Everything you never knew you wanted to know about the Mercury Project
MA-4
From RixWiki
Description of Mission
From SP-45 Mercury Project Summary
The Mercury-Atlas 4 (MA-4) vehicle was launched on September 13, 1961, from the Cape Canaveral launch site; it was a repeat of the MA-3 test and became the first Mercury spacecraft to be successfully inserted into orbit, returned, and recovered. Further objectives of this flight were to evaluate the Mercury network and recovery operations concerned with orbital flight. The space vehicle for this flight was made up of Mercury-Atlas launch vehicle 88-D, with the same modifications as the launch vehicle used on the MA-3 mission, and the spacecraft which was used on the MA-3 mission. The spacecraft had been refurbished and designated 8A for this mission. This was a very complete spacecraft which included a man-simulator onboard to provide a load on the environment control system during orbital flight. Other differences between this spacecraft and spacecraft flown on subsequent missions were:
- The landing bag was not installed
- The spacecraft had small viewing windows rather than the large overhead window used on later spacecraft
- The spacecraft entrance hatch did not have the explosive-opening feature
- The instrument panel had a slightly different arrangement.
The launch vehicle provided the desired orbital path with a perigee of 85.9 nautical miles and an apogee of 123.3 nautical miles. The planned retromaneuver over the coast of California resulted in a landing in the Atlantic Ocean approximately 160 nautical miles east of Bermuda in the primary landing area. The spacecraft was recovered in excellent condition 1 hour and 22 minutes after landing. The mission achieved the desired objectives, even though certain anomalies showed up in systems behavior during the mission. None of the anomalies had serious consequence. The anomalies and action taken are as follows:
- A spacecraft inverter failed during the powered phases of flight. The cause was determined to be a vibration-sensitive component and found to be preventable by more precise and exacting acceptance tests.
- Some anomalies in the spacecraft scanner signals were detected during the mission. Steps were taken to modify the system to make it less sensitive to the effects of cold cloud layers.
- A leak developed in the spacecraft oxygen-supply system during the exit phase of the flight. The leak was small, and sufficient oxygen was available for the mission. Postflight analyses determined that the leak was caused by failure in a pressure reducer. The fault was corrected for subsequent missions.
- Some thrusters in the spacecraft automatic attitude control system had either reduced output or no output during the latter part of the orbit. Postflight analyses indicated that possibly the trouble was contamination of the metering orifices in some thruster assemblies.
MA-4 Gallery
 Recovery of MA-4 |
