Mercury-Atlas 3

Mercury-Atlas 3
	Launch of MA-3
Mission type	Test flight
Operator	NASA
Mission duration	7 minutes, 19 seconds; Failed to orbit
Distance travelled	1.8 kilometres (1.1 mi)
Apogee	7.2 kilometres (4.5 mi)
Spacecraft properties
Spacecraft	Mercury No.8
Manufacturer	McDonnell Aircraft
Launch mass	1,179 kilograms (2,599 lb)
Start of mission
Launch date	April 25, 1961, 16:15 UTC
Rocket	Atlas LV-3B 100-D
Launch site	Cape Canaveral LC-14
End of mission
Landing date	April 25, 1961, 16:23 UTC
	Project Mercury; Mercury-Atlas series
← Mercury-Atlas 2	Mercury-Atlas 4 →

Mercury-Atlas 3 (MA-3) was an unmanned spaceflight of the Mercury program. It was launched unmanned on April 25, 1961 at 16:15 UTC, from Launch Complex 14 at Cape Canaveral, Florida. The Mercury capsule contained a robotic "mechanical astronaut". Mercury spacecraft No. 8 and Atlas No. 8 100-D were used in the mission.^[1]

The Atlas used for the flight (Missile 100D) incorporated a number of technical improvements including thicker skin to handle the added weight of the Mercury capsule and prevent a recurrence of the Mercury-Atlas 1 failure. In addition, it sported a new, transistorized telemetry unit to replace the old-fashioned system used on previous Atlas vehicles which utilized vacuum tubes, was bulky, had high power consumption, and whose signal strength tended to degrade during launch. The revamped telemetery box had first been designed for the Atlas Centaur and quickly adapted for the Mercury program.

However, this flight would prove that the Atlas was still far from a reliable, man-rated booster. The launch proceeded normally until about T+20 seconds when the pitch and roll sequence failed to initiate and the vehicle instead just continued flying straight upward. As Mercury Flight Director Gene Kranz recalled, "The guidance control officer announced 'Negative pitch and roll program.' There was stunned silence in the blockhouse. We all sat and prayed that the roll sequence would start, but it didn't happen and the thing just kept going up and up and up. The Range Safety officer gave the booster all the chance in the world, but eventually the Atlas passed the allowable safety margin indicated on his chart. We were running the risk of it either exploding or pitching back towards land if it kept going, the debris dispersal field widening the higher up the booster got. With almost tears in his eyes, he pushed the big red destruct button. We could hear the distant thumph sound indicating termination of the flight. There was several minutes of silence in the room, after which everyone packed their clipbooks and started to leave."

Only 43 seconds after liftoff, Mercury-Atlas 3's mission ended in a rain of fiery debris falling back to Earth. The escape tower activated the moment the destruct command was sent and lofted Mercury spacecraft #8 to safety. The capsule flew to an apogee of 7.2 km and downrange only 1.8 km. The flight of the Mercury capsule lasted 7 minutes and 19 seconds, most of that time descending on its parachute. The spacecraft was recovered some 20 minutes after launch in the Atlantic Ocean and reused on the next flight (MA-4) as spacecraft No. 8A. One comforting fact to the Mercury team was that the flight verified the reliability of the launch escape system (this was the first Mercury-Atlas launch with a live escape tower).

Investigation of telemetry data quickly narrowed the cause of the failure to a fault somewhere in the guidance system, but the exact nature of it could not be determined. It appeared that the guidance system programmer either shut off completely shortly after liftoff or suffered a power outage, restarted, and then failed to execute the pitch and roll sequence. Then, two months after the MA-3 flight, the Atlas's programmer was discovered buried in mud on a beach not far from the launch pad and analyzed. NASA and Convair engineers concluded that the failure was most likely due to contaminated pins in the programmer causing an open circuit. In addition, the Atlas's guidance system as a whole was found to have a number of serious design deficiencies that needed to be corrected.