An hour after the Agena failure of 25 October 1965, Mission Director William Schneider had left Houston for Florida, where Colonel John B. Hudson, SSD Deputy Commander for Launch Vehicles, had called a meeting of a subpanel of the Agena Flight Safety Review Board for the 26th.* The subpanel members had learned enough from telemetry data to list the tasks to be done: find out why the Agena had failed and what the fixes would entail for design, performance, and schedule; decide if it would be possible to use GATV 5001 and how long it would take to get it ready for launch; and begin cutting red tape that might slow the work.4
 Lawrence A. Smith, Gemini Manager for Lockheed, had already sent the taped record of telemetry signals to the plant in Sunnyvale, California, where W.R. Abbott took charge of the failure-search team. Most likely causes of the disaster were a "hard-start" backfire or an electrical short; Abbott's group soon narrowed its search to the engine as the more probable source of trouble. After reporting to Major General Ben Funk's full Agena Flight Safety Review Board, Hudson took his subpanel to Sunnyvale on 1 November; they agreed with Abbott's analysis that a hard start (similar to an automobile engine backfire) had been the cause and that it had resulted from fuel being injected into the firing chamber before oxidizer.5
The problem was rooted in NASA's original specification for a Gemini target vehicle able to start and stop its main engine five times during a mission, in contrast to the Standard Agena's two-start engine. This 150 percent increase in demands on the engine at once raised the problem of fuel and oxidizer economy. In the two-start engine, the oxidizer began flowing first, while a pressure switch restricted fuel flow until a given amount of oxidizer had reached the firing chamber. This was known to enhance the engine's starting characteristics, but it was also wasteful. Oxidizer leaked through before engine firing, and some continued to flow after shutdown; the oxidizer would be gone long before the fuel ran out. So Lockheed accepted a proposal by the engine subcontractor, Bell Aerosystems Company, to remove the pressure switch and thus allow fuel to enter the chamber first.6
Abbott concluded that in space the presence of fuel in the thrust chamber (perhaps in considerable quantity) had caused the engine to backfire when the oxidizer reached the chamber, causing an explosion. When Funk's review board met in Los Angeles on 3 November to make tentative plans for an engine requalification program, Abbott presented his findings, which were discussed the next day.7
But Abbott's and Hudson's groups were not the only ones working on the problem. At NASA Headquarters, Associate Administrator Robert Seamans told George Mueller to form a NASA review board to look into all aspects of the failure, both technical and managerial. Mueller appointed MSC Director Robert Gilruth co-chairman of a Gemini Agena Target Vehicle Review Board and asked Air Force Major General Osmond Ritland to serve with Gilruth.** 8
And down at Cape Kennedy, Lockheed's Wulfgang C. Noeggerath was working with MSC engineer Horace E. Whitacre to pinpoint the cause of the failure. Unsure that the two of them could explore the matter in the depth needed, Whitacre suggested that Lockheed sponsor  a symposium of rocket experts from around the nation. Noeggerath convinced his superiors that it was a good idea.9
The two-day symposium began on 12 November, with 19 scientists and engineers in attendance*** 10 Noeggerath and Whitacre told the visiting experts that the most likely cause of the Agena explosion had been a premature engine shutdown. Engine firing had produced severe oscillations and mechanical damage. Temperature decreases had indicated fuel spillage. When electrical circuitry failed, the engine stopped, but a valve that controlled tank pressure as fuel was being used remained open. As fuel stopped flowing, pressure built up in the tanks, which ruptured and destroyed the vehicle - a planned flight safety precaution. Whitacre and Noegerrath also reported that the engine had not been tested at simulated altitudes higher than 34,000 meters, since no one believed that the environment above that level made any difference for engine firings.
Although Abbott's backfire theory accounted for the oscillations that had triggered the explosion, not everyone agreed that a single cause was enough to explain what happened. But the symposium could come up with nothing better. On 15 November, it recommended to SSD that engines should be modified so oxidizer entered the chamber first and should be tested at simulated altitudes closer to where Agena would be working - above 76,000 meters.11
Funk now formed a "super tiger" team of three senior engineers**** to review everything that had been found about the explosion and to suggest some answers to the NASA review board. The three agreed with oxidizer starting and with firings at simulated altitudes above 76,000 meters. They also wanted Bell Aerosystems to conduct ground ignition tests for data on engine-firing characteristics. The super tigers presented these recommendations at a meeting in Houston on 20 November,# then to the Gilruth-Ritland review board, which approved them. Lockheed announced the formation of a Project Surefire Engine  Development Task force to carry out the program. This did not end the analysis of the trouble. Reports and recommendations from other NASA centers committed to come to Gilruth until 9 March 1966, one week before the Gemini VIII flight.12
* Present at the meeting were Schneider, Jerome Hammack, Alfred Gardner, Scott Simpkinson (GPO Manager of Test Operations), John A. Edwards (NASA Director of Gemini Flight Operations), Merritt Preston (KSC Director of Launch Operations), Ernst R. Letsch (Gemini Launch Systems Directorate, Aerospace Corporation), and Lieutenant Colonel L.E. Allen (Commander, SLV-3 Division, 6555th Aerospace Test Wing).
** Board members were Seymour Himmel (Lewis), George Dekto (Marshall), Colonel William C. Nielsen (SSD), Colonel Quenten A. Riepe (6595th Aerospace Test Wing), Morton Goldman (Aerospace), John Bailey (MSC), and Robert H. Gray (KSC).
*** Symposium attendees: S. M. King and D. D. Thomas (Aerospace), E. G. Haberman (Air Force Rocket Propulsion Laboratory), Charles E. Feiler (Lewis), Henry O. Pohl and Whitacre (MSC), D. D. Evans and J. H. Rupe (Jet Propulsion Laboratory), F. D. Sullivan and D.M. Wyckoff (Aerojet-General Corporation), T. F. Reinhardt and Craig M. Schmidt (Bell Aerosystems), Jack R. Hahn and R. S. Levine (Rocketdyne Division, North American Aviation, Inc.) J. J. Kapl (The Marquardt Corporation), R. F. Sawyer (Princeton University), and J. L. Grubbs, Jerome Salzman, and Noeggerath (LMSC).
**** The super tiger team consisted of Bernard A. Hohman (Group Director, Gemini Launch Systems Directorate, Aerospace), Colonel John Hudson, and L. Eugene Root president of Lockheed Missiles & Space Company).
# Mathews presided at the meeting, which included Gardner, Smith, Letsch, Schneider, Bailey, Hammack, Colonel Jean A. Jack (Deputy Chief of Staff, Test, Arnold), W. von Lunkhuysen and Frederick a. Boorady (Bell Aerosystems), L. T. Barnes (ARO, Inc., Arnold contractor), George Low (Deputy Director, MSC), Joseph F. Shea ( Apollo Program Manager, MSC), Willis Mitchell (Vehicle and Missions Manager, GPO), and Richard K. McSheehy (MSC Special Assistant for Apollo Support, Propulsion Power Division).
2 Meyer, notes on GPO staff meeting, 31 Aug. 1965, p. 4; TWXs, Mathews to SSD, Attn: Col. Alfred J. Gardner, GV-12216, 28 Sept., and GV-12227, 24 Oct. 1965.
3 Horace E. Whitacre, "A Development History Summary of the Agena Target Vehicle Primary Propulsion System," n.d., p. 9; F[rederick] A. Boorady and D. A. Douglass, "Agena Gemini Rocket Engine Hypergolic Ignition - Hard Start Problem Solved during Project Surefire," n.d., p. 9.
4 William C. Schneider, interview, Washington, 23 Jan. 1967; memo, Gardner to MSC Historical Office, "Comments on draft of Gemini narrative history," 14 Oct. 1969; Whitacre, interview, Houston, 3 June 1969.
5 Gardner memo, 14 Oct. 1969; A. J. Steele, "Summary of Alternate Failure Hypotheses for GATV 5002," LMSC-A 778486, 5 Jan.1966; Harold W. Nolan, interview, Sunnyvale, Calif., 1 July 1966; Jerome B. Hammack, interview, Houston, 19 Aug. 1966; "GATV Progress Report, November 1965," LMSC-A605200-15, 20 Dec. 1965, pp. 2-1, -2; Project Gemini Quarterly Status Report No. 15, for period ending 30 November 1965, p. 21.
6 Whitacre, "A Development History," pp. 1, 3; "Symposium on Hypergolic Rocket Ignition at Altitude," LMSC-A 776842, 1 Dec. 1965, p.3-6; Boorady and Douglass, "Agena Hypergolic Ignition," pp. 3, 4; Whitacre and Nolan interviews; Frederick A. Boorady and Jerome Salzman, "Modification of the Agena Rocket Engine for Gemini Target Vehicle Multiple Restart Capability," September 1965, pp. 2, 4, 15-17; Richard M. Spath, interview, Sunnyvale, Calif., 1 July 1966.
7 Hammack interview; Quarterly Status Report No. 15, p. 21.
8 NASA Management Instruction No. 4-1-7, "Mission Failure Investigation Policy and Procedures," 24 March 1964; memo, Robert C. Seamans, Jr., to Assoc. Adm., Manned Space Flight, "Gemini VI Mission Failure Investigation," 27 Oct. 1965; NASA News Release No. 65-342, "NASA Names Panel to Review Agena Failure," 27 Oct.1965; letter, Mueller to Robert R. Gilruth, 29 Oct. 1965, with enclosure, Mueller, "Gemini Agena Target Vehicle (GATV) Review Board," 29 Oct. 1965; memo, Eberhard F. M. Rees to dist., "Gemini/Agena Target Vehicle Program investigation," 8 Nov. 1965.
9 Nolan and Hammack interviews; "Symposium on Hypergolic Rocket Ignition," p. ii.
10 "Symposium on Hypergolic Rocket Ignition," p. A-1.
11 Ibid., pp. 3-1, -2, -6, -10; Boorady and Douglass, "Agena Hypergolic Ignition," p. 5; Whitacre, "A Development History," pp. 9, 10; Wulfgang C. Noeggerath, "Symposium on Hypergolic Rocket Engine Ignition at Altitude, Lockheed Missiles & Space Company, 12 to 13 November 1965," n.d., p. 1; memo, W. R. Abbott to Jack L. Shoenhair, "Comments on draft of chapter . . . : Trials of Agena and Gemini VIII, " 8 Oct. 1969; letter, Charles E. Feiler to Noeggerath, 18 Nov. 1965; draft memo, [Whitacre] for record, "Scientific meeting at LMSC to discuss possible cause of 8247 hard start," n.d.; memo, [Whitacre] for record, "Specific recommendations for activities relating to reconfiguration of the 8247 engine and verification testing," 19 Nov. 1965.
12 "GATV Progress Report, November 1965." pp. 2-3, -4; [Whitacre] memo, 19 Nov. 1965; [Whitacre] draft memo, n.d.; "Symposium on Hypergolic Rocket Ignition," pp. 5-4, -5; Gardner memo, 14 Oct. 1969; letter, Seymour C. Himmel to MSC, Attn: Mathews, "Investigation of GATV failure by LeRC Agena Project," 7 Dec. 1965, with enclosure, memo, Channing C. Conger and Robert E. Alexovich for record, "Analysis of GATV Flight Data," 30 Nov. 1965; letter, George J. Detko to MSC, Attn: Gilruth, "Investigation of the Gemini 6-Agena Target Vehicle (66-ATV) failure by MSFC," 23 Dec.1965, with enclosure, "G6-ATV Failure Investigation by MSFC," 23 Dec.1965; letter, Robert H. Gray to Dir., MSC, "Analysis of GATV-1 Flight Data," 30 Dec.1965, with enclosure, "GATV-1 Flight Analysis," n.d.; TWX, Mathews to SSD, Attn: Gardner, GV-12344, 27 Jan.1966; letter, Himmel to MSC, Attn: Mathews, "GATV Failure Analysis," 14 Feb. 1966; letter, Detko to MSC, Attn: Gilruth, "Investigation of the Gemini 6-Agena Target Vehicle (66-ATV) failure by MSFC," R-AS-VG-86-66, 9 March 1966; "A Chronology of the Arnold Engineering Development Center," AFSC Historical Publications Series 62-101 [probably 1968], p. 81.