Mercury-Atlas 4 (MA-4) launched from Launch Complex 14 at Cape Canaveral on September 13, 1961, using Atlas 88-D and Mercury spacecraft No. 8A. Although the spacecraft was uncrewed, it carried a mechanical crewman simulator, essentially an instrumented artificial astronaut designed to reproduce some of the environmental demands of a human occupant.
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| A MA-4 launch cover from "SpaceCraft", postmarked at Patrick Air Force Base with a machine cancel on September 13, 1961. |
The mission had become especially important after the failure of MA-3 in April. Interestingly, the MA-4 spacecraft was actually the refurbished Mercury capsule from the failed MA-3 mission. MA-3 had demonstrated that the capsule's escape system could save it after a launch-vehicle failure; MA-4 now had to demonstrate that the complete Mercury-Atlas combination could actually reach orbit and return safely.
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| Photo: A Mercury capsule is lifted to the top of Gantry 14 at Cape Canaveral to be positioned on an Atlas D missile. |
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| A MA-4 launch cover from "Swanson" featuring a rubber-stamped cachet, postmarked at Patrick Air Force Base with a machine cancel on September 13, 1961. |
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| Photo: The mechanical crewman simulator set up inside the Mercury capsule. |
MA-4 completed one orbit of Earth, reaching an apogee of about 123 nautical miles and a perigee of about 86 nautical miles. The spacecraft remained in flight for approximately 1 hour 49 minutes and traveled more than 26,000 miles. One of the more charming aspects of this mission is the mechanical crewman aboard the capsule. It wasn't simply a dummy sitting in an astronaut's couch. The simulator was designed to reproduce certain human-related demands on the spacecraft's systems — it consumed oxygen from the environmental-control system, produced carbon dioxide, simulated minor oxygen leakage, and provided other data that engineers could use to evaluate the spacecraft's ability to support an astronaut. MA-4 also carried special vibration and noise instrumentation, allowing engineers to assess the environment that an eventual astronaut would experience during launch and flight.
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| Photo: An automatic camera on board the unmanned Mercury spacecraft captured a section of the west coast of Africa during its orbit on Wednesday. The photo, released by NASA, was taken as the capsule traveled at 17,519 miles per hour, 110 miles above the Earth. |
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| A MA-4 launch cover from "Velvatone", postmarked at Port Canaveral with a hand cancel on September 13, 1961. |
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| Photo: A diagram illustrating the launch and recovery process of the MA-4 capsule. |
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| Photo: Crewmen from USS Stephen Decatur recovering the MA-4 capsule. |
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| A MA-4 Crew Cover (Type 1) from the USS Decatur, postmarked aboard USS Decatur with a hand cancel on September 13, 1961, signed by Lt J. A. Felt, the Operations Officer. |
The mission was not completely flawless. NASA recorded a small oxygen-system leak, a temporary loss of voice contact over Australia, and an inverter failure in the environmental-control system. Nevertheless, these problems did not prevent the spacecraft from completing its mission.
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| Photo: The recovered MA-4 capsule was loaded onto an airplane for transport back to the United States. MA-4 capsule getting inspected after returned to Cape Canaveral on September 14, 1961. |
(Reference from
Mercury-Atlas 4)
