[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 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.

The RSO (range safety officer) monitoring the launch confirmed the lack of a roll-and-pitch program, then continued to give the Atlas an opportunity to recover and start its track across the Atlantic.

The RSO lifted the cover on the command button and watched as the Atlas raced to a fatal convergence with the limits on his plot board.

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 missile programmer either shut off completely shortly after liftoff or suffered a power outage, restarted, and then failed to execute the pitch and roll sequence.