In the summer of 1965, MSC's Mission Planning and Analysis Division had started tailoring a plan for Gemini VIII, the first results of which were discussed on 26 and 27 August. Among the alternative modes of rendezvous being considered was a rendezvous sooner than the fourth revolution of the spacecraft - the "standard" rendezvous that had been scheduled for Gemini VI. Despite doubts that the flight control team could support any rendezvous earlier than that, the scheme called "M equals 2" (rendezvous in the second revolution) being studied by the mission planners was worth thinking about. Another subject was a proposed phantom rendezvous with an imaginary target, requiring a thrust from the Agena's main engine of at least 150 meters (500 feet) per second, to take place shortly after the first sleep period. The pilot would then exit the spacecraft for more than two hours of extravehicular activity - that is, floating freely around the world! After that, the spacecraft would undock and withdraw from the Agena, to return later for a second rendezvous. Finally, Gemini VIII's Agena would be left in orbit as a passive target for Gemini IX.
No sooner had the Gemini VIII plan been committed to paper than caution flags were raised. One issue was an old one that the earlier crews had fought - sleeping alternately.  Lockheed recommended that one astronaut remain awake whenever the spacecraft and Agena were docked. Mathews consulted with Whitacre, then denied the request on the ground that sleep at this time (after launch, rendezvous, and docking, and before EVA) was necessary for both men. Besides, Whitacre's analysis showed that the tracking network could cope with almost anything that might go wrong. Another question was time. Fuel cell development problems had imposed a limit of two days on rendezvous flights. Could so elaborate a plan be carried out in such a short time? Maybe the time could be expanded. Since the fuel cell's troubles seemed headed toward resolution, McDonnell was asked to see if later rendezvous missions could be extended to three days.37
Meetings continued throughout the fall of 1965, as spokesmen for NASA Headquarters, McDonnell, and MSC began to stress re-rendezvous, which they thought might be good training for Apollo. Discussions on firing the two Agena propulsion systems remained inconclusive, as did talk about flying for three days. When a McDonnell study indicated that the fuel cells could support a 72-hour flight, if all supplies were carefully husbanded, that question appeared to be settled.38 Firing the Agena main engine while docked with the spacecraft, however, was finally rejected for the same reason that it had been on Gemini IV - it was not yet deemed safe enough. That meant the phantom rendezvous was out.39
Toward the end of February 1966, with problems seemingly well in hand, a "final" version of the flight plan appeared. Like the Gemini VII plan, this was more an outline than a precise schedule of events. Crew and flight controllers had a range of options to deal flexibly with circumstances as they arose in the course of the mission.40
Operations planning was being paralleled by experiments planning. By November 1965, the Manned Space Flight Experiments Board at NASA Headquarters had approved eight tasks for Gemini VIII. Eventually, ten experiments were approved for the mission,* three of them requiring extravehicular activity. Of these, two were scientifically oriented - S-9, Nuclear Emulsion, to expose an experimental package to radioactivity in space (especially in the South Atlantic Anomaly), and S-10, Agena Micrometeorite Collection, to study the micrometeorite content of the upper atmosphere. In the third, proposed by the Department of Defense, Scott would use a power wrench for weightless work. He would go to the adapter area, pull out a box containing a torqueless motor-driven wrench, use the tool to take five nuts off a special plate, and then rebolt the plate to the box. This simple task - with and without knee tethers - would be compared with doing the same thing on the ground to show the differences in working  in one gravity and in weightlessness. Scott and George C. Franklin of the Flight Crew Support Division decided to augment this experiment by adapting a cheap standard socket wrench to fit the nuts and the pressurized glove. They believed that comparing the muscle-powered and the electrically-operated tools would say something useful about energy usage in space.41
Mission plans and flight schedules were inseparable, and Apollo again began to intrude. Apollo mission 201 was planned for February 1966; if there were any delays, it would slip into March. The problem was not with launch pads nor, in most cases, with people. A tracking ship, the Rose Knot Victor, was the source of conflict. For Apollo 201, a suborbital flight, the ship would be sailing the Atlantic Ocean. But its station for Gemini VIII was in the Pacific. Mueller ruled that the Gemini flight had priority; but Apollo 201 flew as scheduled on 26 February, giving the slow-moving Rose Knot time enough to keep its date with Gemini VIII.42
Flight Control also shifted for Gemini VIII. Christopher Kraft, who had directed flights for Mercury and all Gemini missions through VII/VI-A, had to leave Gemini to begin planning for lunar landing missions as Apollo neared operational status, although he expected to keep an eye out for Gemini lessons that might be of use to Apollo. Kraft's move left Gemini Mission Control short of experienced flight directors. His successor, John Hodge, who headed the Flight Control Division, divided flight direction into 12-hour shifts with Eugene Kranz, Chief of the Flight Control Operations Branch. Clifford E. Charlesworth, flight dynamics officer on past Gemini missions, began training as a flight director.** 43
In the two weeks before the scheduled launch, equipment problems remained a threat. The extravehicular gear, in particular, was still in trouble, with lines icing and valves cracking. Then, at Cape Kennedy, the spacecraft environmental control system began acting up; and, over on pad 14, Atlas fueling ran into some difficulties. These last two problems did cause a day's delay, from 15 to 16 March. Then everything was ready to go.44
* See Appendix D.
** See Appendix F for Mission Control Center position descriptions and responsibilities.
37 Memos, Mathews to dist., "Mission Planning," GV-66170, 2 Sept., and GV-66198, 25 Sept. 1965; memo, Mathews to dist., "Mission Planning for Agena," GV-66245, 21 Oct. 1965; memo, Whitacre to Mgr., GPO, "Astronaut sleeping during the Gemini-Agena docked-mode operation," GV-66359, 12 March 1966; TWX, Mathews to SSD, Attn: Gardner, "Crew Sleeping on Docked Agena," GV-12375, n.d. [probably 12 March 1966].
38 Mathews memos, GV-66170, GV-66198, GV-66245; memo, Mathews to dist., "Mission Planning for Gemini VI through XII," GV-66208, 1 Oct. 1965; memo, Mathews to Mgr., EXPO, "Mission duration," GP-62009, 21 Feb. 1966.
39 Memo, Mathews to dist., "Mission Planning Gemini VIII," GV-66252, 4 Nov. 1965.
40 Tommy W. Holloway, "Gemini VIII Flight Plan," Final, 24 Feb. 1966.
41 Memo, George C. Franklin to James M. Grimwood, "Power Tool Experiment (D-16), Gemini VIII," 11 July 1969; Franklin, telephone interview, 11 July 1969; "Abstract of Meeting on Experiments for Gemini VIII, October 8, 1965," 15 Nov. 1965; "Abstract of Meeting on Gemini Experiments Status Review, November 9 and 10, 1965," 23 Nov. 1965; TWX, Mathews to NASA, Attn: Day, "Gemini Experiment D-3," EX4/T3-65, 17 Dec. 1965; memo, Mathews to Chief, Gemini Spacecraft Procurement Sec., "Engineering Review of McDonnell Aircraft Corporation Report A492-16A, Cost and Delivery Proposal for Experiment D-16 (Minimum Reaction Power Tool), dated April 9, 1965," GP-61342, 2 June 1965; "D-16 Experiment Briefing," 10 March 1966; TWX, Mathews to NASA, Attn: Bay, "Gemini VIII Experiment S-9, Nuclear Emulsion," EX42/T14-66, 16 Feb. 1966; memo, Schneider to Willis B. Foster, "Use of Agena for Experiment Package," 21 June 1965; TWX, Mathews to SSD, Attn: Gardner, "Stability of Non-Powered Agena," GV-12186, 6 Sept. 1965; memo, Mathews to Mgr., EXPO, Attn: Norman G. Foster, "Incorporation of Experiment S-10 on Gemini Agena Target Vehicles," GV-66182, 17 Sept. 1965; Jocelyn R. Gill and Willis B. Foster, "Science Experiments Summary," in Gemini Summary Conference, pp. 301302, 303; Norman G. Foster and Olav Smistad, "Gemini Experiments Program Summary," ibid., p. 225; NASA Release No. 66-52, "Project: Gemini 8," press kit, 8 March 1966, pp. 29-30; "Gemini 8 Experiments Briefing at Cape Kennedy," 14 March 1966.
42 Note, Schneider to Mueller, 9 Feb. 1966, with enclosure, memo, Robert O. Aller to John A. Edwards, "RKV Support of AS 201 on Gemini VIII," 4 Feb. 1966; MSC News Release No. 66-13, 11 Feb. 1966; MSC News Release No. 66-16, 17 Feb. 1966; "Postlaunch Report for Mission AS-201 (Apollo Spacecraft 009)," MSG-A-R-66-4, 6 May 1966.
43 MSC Announcement No. 64-120, "Designation of Flight Directors," 31 Aug. 1964; memo, Low to Christopher C. Kraft, Jr., "MSC Apollo Operations Plan," 1 Feb. 1966; memo, Krait to dist., "MSC Apollo Operations Plan," 3 Feb, 1966, with enclosures, (1) Low letter, 1 Feb. 1966, and (2) "Manned Spacecraft Center Apollo Operations Plan," February 1966; William Hines, "Launch Now Slated Wednesday Morning," The Evening Star, Washington, 14 March 1966; letter, Low to James C. Elms, 25 March 1966; note, Schneider to Elms, "The Role of Mr. Kraft during Gemini VIII," 31 March 1966; William M. Bland, Jr., telephone interview, 1 Aug. 1969.
44 TWX, Mathews to SSD, Attn: Dineen and Gardner, GP-7479, 2 March 1966; TWX, Mathews to McDonnell, Attn: Burke, "Contract NAS 9-170, Gemini, Results of Spacecraft 8 Flight Readiness Review," GP-7482, 7 March 1966; memo, Mathews to dist., "Spacecraft 8 Extravehicular Equipment Flight Readiness Review," GP-62075, 9 March 1966; letter, Mathews to Burke, "Contract NAS 9-170, Gemini, results of Spacecraft 8 Extravehicular Equipment Flight Readiness Review," GP-62069, 9 March 1966; memo, Mathews to dist., "Gemini Spacecraft 8 Design Certification Review," GP-62077, 9 March 1966; Mathews memo, GA-60,161; transcript of telephone conversation, Mueller and Seamans, 14 March 1966, 9:45 a.m.; Howard Simons, "Capsule Leaks Delay 3-Day Gemini Flight," The Washington Post, 15 March 1966; Albert Sehlstedt, Jr., "Gemini 8 Delayed at Least a Day," The Sun, Baltimore, 15 March 1966.