To measure man's potential as a spatial navigator, Voas wanted the astronaut to look for the smallest detectable landmark, to estimate the effects of weather conditions on visibility, and to judge precisely the occultation of the stars by Earth's atmosphere. Theoretically, from the vantage point of the orbital flight trajectory an astronaut should see about a 900-mile arc of the horizon. He should be able to determine how much of this was effective horizon in terms of his ability to recognize a landmark with the unaided eye. One important facet of any later space exploration, Voas said, would be man's visual acuity in estimating spatial depth and distance; tracking an artificial object in a nearly identical orbit during a Mercury circumnavigation would partially test this ability. The spent Atlas tankage trailing the capsule should offer an excellent opportunity in this respect.
Ever since the Soviet reports of Gherman Titov's sensations of dizziness and nausea caused by his head and body movements, some aeromedical specialists had worried that perhaps the prolonged absence of gravitational stress did adversely affect a space passenger or pilot. Voas, considering this subject, contended that it was impossible to say whether Titov had had a purely personal aversion to weightlessness or whether men in general would have similar troubles under zero g. Neither Alan Shepard nor Virgil Grissom had experienced vertigo during the two Mercury suborbital flights. Voas felt that if disorientation and nausea were in fact products of longer durations of weightlessness, as some physicians and physiologists believed, the symptoms could be remedied through preflight training, proper flight procedures, or, if necessary, by drugs.
Voas acquainted the astronauts with the probable effects of weightlessness on their sensory organs. The otoliths, the ear's angular accelerometers, should not be affected, he said. Muscle and skin sensory functions should be affected only slightly, but those muscles sensing the amount of gravity would lose their acuity completely. By and large, the general diminution of sensory perception accompanying space flight should be overcome by the astronaut's eyes and his memory. To test his theories, Voas prescribed an experiment to be conducted on the dark side of Earth. The pilot would touch certain panel dials with his eyes open and then with his eyes closed, after moving his head quickly to the right, left, and forward. Gordon Cooper expressed qualms felt by several people over Voas' "blind flying" test when he remarked, "You shouldn't be reaching over on this panel with your eyes shut."
Other tasks planned by Voas included taking pictures through the window and periscope with a hand-held camera, describing the cloud cover on the day side, and looking for lightning in squall lines as requested by the United States Weather Bureau. On the night side the pilot should repeat those tasks and observe the aurora and luminescence of Earth's clouds. Finally, he should scan the star fields, the Milky Way, and note the size and appearance of the Moon as well as describe a moonset.6
The September study by Voas included the initial efforts of the Space Task Group to foster a scientific inroad into the manned space flight program. After distributing his paper among the astronauts and receiving favorable comment from several, Voas then sought the assistance of NASA Headquarters to obtain a broader base for possible astronaut activities in space from the various scientific disciplines that were available. Homer E. Newell and Nancy G. Roman of that organization reacted by directing the formation of an ad hoc committee for astronomical tasks for the Mercury pilots, assigning Jocelyn R. Gill as the committee chairman. This group was an offshoot of the formal Astronomy Subcommittee, a part of NASA's Space Sciences Steering Committee.7
As a beginning Gill and Voas attended a meeting of the Astronomy Subcommittee held at the Grumman Aircraft Engineering Corporation, Bethpage, New York, on October 30-31, 1961. Voas reviewed the abilities of the astronauts  to assume some additional tasks, such as observations of astronomical phenomena. He also cautioned that any integration of scientific equipment inside the spacecraft would have to be severely restricted in weight. The Astronomy Subcommittee discussed the possibilities and then suggested 10 tasks that an astronaut might accomplish. A few of these were: observe the night airglow as to its intensity and structure, look for comets before sunset and after dawn, note the frequency of meteor flashes, look for the aurora and describe its intensity, sketch the zodiacal light relative to the star background, and observe the size and position relative to the star background of the gegenschein.8
Besides generally acquainting the Mercury astronauts with the spatial environment, their possible reactions, and what they might accomplish in the way of operations and scientific observations, Voas also had pressed forward with a plan for a specific training program to prepare the crewmen to operate and manage the spacecraft systems on orbital missions. He first compiled a list of proposed training activities, and then he called a meeting at Langley on September 26 to discuss his report. The STG officers present adopted the training proposal, which became a formal working paper on October 13. With slight subsequent amendments, this working paper, No. 206, spelled out the astronaut training and preparation procedures that would be followed for the rest of the Mercury program.9
The first stated prerequisite for the astronaut, as formulated by Raymond G. Zedekar of STG, was a thorough familiarity with the spacecraft and all its systems. He must know every mission detail, including every flight and ground rule; he would be expected to demonstrate peak performance in every task during the flight; and his skills must include making failure diagnoses and taking the proper corrective action.
Preparing the pilot for his role during an orbital mission, the astronaut training personnel obviously could draw heavily on Shepard's and Grissom's suborbital experiences. The nine separate checkouts of the spacecraft after it arrived at the Cape, they felt, would provide excellent familiarization and systems training for the prime pilot and his alternate, who would be assigned to take turns in the capsule's contour couch. Then, if any modifications to the hardware or change in methods should become necessary, either man would be fully prepared to give valuable advice as well as to learn how the component change or new procedure would affect the mission. But by all accounts, as particularly ascribed to by the Mercury suborbital pilots, the best training sessions for practicing both normal and abnormal flight conditions in the Mercury program were those held in the procedures trainer. There all phases of a mission - prelaunch, countdown, launch, orbit, reentry, recovery, and emergency - could be simulated. The training planners decided that at least 30 hours of practice would be scheduled in this McDonnell-made trainer. On some occasions the simulation called for hooking the trainer in with the Mercury Control Center and the Bermuda tracking site, an exercise that also would help the flight controllers check, promulgate, or practice their communications and control procedures.
 Voas and his colleagues scheduled numerous other training activities that would supposedly hone the astronauts to a fine edge. One such plan called for the pilot or his designated stand-in to attend the spacecraft scheduling meetings, operational planning sessions, and booster, spacecraft, and mission reviews. After the spacecraft had been mated with the booster, the astronaut would have a key role in the capsule systems test, sequential and abort exercises, and the simulated flight that accompanied each countdown launch simulation. With the astronaut sitting in the spacecraft, all countdown checks would be run up to the point of hatch installation. Voas' training document stipulated that even the exercise of slipping the pilot into his capsule should be practiced until the insertion crew had it down perfectly. Besides all this work at the Cape, preflight trips were planned to the Morehead Planetarium in North Carolina, so that the astronaut and his backup pilot could fix star patterns in their minds as an aid to their orbital celestial observations. To obtain a familiarity with angular motion, they would attend sessions in the Pensacola Naval Air Station's "rotating room" and on the human disorientation device. Egress training, the value of which Grissom vouched for after his harrowing recovery, was scheduled on the open water in the Atlantic. Finally, there were Morse code instruction, map study, and briefings by the Weather Bureau support team on observation procedures.10
All these varied tasks had to be scheduled in logical progression to bring about a status of "flight readiness." The original training directive specified that an intensive training program for an upcoming flight should begin with a comprehensive study of all capsule instrumentation about 81 days before the launch was scheduled. Nine days later, after the astronaut and his alternate had memorized everything they could about the capsule instrument panel, they would start spending at least three hours per week in the procedures trainer, making brief excursions to Langley for sessions on the air-lubricated, free-axis (ALFA) trainer. In the procedures trainer they would go through specific mission profiles. These included a normal one-orbit mission, lasting about 90 minutes, with the astronaut in casual clothes; five-hour sessions simulating three orbits, with the astronaut wearing a pressure suit on some occasions; and 30-minute abort simulations, including such hazards as the failure of the retropackage to jettison, failure of the spacecraft's main batteries shortly after orbital insertion, and many other malfunctions covering every conceivable contingency that the training officers could devise.11
By December 1961, after Glenn and Carpenter had been publicly named for the Mercury-Atlas 6 mission, training plans were expanded to include their medical evaluations. For the altitude chamber simulated flight conducted about 45 to 60 days before the anticipated launch, Glenn was examined, fitted with biosensors, suited, pressure-checked, and then loaded into the transfer van and medically observed during the trip to the altitude test chamber. After he seated himself in the couch, his biosensor data were checked, his electrocardiogram leads were monitored, and the newly fabricated blood pressure equipment was exercised. Also there was a checkout of the spacecraft's environmental control system.12
Jocelyn Gill also began planning the scientific aspects that Glenn might attend to while he was in orbit, when she called the first meeting of the ad hoc committee in Washington on December 1, 1961. William K. Douglas, Voas, and John J. Van Bockel attended from the Manned Spacecraft Center. The main purpose of this gathering was to adjust the suggestions emanating from the earlier meeting of the Astronomy Subcommittee into a workable order to provide the astronauts with as much background as possible of what they might expect to see in space. The first piece of equipment for scientific purposes aboard the spacecraft discussed was a small filter planned for use in studying the irregularities of the night-sky illumination and aurorae. For later missions an ultraviolet camera was suggested for possible use in photographing the stellar spectra.13
Some eight days later Glenn, Carpenter, and Schirra accompanied Voas and Douglas to a second meeting called by Gill. Point by point the requested astronomical observations were explained to the three astronauts. Because of their evident interest, Gill was of the opinion that such briefings, perhaps with even more detailed information, should be provided at intervals as well as just before flight time.14
During the month before the MA-6 mission, Glenn underwent at the launch site a realistic test termed "Pad Rehearsal No. 1." This exercise started with biosensor and suiting-up preparations at the hangar, transportation to the pad, and insertion of the astronaut into the spacecraft. Both the blockhouse and the Mercury Control Center were tied into and participated in this exercise. Several days later this operation was carried out again, and this time the gantry was pulled away to make conditions more realistic. Then about three days before the scheduled flight, after he had already begun his low-residue diet, Glenn went through a simulated mission encompassing the entire flight plan.
Other preflight medical activities included a complete physical examination two days before the anticipated launch. The Mercury physicians issued Glenn a number of medications for his survival pack, including morphine for pain, mephentermine sulfate for shock, benzylamine hydrochloride for motion sickness, and racemic amphetamine sulfate (a common pep pill) for a stimulant. Radiation-measuring film packs were tucked inside the spacecraft.15
Glenn and Carpenter had completed most of their preflight training program by the end of January, but the continuing delay of the MA-6 launch forced them to go on with their crowded routine. Glenn spent 25 hours and 25 minutes in the spacecraft during the hangar and altitude test chamber checks and uncounted hours on the pad after the launch rocket and spacecraft were mated. On the procedures trainer between December 13, 1961, and February 17, 1962, he logged 59 hours and 45 minutes (far beyond the 30 required by the training directive) and worked through 70 simulated missions in the process, reacting to some 189 simulated system failures. Glenn and Carpenter, along with Donald Slayton and Walter Schirra, already picked for MA-7, participated in a two-day (December 11 and 13, 1961) recovery exercise on the Back River near Langley Air Force  Base, Virginia, easily making both top and side hatch exits. Later Glenn and Carpenter, wearing life vests, carried out a survival equipment exercise off the beach at Cape Canaveral.16
Not only the pilots but many others were training for the MA-6 mission. On January 15, 16, and 17, 1962, recovery team swimmers practiced jumping from helicopters and placing the new auxiliary flotation collar around a boilerplate capsule. The flight controllers who were to deploy to the remote tracking sites got their final briefing on January 3 and left for their respective stations, where they engaged in seven rather extensive network exercises. Mercury Control, Goddard, and the Bermuda site conducted tests to check the Control Center-Bermuda abort command sequence. On January 25, Eugene F. Kranz reported to Christopher C. Kraft, the flight director, that the network team was at its peak condition. He feared that motivation and performance might decline if the flight continued to be delayed.17
Although this was to be the first manned orbital flight in Project Mercury, earlier flights set many precedents in the planning process for such items as recovery requirements, mission rules, and test objectives, and consequently the mission planning for MA-6 was almost routine. The launch azimuth heading was to be the same that Enos had followed into orbit riding MA-5; the recovery forces, now thoroughly seasoned, although somewhat larger than for MA-5, were stationed to cover essentially the same landing areas; ignition procedures and range rules for the launch were about the same as on previous Mercury-Atlas missions.18
5 Memo, Robert B. Voas to Mercury astronauts, "Suggested Activities for Orbital Flights," Sept. 18, 1961.
7 Interview, Jocelyn R. Gill, Houston, Oct. 11, 1965.
8 NASA, "Summary Minutes: Astronomy Subcommittee of the NASA Space Sciences Steering Committee (Meeting No. 8)," Dec. 5, 1961, and App. I, "Suggested Astronomical Tasks for the Mercury Astronauts," Nov. 3, 1961.
9 Memo, Voas to Williams, "Astronauts' Preparation for Orbital Flight," Sept. 25, 1961; "Project Mercury Astronaut Preparation for Orbital Flight," NASA Project Mercury working paper No. 206, Oct. 13, 1961.
11 Ibid. In the event of slow pitch upthrust, the astronaut was to assume manual control of pitch. In retrosequence failure, he was to use manual override. If the main electric power supply failed, he was to select a standby source and determine whether reentry was possible at the end of the first orbit or whether earlier entry was necessary.
12 "Project Mercury Astronaut Preparation and Activities Manual for Mercury-Atlas Mission 6 (MA-6, Spacecraft 13)," NASA Project Mercury working paper No. 215, Dec. 1, 1961.
13 NASA, "Summary Minutes: Ad Hoc Committee on Astronomical Tasks for the Mercury Astronauts," Jan. 11, 1962.
14 NASA, "Summary Minutes: Ad Hoc Committee on Astronomical Tasks for the Mercury Astronaut (Meeting No. 2)," Dec. 20, 1961.
15 "Astronaut Preparation and Activities Manual for MA-6."
16 "Project Mercury Status Report No. 13 for Period Ending Jan. 31, 1962," STG, 15, 23; "Postlaunch Memorandum Report for Mercury-Atlas No. 6 (MA-6), Part I, Mission Analysis," March 5, 1962; memo, Richard M. Dunham to Voas, "Personnel Survival Equipment Exercise for 2/7/62," Feb. 8, 1962. The life vest was fabricated as a solution for Grissom's swimming problem at the end of the MR-4 mission. The inflated vest had a bulk of less than 20 cubic inches and weighed less than a pound. Results of the First United States Manned Orbital Space Flight, February 20, 1962 (Washington, 1962), 39. Also John H. Glenn, Jr., "I'll Have to Hit a Keyhole in the Sky," Life, LI (Dec. 8, 1961).
17 "Status Report No. 13," 24; James M. Grimwood, Project Mercury: A Chronology, NASA SP-4001 (Washington, 1963), 157; memo, Eugene F. Kranz to Christopher C. Kraft, Jr., "Report on Test 5460 (MA-6)," Feb. 20, 1962. The flotation collar mentioned in the swimmer-training program resulted partly from the loss of Grissom‘s spacecraft. It was also the product of two years' work, and credit for its design must go to Donald E. Stullken of the Pensacola Naval Air Station. Early in the Mercury program the engineers realized that their hope of adapting a 20-man life raft to keep a spacecraft afloat was not feasible. The "Stullken collar" passed its final test on Jan. 3, 1962. At that time 50 collars had been made at Pensacola and delivered to the recovery forces. In an earlier test, off Wallops Island, one of the collars had kept the MR-2 capsule afloat for 70 hours in waves up to 7 feet high. The collar was made of five-ply life-raft fabric, was attached to the spacecraft by cables around the impact skirt, and was inflated after attachment. Stullken later became an employee of the Manned Spacecraft Center. Space News Roundup, MSC, I (Jan. 10, 1962), 23.
18 "Project Mercury Mission Directive for Mercury-Atlas Mission 6 (MA-6, Spacecraft 13)," NASA Project Mercury working paper No. 216, Dec. 15, 1961; "Project Mercury, Mercury-Atlas No. 6 Recovery Requirements," Dec. 2, 1961. The latter document said that reentry (.05 g) would start about 60 miles west of Florida's Atlantic coast. Recovery forces were told that as a safety measure the ground track was set to continue 1,000 miles beyond the third orbit landing area and that the explosive egress hatch had been modified to keep the cover from traveling more than two feet. Several ships had their cranes or davits fitted with a "shepherd's crook," consisting of a 16-foot aluminum pole with a hardened stainless-steel hook at the cable end which was capable of lifting 10,000 pounds. ("Technical Information Summary for Mercury-Atlas Mission 6 (MA-6, Spacecraft 13)," NASA/MSC, Dec. 19, 1961; "Detailed Test Objectives, NASA Mission No. MA-6, Project Mercury, Contract No. AF 04(647)-930," Aerospace Corp., Nov. 10, 1961.) A planning document for the MA-4 mission had indicated that the Atlas hold-down time would be three seconds, to assure that combustion would smooth out; thereafter, beginning with MA-5, the time would be reduced to two seconds. For MA-6 the hold-down time still was listed for three seconds duration.