Preparations for the MR-2 mission had begun long before the actual flight. Between manufacturing the capsule and flight readiness certification, several months of testing and reworking were necessary at the McDonnell plant, at Marshall Space Flight Center, and at Cape Canaveral. Capsule No. 5, designated for the MR-2 flight, had been near the end of its manufacturing phase in May 1960. When it was completed, inspectors from the Navy Bureau of Weapons stationed at St. Louis, in cooperation with STG's liaison personnel at McDonnell, watched it go through a specified series of tests, and the contractor corrected all detected deficiencies.23 After capsule systems tests and factory acceptance tests, capsule No. 5 was loaded into an Air Force cargo plane and shipped to Marshall Space Flight Center on September 3, 1960. At Huntsville, Wernher von Braun's team hurried through its checkouts of the compatibility of capsule No. 5 with Redstone booster No. 2, and had finished well before its 16-day time limit.24 On October 11, 1960, the capsule arrived by air at the Cape, where the first checkout inspections, under the direction of F. M. Crichton, uncovered more discrepancies, raising to 150 the total of minor rework jobs to be done. Because of the complexities of the stacked and interlaced seven miles of wiring and plumbing systems in the Mercury capsule, however, each minor discrepancy became a major cost in the time necessary for its correction. Checkout work in Hangar S required 50 days for systems tests and 60 days for rework. The capsule designated for the first manned space flight, No. 7, also had arrived at the Cape for preflight checkouts, but the launch vehicle for MR-2 was delivered to the Cape by air freight on December 20, 1960, the day after MR-1A was launched. It too had undergone exhaustive reliability testing in the shops and on the stands in the hills west of Huntsville, Alabama. When Joachim P. Kuettner, representing von Braun, transferred the MR-2 booster to Emil P. Bertram, representing Kurt H. Debus' Launch Operations Directorate, their confidence in this particular booster of the "Old Reliable" series was high but not towering.25
Using the "quick-look" evidence from the MR-1A flight, Marshall guidance engineers set about correcting the conditions that had made the trajectory too steep and accelerations too high. MR-1A had climbed to its programmed apogee of about 130 miles and landed 235 miles downrange, and high altitude [311] winds had carried it too close to the range borders. Range safety restrictions dictated that a launch vehicle must get out and away from the Cape as soon as possible. For these reasons, Walter C. Williams, STG's Associate Director for Operations, agreed with H. F. Gruene and Kuettner that the MR-2 trajectory should be flattened. An apogee of 115 miles on a downrange distance of 290 miles should be well within the allowable safety limits. Gruene and others calculated that this trajectory would still provide almost five minutes of weightless flight and a reentry deceleration of 10 g. Since this g load was slightly less than that desired by STG, Williams had to use his best persuasion during a series of consultations on the reentry loads to get Marshall to match the 12-g median reentry load by moving the engine cutoff time ahead to assure such conditions. At the same time, the range safety officer felt that the designated 105-degree launching azimuth was uncomfortably close to the shoreline. Williams, Charles W. Mathews, and Christopher C. Kraft, Jr., held out against a requested change to a 100-degree azimuth, because they wanted to minimize pilot retrieval time in case of an abort. To this STG later acceded, in exchange for its point on the 12-g reentry load; Marshall added a timer switch that would cut off the ignition if the accelerometer cutoff signal should fail before fuel depletion.26
Capsule No. 5 contained several significant innovations. There were five new systems or components that had not been qualified in previous flights: the environmental control system, the attitude stabilization control system, the live retrorockets, the voice communications system, and the "closed loop" abort sensing system. Capsule No. 5 also was the first in the flight series to be fitted with a pneumatic landing bag. This plasticized fabric, accordion-like device was attached to the heatshield and the lower pressure bulkhead; after reentry and before landing the heatshield and porous bag were to drop down about four feet, filling with air to help cushion the impact. Once in the water, the bag and heatshield should act as a sort of sea anchor, helping the spacecraft to remain upright in the water. Chronic problems with wave-induced fatigue of the fabric bag led STG and McDonnell engineers to concentrate on the harness linkages inside. After the Big Joe ablation flight test in September 1959, STG had decided to use on the Redstone flights, simply because they were on hand, the expensive beryllium heatshields that had first been ordered for orbital reentry. Since the anticipated reentry temperature would reach only 1000 degrees F, the beryllium shields were not necessary as heatsinks, but they served as readymade impact bumpers. Temperatures on the conical portion of the spacecraft might approach 250 to 300 degrees F, but, compared with about 1,000 to 2,000 degrees for an orbital mission, the ballistic flights should be cool.27
Publicity once again focused on the biological subject in the MR-2 experiment. The living being chosen to validate the environmental control system before committing a man to flight was a trained chimpanzee about 44 months old. Intelligent and normally docile, the chimpanzee is a primate of sufficient size and sapience to provide a reasonable facsimile of human behavior. [312] Its average response time to a given physical stimulus is .7 of a second, compared with man's average .5 second. Having the same organ placement and internal suspension as man, plus a long medical research background, the chimpanzee chosen to ride the Redstone and perform a lever-pulling chore throughout the mission should not only test out the life-support systems but prove that levers could be pulled during launch, weightlessness, and reentry.28
A colony of six chimpanzees (four female and two male), accompanied by 20 medical specialists and animal handlers from Holloman Air Force Base, where the "astrochimps" were stationed and trained, moved into quarters behind Hangar S on January 2, 1961. There the animals became acclimatized to the change from the 5,000-feet altitude in New Mexico to their sea level surroundings at the Cape. Separated into two groups as a precaution against the spread of any contagion among the whole colony, the animals were led through exercises by their handlers. Mercury capsule mockups were installed in each of the compounds. In these, the animals worked daily at their psychomotor performance tasks. By the third week in January, 29 training sessions had made each of the six chimps a bored but well-fed expert at the job of lever-pulling. To condition the chimps to respond properly, they received banana pellets as rewards and mild electrical shocks as punishments.29
Although recovery procedures had worked well until now, recovery operations for MR-2, carrying life into space from the Cape rather than from Wallops Island, demanded extra care and attention. So STG provided the Navy with the detailed requirements, and the Navy again assigned Rear Admiral F. V. H. Hilles to command the recovery forces. Under Hilles were several task elements. One, located on the beach near the launch pad, consisted of numerous amphibious vehicles and several helicopters. Should an abort occur near the pad, these vehicles on the scene would pick up the pieces. Offshore the next recovery perimeter was covered by a small naval vessel, the Opportune (Auxiliary Recovery Ship 41). The largest recovery unit, the one in the anticipated landing area, consisted of six destroyers and a landing ship dock (LSD) with three helicopters on board. If the capsule were shot beyond the expected impact area, an air recovery unit consisting of four P2V aircraft from Jacksonville, Florida, would go into action.30
STG's man in charge of recovery operations was Robert F. Thompson, a Navy veteran who once had been first lieutenant of the deck crew aboard a destroyer and who by now had coordinated STG's recovery requirements for over two years. Through Walter Williams, Thompson asked the Navy to provide for the recovery personnel participating in the exercise and to take along photographers and public information people as well. Thompson assigned Donald C. Cheatham to brief the naval crews from Charleston, South Carolina, on postflight procedures for removing the biopack and primate from the spacecraft.31
According to the "Master Operational Schedule," a guidebook prepared by [313] Debus' experienced staff, a simulated or dress rehearsal flight must always be conducted three days before launch. For this exercise, the countdown started only 180 minutes before "launch," when Complex 56, Pad 5, the site of all the Mercury-Redstone launches, switched on the power to all systems in the Redstone. The team training of the launch crew, even for the old Redstone, required thousands of coordinated actions and easy familiarity by each of the 70 or so members of the blockhouse crew, by each of the 100 men in the Mission Control Center, and by each of another 100 people around the launch site to get a flight off the ground. While the booster was ready for mate with the capsule as scheduled in mid-January, the capsule was not ready, and the simulated flight test was carried out on January 27 for a "mission" that lasted 455 minutes.32
One of the procedural safeguards developed in the effort to man- rate the Redstone was the "split-count," with a built-in hold in the countdown checklist. The count began at 640 minutes before launch and stopped for a rest period 390 minutes short of liftoff time (T). At 640 minutes the complex went on critical power and the prescribed systems checks were started, the communication network readiness was verified, range equipment was checked, and the launch vehicle telemetry was tuned. At T minus 390 minutes all systems were secured for the standby period so that the crew could relax. This "split-count" became a standard part of manned preflight operations.
Before the second half of the count began, on the following day, the booster was again supplied its electrical power, the escape rocket igniter was installed but not connected, the liquid oxygen trailer truck was moved into position, weather forecast and range clearances were checked, and the booster guidance and control battery safety wires were installed. When the count was resumed at T minus 390, there were still at least 330 specific jobs to be performed or functions to be validated before liftoff.
The launch plan for the MR-2 mission followed closely all of the foregoing preparations, with each event preplanned and budgeted on the schedule. Many new systems were being qualified and, with the chimpanzee aboard, the control systems had to operate in the automatic mode. The operations directive for MR-2 specified that in case of an unduly long hold, the test would be canceled at high noon to avoid the risks of a recovery in darkness.33
Telemetry was to be all-important for the MR-2 mission. For that purpose two transmitters were installed in the capsule, providing eight channels of information to ground stations. These included three aeromedical channels to transmit pulse, respiration rate, and breath-depth information. The other channels carried information on structural heating, cabin temperatures, pressures, noise, and vibrations from 90 different points throughout the spacecraft.34
All six chimps in the colony were accorded equal treatment until the day before the flight, when James P. Henry of STG and John D. Mosely, the veterinarian from Holloman, had to choose the test subject and his substitute. First the animals were given a physical examination, and then they were each checked [314] on sensors, the psychomotor programmer, and consoles for comparative ratings. The competition was fierce, but one of the males was exceptionally frisky and in good humor. A female was selected as his alternate. At nineteen hours before launch these two animals were put on low-residue diets, fitted with biosensors, and checked out in their pressurized couch-cabins. Seven and one-half hours before the flight a second physical examination was given, followed by more sensor and psychomotor tests. About four hours before launch, the two chimps were suited up, placed in their couches, and brought aboard the transfer van, where their environmental control equipment was attached. The trailer truck arrived at the gantry alongside MR-2, and there, an hour and a half before the scheduled launch time, the chimpanzee named "Ham," in honor of Holloman Aerospace Medical Center, still active and spirited although encased in his biopack, boarded the elevator to meet his destiny.35
At sunrise on January 31, 1961, feverish preparations were underway in the community around Launch Complex 56. Walter Williams was directing operations for the third time from the newly completed Mercury Control Center. Supporting him were some 500 men from NASA, the military services, and industrial contractors. Key supervisors included the recovery force commander, range commander, launch director, capsule test coordinator, flight director, Atlantic Missile Range coordinator, network status monitor, range safety observer, and director of medical operations.36 About 5 o'clock systems checks were progressing well, and Tecwyn Roberts, flight dynamics officer, reported that the command checks were all working "A. OK."37 Communications checks were the same, with the exception of the Goddard link from Mercury Control on the data selection loop, and trajectory checks and displays appeared to be in order. The broken link with Goddard, discovered well before the flight, was cleared and the data selection loop restored. Although the weather was threatening and five-foot waves were reported in the recovery area, the second half of the countdown began at 7:25 a.m. After the count had progressed 20 minutes, the first trouble of the morning appeared with a report that a tiny but important electronic inverter in the capsule automatic control system was overheating. Nevertheless, at 7:53 Ham was inserted into the spacecraft, and the clear-the-pad signal horn was sounded.
A few minutes after Ham went aboard, the inverter temperature began to rise again, causing several more holds. As the wait wore on, Christopher Kraft, the flight director, sought advice about Ham's ability to endure a long hold. William S. Augerson, medical monitor in the blockhouse, assured Kraft that the animal was all right. Ham's suit temperature remained in the comfortable mid-60s, while the inverter temperature was at least three times that hot. Eventually the inverter cooled to 150 degrees F, and the count was resumed at 10:45. As soon as the power was turned on again, the inverter temperature shot up again. So another cooling-off period was called until 20 minutes before noon, when it [315] was decided that now or never was the time to go today. The countdown had been delayed almost four hours because of the hot inverter, but there were some other minor problems as well. The gantry elevator got stuck; too many people took too long to clear the pad area; checking the environmental control system required 20 minutes longer than planned; and the booster tail-plug cover flaps were jammed for a while.38
At last, five minutes before high noon on the last day of January 1961, MR-2 ignition occurred and liftoff of the Redstone followed in less than a second. As the launch vehicle rose, a transistorized television camera mounted externally near the top of the Redstone scanned the surface of the capsule and adapter ring to provide engineers with bird's-eye data on the flight behavior of the spacecraft when it blasted away from the launch vehicle. Computers sensed one minute after launch that the flight path angle was at least one degree high and rising. At two minutes, the computers predicted a 17-g load. Then, 137 seconds into the flight, the liquid oxygen supply became depleted, and in another half second the engine shut down according to the new timer-programmed plan. The closed-loop abort system on the Redstone sensed the change in engine chamber pressure upon depletion of the lox supply and fired the capsule escape system earlier than planned, within another half second. The abort properly signalled the expected Mayday message to the recovery forces, and they sped off toward a computed impact point farther downrange.39
The high flight angle, coupled with the early abort, added 52,000 pounds of thrust for one second, and yielded a maximum velocity of 7,540 feet per second, against a planned 6,465 feet. The retrorockets jettisoned prematurely when the tower aborted, which meant that the spacecraft on reentry would not be artificially slowed down and therefore would gain still more downrange mileage.40
An unexpected and nearly ultimate test of the chimpanzee's air circuit arose just before the abort, 2 minutes and 18 seconds into the flight, when cabin pressure dropped from 5.5 to 1 pound per square inch. This malfunction was traced later to the air inlet snorkel valve, a device that was spring-loaded to the closed position and held in place by a small detent pin. Apparently vibrations had loosened this pin and allowed the valve to open, as it was intended to do only after the main parachute opened on descent toward a water landing. Ham did not suffer, for although cabin pressure was lost, his couch pressure remained nominal, and suit temperature stayed well within the 60- to 80-degree optimum range. But the open valve caused problems after the capsule splashed.41
Because of overacceleration of the launch vehicle plus the added energy of the escape rocket, a speed of 5,857 miles per hour was attained instead of the 4,400 miles per hour planned, resulting in an apogee of 157 miles rather than the charted 115. At its zenith Ham's spacecraft was already 48 miles farther downrange than programmed, and Ham endured the weightless state for 1.7 minutes longer (6.6 minutes total) than the 4.9 minutes scheduled. He landed 422 miles [316] downrange after a 16.5-minute flight; the preplanned figures called for 290 miles and 14.25 minutes. His peak reentry g was 14.7, almost 3 g greater than planned.42
How did Ham fare through all this? The physician in the blockhouse, William Augerson, reported that at liftoff he was stable and working his levers perfectly to avoid the punishment that came from inattention. At waist level in the chimpanzee's couch was a dashboard with two lights and two levers that required two pounds of effort to depress. Ham knew well how to stay comfortable by avoiding a series of electrical shocks. Each operation of his right-hand lever, cued by a white warning light, postponed the next scheduled shock for 15 seconds. At the same time, the animal had to push the left-hand lever within five seconds after a blue light flashed, about every two minutes, in order to avoid another series of shocks to the soles of his feet.
Ham performed these tasks well, pushing the continuous avoidance (right) lever about 50 times and receiving only two shocks for bad timing. On the discrete avoidance (left) lever, his score was perfect. Reaction time on the blue-light lever averaged .82 second, compared with a preflight performance of .8 second. Ham had gone from a heavy acceleration g load on exit through six minutes of weightlessness and to another heavy g load on reentry hardly missing a trick. Onboard cameras filming Ham's reaction to weightlessness also recorded a surprising amount of dust and debris floating around inside the capsule during its zenith. The cleanliness problem still was not licked.43
When Ham's capsule touched down, about 12:12 p.m., no human being was in sight. Some 12 minutes later, the first electronic recovery signal from the capsule was received, and quick triangulations showed that the capsule was about 60 miles from the nearest recovery ship, the destroyer Ellison. Some 27 minutes after landing, Technician G. T. Beldervack, aboard a P2V search plane, sighted the capsule floating upright alone in the Atlantic. Reckoning that the Ellison would require at least two hours to reach that point, STG officials decided to request the Navy to dispatch its helicopters from the next closest ship, the LSD Donner. When the helicopters arrived on the scene, they found the spacecraft on its side, taking on water, and submerging. Wave action after impact had apparently punished the capsule and its occupant severely. The beryllium heatshield upon impact had skipped on the water and bounced against the capsule bottom, punching two holes in the titanium pressure bulkhead. The plastic fabric in the landing bag had worn badly, and the heatshield was torn free from the spacecraft before recovery. After the craft capsized, the open cabin pressure relief valve let still more sea water enter the capsule. When the helicopter pilot, First Lieutenant John R. Hellriegel, and his copilot George F. Cox, finally latched onto and picked up Ham's spacecraft at 2:52 p.m., they estimated there was about 800 pounds of sea water aboard.44 After a dangling flight back to the Donner, the spacecraft was lowered to the deck and nine minutes later Ham was out. He appeared to be in good condition and readily accepted an apple and [318] half an orange.45 Ham had functioned like a normal chimpanzee in his flight into space. Could homo sapiens do as well?
Ham's flight on MR-2 was a significant accomplishment on the American route toward manned space flight. Now the Space Task Group knew that even with some hazardous malfunction it might reasonably hope to complete a manned ballistic mission successfully. Ham's survival, despite a host of harrowing mischances over which he had no control, raised the confidence of the astronauts and the capsule engineers alike. Except for an intensive effort to redesign the harness and impact attenuation system inside the landing bag, an exhausting final "quick-fix" led by Rodney G. Rose and Peter J. Armitage of STG, the Mercury capsule and all its systems seemed ready to carry man into space. Since overacceleration had occurred in both the MR-1A and MR-2 missions, however, the booster engineers responsible for "Old Reliable," Wernher von Braun and Joachim Kuettner, Kurt Debus and Emil Bertram, neither shared STG's optimism nor yet were satisfied that their launch vehicle was man-rated.46
23 Excerpts from messages compiled by Purser, special assistant to director, STG, re status of spacecraft No. 5. During one of the McDonnell tests, when the air leakage rate was being checked, the inspectors found that gas seepage was too great. The best seal they could obtain left a leakage rate of 1,725 cc./ min. at 4.9 p.s.i. for 45 minutes, as against the specified maximum rate of 650 cc. The defect causing this was found at the umbilical connector and traced to warpage of the capsule frame. McDonnell reworked the struts and stringers to make a better fit. This is but one sample from daily reports to STG about the rework status of one selected component. Afterward, on July 5, 1960, STG approved a spacecraft leak rate of 1,000 cc per minute. Memo, Richard S. Johnston, Asst. Head, Life Systems Branch, to Chief, Flight Systems Div., "Capsule Leakage Rates," July 5, 1960.
24 Message, John J. Williams, Launch Operations, Marshall Space Flight Center, to G. Merritt Preston, STG Cape Operations, Oct. 4, 1960; "Postlaunch Report for Mercury-Redstone No. 2 (MR-2) ," NASA/STG, Feb. 13, 1961; NASA News Release 61-14-1, "Project Mercury Background," Jan. 28, 1961. For the MR-2 mission directive, see NASA Project Mercury working paper No. 138, dated Apr. 15, 1960, rev. Nov. 29, 1960, and Jan. 27, 1961.
25 David S. Akens, Paul K. Freiwirth, and Helen T. Wells, History of the George C. Marshall Space Flight Center (Huntsville, Ala., May 1961), Vol. I. Appendix B, "Mercury-Redstone Chronology," 28, 32; Francis E. Jarrett, Jr., and Robert A. Lindemann, "Historical Origins of NASA's Launch Operations Center to July 1, 1962," Kennedy Space Center Historical Monograph No. 1, Cocoa Beach Fla., Oct. 1964, B-26.
26 Akens, Freiwirth, and Wells, History of Marshall Space Flight Center, Vol. I, 32; memo, E. D. Geissler, Aeroballistics Div., Marshall Space Flight Center, to STG, "Project Mercury-Redstone: Trajectory Data for MR—2," Jan. 23, 1961; memo, Walter C. Williams, Operations Dir., STG, to Marshall Space Flight Center, "Launch Trajectories for MR-2 and Subsequent Flight," Dec. 20, 1960; "Technical Information Summary of Mercury-Redstone Mission MR-2," Marshall Space Flight Center, Jan. 20, 1961. Williams' 12-g nominal reentry decelerations were not connected with the 12-g emergency maximum advocated by the Air Force in 1958 for the "man-in-space" study program. The 12-g maximum desired for the MR-2 mission was set for two reasons: (1) It represented the midway point between a normal Mercury-Atlas reentry (about 8 g) and the worst Mercury-Atlas reentry (about 16 g); and (2) normal reentry for the Mercury-Redstone was about 11 to 12 g. STG felt it was necessary to study the g-load effects on the chimpanzee in this range. The fact that both acceleration and deceleration g loads surpassed 12 served to prove the supine couch concept.
27 "Project Mercury Technical Information Summary of Mercury- Redstone Mission No. 2 (Capsule No. 5) ," NASA/STG, Jan. 24, 1961; "Technical Information Summary Concerning Mercury-Redstone Mission MR- 2," MSFC report TPR-M-60-1; NASA News Release 61-14-2, "MR-2 Flight Profile," Jan. 28, 1961; "Project Mercury Background."
28 NASA News Release 61-14-3, "Animal Flight Program," Jan. 28, 1961; "Information Guide for Animal Launching," July 23, 1959; "Countdown and Procedures (Animal Subject) for Project Mercury Flight MR-2," USAF Aeromedical Field Laboratory, Holloman Air Force Base, N. Mex., Dec. 1960.
29 Norman E. Stingely, John D. Mosely, and Charles D. Wheelwright, "MR-2 Operations," in Results of the Project Mercury Ballistic and Orbital Chimpanzee Flights, NASA SP-39 (Washington, 1963), 7.
30 "Recovery Operations Requirements for Mercury-Redstone Test No. 2," STG, undated [about Jan. 12, 1961]; "Mercury Recovery Forces," NASA fact sheet, undated; Message, Cdr., DesFlotFour, to STG, "Public Information for MR-2," Jan. 5, 1961. The helicopters were from Marine Aircraft Group 26, the Mercury project officer of which was 1st Lt. Wayne E. Koons, USMCR.
31 Letter, Walter Williams, STG, to Cdr., DesFlotFour, re NASA personnel assignment for MR-2 test, Jan. 6, 1961.
32 "Master Operational Schedule, MR-2," Marshall Space Flight Center, Jan. 20, 1961, 5-26, 27-30, 32-47, 48-77; Final Report: Mercury-Redstone Project Launch Operations, Marshall Space Flight Center, May 28, 1962, 121, Appendix L, "MR-2 Daily Log Summary," 1-4.
33 "MR-2 Flight Test Profile - Operations Directive No. 1904, Mercury-Redstone Launch," Air Force Missile Test Center, Jan. 5, 1961, 4-10.
34 Ibid. Ham's depth of respiration was measured by a pneumograph consisting of a rubber tube filled with copper sulfate solution. Electrical resistance of the solution varied as the tube was stretched. At one point during the testing of sensors for measuring the primate's respiration, technicians discovered that when the pneumograph was attached high on the thorax, the chimp breathed low and vice versa. One solution was to use two pneumograph straps in conjunction. Results of the Project Mercury Ballistic and Orbital Chimpanzee Flights; A. D. Catterson, MSC Medical Support Operations, interview, Houston, Oct. 23, 1964.
35 "Countdown and Procedures (Animal Subject) for MR-2"; "Animal Flight Program"; Marshall Star, Feb. 1, 1961; Stingely, Mosely, and Wheelwright, "MR-2 Operations," 9-11. Each animal received 15 commercial food pellets and a fourth of an orange at a feeding. One 12-ounce serving was given at about T minus 20 hours and another at T minus 15 hours. Water intake was limited to 800 cc. from T minus one day through recovery. The name "Ham" also honored the commander of Holloman Aeromedical Laboratory, Lt. Col. Hamilton Blackshear.
36 "MR-2 Flight Test Profile - Directive 1904." Staff members under the operations director had a variety of duties and responsibilities. For example, the launch director, located in the blockhouse, reported on the readiness of the launch vehicle; the launch conductor, also in the blockhouse, was responsible for detailed supervision of launch operations; the capsule test conductor had a similar duty on the countdown; and the flight director, located in the Mercury Control Center, had detailed flight-control responsibility from liftoff to touchdown.
37 Memo, Tecwyn Roberts, Flight Dynamics Officer, to Flight Director, "Report on Test 3805," Feb. 2, 1961; penciled notes on the countdown of MR-2, anon., Jan. 31, 1961. The origin of the popular space term "A.OK" is a matter of widespread public interest. In reporting the Freedom 7 flight, the press attributed the term to Astronaut Shepard, and indeed NASA News Release 1-61-99, May 5, 1961, has Shepard report "A.OK" shortly after impact. A replay of the flight voice communications tape disclosed that Shepard himself did not use the term. It was Col. John A. "Shorty" Powers who reported Shepard's condition as "A.OK" in a description of the flight. Tecwyn Roberts of STG and Capt. Henry E. Clements of the Air Force had used "A.OK" frequently in reports written more than four months before the Shepard flight. Roberts attributed coinage of the term to Paul Lein, of the Western Electric Co., while the tracking network was being constructed. Lein, however, said that "A.OK" was a communal development among communications engineers while circuits were first being established downrange from Cape Canaveral. The voice circuits at first gave poor quality. The bands were narrow, and the systems operated on 1,500 cycles. There was much static and background noise. Words got lost in voice circuit systems checks. To make transmissions clearer, the communicators started using "A.OK" because the letter "A" has a brilliant sound. Other sources claim that oldtime railroad telegraphers used "A-OK" as one of several terms to report the status of their equipment. Be that as it may, Powers, "the voice of Mercury Control," by his public use of "A.OK," made those three letters a universal symbol meaning "in perfect working order."
38 Penciled notes on MR-2 countdown; memo, William S. Augerson, Life Systems Group, to Christopher C. Kraft, Mercury Control Center Flight Dir., "Blockhouse Medical Monitoring of MR-2," Feb. 6, 1961; W. J. Kapryan, "Postlaunch Report for MR-2," Feb. 2, 1961. Some flight notes on MR-2, author unknown, dated Feb. 1961, indicated that the inverter had operated at temperatures as high as 200 degrees F.
39 "Postlaunch Report for MR-2," 9; NASA News Release, Cape Canaveral, Jan. 30, 1961; Roberts memo; memo, Warren J. North, Head, Manned Satellites, NASA Hq., to Franklyn W. Phillips, NASA Hq., "MR-2 Flight Results," Feb. 1, 1961; tape of press conference following MR-2 launch, Cape Canaveral, Jan. 31, 1961. Cf. Carl R. Huss comments, Oct. 5, 1965.
40 "Postlaunch Report for MR-2," 9; memo, North to STG, "Retrocontrollers Comments," Feb. 9, 1961. Brief accounts of Ham's flight may be found in Kenneth F. Weaver, "Countdown for Space," National Geographic, CXIX (May 1961), 725-734; and in Judith Viorst, Projects: Space (New York, 1962), 37-38.
41 Memo, Morton Schler, capsule environment monitor, to Kraft, "MR-2 ECS Flight and Postflight Summary," Feb. 6, 1961.
42 "Mercury-Redstone II Flight Parameters," chart, Feb. 7, 1961; "Calculated Preflight Trajectory Data for MR-2," Project Mercury working paper No. 168, Jan. 19, 1961. See also North memo.
43 NASA Fifth Semiannual Report to Congress. See also NASA films, MR-2 Launch, March 1961, and Sixth Quarterly Report, April 1961.
44 "Postlaunch Report for MR-2," 10; MR-2 flight parameter chart; tape of press conference following MR-2 flight; some flight notes on MR-2, anon., dated Feb. 1961; House Committee on Science and Astronautics, 87 Cong., 1 sess. (1961), Project Mercury, Second Interim Report, 34-37; Wayne E. Koons and James L. Lewis, interviews, Houston, Sept. 16, 1965. Robert F. Wallace, an STG information officer on the scene, reported that Ham was excited when returned to Hangar S after his flight. Being unable to debrief his handlers, Ham alone knew at this time how grueling his flight had been. Flashbulbs and crowding newsmen made him highly agitated, and he snapped at several people. Back in his trailer, his suit was not removed until he became calm, and at that time a famous "grin" photograph was made. Later, when his handler led him back toward a capsule for pictures requested by the TV crews, Ham again became highly perturbed. It took three men to calm the "astrochimp" for the next round of pictures. On April 2, 1963, Ham was given to the National Zoological Park, Smithsonian Institution, Washington, D.C., where for the past several years he has been in good health and has thrilled many children.
45 The amount of water in the spacecraft caused great concern to members of STG's Life Systems Group when they found the heatshield had punctured holes in the lower pressure bulkhead. Life Systems renewed studying alternatives, making either optional or impossible the deployment of the landing bag. More drop tests were undertaken by the Aeromedical Biophysics Group of the Wright Air Development Division. Simulating the Mercury drop rate of about 30 feet per second, the Wright group found that human test subjects could sustain impacts of about 35 g and recover from "a confused state" in about five seconds. STG considered this within fairly safe limits for an interim measure, but the margin of safety was too small to accept for the routine operation of a Mercury mission. Memo, Gerard J. Pesman to Assoc. Dir., "Use of Impact Bag for Water Landings," Feb. 13, 1961. In all of the manned missions the impact bag was deployed.
46 See R. I. Johnson, et al., "The Mercury-Redstone Project," Saturn/Apollo Systems Office, Marshall Space Flight Center, June 1964, 8-9. Cf. Huss comments. Regarding the impact bag problems at this time, see memo, Rodney G. Rose to Chief, STG Engineering Div., "Summary of Air Drop and Fatigue Program with Production Capsule No. 5," May 4, 1961, and Ms. paper, "Project Mercury Water Landing Problems," presented to 30th annual AIAA meeting, New York City, Jan. 24, 1962.