Final Rehearsals

With the 1961 Labor Day holiday passed, the Space Task Group buckled down to an exceptionally busy season, one that was to be climaxed with STG's own demise and phoenix-like resurrection. Its activities had become far flung. Dead ahead, at Cape Canaveral, loomed the first orbital flight test of a Mercury capsule, carrying a true "black box," called a "crewman simulator," instead of an astronaut. Then, too, plans long had been ripening for a multi-orbital Mercury-Scout flight to qualify the ground tracking and communications network. A second orbital flight carrying a chimpanzee in the spacecraft couch also had an early place in the program.

Meanwhile NASA agents had completed an extensive survey of potential sites for the new development and operations installation for manned space projects of the future. At its Langley Air Force Base domicile, STG was busy planning for its expanding role in manned space exploration. Its personnel were weighing persistent rumors that the new Manned Spacecraft Center might be located in Texas, somewhere near the booming city of Houston.

The first objective of all this simultaneous activity was Mercury-Atlas 4, the fifth flight of an Atlas-launched spacecraft. This mission had been planned and replanned many times before the unsuccessful launch of MA-3 back in April 1961, and the failure of that mission directly affected the MA-4 plans. During the early months of 1960, MA-3 had been scheduled for a suborbital flight, with a crewman simulator aboard. First plans called for the Atlas booster to be held 150 feet per second below orbital velocity, with capsule separation occurring at the normal 100-mile-orbital-insertion altitude. Forty seconds after separation, retrofire was to have produced a landing beyond the Canary Islands and about 100 miles short of the African coast. And when this test was completed successfully, MA-4 was to repeat MA-3, but with a chimpanzee in the cockpit. Spacecraft No. 9 was to be specially fitted for the MA-4 flight.

Toward the end of 1960, however, Walter C. Williams advised the commanding officer of the recovery force, Destroyer Flotilla Four, that MA-4 would try for three orbits with a crewman simulator aboard and that the targeted launch date was April 1, 1961. But the MA-3 launch, still scheduled for a sub-orbital flight with its "mechanical astronaut," slipped to April 25. While many Americans worried over the Soviet space coup represented by Yuri Gagarin's one-orbit flight on April 12, Robert R. Gilruth and Williams already had made the decision to change MA-3 to a one-orbit mission.¹

April 25, 1961, came, but the day's recorded results were far from heartening. The MA-3 launch vehicle failed to program over into the proper trajectory; after 40 seconds of flight straight upward the Air Force range safety officer destroyed the Atlas booster. So it was necessary on MA-4 to strive for the same one-orbit objective and to delay still further the nominal three-orbit Mercury mission.

Meanwhile, for various reasons, production of the spacecraft and booster for MA-4 fell behind schedule. Atlas No. 88-D, allotted for MA-4, did not receive its factory rollout acceptance inspection until June 29-30, 1961, and it was July 15 before it was delivered to Cape Canaveral. And spacecraft No. 9 was not used, though originally planned. Instead No. 8 was fished from the Atlantic after its ill-fated flight in MA-3 and shipped back to McDonnell in St. Louis on April 27 for extensive overhauling. That meant cleaning, installing new insulation, replacing the external portion of the hydrogen peroxide control system, making spot-weld repairs in the large pressure bulkhead, and replacing the heatshield, antenna canister, escape tower, tower clamp ring, adapter, main clamp ring, and the inlet and outlet air snorkels. The overhauled spacecraft, redesignated 8-A, was returned to the Cape, but G. Merritt Preston's crew still had plenty of work. A leak had to be repaired in a reaction control system fuel tank; the environmental control system and the automatic stabilization and control system had to be reworked. A fairing to reduce launch vibration, like the one used on the Little Joe 5-B flight on April 28, 1961, and similar to that used on Virgil I. Grissom's suborbital mission in July, was added to the adapter clamp ring.²

Because of all this modification and overhaul, it was August 3 before the spacecraft for MA-4 was delivered to the pad and mated with the booster, supposedly to be launched on August 22. The day before the scheduled flight the Air Force's Space Systems Division in California called Cape Canaveral and reported that solder balls had been found in some transistors of the same brand that had been installed in the MA-4 booster. Coordination of this information among the various Mercury-Atlas teams at the Cape brought to light the fact that these types of transistors also had been used in the spacecraft. There was nothing left to do but postpone the launch and give both vehicles a thorough going-over to replace the defective transistors. On August 25 the spacecraft was returned to Hangar S, when it became apparent that this work might encompass several days. After these labors in the hangar, spacecraft 8-A was mated with the booster again on September 1. This time the engineers conducting the prelaunch checkouts found nothing wrong. Although 8-A was a secondhand capsule, its landing bag had not been installed, it had ports instead of the new window, and the explosive egress hatch had been omitted, it still passed inspection.³

Besides the problem with the defective transistors, the Mercury-Atlas booster had been proceeding along the same tortuous route as the capsule toward flight qualification. By September, the Atlas had undergone so many changes that had to be integrated into launch vehicle No. 88-D, and experienced so many setbacks, that a successful orbital mission was necessary for the sake of NASA and national morale and to forestall any new attacks on the Atlas as the Mercury launch vehicle. The year in which the Soviets had orbited a man now was in its ninth month, yet the United States was still preparing to orbit a box full of instruments. The Mercury-Atlas flight record had produced only one completely successful launch - the MA-2 reentry heating test - out of four tries.

This was scarcely an enviable record. Many hours, days, and months had been spent by special committees and working groups in ferreting out the sources of trouble. The STG, Space Technology Laboratories, Convair, and Air Force engineers who had reviewed the failure of MA-1 had concluded that the forward end of the Atlas was not designed to withstand the flight dynamic loads fed through the adapter section, that the adapter was too flexible, and that stiffeners were needed. MA-2 had confirmed the controversial "fix" of the adapter section. MA-4 would be the second of the "thick-skin" Atlases. Reviewing the MA-3 abort, the engineers assumed that the programmer's failure to pitch the booster into a proper trajectory was due to a transient voltage. Also, some two years previously, another anomaly caused the Big Joe Atlas to fail to stage, and even in MA-2 there had been some propellant sloshing in the booster. To correct the programmer problem, Convair modified the autopilot controls to give the gimbaling engines of the Atlas a preventive counteraction capability. One objective of MA-4, therefore, was to assess this innovation.⁴ In September the NASA-Air Force- contractor engineering team that had been beset with Atlas problems for two years felt that the ICBM-turned-space-launcher was ready to do its part in Project Mercury. In the words of Scott H. Simpkinson, STG's liaison man at the Convair factory, "MA-4 just had to work."

Not only would a successful orbital mission on MA-4 provide the necessary data on the performance of systems and components, but the Mercury tracking network crews and Department of Defense recovery forces would receive valuable training for supporting a manned orbital circumnavigation by an American. Many components, elements, procedures, and flight maneuvers had to be watched and assessed before one of the "Mercury seven" could be committed to an orbital mission around Earth.

Of the manifold segments of an orbital flight, reentry was perhaps the most critical. As it dropped back into the heavy atmosphere, the capsule would be subjected to searing temperatures of about 2,000 to 3,000 degrees F for six or seven minutes, or about eight times longer than on the previous Mercury suborbital shots. Retrofire between Hawaii and Guaymas, Mexico, would bring about a gradual descent over the North American continent. About 345 miles east of Savannah, the first contact with atmospheric resistance would begin, at an altitude of 55 miles. At this point the appearance of the .05-g light on the panel would telemeter a signal that reentry was coming up. Peak aerodynamic heating would come when the spacecraft had descended to an altitude of 37 miles and was traveling at 15,000 miles per hour. Braking would be dramatic. Between 46 and 12 miles high, traveling over a slant range of 460 miles, the capsule's air speed would be reduced from about 17,000 to 1,350 miles per hour. Aerodynamic stresses in this region would provide a severe test of the spacecraft's structural strength, particularly the heatshield and the afterbody shingles.

Perhaps the second most critical segment of the orbital mission would come during the powered phase of the flight. The Space Task Group, supported by the DOD and industry, would also monitor carefully the vibration levels to ascertain if they would be tolerable for an astronaut. Even more important as the capsule was rocketed toward orbit was a reliable escape system, to wrench the capsule clear if the launch vehicle failed to perform. Also it was necessary to judge the ability of the Atlas to release the spacecraft, to evaluate the abort sensing and implementation system, to determine if the launch vehicle could withstand the aerodynamic loads of max q, and to demonstrate the capability of the Mercury network to perform its intended flight-control and data-collection functions.⁵ If all went well, MA-4 would provide data proving the validity of years of engineering calculations.

MA-4 would be launched from complex 14 at the Cape on a true azimuth heading of 72.51 degrees east of north. Following engine ignition, after being held to the pad for three seconds to ensure smooth combustion, the Atlas booster engines would propel the spacecraft within two minutes to a speed of about 6,500 miles per hour and an altitude of 35 miles over a downrange distance of 45 miles. The sustainer engine would continue to burn. A gradual pitch program would begin to tilt the Atlas toward the sea about 20 seconds after liftoff. Seconds after booster engine cutoff (called "BECO" by the various Mercury-Atlas working teams at the Cape), or at about 41 miles' altitude and a slant range of 56 miles from the pad, the launch vehicle programmer would trigger a greater pitch-over maneuver to put the Mercury-Atlas combination on a course parallel to Earth's surface. At this time the escape tower would be jettisoned. After capsule separation, orbital insertion would occur about 498 miles downrange from the pad at an altitude of about 100 miles. The nominal inertial velocity at this point was supposed to be 25,695 feet per second, increased to 25,719 feet per second by the ignition of the posigrade rockets, which separated the spacecraft from the booster. Within 50 seconds, the spacecraft should have drifted some 790 feet from the booster. The Atlas, rather than falling away, would trail the orbiting spacecraft around Earth at an altitude of about 100 miles, and should complete each circle about once every 90 minutes for an estimated three days.⁶

Instrumentation affixed to the spacecraft would provide data from nearly every conceivable point about the capsule. Noise levels in the vicinity where an astronaut's head would rest would be measured and recorded on magnetic tape. Excess vibration, a problem during early Mercury-Redstone flights, would be monitored closely by seven strategically placed sensors, mostly in the area where capsule and adapter joined. To determine what radiation dosages a pilot would encounter, four standard and two special film packs would be carried. The standard packs were placed on the sides and at the top and bottom of the couch. Carrying a heavier emulsion, the two extra packs would measure the radiation spectrum - the range of all kinds of radiation to which the capsule would be exposed - as well as penetration levels. Flight data other than radiation would be transmitted by two separate telemetry links, each providing essentially the same information.

The flight would be well covered photographically. Located on the left side of the capsule cabin was the instrument panel camera, which would start operating at liftoff, provide about 20,000 frames of panel information during the mission, and cease five seconds after impact. Placed near the right-side port, the Earth-sky camera was loaded for about 600 frames of pictorial data, which would be exhausted somewhere over the Indian Ocean. A third camera, affixed to the periscope, was loaded with about 10,000 frames of film for the mission. This camera would provide especially useful information on the spacecraft's orbital attitude reference to Earth at points where landmarks were recognizable.

Five recorders aboard the spacecraft would tape most of the mission data. Three were seven-track systems to record all telemetry outputs, vibration levels, noise, and shingle strain. The two others were single-track recorders, to be operated in tandem and used to check the reliability of the tracking network communications system.⁷

Plans for spacecraft operations after the powered phase were essentially the same as those for the suborbital flights, only on a much larger scale. Retrofire was scheduled at 1 hour, 29 minutes, and 4 seconds after launch, with the three rockets firing at five-second intervals in order: top-left, bottom, top-right.⁸ Recovery plans for orbital missions were considerably more complicated than they had been for the suborbital flights, since many more contingency areas, including abort and overshoot, had to be considered. Besides the nominal landing area off the coast of Bermuda, five secondary landing areas were selected. Providing that the launch was nominal and proceeded according to the preflight calculated trajectory, the abort recovery areas were spaced as follows: Area A began about 13 miles from the launch pad and continued along the track for 2,200 miles. For the first 550 miles the coverage extended 30 miles to each side of the track. This area covered the first 72 seconds after launch, or through booster staging. The remainder of Area A, accounting for the period up to 298 seconds after launch, narrowed to about 15 miles on either side of the track. Areas B and C were small elliptical blips on the track, 4 and 8 degrees of longitude beyond A. These were designated for a possible abort at 298 or at 301 seconds, respectively. The third contingency site, Area D, was a longer ellipse (20 by 122 miles) beginning about 7 degrees of longitude past C. At this point the "go/no go" flight decision would be made. The last, Area E, an ellipse 24 by 231 miles along the track, covered aborts up to 304 seconds after the go/no go decision.⁹

The MA-4 capsule also was fitted with a number of aids to assist the DOD forces in their recovery task. Two one-pound sofar bombs, one set to eject upon main parachute deployment and the other set to detonate at 4000 feet of hydrostatic pressure if the spacecraft sank, were carried. A flashing light with a life of about 24 hours was set to activate upon impact. Fluorescein dye, ejected at touchdown, would be visible for about six hours. Navy recovery forces were asked to attempt the recovery of the drogue and main chutes and the spacecraft antenna canister. Balsa wood blocks and Styrofoam had been attached to these components for flotation.¹⁰

As the launch date of the Mercury-Atlas 4 combination neared, weather problems began to threaten this attempt to orbit a "mechanical astronaut." Not one but two hurricanes thrashed the Mercury tracking areas. "Carla" raked the Corpus Christi tracking station, while "Debbie" moved in a northerly direction on the day before the launch, menacing and causing the ships to get rather a "rough ride" in the prime recovery zone. The equipment at the Texas site withstood the storm without damage. The STG-Air Force-Navy recovery planners at the Cape felt that Weather Bureau support predictions had given them a sufficient margin of safety in the Atlantic to allow the mission to proceed.¹¹

Mercury Orbits at Last

On launch day, September 13, the cloud coverage was scattered; visibility was 9 miles; the wind velocity was about 11 miles per hour; and the temperature was 78 degrees. Ninety minutes before launch time a half-hour hold was called to replace a broken screw in one of the afterbody shingles. The liquid oxygen was loaded by 8:30 a.m., and 5 minutes later the operations crew determined that all systems were go. At 8:57, however, the low-speed data timing was momentarily lost at the Bermuda tracking site, and the countdown was recycled to T minus 3 minutes and 30 seconds.

A little after 9:04 a.m. on September 13, 1961, MA-4 was launched on its one-orbit mission. During the first 20 seconds from liftoff, fairly severe booster vibrations were detected by the flight dynamics officer in the Control Center. The "thick-skin" Atlas passed its max-q test. At the 52-second point, a spacecraft inverter that was converting electrical power from direct to alternating current failed, but the standby inverter switched on automatically. Guidance data soon disclosed that the trajectory was .75-degree high; later, at engine cutoff, it was .14-degree low. Although booster engine cutoff occurred 2.5 seconds early, booster velocity was about 100 feet per second too high. Then the sustainer engine cut off 10 seconds early, so the desired velocity was essentially achieved. Despite these dispersions, which were within design limits, perigee and apogee of the orbit were only slightly more than a mile and 12 miles, respectively, below plan. The Goddard computers instantly indicated a go for the mission. The powered phase, plus posigrade rocket increment, provided a peak velocity of 25,705 feet per second; g loads during the powered phase reached a peak of 7.6.¹²

Despite a slight disturbance in the roll, pitch, and yaw of the booster, separation occurred properly, and after a 5-second steadying or damping period the capsule began its turnaround maneuver. Soon, however, large attitude excursions were observed, and the spacecraft took 50 seconds to reverse its ends to heatshield forward, as opposed to a normal 20 seconds, using 9.5 pounds of hydrogen peroxide attitude control fuel against the 2.2 pounds supposedly required. Even with the abnormal turnaround, the spacecraft attitude gyros and scanners soon transmitted nominal readings, and there seemed no doubt that the mission would proceed to its orbital conclusion. The cause of these undue excursions later was found to be an open electrical connection in the pitch- rate gyro.¹³

A high oxygen usage rate like that on Grissom's suborbital mission cropped up early and continued throughout the flight. At the 27,000-foot point the system sealed off at 5.5 pounds per square inch; then an abrupt drop was indicated in the primary oxygen supply and a concurrent rise in cabin and suit pressure values to 6 pounds per square inch. "Primary oxygen going down fast," Paul E. Purser jotted in his notes as he listened to the communications circuit. "Zanzibar reported 30 percent of primary oxygen left," he later added. Toward the end of the mission, with the primary supply depleted, the system switched over to secondary. Usage from this source was so slight, however, that Walter Williams commenting on the high usage problem in a press conference following the mission, said that the secondary supply was virtually untouched. Throughout the flight the crewman simulator continued to use oxygen to produce moisture and carbon dioxide, and to monitor the operations while recording heat and suit pressure changes.¹⁴

Despite the abnormalities with the oxygen supply, once the automated Mercury spacecraft was on its orbital course, the computers indicated that the mission could go for more than seven orbits. In general, the control systems operated well, although on three occasions the spacecraft dropped out of its 34-degree, Earth-reference mode, once just before the ignition of the retrorockets and twice just before the .05-g light telemetry signal. These attitude variations came from the failure of a one-pound yaw-positive thruster and a one-pound roll-negative thruster.

Communications between the capsule and the tracking stations were good, especially on high frequencies, which on the earlier suborbital flights had been virtually unsuccessful. In some cases radar tracking was not good, largely because a few of the operators lacked experience. Telemetry reception was excellent, with some 137 observations received by the various tracking stations during the flight.¹⁵

MA-4
Sept. 13, 1961

One hour, 28 minutes, and 59 seconds after MA-4's liftoff, the first retrorocket fired in the vicinity of Hawaii. Monitors at the Guaymas station in Mexico indicated that retrofire, triggered by the spacecraft clock, had gone off as planned. Within the range of the Cape Canaveral control center, telemetry data disclosed that MA-4 was in the proper reentry attitude. Over the Atlantic the drogue parachute opened at 41,750 feet, and the main chute deployed at 10,050 feet. At 10:55 a.m. the capsule splashed down 176 miles east of Bermuda. After an hour and 22 minutes, the destroyer Decatur, which had been about 34 miles from the impact point, pulled alongside the spacecraft and hoisted it aboard. From there the capsule and its robot "astronaut" rode to Bermuda, whence they were airlifted to the Cape for an exhaustive examination.¹⁶

The cause of the oxygen supply malfunction was immediately attacked by the STG and McDonnell engineers. Onboard film, they found, disclosed that the oxygen supply emergency light had blinked on, which would have signaled an astronaut to take corrective action. The inspectors also learned that vibration had dislodged the rate handle from its detent, allowing a valve to crack open. But the flow rate had not been sufficient to trip the microswitch that would have given the Mercury Control Center a telemetry indication of an emergency rate actuation while the mission was in progress. Normally a force of from three to eight pounds was needed to break the handle free from the detent, whereas in this case the inspectors moved the handle with very little force. A new emergency rate handle with a positive latching mechanism was to be devised for later missions.¹⁷

Other postflight analyses by the engineers found the MA-4 spacecraft and its systems in good condition. There was no afterbody shingle buckling or warping, and the structural materials were only mildly discolored. The horizon scanner window was partially coated with a film of oxidized material caused by aerodynamic heating. Some internal debris, including solder balls and washers, had apparently escaped preflight tumbling and vacuum cleaning. Six buckled skin panels between the base ring and the lower pressure bulkhead indicated that the capsule landed with the heatshield edge striking the water first. Still the inspectors concluded that the structural damage was not enough to have endangered an astronaut. The center section of the heatshield was partially delaminated and the center plug was loose, conditions apparently caused by water impact and cooling. Two cracks were found on the shield in the vicinity of the water-impact point. The depth of the char on the ablation shield was very shallow.¹⁸

NASA officials showed their pleasure at the success of MA-4 at the pres conference held at the Cape immediately after the flight. Gilruth pointed out that this had been the hardest test flight in the whole NASA program. He added that the Atlas had demonstrated that it was capable of boosting a man into orbit, as he, Maxime A. Faget, Purser, and others from NACA-Langley days had long believed. Without hesitation Gilruth concluded that a man would have survived the flight.

At that point a reporter asked whether a man would fly the next Mercury orbital mission. Walter Williams answered that a three- orbit circuit, either unmanned or carrying a chimpanzee, was still necessary. Then why was the upcoming Mercury-Scout mission necessary, asked a newsman. Again Williams affirmed his confidence in the wisdom of the agreed-upon schedule of flights.¹⁹

Space Task Group Gets a New Home and Name

Between flight planning and scheduling launches in August 1961, a NASA site survey team headed by John F. Parsons, Associate Director of Ames Research Center, had inspected a number of sites competing for the permanent location of a center for manned space flight projects. The new center had been approved in principle by President Kennedy in accordance with his strategic decision, endorsed by the Congress, to accelerate the space program. The team appraised the sites on 10 points, briefly stated as follows: availability of educational institutions and other facilities for advanced scientific study, electric power and other utilities, water supply, climate, housing, acreage, proximity to varied industrial enterprises, water transportation, air transportation, and local cultural and recreational resources. On September 19, 1961, NASA Administrator James E. Webb announced that the new Manned Spacecraft Center (MSC) would be established on a 1,000-acre tract to be transferred to the Government by Rice University, near Houston. The site was in Harris County, Texas, on the edge of Clear Lake, an inlet of Galveston Bay on the Gulf of Mexico.²⁰

Webb maintained that selection of the Houston site had been influenced by recent decisions to expand the launch complex at the Atlantic Missile Range and to establish a fabrication facility for large booster and space vehicle stages at the Michoud Plant, near New Orleans, where torpedo boats had been manufactured during World War II. The Manned Spacecraft Center, the Michoud Operations, and the Cape Canaveral complex would become a vast integrated enterprise coordinating the development, manufacture, and operation of the manned space flight program.

Not unexpectedly, there was some criticism of the Texas site chosen for the new development center. Charges of inordinate political influence involved the names of Vice-President Johnson, a Texan and chairman of the National Aeronautics and Space Council, and Democratic Representative Albert Thomas of Houston, Chairman of the House of Representatives Independent Offices Subcommittee of the Appropriations Committee. NASA spokesmen categorically denied that there had been any improper influence. Particularly crestfallen were the citizens of the Virginia peninsula, who realized they were losing some of the activities at the Langley Research Center and the Wallops Station. All through August, September, and October, the dailies of Newport News echoed this disappointment. To Houston, of course, this was "wonderful news," as the Chamber of Commerce proclaimed, and local business leaders dispatched representatives to brief the transferring NASA employees in Virginia on the advantages of the Texas coast.²¹

Less than a month after Webb's announcement, a Houston journalist went on an inspection tour of the site planned for the spacecraft center. He found cowboys driving herds of cattle to new pasture, a crew of surveyors from the Army Corps of Engineers mapping the prairie near Clear Lake and fighting snakes, and a lone wolf hunter with the carcass of a freshly slain wolf. The hunter said he had just seen several wild turkeys, a fox, and many deer tracks.²²

Gilruth and other officials of the Space Task Group reacted quickly to the Webb announcement. The very next day they flew into Houston to begin a search for an estimated 100,000 square feet of temporary floor space. Moving began in October 1961, when Martin A. Byrnes, as the local manager, and a small cadre of center operations, procurement, and personnel employees opened offices in Houston's Gulfgate Shopping City. By mid-1962, when the move was completed, activities were scattered in 11 locations, occupying 295,996 square feet of leased office and laboratory space in the vicinity of Telephone Road and the Gulf Freeway. For both old and new employees, a street map was a necessity in the coordination of information among the various offices located in the dispersed buildings. Besides the leased quarters, NASA personnel liberally used surplus facilities available at nearby Ellington Air Force Base.²³

By early October 1961, the Space Task Group had established an information relocation center in its Public Affairs Office to help personnel facing the move. Inquiries from the employees about schools and housing were numerous. Shortly thereafter, members of the Space Task Group received procedure directions for permanent change of duty station and then were advised on November 1, 1961, that "the Space Task Group is officially redesignated the Manned Spacecraft Center." The center was now a de facto NASA unit, a nerve center of the accelerated manned space flight program. It was several months, however, before the administration of projects was subdivided for management of the three major programs - Mercury, Gemini, and Apollo. NASA outlined its building requirements for the center on October 13, 1961, at which time two plans were under consideration, one with 13 major buildings and the other with 14, to accommodate 3,151 people. The estimated cost was $60 million for the first year's construction.²⁴

Wires Get Crossed: Mercury-Scout I

Despite the flurry of activity at Hampton, Virginia, Houston, and elsewhere, generated by the impending move, STG did not pause in its scheduled Mercury flight test program. Plans had been in progress for several months and by the summer of 1961 were well developed for Mercury-Scout, whose flight was to provide a dynamic checkout of the Mercury tracking network.

Early in May, Purser and Williams of STG, Charles J. Donlan, who had returned to the Langley Research Center rolls in April, and Warren J. North of NASA Headquarters had met to discuss how the Mercury tracking network, completed at the end of March, could be exercised and evaluated. They agreed that the four-stage, solid-propellant Scout, originally designed at Langley and popularly called the "poor man's rocket," could perform this task economically. North briefed Abe Silverstein, NASA Director of Space Flight Programs, when he returned to Washington from Langley. In the meantime, William E. Stoney of STG had inquired of the Air Force, which also used the Scout, about the availability of a Scout launch vehicle. The planners proposed to use the Air Force and its contractors for payload design and construction and for vehicle assembly and launch. On May 11, Air Force officials replied that a Scout was available, but concurrently North reported that Silverstein was not interested in a Scout shot. Purser, relaying this information on to Gilruth, remarked that "you or Williams will have to talk to him [Silverstein] about it." Mercury-Scout mission planning, meanwhile, was already in progress, and Marion R. Franklin of STG was temporarily appointed as project engineer. This responsibility took on the aspects of a revolving door, with the assignment being shuffled among several Task Group engineers. James T. Rose was named to head the project a few days later; then Rose and Lewis R. Fisher had co-responsibility, until Rose was relieved to continue his work with James A. Chamberlin on what became the Gemini two-man spacecraft project proposals.²⁵

Although Silverstein at Headquarters opposed such a test, those on the operations end of Mercury felt that a flight to train the operators and check the tracking stations was a necessity. On May 15, 1961, personnel of NASA Headquarters and several of its cognizant centers, including Harry J. Goett of Goddard, Williams and Purser of Space Task Group, Low from NASA Headquarters, and Thomas A. Harris, G. Barry Graves, and Paul Vavra from Langley, met to review the proposed Scout launch in view of Silverstein's reluctance. They still concluded that the Scout was the best booster for network checkout purposes. The problem was how to sell the idea to Silverstein.

Low and Graves saw Silverstein the next day. They told him that only a one-orbit flight, possibly carrying a chimpanzee, was scheduled for the next six months; moreover, the Air Force had a spare research and development Blue Scout booster. This readiness gave promise of a reasonably early launch date, which was necessary if the communications exercise were to be worthwhile. Silverstein tentatively acquiesced, but he demanded assurance that all the design problems, including payload and antennas, would be resolved before he gave final Headquarters approval. After that approval, he added, all effort should be made to meet an August 15, 1961, firing date.²⁶ This stipulation apparently was made so that the flight would precede the scheduled August 22 launch date of the MA-4 one-orbit flight.

With Silverstein's reluctant blessing, the planners wasted no time in getting the Scout enterprise rolling. At a meeting at Langley on May 17, attended by Williams, Purser, Merritt Preston, Franklin, and Chamberlin of STG; North of NASA Headquarters; and Graves, Virgil F. Gardner, and Elmer J. Wolff of Langley, responsibilities were assigned and some general requirements were outlined. As noted, Rose and Fisher were named project engineers. Rose was in Los Angeles discussing boosters for the two-man project at the time. He received a call from Chamberlin requesting him to go to Aeronutronic in Newport Beach, California, to talk about instrumentation for the payload. He was joined there by Earl Patton, communications expert from McDonnell Aircraft Corporation. Graves asked the Goddard Space Flight Center to supply minitrack equipment and Goddard tentatively agreed to do so. The purpose of the minitrack equipment (used in the instrumented satellite programs) was to furnish data for comparison with that which would be transmitted by Mercury instrumentation. Mercury instrumentation was to include C- and S-band beacons, telemetry carriers, and either a command channel on the minitrack or a receiver operated by a command transmitter. Graves also planned to arrange with Goddard for minitrack drawings, and Chamberlin volunteered to contact McDonnell for the Mercury instrumentation drawings and hardware components. Some thought was briefly given to the possibility of using the Langley Research Center to instrument the payload; otherwise the Ford Motor Company's Aeronutronic Division, Air Force contractor for the Scout, probably would provide the instrumentation.²⁷

On May 23, North in Washington telephoned Purser at Langley and reported that Silverstein "had bought the Scout." There was a qualification, however: planning could proceed, but money was not to be committed until Robert C. Seamans, Jr., NASA's "general manager," approved. Silverstein immediately sought Seamans' concurrence, offering the inducement that only the payload would require NASA funding ($130,000); the Air Force, using the operation to provide experience for its launch crews, would bear the cost of the launch vehicle and launch. Silverstein argued to Seamans that delays in the Mercury-Atlas program, with a reduction of the flights to be conducted before a manned orbital mission, made using the Scout to check out the network seem sensible. The proposed payload, he said, would be prepared by Ford Aeronutronic, using components from Mercury capsule No. 14, which had already flown in the Little Joe 5-B test of April 28, 1961. The STG planners estimated that the earliest possible launch date was sometime in July, but Silverstein told Seamans that an August date seemed more realistic. Seamans agreed and returned the formal STG request on May 26, stamped "approved."²⁸

Now that the blessing was official, the Space Task Group made a sustained effort to launch in July. In June STG engineers considered the components that were to make up the 150-pound payload. Since Associate Administrator Seamans at NASA Headquarters had suggested in his approval document that a backup launch vehicle be obtained, STG secured the Air Force SSD's commitment to supply a second four-stage Scout. Seamans' suggestion proved to be prophetic; although no second Mercury-Scout mission was ever launched, the backup fourth stage had to be used in the first attempt.²⁹

By early July, the trajectory data and mission directive for Mercury-Scout were completed. MS-1 would be launched at the Cape from complex No. 18-B, formerly the Project Vanguard launching site, on a true azimuth heading of 72.2 degrees east of north, aiming at an apogee of about 400 miles and a perigee of about 232 miles. Orbital insertion of the payload was to occur some 1,100 miles from the Cape, at a speed of 25,458 feet per second and an altitude of 232 miles. A small rectangular box held the payload, which consisted of a C- and S-band beacon, two minitrack beacons, two command receivers, and two telemetry transmitters, all with antennas; a 1500 watt-hour battery; and the fourth-stage instrumentation package. The payload equipment was to function for 18 1/2 hours in orbit. To conserve electrical power while in flight, the equipment would be turned off by a ground command after the first three orbits. During shutdown, the results would be analyzed, and the equipment would then be activated to make another three-orbit data collection. The planners felt that by repeating the shutdown and reactivation operation they could obtain data equivalent to three full missions, gather a wealth of information for comparison, and give the DOD and NASA trackers a good workout.³⁰

The launch vehicle for the mission was a 70-foot, solid-propellant Scout rocket weighing 36,863 pounds at liftoff. The booster had four stages. Starting from the bottom, these included an Aerojet Algol engine with a steel case and steel nozzle, burning polyurethane fuel and guided by hydraulic exhaust vanes; a Thiokol Castor motor, also with steel case and nozzle, burning a polybutadiene-acrylic acid propellant, with a precision autopilot employing hydrogen peroxide reaction motors; an Allegheny Ballistic Laboratories Antares motor encased in filament-wound fiber impregnated with epoxy resin, propelled by nitrocellulose nitroglycerin, and guided by an autopilot identical to that in the Castor; and an Allegheny Altair engine of the same construction as stage 3, using the same propellant, but with a spin-stabilizing control mechanism.³¹

The Scout was erected on the pad on July 25 to await mating with the payload. Ford Aeronutronic had completed what turned out to be the initial packaging and had shipped the payload to the Capeon July 3. There the equipment underwent spin-ballast and operational checks and was mated with the booster. But trouble with faulty solid-state telemetry transmitters, developing during the pad checkout, caused such a delay that a July launching became impossible. At about that same time NASA Headquarters decided that the payload had not had sufficient vibration testing, so it was shipped to Aeronutronic at Newport Beach, California, for testing and repackaging. After it returned to the Cape, malfunctions appeared in the Scout's fourth stage, and the Cape engineers had to lift the fourth stage from the backup vehicle. The question in August was which would be ready first, the launch vehicle or the payload. Then on September 13, MA-4, carrying its mechanical astronaut, essentially preempted the Mercury-Scout by its orbital trek around Earth. The Scout payload reached the Cape on September 20, but all four Scout stages did not return to the pad until October 22. The anticlimactic Scout launch was supposed to take place on the 31st.³²

MS-1
Nov. 1, 1961

On Halloween, 1961, a launch crew under the technical supervision of the Air Force launch director (who, in turn, was responsible to the NASA operations director) attempted the Mercury-Scout launch. The countdown proceeded well down to the moment of ignition - when nothing whatever happened. The ignition circuits were rechecked and repaired and the next day, November 1, 1961, Mercury-Scout took off. Immediately after liftoff, the vehicle developed erratic motions, and after 28 seconds the booster began tearing apart. The range safety officer gave the destruct signal 43 seconds after launch. The failure, it was later determined, resulted simply from a personal error by a technician who had transposed the connectors between the pitch and yaw rate gyros, so that yaw rate error signals were transmitted to pitch control, and vice versa.³³ Six months of plans and labors had disintegrated in less than a minute.

Ambitions for a second Mercury-Scout, such as had been advocated earlier by Seamans, collided with the reality that another Scout rocket would not be ready before a Mercury-Atlas launch afforded a satisfactory and complete ground-tracking network checkout. The first stage of the backup Scout rocket failed its inspection tests, while the fourth stage had been used on the ill-fated Mercury-Scout 1 mission. Besides, Mercury-Atlas 5 was scheduled to go in mid-November, and the first manned orbital mission was set for December 19. Consequently, Low recommended the cancellation of the Mercury-Scout program to D. Brainerd Holmes, who had taken on manned space flight duties in NASA Headquarters.³⁴ So the Scout had a short but chaotic life as a member of the Mercury family of launch vehicles.

Man or Chimpanzee for MA-5?

From its unseemly beginning embodied in the Mercury-Scout failure on the first day of its formal existence, the newly titled Manned Spacecraft Center would go on in November to direct and record a resounding success, Mercury-Atlas 5. A curious atmosphere surrounded the approaching animal orbital mission, a sense of impatience, as though the Nation wanted to see it done quickly so the program could hurry forward to a manned orbital shot. The press clearly deplored any slip in MA-5 that would delay the manned flight. Putting an American into orbit before the end of 1961 was popularly regarded as something sorely needed for national prestige. NASA officials obviously were influenced by these pressures, and rank-and-filers in the space program were like members of a football team committed to a warm up game before a conference classic.³⁵

Some NASA leaders flatly opposed the chimpanzee flight. Administrator Webb's office questioned MSC on the need for another unmanned Mercury mission in view of the successful orbital flights of Cosmonauts Gagarin and Titov. A Washington newsman suggested that the President's advisers feared another American animal flight would only invite Soviet ridicule. Paul P. Haney, a public-affairs spokesman at NASA Headquarters, finally cleared the air when he announced to the public, "The men in charge of Project Mercury have insisted on orbiting the chimpanzee as a necessary preliminary checkout of the entire Mercury program before risking a human astronaut."³⁶

Other space-related events soon distracted public attention from the impending primate voyage on MA-5. One was the perfect launching of the mammoth Saturn I on its maiden flight. On the morning of October 27, the 163-foot-tall vehicle, with its 1.3 million pounds of thrust, rocketed 215 miles into space. The flight immediately triggered public discussion of whether a super-Saturn might be selected for launching the lunar mission spacecraft.³⁷ In Houston, the Manned Spacecraft Center, site for the direction of manned space projects of the future, captured the imagination of local citizens. A space-age tradition was born when H. T. Christman, a procurement officer, became the first member of the organization to buy a home in the Houston area, which was located in the Timber Cove residential development that was to become the neighborhood of several Mercury astronauts, near the site of the to-be-constructed Spacecraft Center.

Preparation for MA-5, initiated many months previously, continued without much fanfare. As early as January 1961, notes on the status of hardware for this mission had begun to appear in STG's quarterly progress reports to NASA Headquarters. Both booster and spacecraft then were being manufactured and tested. On February 24, spacecraft No. 9 had arrived at the Cape to begin a 40-week preflight preparation. This lengthy period, longest in the Mercury project, derived from the various flight program changes that required corresponding configuration changes. No. 9 had been configured initially for a ballistic instrumented flight, then for a ballistic primate flight, next for a three-orbit instrumented mission, and finally for a three-orbit chimpanzee flight.³⁸

Another factor contributing to the long preparatory period was that the data obtained from the MA-4 mission demanded a number of modifications. For the environmental control system, a locking device was added to the oxygen emergency rate handle, while the inverters, one of which had failed during MA-4, were put through a severe vibration-test program. Since some unbonding had occurred on the heatshield of the MA-4 spacecraft, x-rays twice were made of the ablative layer to determine the soundness of the glue line. For the explosive side egress hatch, as yet untried on an orbital mission, thermocouples were added and a limit switch was installed to signal any premature hatch firing, an experience that cost the loss of a flight-tested spacecraft in MR-4. And the horizon scanner sensor system was modified to avoid the erroneous signals transmitted during the orbit of the "mechanical man."³⁹

Thus the spacecraft mounted on Atlas No. 93-D for MA-5 differed considerably from that used on the September orbital flight. This was another reason Haney had said that "the men in charge of Project Mercury" wanted another qualifying round before a manned mission. Besides modifications already described, No. 9 had a landing bag installed and a large viewing window. Although the window had been used on MR 4 and had proved useful to Astronaut Grissom, it had not been subjected to the much greater reentry heat the MA-5 capsule would encounter. Aside from these new components, No. 9 had about the same equipment as carried in MA-4 - tape recorders for gathering data and exercising the communications network, cameras, and radiation film packs. Of course, "Enos," the chimpanzee eventually selected from the colony in training, would need no simulator to do his breathing or perspiring. He had his own metal-plastic pressure couch, which was connected to the suit circuit of the environmental control system.⁴⁰

The spacecraft operated in a fashion similar to the first orbital Mercury vehicle. Once again, as during MA-4, the hydrogen peroxide fuel supplies for the automatic and manual control systems were linked to provide a common reservoir. The automatic stabilization and control and rate stabilization control systems would be operated separately, so that the performance of each could be evaluated. The automatic system was programmed to exercise capsule attitude control until one minute after the .05-g light signal; then the rate system would take over for reentry, providing a constant-roll rate of about 7.5 degrees per second as well as damping motions in the yaw and pitch axes. The rate system would switch off at main parachute deployment.⁴¹

Recovery aids and operations, too, were about the same as for MA-4, including radar chaff, sofar bombs, a flashing light, and dye marker. The probable launch abort recovery areas were spaced and designated as before, although there were more contingency recovery areas because the mission was longer. For each of the three planned orbits about five contingency locations were selected. During the second orbit, for example, the emergency landing areas included the Atlantic Ocean near the west coast of Africa, the Indian Ocean near the east coast of Africa, the Indian Ocean near the west coast of Australia, and the Pacific Ocean either 440 miles southeast of Hawaii or 165 miles southwest of San Diego. The primary recovery zone shifted following the completion of each full orbit.⁴²

Space Task Group officials expected delivery of the MA-5 launch vehicle, Atlas No. 93-D, about mid-August 1961, but it was decided by STG and the Air Force to delay shipment until the flight of MA-4. Then, when faulty transistors had delayed the MA-4 launch, intensive quality assurance inspections of the transistors had to be initiated. The electronic gear of the rocket was also modified, its 100-watt telemetry system was replaced by a 3-watt transistorized unit, and the autopilot circuitry was altered to alleviate the high vibrations experienced during the first orbital Mercury flight. These changes dragged the delivery date back to October 9, 1961. In Washington, George Low warned Seamans that the time needed to secure several components necessary for these modifications might affect the delivery date of Atlas No. 109-D, the booster scheduled to launch the first astronaut into orbit. No. 93-D was the third "thick skin" Atlas booster, employing a heavier gauge of metal in its forward tank.⁴³

According to plans, which now were to approximate those for the manned orbital mission as nearly as possible, MA-5 would rise from complex 14 at Cape Canaveral on a heading 72.51 degrees east of north. Orbital insertion of the spacecraft should occur about 480 miles from the Cape at an altitude of 100 miles and at a speed of about 25,695 feet per second. Retrofire to initiate entry into the atmosphere was planned for 4 hours, 32 minutes, and 26 seconds after launch. Twenty-one minutes and 49 seconds later the spacecraft should hit the water in the Atlantic. Estimated temperatures during reentry should be about 3,000 degrees F on the heatshield, 2,000 degrees on the antenna housing, 1,080 degrees on the cylindrical section, and 1,260 degrees on the conical section. The STG operation planners estimated that the spent Atlas sustainer engine would reenter the atmosphere after 9 1/3 orbits, a considerable change from their estimates for the descent of the MA4 rocket.⁴⁴

Training Primates and Men

For the all-important task of checking out the environmental control system on a long-duration flight, a chimpanzee was chosen to "stand in" for man. As in the preparation for Ham's suborbital mission on MR-2, two colonies of chimps traveled to the Cape about three weeks before the flight date. Again the military handlers from Holloman Air Force Base separated the colonies to prevent cross-infection. Training involved restraining the animals in a pressurized flight couch, with biosensors attached to their bodies at various points. And psychomotor training that had been started in New Mexico was continued at the Cape so that the animals' proficiency would not deteriorate.⁴⁵

On October 29, 1961, three chimps and 12 medical specialists moved into their Cape quarters to join two other simians and eight persons already in flight preparation status. The name given to "Enos," the animal selected as the flight test subject, in Greek or Hebrew means "man," and the training and flight performance recorded by this chimpanzee proved the sobriquet to be well chosen. Captain Jerry Fineg, chief veterinarian for the mission, described Enos as "quite a cool guy and not the performing type at all." This "immigrant" from the French Cameroons had none of the tendencies of his circus-trained counterparts. Enos' backup "pilots," listed in order of their flight readiness ability, were "Duane," named for Duane Mitch, a veterinarian; "Jim," named for Major James Cook, of the same profession; "Rocky," named for a well-known pugilist (Graziano) because of his cauliflowered ear and pugnacious spirit;and "Ham," the astrochimp veteran. The ratings were made by Fineg and another Air Force officer, Marvin Grunzke. Fineg later learned that when these same chimps had gone through their earlier launch and reentry training on the centrifuge at the University of Southern California, they had been rated in the same order.⁴⁶

The psychomotor equipment used by Enos on the MA-5 mission was more complicated than that operated by Ham during the Mercury-Redstone 2 suborbital flight. Housed in the cover of his pressurized couch, Enos' package was rigged to present a four-problem cycle. The first would last for about 12 minutes, and the second followed six minutes of rest. The routine would proceed until the cycle was completed, then the four problems would be repeated until the mission ended. Problem one would offer right- and left-hand levers that Enos could use to turn off lights, avoiding a mild shock in the left foot (the same as for Ham). The second problem planned was a delayed-response experiment. Twenty seconds after a green light would appear on the panel, Enos would have to press a lever to receive a drink of water. Although there would be no penalty for his failure to respond, if the chimpanzee should pull the lever too early the problem would simply recycle and he would receive nothing. The third, a fixed-ratio problem, would involve pulling a lever exactly 50 times to receive a banana pellet. This would also be voluntary and without penalty. Chimpanzee intelligence would be tested in the fourth. Three symbols - circles, triangles, and squares - would appear in various two-of-a-kind combinations, with the task being to pull a lever under the odd symbol to avoid a mild shock. Lack of response during rest periods would give the indication that the animal was well oriented to his spacecraft environment.⁴⁷

Planning for this second trial of the Mercury worldwide tracking network was elaborate. Supporting the MA-5 mission were 18 stations, plus the Goddard Space Flight Center and the Mercury Control Center. Goddard and the Control Center furnished computer support and management of the overall operation, respectively.

With the exception of White Sands, all stations would receive "real time" telemetry data, consisting of magnetic tape recordings, Sanborn recorder displays, meter displays, and clock displays. The overall operation of this network was a vast cooperative undertaking of the Department of Defense, NASA, and industry.⁴⁸

Seventy-three key people assigned to the various stations received their final mission briefing on October 23. Once again the tracking teams included several Mercury astronauts. Shepard was assigned to Bermuda, Schirra to Australia, Slayton to Guaymas, and Cooper to Point Arguello, while at the Cape, Carpenter had a station in the blockhouse, Grissom was the capsule communicator in the Mercury Control Center, and Glenn served as backup capsule communicator in the center.⁴⁹

Chimpanzee into Orbit

By mid-October, reported George Low to NASA Headquarters, problems with capsule No. 9 and booster No. 93-D had forced STG to delay the launch from November 7 to November 14. On November 11, however, after the preflight checkout crew found a hydrogen peroxide leak in the fuel line of the capsule manual control system, the earliest possible launch date slipped to November 29.⁵⁰ Although NASA did not comment officially on the effect of the delay, chances for a manned orbital mission in 1961 now were dim.⁵¹

MA-5
Nov. 29, 1961

On November 28, 1961, an 11 1/2-hour launch preparation count began for MA-5. The count stopped at T minus 390 minutes, to be resumed the next day. Some 11 hours before the launch, Enos, the 39-pound chimpanzee, underwent his final physical examination, stood still as his medical sensors were taped on, allowed himself to be secured in the specially constructed primate couch, and rode in the transfer van to the gantry. About 5 hours before launch the couch was inserted in the spacecraft. Thereafter Enos' condition was monitored by lines connected to his couch in the Mercury capsule and by radio telemetry. He was relaxed during countdown. His temperature ranged from 97.8 to 98.4 degrees, normal for the suit inlet temperature of about 65 degrees; his respiration averaged 14; and his pulse rate was 94. The only time Enos displayed agitation was when he was roused by the opening of the hatch during a countdown hold caused by a telemetry link failure at T minus 30 minutes. The gantry was hauled back to the spacecraft, the hatch was opened, and an off-and-on switch was correctly positioned. This hold lasted 85 minutes. Some members in the control center joked that Enos had turned the switch off because he had talked to Ham and did not want to go.⁵²

In the Mercury Control Center the flight control monitors had manned their stations and were busily checking out their consoles. Tecwyn Roberts, serving as flight dynamics officer, noted the intermittent problems cropping up in the data-gathering and translating computers. A faulty transistor in the direct data receiver caused one hold, and when the replacement was also faulty, several more minutes were lost in repairing the computer. Morton Schler, the capsule environment monitor, reported that the environmental control system was working smoothly. The Freon flow rate, he reported, leveled at a comfortable 20 pounds per hour in the prelaunch period. From the oxygen partial-pressure transducer some erratic readings proved erroneous; Mercury Control teletyped the tracking stations to discount these readings as the spacecraft passed over.⁵³

Holds during the countdown amounted to almost 2 hours and 38 minutes. Shortly after the hatch was bolted at T minus 90 minutes, the technicians discovered that they had failed to install some hatch cover heat insulation material. They took a little more than an hour to correct this oversight. Then, at T minus 30 minutes, the discovery of an improperly positioned switch necessitated the 85-minute hatch-opening hold. And finally, at T minus 15 minutes, a 4-minute hold was called to correct a data-link problem between Mercury Control and the General Electric ground command guidance equipment.

Walter Williams, the mission director, listened as the various difficulties arose and became somewhat agitated at the chain of events. Although his usual position during such times was at a console in the mission control center, he left the building and quickly drove the distance to pad 14 to personally express his expectations that things would proceed in a more orderly manner. As a member of Convair later said, "Williams was a master in imparting a need for orderly urgency."

Despite these holds, weather conditions remained favorable. Only a few thin cirrus clouds hung in the sky, visibility was 10 miles, and the surface wind velocity was at a moderate 11 miles per hour from the northwest. In the landing area the weather was even better.⁵⁴

The Goddard computers received the liftoff signal 13 seconds before the booster actually rose from the pad, an error apparently caused by feedback between two recorders. Nor was this the last incorrect signal. The Goddard computers registered sustainer engine cutoff twice before that event happened, once shortly after liftoff and again two minutes after launch. In each case the Mercury Control Center had to switch to override the signal until the panel indicator cleared.⁵⁵ Liftoff came at 10:08 a.m. The powered phase of the flight went well, although there were minor discrepancies. Between liftoff and staging, the horizon-scanner signal was lost briefly. All spacecraft systems nevertheless appeared to be working normally, with the guidance system of the Atlas keeping the booster on an almost perfect insertion trajectory. Guidance system noise was only about half that recorded during MA-4, and vehicular vibration also was much lower. Four and a half minutes after launch, Christopher C. Kraft, Jr., unhesitatingly made the go-for-orbit decision. At sustainer engine cutoff, the velocity, flight angle, and altitude were nearly perfect. The Atlas hurled the spacecraft into an orbit with a perigee of about 99 miles and an apogee of 147 miles, .5 and 5.4 miles low, respectively.⁵⁶

Spacecraft and booster separation occurred precisely as planned, while the turnaround maneuver took less than 30 seconds. The capsule's position excursions were very slight, which contrasted sharply with the erratic turnaround of MA-4. The spacecraft quickly dropped into its 34-degree orbit mode and began streaking over the oceans and continents. Of the 61.5 pounds of control fuel aboard, turnaround and damping had consumed 6 pounds, as opposed to 9.5 for MA-4. From that point and on through the first orbit the thrusters used only 1.5 pounds to maintain a correct position, with the automatic stabilization and control system functioning perfectly.

The environmental control system and the tracking and communications network performed in a satisfactory fashion. On this mission, for the first time, the primary and secondary oxygen bottles were pressurized at 7,500 pounds per square inch (the design specification) rather than at 3,000, as on previous flights. A functioning water separator also was used for the first time. Each tracking station's range on the ultra-high-frequency band lasted for about six minutes; on high frequency, overlap communications between stations were similar to that experienced during MA-4. The Goddard computers received valid telemetry data from all stations except Woomera, but there were instances when communications were momentarily lost at particular stations. Just before retrofire, for example, Point Arguello, the site giving the firing command, lost contact with the Cape. In each instance, as Walter Williams would point out at the postflight press conference, communications were reestablished whenever that particular station was needed.⁵⁷

Enos, the orbiting chimpanzee, fared well. He withstood a peak of 6.8 g during booster-engine acceleration and 7.6 g with the rush of the sustainer engine. He had been performing his lever-pulling duties for some two minutes before the Atlas roared and rose from the pad. During his two orbits he made 29 pulls (divided among four sessions) on the continuous-avoidance and discrete-avoidance levers, receiving only one shock in each category. On his second problem, which required at least a 20-second delayed response to receive a drink of water, his average delay was about 33.8 seconds. For these labors he was rewarded with a total of 47 measures of water, or about a pint during the three-hour mission. For the fixed-ratio task, problem three, Enos pumped his lever and received 13 banana pellets during his four opportunities. On the first session of problem Four, Enos was correct for 18 out of 28 symbol presentations (64.2 percent), thus receiving 10 shocks as a result of his miscues. On the second session of problem four, however, the center lever malfunctioned, causing shocks even if he pulled the correct lever. He received 36 and 43 successive shocks on the third and fourth sessions, respectively, because a manmade device had failed. The shocked and frustrated chimpanzee nevertheless kept pulling the levers. As he was also trained to do, Enos remained at rest during the six-minute intervals between problems.⁵⁸

Near the end of the first orbit, the tracking monitors noted that the capsule clock was about 18 seconds too fast and as it passed over the Cape a corrective command was dispatched to and accepted by the clock. At that time the Mercury Control Center display panels indicated that all spacecraft systems were in good order. Suddenly the Atlantic tracking ship reported that inverter temperatures were rising. The Canary Island trackers confirmed the environmental control system malfunction. Since abnormal heating had occurred on earlier flights and the inverters had continued working or had switched to standby, there was no alarm among members at Mercury Control. Then, across the world from the Cape, Muchea, Australia, detected high thruster signals and capsule motion excursions, although other data indicated that the 34-degree orbit mode was being maintained. The Woomera, Australia, tracking station failed to confirm this report, and it was discounted.⁵⁹

By the time the MA-5 capsule reached the vicinity of the Canton Island station, the operations team realized that the attitude control system was allowing the vehicle to go out of its proper orbital mode. A metal chip in a fuel supply line (the postflight inspection would reveal) had cut off the propellant flow to one of the clockwise roll thrusters. This inactive thruster allowed the spacecraft to drift minus 30 degrees from its normal attitude, at which point the automatic stabilization and control system brought the spacecraft to zero in a normal roll-turn maneuver. Then the spacecraft swung briefly back into the nominal 34-degree orbital attitude, and the sequence started again. The spacecraft repeated this process of drift and correction nine times before retrofire and once more between retrofire and the receipt of the .05-g light telemetry signal. The still-active thrusters used about 9.5 pounds of control fuel working to keep the capsule properly aligned. Each loss of orbit mode cost a little over a pound of fuel compared with a first-orbit expenditure of only 1.5 pounds.⁶⁰

The cooling equipment in the environmental control system also began to give trouble during the second orbit. Between the Canary Islands and Kano, the suit circuit temperature rose rapidly from 65 to 80 degrees, indicating a freezing condition in the heat exchanger. As water in the felt evaporator pad of the exchanger turned to ice, Enos' body temperature climbed to 99, then to 100 degrees. The medical observers began to worry, especially about the chimp's ability to handle his psychomotor test problems. Then, at 100.5 degrees, his body temperature appeared to stabilize, suggesting that the environmental system was ceasing to overheat. Their fears relieved, the physicians felt that the mission could continue. Although the cooling system had seemed to correct itself, Kraft, the flight director, later remarked that a deicing unit should be added to warm the troublesome unit, which had also caused a freeze-up on MA-4.⁶¹ Although the medical monitors were willing to allow the mission to proceed through its scheduled third pass around the world, the operations team believed that the problem of the spacecraft's erratic attitude was too grave to live with. The engineers felt that there simply was not enough attitude fuel left to complete the circuit and then go through the reentry phase, in which, even under normal circumstances, fuel usage would be high.

After the attitude aberrations were first noted, Kraft had alerted the tracking unit in Hawaii for a possible clock change to initiate retrofire during the second orbit. Then he decided to continue the flight toward California and notified Gordon Cooper at Point Arguello that that station might have to initiate a ground command for retrofire. Meanwhile, the capsule continued to drift and swing in and out of the orbital mode, demonstrating that the attitude control system, unlike the environmental control system, would not solve its own problems. Twelve seconds before the retrofire point was reached for the normal second-orbit primary recovery point, Kraft decided to bring Enos back to Earth. Arnold Aldrich, MSC's chief flight controller at Point Arguello, correctly executed the command.⁶²

With the exception of the one repeated variation in attitude position, caused by the dead roll thruster, reentry went according to plan. The destroyers Stormes and Compton and a P5M airplane began preparing for spacecraft retrieval in Station 8, the predicted impact point. Three hours and 13 minutes after launch and about nine minutes from water impact, the P5M spotted the descending spacecraft at an altitude of about 5000 feet and radioed the Stormes and the Compton, 30 miles away. All spacecraft recovery aids except the sarah beacon functioned properly. During the spacecraft's descent, the airplane circled and reported landing events, then remained in the area until the Stormes arrived, an hour and 15 minutes after the landing, and hauled Enos and his spacecraft aboard. Shortly thereafter the hatch was explosively released from outside the capsule by a pull on its lanyard, causing the chimp's "picture" window to crack.⁶³

Aboard the Stormes and later at Cape Canaveral, Manned Spacecraft Center and McDonnell engineers gave the capsule the usual close scrutiny and happily found that it had held up well. Except for a slight discoloration caused by aerodynamic heating, the exterior showed no buckling or warping. The interior was in good shape, too, although the inspectors did find a small amount of salt water. Activation of the explosive hatch caused minor damage in the form of the cracked window, several bolts pulled from the skin, and a slight buckle. Thermodynamic effects on the ablation heatshield had produced several radial and circular cracks, none of which had been severe enough to threaten the capsule's structural integrity. The center plug of the heatshield was missing (it had only worked loose on MA-4 ), but close inspection of the opening showed that the plug had evidently been in place during reentry. Condition of the impact bag, which had survived its first orbital test, was fairly good, although several straps were broken and others were severely bent. Again the plastic bulkhead was pierced, probably by the heatshield, and the honeycomb material was crushed in several places. There was no damage to the tubing or wiring in this area.⁶⁴

At the Cape postflight press conference the leaders of Project Mercury revealed no regrets over missing a third orbit. They seemed to regard the reprogramming operation, conducted in the middle of the mission, as a satisfying technical accomplishment. In view of the decisiveness with which the various potentially critical difficulties had been overcome or circumvented, MA-5 had to be termed an excellent operation, one that had achieved most of its objectives and that would become a milestone on the road into the unknown.

Enos had been weightless for 181 minutes and had performed his psychomotor duties with aplomb. Operations director Williams felt that an astronaut riding in the MA-5 spacecraft could have made the necessary corrections in flight to complete the three-orbit mission normally. On the spacecraft attitude control problem, for example, a man could simply have switched from automatic to manual mode, he said. At the same time, Williams was pleased that the automatic systems had worked well for over two hours. Equally significant, the vast network of NASA, military, and industry personnel had performed like veterans during the emergency. The spacecraft had reentered and landed without handing the Navy any unexpected recovery problems.

Now a Man in Orbit?

The press corps at the usual postflight press conference listened courteously to this technical postmortem, but their main concern was whether another test mission would be flown before a manned orbital flight. Williams and Gilruth cautiously replied that first the MA-5 data would have to be thoroughly evaluated. Then the reporters wanted to know who had been selected to make Mercury's first manned orbital flight. Gilruth was ready for that one; he announced the team members for the next two missions. John H. Glenn was the selected prime pilot for the first mission, with M. Scott Carpenter as his backup. Donald K. Slayton and Walter M. Schirra were pilot and backup, respectively, for the second mission.⁶⁵ This announcement represented a considerable change from the tighter news policy regarding crew selection that had prevailed in suborbital days.

Meanwhile Enos had his moment. After the urbane anthropoid came aboard the Stormes, he ate two oranges and two apples, his first fresh food since he had gone on a low-residue pellet diet. The destroyer dropped Enos at the Kindley Air Force Base hospital in Bermuda, where Jerry Fineg took over. The chimp was walked in the corridors and appeared to be in good shape. His body temperature was 97.6 degrees; his respiratory rate was 16; and his pulse was 100. Apparently reentry, reaching a peak of 7.8 g, had not hurt him. His composure at his "press conference" surprised the correspondents. One reporter remarked that Enos, unlike Ham, did not become "unhinged" with the popping of the flash bulbs. On December 1, Enos reached the Cape for another round of physicals, and a week later he departed for his home station at Holloman, and well-deserved retirement.⁶⁶

Enos' fame was short-lived. Public attention now turned to the supposedly imminent American manned orbital flight, although there still was no assurance that a spacecraft would next carry a man. Speculation mounted when Atlas 109-D was hauled into the Cape on the night of November 30. Newsmen immediately gathered around B. G. MacNabb, the Convair preparation chief, to ask when the checkout would start. "Tomorrow," he replied. When asked if there would be a crash effort in order to make the flight in 1961, Williams said that three shifts were working a 168-hour week (all the hours possible), and that no special pressure would be applied. None of these statements dampened speculation by the press early in December. Signs, rumors, and portents cropped up daily. One correspondent, for example, noted that John Glenn had moved into special quarters at the Cape, adding that NASA had requested Atlantic Missile Range support beginning on December 20 and continuing to year's end.⁶⁷

If NASA had ever been involved in a drive to put an American in orbit in the year of the Vostoks, that effort halted on December 7, the 20th anniversary of the Pearl Harbor attack. Almost casually Gilruth and Williams announced that the flight was now scheduled for early 1962. The decision, said MSC officials, had been influenced by "minor problems dealing with the cooling system and positioning devices in the Mercury capsule." The official press release did state that NASA considered the spacecraft, its systems, and the tracking network qualified for manned flight. It had been apparent to many NASA officials for some time that the manned orbital launch might have to be postponed until 1962. George Low, at NASA Headquarters, had recognized the probability soon after mid-October, when he wrote, "The pad conversion time between MA-5 and MA-6 is exceedingly short if MA-6 is to remain on schedule." On schedule meant December 19.

Hugh L. Dryden summed up his philosophy regarding adherence to schedules for manned flight when he said, "You like to have a man go with everything just as near perfect as possible. This business is risky. You can't avoid this, but you can take all the precautions you know about."⁶⁸

Although there was regret that this country did not get a man into orbit before the Soviets, or at least in the same year, 1961 had recorded substantial progress toward making the United States a spacefaring nation. In contrast with the atmosphere of uneasiness marking the end of 1960, the Manned Spacecraft Center engineers now knew that they were on the brink on fulfilling Project Mercury's basic objectives. The rehearsals were over.