Encyclopedia Astronautica
1960.08.01 - Exhaustive review of Mercury-Atlas after dual Atlas failures.

Because of the failure of the Big Joe Atlas test flight and the Mercury-Atlas 1 (MA-1) flight to attain all its mission objectives, the overall Mercury-Atlas program underwent an exhaustive review.

In the Big Joe firing, velocity and range had been considerably below nominal values because the launch vehicle had failed to stage, and spacecraft separation had been delayed because of recontact. In the Mercury-Atlas 1 flight, launch vehicle performance was normal until about 57.6 seconds of flight, and the launch vehicle was destroyed at 59 seconds. Neither flight had sufficient instrumentation to pinpoint the exact cause of the failures; therefore, an extensive evaluation and test program was initiated. Meetings on these matters began immediately among the interested parties to coordinate findings and recommendations for solutions (for instance, Aug. 9 - summary evaluation of Mercury-Atlas 1 data at Los Angeles; Aug. 11 - evaluation summary meeting at the Atlantic Missile Range; Aug. 22 - Investigation Panel meeting at McDonnell; Sept. 9 - Investigation Panel meeting at Convair Astronautics; Sept. 14 - management meeting at Atlantic Missile Range; Sept. 26 - Instrumentation and Wind Tunnel Test Conference at Space Task Group; Oct. 3-8 - Vibration Tests at McDonnell; Oct. 3-8 - wind tunnel tests at the Arnold Engineering Development Center; and Nov. 16 - test program summary at Space Task Group. During the course of these meetings and tests, it was the considered opinion of Space Task Group and other interested parties that the trouble had developed in the spacecraft interface area. One of the tests involved stiffening the adapter rings, and later tests showed that this solution was quite satisfactory. Tests also showed there were some moderately high stresses in the launch vehicle near a welded joint just aft of the adapter, and this area was strengthened by adding a band stiffener, which proved to be satisfactory. It was also decided for the upcoming Mercury-Atlas 2 (MA-2) mission that additional instrumentation would be integrated with the spacecraft and launch vehicle in order to define loads on the vehicle in the interface area, to measure pressure on and in the adapter, and to measure any undue responses in this area. Still another decision was that the Atlas launch vehicle, commencing with Mercury-Atlas 3 (MA-3) would be a 'thick-skin' configuration. These findings and recommendations were presented to a NASA/Air Force ad hoc group on February 13 through 17, 1961, commonly known as the Rhode (NASA)-Worthman (Air Force) committee. The committee studied the Space Task Group proposals for the Atlas launch vehicle and adapter modifications and approved the test findings and the contemplated action.

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