Mercury Atlas 12Spacecraft:S/C-10 Launch Vehicle: Atlas 77-D Scheduled Launch: 1 Sep 1963 Last Scheduled: 1 Jul 1962 |
Prime Crew |
Description: 4th Mercury Atlas manned orbital |
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W M Schirra 
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Backup Crew |
L G Cooper
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| On July 27, 1961 NASA met with McDonnell engineers to discuss modification of the Mercury spacecraft for Project MODM (Manned One-Day Mission). On October 25, 1961 NASA authorized McDonnell to proceed with the modification of four capsules and associated testing to support four manned MODM flights beginning in late 1962 and finishing by the end of 1963. From then until April 1962 NASA's Mercury program plan included four one-day flights in 1963: MA-10 through MA-13. But by October 1962 the decision was taken to cancel the last short-duration flight and move directly to the one-day flights. Therefore Carpenter's MA-9 flight switched capsules from the short duration SC19 to the long-duration SC20. By this time the decision had been quietly taken to limit the long-duration flights to only MA-9 and MA-10 (SC15B). There were several good reasons for this. The Mercury program was behind schedule and it would be difficult to fly more than two long-duration flights before the mandated completion of the program at the end of 1963. The flight roster of astronauts had been reduced to four, and of these only Grissom would not have made an orbital flight.
If SC12B had flown on a long-duration flight it would have been crewed by Grissom. Given the plans to follow SC15B for three days, it probably also would have undertaken a three to six day flight. Grissom was however already deeply involved with the follow-on project Gemini. It is likely that, as a test pilot, he considered commanding the first manned Gemini flight a far superior assignment to spending several days in the cramped, trouble-prone Mercury design that had already tried to kill him once. Cooper would have been the only available alternate pilot. The mission insignia shown above is post factum, and it is backed by no historical evidence. It assumes that Schirra would have followed Shepard's schema for naming his Mercury Atlas 10 mission. The Roman "II" had by then been incorporated into the Project Gemini insignia, signifying the program's roots as Mercury Mark II and the spacecraft's design to carry two men, as well as "II" being the zodiacal symbol for the Gemini constellation. By extension, the use of "II" on the long-duration missions closing out the Mercury program would have symbolized their function as a bridge to the Gemini program. References:
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