The metamorphosis of Space Task Group into Manned Spacecraft Center, followed by its move from Virginia to Texas, flowed directly from this decision. STG had been created solely to manage Project Mercury; as a single-purpose task force, it was outmoded. Project Mercury now became only the first step on the path that was to lead Americans to the Moon before 1970.
As always, the lunar mission, in whatever form, held center stage. This was just as true in Headquarters as it was in the field.  Although Washington's chief planning concern was the voyage to the Moon, research and development in the field focused on specific problems raised by a lunar mission and the hardware needed to surmount them. STG, of course, had Project Mercury to worry about; but when it had time to look ahead, what it looked at was the Moon. Even before the President's decision for a lunar landing, STG engineers were hard at work on the spacecraft that would ultimately carry men there.
Once a deadline had been set, the question of rendezvous as part of the lunar mission took on a new guise. By holding out the prospect of using smaller and thus more quickly developed boosters, rendezvous offered a chance to reach the Moon sooner than did a direct approach. During the spring and summer of1961, discussion of this promise became widespread, and support for some form of rendezvous mission gathered strength. Even those who objected to chancing a lunar mission on an unproved technique were quite willing to admit that the technique needed to be developed, if only for its intrinsic value in future manned space flight. The growing conviction of the need for rendezvous, still further bolster by studies during the fall of 1961, provided the framework for what became Project Gemini.
By the time NASA decided that it needed a rendezvous development program, a freshly designed spacecraft was on the drawing boards. Mercury Mark II was not so much the product of planning as it was of a kind of technological imperative, the ceaseless and unquenchable desire of working engineers to perfect their machines. Some features of Mark II did, of course, spring from thinking about the objectives of a program to follow Mercury. But most of the changes in the new design suggested improvement in the abstract, rather than means to defined goals.
When Chamberlin talked about the design, it was in terms of accessibility and convenience, serviceability and simplification, "a better mechanical design" that was "more reliable, more workable, more practical." These are qualities that can never be absolutely realized, though they may be endlessly pursued. During the first half of 1961, Chamberlin, Blatz, and the others pursued them far beyond the intent of those who had set them the task. By July they had reached a point where they were willing to pause, although, as the later career of Gemini was to show, it was not a point at which they could long rest content.
When Silverstein endorsed the two-man Mark II, its designers faced a new task. The gap between a spacecraft design, whatever its merits, and a manned space flight project was a wide one. Early in 1961, NASA Headquarters had set up a formal procedure for planning and carrying out new projects.110 The first step for such large and complex projects at Mercury Mark II now promised to be was a preliminary project development plan. This was the task to which Chamberlin and his colleagues now turned.
110 NASA General Management Instruction 4-1-1, "Planning and Implementation of NASA Projects," 18 Jan. 1961. The significance of this document is discussed in Rosholt, Administrative History, pp. 228-29.