Benjamine J. Garland, one of Faget's fellow authors of the seminal 1958 NACA paper for Mercury, prepared a special report for Gilruth on the probability of damage to the capsule by micrometeoroids during an orbital flight. Garland advised that the danger to the capsule during an orbital flight from sporadic meteoroid activity was very small. He calculated probabilities of hits during a major meteoroid shower and found the danger was "still small but . . .  an order of magnitude greater than the danger due to the sporadic background. Since the periods of activity of the major showers are known, it is possible to avoid operations during these periods and would be advisable to do so."55
Normal sequence of events for Mercury-Redstone flight.
Because qualification and reliability tests on the retrograde and posigrade rocket systems proved disappointing in their later results, Gilruth's team called for help from the Ames and Lewis Research Centers. Robert R. Nunemaker led a group at Lewis, monitored by John B. Lee of STG, who found some serious difficulties with retrorocket alignment and escape tower separation. Among other things, they found that some igniters were faulty and that the jettisoning of the escape tower under certain conditions might permit a smashing recontact.
But the most serious problem with capsule systems at this time was the outside chance that one or more of the three retrograde braking rockets might fail. There was considerable margin for error in the design of the retropackage, but there was no emergency braking system. STG's mission analysis group under John P. Mayer had thoroughly investigated an inflatable balloon for this purpose, and Gilruth himself proposed an emergency brake-that would have looked like a Chinese dragon kite trailing in the wake of the orbiting capsule. This auxiliary drag device to back up the retrosystem and to bring the capsule down sooner than in the 24 hours theoretically required for a normal decay of Mercury's orbit was independently appraised by Howard K. Larson and others at Ames. Meanwhile John Glenn and the other astronauts asked STG's mission analysts to study the effectiveness of a "fish-tailing" maneuver as a backup reentry mode of last resort. Both ideas were reported feasible, but the former was not pursued past the end of the year, when the reliability of the retrorockets and pyrotechnics began to rise appreciably.56
Among the number of unsolved problems regarding man-machine integration in late 1960, the complex final phase of the mission profile aroused much concern. If an astronaut could survive launch, insertion, orbiting, reentry, and the free-fall, nothing must jeopardize his chances to survive impact, exit from the capsule, and recovery. But as the capsule developed into flight hardware, the differences between its theoretical design and its measurable performance required constant restudy, redesign, and in some cases redevelopment.57 While studying the Mercury capsule's stability in water, for example, Peter J. Armitage and E. N. Harrin of STG found that the deletion of the flotation bags and the addition of the impact skirts had seriously compromised the floating trim if not the seaworthiness of the capsule.58
After summarizing recent investigations by both McDonnell and STG engineers, Armitage and Harrin pointed out a number of unknowns and recommended close scrutiny of any changes to capsule center-of-gravity positions to keep the capsule within acceptable stability limits. While the model-makers at Langley were fabricating and testing 24 new impact skirts, Astronauts Shepard, Grissom, and Schirra practiced getting out of the capsule; it now listed at severe angles and sometimes even capsized.59
 During September 1960 all the Mercury astronauts began to train more pointedly for the Mercury-Redstone mission. Early in October they gathered their personalized couches, pressure suits, and accessories for centrifuge runs at the Navy's Aviation Medical Acceleration Laboratory at Johnsville, Pennsylvania.Fitted with a production handcontroller assembly and environmental control system, the gondola of the centrifuge whirled each man as if he were experiencing the calculated acceleration profile of the MR-3 flight. At Johnsville the astronauts gained experience in attitude and rate control, monitored the normal sequencing functions, and learned to cope with emergency conditions like overacceleration and decompression. Alan Shepard, for instance, took 10 training "flights" during the October session.60
On September 8, 1960, Silverstein called to Washington NASA's and McDonnell's chief engineers at work on Mercury to discuss plans for compressing the Mercury-Redstone schedule by expediting the capsule systems tests and checkout procedures for capsules Nos. 5 and 7, to be flown on MR-2 and MR-3, respectively. Once again Silverstein asked that McDonnell assign independent systems engineers to verify all hardware installations. Especially they were to improve the quality of capsule No. 7 before the formal systems testing period. This was done during October and November; for 43 days No. 7 underwent performance trials of all its systems except its reaction controls, automatic stabilization controls, and instrumentation and communications gear. McDonnell, Navy, and STG liaison inspectors tried hard to meet Silverstein's Cape delivery deadline of November 15, but two major discrepancies could not be allowed to pass. One problem had been perennial: overheating DC/AC inverters. Investigations disclosed that as long as the ambient temperature was kept below 165 degrees F they functioned properly. McDonnell attempted to cure this overheating problem by replacing the honeycombed inverter sockets with aluminum shelves that doubled as heat sinks.61
The second problem was new: tiny cracks were noticed in the outer titanium skin of the capsule pressure vessels. Samples of fractured material were sent to the Battelle Memorial Institute, an endowed foundation for applied scientific research, at Columbus, Ohio. Battelle found that the heated zones adjacent to the seam welds contained an excessive amount of precipitated hydrides, compounds of hydrogen and other elements. These impurities lowered the ductility of the skin of the pressure vessel, increased leakage rates, and increased the danger of structural collapse upon impact. But since capsule No. 7 had the best record of all in the capsule systems tests, it passed muster to begin its final factory shakedown tests on November 21, 1960. For later capsules, welding methods, vibration testing, and microscopic inspections were improved, but the long-standing "skin-cracking" problem required that the search be renewed for ways to eliminate hydride formations near the beads of fusion welds.62
On December 1, 1960, Jerome B. Hammack, the MR-3 project engineer for STG, and his assistant, James T. Rose, certified that capsule No. 7 was ready for  its manned mission, though some 20 days behind schedule. "The writers would like to stress that the majority of time spent during this period was spent on correction and rework rather than the actual CST and that every effort should be made in the future to achieve manufacturing perfection prior to the capsule entering CST."63
Meanwhile capsule No. 2, being readied for the first Mercury-Redstone flight, was delivered to the Cape at the beginning of August. This flight, MR-1, was then scheduled for launching early in October. Both McDonnell and STG preflight checkout crews in Hangar S worked around the clock to make ready the maze of systems in their capsule. Christopher Kraft talked over Mercury command functions with the Redstone launch team under Debus and with Air Force range safety officer Lieutenant Colonel R. D. Stephens early in September. They then decided to fly the MR-1 mission with the automatic abort system in the open-loop mode to lessen any possibility of a nuisance abort on this qualification flight.
On a trial basis, a smaller Flight Safety Review Board for the spacecraft (tailored after the Atlas boards by the same name), chaired by Walter Williams and consisting of Astronaut Cooper, F. J. Bailey, Jr., Kenneth S. Kleinknecht, and William M. Bland, Jr., was established at the Cape to pass final judgment during the week before the countdown on the readiness of the mission. During the first week in October, final preparations were made to launch MR-1, and on the morning of October 9, 1960, an unbroken countdown proceeded to within 22 minutes of launchtime before the shot was scrubbed because of a malfunction in the capsule reaction control system.64
 By the first of November both LJ-5 and MR-1 appeared ready for launching on November 7, 1960. But both launches had to be postponed again (the day before the election) because of inclement weather at Wallops Island and because at the Cape a serious leak developed in the helium tank of capsule No. 2. Without helium to pressurize the hydrogen peroxide thrusters, the payload after posigrade release might not reorient itself properly for reentry. So heavy had the workload at the Cape become that Williams decreed a maximum of 12 hours' work for any one person in any one day.65
The possible political significance of these launches now was seen by the press and by the legislative staffs on Capitol Hill and at NASA Headquarters. George Low's routine report for James P. Gleason, Assistant Administrator for Congressional Relations, carefully explained the technical reasons first for delay and then for speedup on the launch schedules. Regarding Little Joe 5, Gleason informed the staff director of the Senate space committee that NASA Headquarters was keeping close tabs on MR-1 scheduling information because of the need to coordinate interagency activity, but that Little Joe missions "requiring no major coordination with non-NASA organizations" had always been handled on a less formal basis:
You will notice that the launch target date was delayed from October 8, 1960, to November 11, 1960, at the time when it became apparent that the capsule delivery would be delayed until about August 1, 1960. Between August 17 and August 31, a large number of checkout difficulties was encountered in the noise and vibration test program. It was then expected that the capsule would not arrive at Wallops until October 5, and hence the launch date was moved to November 16.Less out of sensitivity to the political winds than because the facts seemed to warrant it, the apolitical civil servants in the Task Group sent an encouraging status report on Project Mercury to their administrative superiors in Washington at the end of October 1960. There were a couple of negative items: the cause of the MA-1 failure was still unknown, and the checkout time at the Cape for capsule No. 2 for MR-1 was stretching interminably, it seemed. On the plus side, three capsules (Nos. 2, 5, and 6 for MR-1, MR-2, and MA-2, respectively) were on hand, and two more (Nos. 7 and 8 for MR- 3 and MA-3) were expected  at the Cape momentarily. The Mercury Control Center, a command-post building trisecting the area between the two blockhouses beside the launching pads and the industrial hangars, was open and almost ready for operations. Four preflight checkout trailers supplied by McDonnell were already in full use. Procedures Trainer No. 2 was being wired to its computer banks, and the ground-test qualification program seemed almost complete.
In the early part of September, the rate of progress at Langley picked up, and the capsule was actually shipped to Wallops on September 27th. Nevertheless, the projected launch date was not moved to an earlier date, since simultaneous experience with MR-1 at Cape Canaveral gave every indication that the prelaunch checkout would take longer than planned.
In actual practice, the Wallops Island checkout ran very smoothly. Accordingly, a new target date of November 7 was established late in October. Barring difficulties during the final checkout period, and assuming that the weather will be clear and calm, the launching will take place on that date.
. . . I feel that our project engineers have done an excellent job at predicting these dates; it is very seldom that actual dates on as complex a research and development program as this one have come out so close to the predicted dates as these have.66
The tracking and communications network was essentially finished, except for the stations at Kano, Nigeria, and on Zanzibar. The Atlas ASIS was looking good, and with luck the first truly complete Mercury-Atlas configuration, MA-2, still might possibly be flown during the quarter. Cost accounting for the program was still a black art, but according to STG's own estimates the summary of funds required to accomplish the Mercury mission as defined in October 1960 approached $110 million:67
|Mercury capsules (20)||$48,720,000|
|Mercury network (incl. operations)||$18,953,000|
|Mercury recovery (incl. operations)||$10,573,000|
|Biological and human engineering||$1,922,000|
55 Memo, Benjamine J. Garland to Project Director, "Possible Meteoroid Damage to Mercury," with enclosure, June 2, 1960, 3.
56 Letter, Smith J. DeFrance to Alan B. Kehlet, "Information Requested by STG on Pressure Transducers and an Auxiliary Drag Device for Mercury," with enclosures, Sept. 16, 1960; memo, Caldwell C. Johnson to Faget, "Auxiliary Drag Device - Mercury," Nov. 2, 1960; John P. Mayer, comments, Sept. 8, 1965. Back in 1957 Avco had proposed a metallic drag chute shuttlecock configuration for the same purpose for the Air Force Man-in-Space studies. See also "Summary of Several Short Studies Pertaining to the Retro-Rocket System Capabilities for the Mercury Mission," NASA Project Mercury working paper No. 160, Nov. 9, 1960.
57 The reinstatement of development work on the pneumatic impact bag followed after Gerard J. Pesman learned the details of more experiments on human impact at Wright-Patterson late in 1960. For a resume of this work see J. W. Brinkley, R. A. Headley, and K. K. Kaiser, "Abrupt Acceleration of Human Subjects in the Semi-Supine Position," paper, Symposium on Bio-Mechanics of Body Restraint and Head Protection, Naval Air Materiels Center, Philadelphia, Pa., June 14-15, 1961.
58 Memo, Peter J. Armitage and E. N. Harrin to Chief, Operations Div., "Mercury Capsule Water Stability," Oct. 31, 1960.
59 Memo, Harrin to Chief, Operations Div., "Static Water Stability Tests of Personal Egress Capsule," Jan. 10, 1961.
60 "Project Mercury Status Report No. 8 for Period Ending October 31, 1960," STG, 17-18; "Astronaut Preparation and Activities Manual for Mercury-Redstone No. 3," NASA Project Mercury working paper No. 174, Feb. 6, 1961.
61 Memo, Yardley and G. M. Preston to Silverstein, et al., "Summary of Conclusions Reached Regarding the CST Plans and Cape Checkout Plans for Capsules 5 (MR-2) and 7 (MR-3)," Sept. 9, 1960, 3. For MAC's home factory response to the field workers' difficulties with electrical, piping, sequencing, inspection, and cleanliness problems, see draft memo by H. Earle Moore and Walter F. Burke, "Quality Assurance - Project Mercury," Sept. 12, 1960.
62 Memo, Richard Sachen and James T. Rose to W. H. Gray, "General Summary of Capsule Systems Tests on Capsule No. 7," Dec. 1, 1960, with enclosures. Convair/Astronautics had encountered the skin- cracking problem in 1955 during the Atlas development program. At that time no solution had been discovered.
63 Memo, Jerome B. Hammack and Rose to W. H. Gray, "General Summary of Capsule Systems Tests on Capsule No. 7," Dec. 1, 1960, 5, 6. This memo, with enclosures 1-17, gives a detailed engineering history of the problems encountered during the systems testing of the first manned Mercury capsule. Although STG inspectors found 189 electrical and mechanical discrepancies in their final acceptance test, MAC's own inspectors had listed some 370 such discrepancies before their final cleanup prior to delivery.
64 See Leutjen, "Ground Checkout and Launch Procedures," 3. Revised procedures for expediting checkout "squawk sheets" and discrepancy reports were issued shortly thereafter: see memo, Yardley and Preston to Hangar S Supervisors, "Cape Inspection Policy Clarification," Oct. 20, 1960.
65 Letter, Williams to Commanding Officer, Air Force Missile Test Center, attention Lt. Col. R. D. Stephens, Sept. 6, 1960; "T-605 Operation, MR Mission," STG, Sept. 8, 1960; "MR-1 Mission Rules," STG, Nov. 2, 1960; letter, Williams to Kurt H. Debus, "Flight Safety Review for MR Missions," Sept. 22, 1960, with enclosure, "Flight Safety Review Plan"; letter, Williams to Cdr. DesFlotFour, "NASA Personnel Assignment for MR-1 Test," Sept. 28, 1960, with enclosures; memos, Low to Administrator, "Tests of Mercury Redstone 1 and Little Joe 5," Nov. 2, 1960; and "LJ-5 and MR-1 launchings," Nov. 4, 1960; Williams, Management Memorandum, No. 13, "Working Hours, Launch Operations Branch," Oct. 5, 1960.
66 Letter, James P. Gleason to Kenneth E. BeLieu, Nov. 7, 1960. For one source of this concern, see Drew Pearson, "Space Shot Moved to Election Eve," Washington Post, Nov. 2, 1960.
67 "Project Mercury Status Report No. 8"; "Project Mercury Discussion," briefing charts, Oct. 31, 1960.