Briefing the Briefers

The initial postflight period of debriefing, held aboard the recovery ship, included a medical examination and free dictation by the astronaut of his flight impressions. This was followed by a short debriefing questionnaire. From the ship, the astronaut was taken to Grand Bahama Island for an exhaustive two-day debriefing by medical and technical personnel. This session used a prepared list of questions. Interrogations were led by Carmault B. Jackson on medical matters, by Robert Voas on pilot activities and performance, and by Harold I. Johnson and Sigurd A. Sjoberg on systems performance. Some 32 specialists joined in the Grand Bahama debriefing, including program managers, operations physicians, engineers, photographers, and public relations personnel.

[359] His pressure suit, Shepard said, was generally comfortable and allowed sufficient mobility, but the left wrist pressure gauge was difficult to see during acceleration. It should be moved, perhaps to the knee. And there was a circulation problem caused by the rubber cots at the ends of his gloved fingers, which meant he had to keep drawing his fingers back inside the gloves to maintain comfort. The helmet was satisfactory. Shepard had obtained an enlarged faceplate for his own helmet to gain better vision. He had no complaints against the couch or restraint harness. He remembered only minor pressure points from the couch while waiting on the pad. The straps around his shoulders had seemed tight at times before launch, but slight shrugs had relieved the tension and stimulated circulation.

The biosensors caused some skin irritation for Shepard, as they had for others in the Mercury program, both astronauts and test subjects. Better adhesives were promised. Throughout the mission the suit temperature and humidity had been quite comfortable, Shepard reported. During the hours while he was waiting on the pad he was able to maintain a suit reading of 75 degrees, although this rose to 77 degrees a minute or two before liftoff. His suit temperature dropped back to 74.5 degrees for most of the flight, with a brief rise to 82 degrees during reentry. Just before the loss of contact as the spacecraft dropped below the radio horizon, his suit temperature dropped to 77 degrees. Then, in the capsule awaiting pickup, Shepard experienced the hottest part of the mission. When Byrnes suggested that ventilation procedures should be improved, Shepard remarked that he could have obtained some relief by simply unzipping his suit.31

Other parts of the environmental control system also worked satisfactorily. The cabin temperature inside Freedom 7 stayed within a tolerable range from 92 to 100 degrees. Only part of one of the two four-pound bottles of oxygen aboard had been needed. The drain on the coolant supply had been slight.

The engineers among the debriefing team quizzed Shepard about the whole of the spacecraft attitude control systems, but especially about the workings of manual control. According to the flight plan, Shepard was to exercise three modes of control - automatic, manual, and the fly-by-wire combination of the two. He reported that the manual mode was quite responsive and felt the same as the manual mode in the procedures trainers. There seemed to be a tendency for the spacecraft to roll slightly clockwise while in the manual control. Postflight inspectors found a small piece of debris lodged in the hydrogen peroxide tubing, which probably caused the jets to leak a tiny increment of thrust. Near the six-minute point in the flight, according to plan, Shepard was supposed to switch to the fly-by-wire mode of control. Apparently he forgot to turn off the manual valve, so the capsule's attitude control system sucked fuel from both manual and automatic tanks. The debriefing interrogators asked him whether he got more control than desired; he replied that rate changes seemed high but that he thought this was caused by microswitch positions rather than the addition of manual proportional fuel. Shepard could not recall for certain whether he had turned [360] off the manual valve; telemetry data monitoring the spacecraft movements and countermovements indicated that he had not.

The accessory rockets and pyrotechnics on the capsule performed adequately during the Freedom 7 mission, each sequence firing on time and as designed. One exception was a secondary escape- tower jettison rocket, which was later disassembled and found to have ignited by manual pull-ring actuation. Since Shepard did not remember whether or not he pulled that ring, how the rocket fired remained a mystery. It was known that this backup component had not been used to separate the escape tower from the spacecraft. Otherwise the capsule rocketry had performed flawlessly. The posigrades effected spacecraft separation, the three retrograde rockets ripple-fired to provide a 510-feet-per-second velocity decrement, and the drogue parachute mortar discharged correctly. The green sequence lights appeared on Shepard's panel with heartwarming regularity except for the retropack jettison indicator.

At impact the landing bag had performed as designed to cushion the shock, but one heat sink stud did pierce the fiber-glass protective shield. While the pressure vessel was undamaged, recovery had been too rapid for the seaworthiness of the impact bag to be tested. Several rips observed in the impact skirt aboard the carrier apparently occurred during postflight handling rather than at impact or by bobbing in the water.

In general the radio communications during flight had been extremely clear. Slayton, the Mercury Control Center capsule communicator ("Cap Com"), said Shepard's voice transmissions were slightly garbled at liftoff but that seconds later the quality improved markedly. Using the ultra-high-frequency system, Slayton was able to maintain crisp contact with Freedom 7. Shepard and Slayton stayed on UHF, using the Cape antenna, but then as distance increased, voice communications deteriorated. In Mercury Control Center the communications technician monitoring the Grand Bahama Island antenna reception switched Slayton onto a relay from Bahama, and Shepard came in loud and clear once again. Slayton and Shepard communicated well with each other until main parachute deployment. The Mercury Control Center communicator then tried unsuccessfully to use Cardfile 23, the communications relay airplane. Having lost contact with Cap Com, Shepard had expected the recovery forces to garble the radio in competition to talk with him, but circuit discipline was businesslike both before and after countdown.32

31 "Postlaunch Report for MR-3"; memo, Morton Schler to Kraft, "Postlaunch Summary Report of MR-3 Mission," May 5, 1961; Byrnes memo; Sjoberg, Aug. 22 memo.

32 Ibid.; memo, Slayton to Flight Dir., "MR-3 Mission Report," May 15, 1961. The ships did have a communications problem during spacecraft descent, however, because of background interference from Latin-American broadcasting stations.

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