Through the winter and spring of 1960, the big event toward which Mercury watchers looked with most anticipation was the launch of the first Atlas vehicle topped by a McDonnell capsule. Immediately after Big Joe, Gilruth had requested the Ballistic Missile Division to fly another Atlas along a Big Joe-type  trajectory to qualify the McDonnell capsule for launch and reentry from a circular orbit roughly 105 miles high. At the beginning of 1960, it still had looked as though this could be accomplished by the end of May. A semifinal Defense Department operations plan outlining the support tasks of a dozen different military commands was under intensive study during this period. Serious reappraisals of schedule requirements and alternatives were underway in many areas, most of which threatened to delay the start of the qualification flight. By the end of January it was obvious that the payload, McDonnell's capsule No. 6, for the first Mercury-Atlas launch (MA-1) could not be ready soon enough.54
The bottleneck was the production line. Back in October 1959, when a letter amendment to the prime contract for six additional Mercury capsules was being processed, McDonnell had estimated it could deliver capsule No. 1 by the end of November. To be sure, this would be a stripped model suitable only for an off-the-pad or beach-abort mission, but at that time it looked as if the firing date for this first qualification test could be set for the last day of 1959. It then seemed that capsule No. 2, allocated to the first Mercury-Redstone flight, also could be delivered before the end of the year and shot about March 20, 1960. The sixth capsule, farther down McDonnell's production line, originally was allotted to the first Mercury-Atlas flight. It was barely framed, but McDonnell had hoped to deliver it by the end of February for a tentative launch date in mid-May. While STG was immersed in the Little Joe program, however, the production managers at McDonnell became aware that actual final assembly of the first capsules and equipment would take far more time than anticipated. On November 3, 1959, Sherwood L. Butler, the procurement officer at Langley, had notified NASA Headquarters that capsules Nos. 1 and 2 each would be delayed a month; No. 6 might be expected by the end of February.55
What, precisely, was causing these delays? Logan T. MacMillan, Edward M. Flesh, Yardley, and Dubusker of McDonnell felt constrained to answer as the pressure for delivery increased - as did certain conditions that obviously needed to be corrected. Incorporating the smallest changes during the final assembly of the first six capsules required many hours of disassembly, reassembly, and rechecking. Only one or two men at most could work in the confined space of the pressure vessel's interior, and rising standards of quality control imposed by McDonnell, STG, and resident Navy inspectors required much reworking.
For example, on the first shift on January 6, 1960, J. E. Miller, the McDonnell inspector on the floor at the time, logged in his record book a local cause of delay:
Insp. discontinued all work on Cap. #1 this A.M. until the filthy condition of the capsule was cleaned up. A meeting of Prod. Supervision was called by Insp. & Engr., was asked to set [sic] in. Quality control was main subject & all agreed to extend more effort toward better quality control although Prod. did not think they could do much better than what was already being done.56The next week at a capsule coordination meeting in St. Louis, Purser and  MacMillan, Yardley and Faget persuaded Robert Gilruth to save MA-1 by swapping capsule No. 6 for capsule No. 4, which had been scheduled for a static firing on the Redstone. Number 4 should be tidied up as quickly as possible and shipped to Langley by the end of the month. Only a structural shell, this first delivered piece of production hardware did include the exterior shingles, heatshield, landing and recovery gear, missile adapter-ring, retropackage and straps, with dummy retros and live posigrades. STG undertook to install Big Joe-type instrumentation and sequencing for its rescheduled use on the first Mercury-Atlas flight. The plan was to return the capsule to McDonnell by April1 for final shingle fittings and adapter matings, then ship the completed capsule to the Cape by mid-April. At the same time it was decided to eliminate the flotation bags, which had proved to be too delicate to last long in the open ocean, from all capsules and to keep the configuration of capsules Nos. 5 and 7 unchanged in hope of making possible an earlier manned shot. Problems with the afterbody shingles and with the erosion of the window by the blast of the escape rocket were among a number left unsettled.57
As costs of solutions to these kinds of technological and training problems rose, NASA administrators appeared more frequently before Congressional committees and admitted their growing concern with manned space flight, as opposed to other space activities. T. Keith Glennan requested $23 million supplemental appropriation to the fiscal 1960 NASA budget of $500.6 million and justified $19 million of that extra sum on the basis of the urgent technological demands of Project Mercury. "It would be no exaggeration to say that the immediate focus of the U.S. space program is upon this project," stated Glennan.58
53 House Committee on Science and Astronautics, 86 Cong., 2 sess. (1960), Hearings, Review of the Space Program, testimony of George M. Low, Feb. 16, 1960, Part II, 761. See also Parts I and III for the overall presentation of a response to NASA's 10-year plan as discussed between Jan. 20 and Mar. 7, 1960. Cf. NAX Major Activities in the Programs of the National Aeronautics and Space Administration, October 1, 1959-March 31, 1960 [Third Semiannual Report to Congress], (Washington, 1960).
54 Letter, Gilruth to Comdr., Air Force Ballistic Missile Div., Oct. 12, 1959; "Project Mercury Quarterly Report No. 5 for Period Ending Jan. 31, 1960," STG, Jan. 31, 1960. See also Leighton I. Davis, Maj. Gen., USAF, Operations Plan 60-1: Department of Defense Support for Project Mercury, AFMTC, May 31, 1960; cf. "Overall Plan Department of Defense Support for Project Mercury Operations," AMR, Jan. 15, 1960.
55 Sherwood L. Butler, "Monthly Status Report - Project Mercury," Oct. 2, 1959; "Monthly Status Report - Project Mercury," Nov. 3, 1959.
56 J. E. Miller, "M-133 Elect. Coor. Tie-In Record," McDonnell Aircraft Corp., Jan. 6, 1960.
57 Frank G. Morgan, Jr., "Summary of Capsule Coordination Meetings," McDonnell Aircraft Corp., Jan. 11, 12, 1960; message, Paul E. Purser to Logan T. MacMillan, Jan. 25, 1960.
58 T. Keith Glennan, in House Committee On Appropriations, Special Subcommittee on Deficiencies, 86 Cong., 2 sess., Hearings, Feb. 1, 1960, Supplemental National Aeronautics and Space Administration Appropriations 1960, 2; cf. pp. 27 and 55.