reentry fireball, forms the base of the bag. Thus, if the bag should be deployed in space, it would result only in disaster. Without making any announcement over the flight director’s loop, Chris Kraft leaves his desk to speak with Al Shepard and systems monitor Don Arabian at the voice communicator’s station. Neither had heard or seen anything to suggest that the heat shield is loose. It clearly seems impossible, but it is too important not to be checked carefully.
Outwardly there is no change. To those watching through the one-way glass from the visitors’ gallery overlooking the control room and to the reporters crowded into the Mercury press site, all is normal. Now a complicated drama of engineering sleuthing begins as the entire facilities of Project Mercury are brought into play. John Yardley, McDonnell’s chief engineer at the Cape, is called out of the VIP viewing area onto the floor and given the job of running down the problem. Soon engineers back in the Mercury hangar are pouring over blueprints while others are on the phone to the McDonnell Aircraft plant in St. Louis and to the Project Mercury headquarters in Virginia, getting answers to the numerous questions raised by segment 21.
At the moment, the heat shield seems to be in its normal position, but if the release mechanism has actuated, it might be held in place only by the retro rockets strapped over the shield. Segment 21 could be a false signal, but it is impossible to be sure. The safest course appears to be to keep the retro package on through reentry in hopes that if the shield has been released it will be kept in place by the retro rocket straps.
Still, there are bothersome questions unanswered. Wind tunnel tests have demonstrated that reentry with the retro rockets is possible, but will it be safe in actual flight when the spacecraft generates temperatures as hot as the surface of the sun within a few inches of John Glenn’s head? Moreover, when the retro pack burns off, will the pressure of the air itself against the heat shield be enough to keep it in place? Or will the motions of the spacecraft quickly pull it loose and leave the inner shell of the spacecraft unprotected like wax paper in a flame?
Concern mounts among the flight controllers who are aware of the dangers. Al Shepard counsels against worrying John Glenn with the problem. So, unaware of the tension below him, John carries on with his flight plan while studying the slight problem he is having with the attitude control system. Occasionally he gets a somewhat cryptic query from the ground about the heat shield. Is his landing bag switch in the “off” position? Can he hear a “bumping” noise behind him where the heat shield is? Too fascinated by the magnificent view out the spacecraft window, too busy evaluating the control characteristics of the spacecraft, John shrugs off these occasional inquiries without interest.
The first indication he has of a departure from normal procedures comes after the retro rockets have been fired, from flight controller George Guthrie at the Texas station. “We are recommending that the retro rockets not, I say again, not, be jettisoned. This means that you will have to override the .05 g switch which is expected to occur at 04 43 53. This is approximately 4½ minutes from now. This also means that you will have to retract the scope manually. Do you understand?”
There is a slight pause. I could feel John’s surprise, his quick search for the reason behind this decision from the ground. He could not account for it, and his normal reaction would be to follow his own best judgment. But eighteen years of military life have also developed a habit of following orders. “Roger, understand.”
John carries out his instructions carefully, and exactly as they came from the control center. Just before he passes out of range, Al Shepard gives him a brief explanation for the decision not to jettison the retro rockets. Now all the world is aware of the impending problem.
“This is Friendship 7 going to fly-by-wire. I’m down to about 15% on manual.” John’s voice fades away as he enters the black-out period. Within the control center the tension is clear from the positions of the monitors; a living still photo, each man frozen in place, almost afraid to move, waiting for the first static-choked words that will indicate John is safely through the flaming reentry. Bill Douglas, the astronauts’ flight surgeon, head bowed, hands folded, joins the multitudes of Americans at their TV sets in a brief prayer.
Far above, Friendship 7 hurtles through its severest test. For the moment completely out of touch with the world, John sits alone in the middle of a fireball. The needles of his attitude indicators leap wildly back and forth, while fiery chunks of metal fly across the window just above his head. Then his voice is heard again. “Hello, Cape, Friendship 7. Do you receive? Over.” Flame-tested, man and metal are returning to earth.