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| A Titan II N-14 Test Flight cover featuring a "Swanson" stamped cachet, postmarked at Cape Canaveral with a hand cancel on May 9, 1963. |
At this point, NASA and the U.S. Air Force were working closely to make the Titan II reliable enough to carry astronauts. A major concern was that a missile designed for military use was not automatically suitable for human spaceflight. NASA selected a modified Titan II as the launch vehicle for Project Gemini because it could provide the necessary performance for the two-person spacecraft. But it needed modifications to make it "man-rated".
