This successful flight provided important data and insights for NASA's Project Mercury, supporting the planning and development of upcoming crewed missions in the program.

Further delays happened when it was discovered that the brand of transistor used in both the Atlas and Mercury were prone to forming solder balls, thus the entire last week of August was spent laboriously repairing them.

The payload consisted of a pilot simulator (to test the environmental controls), two voice tapes (to check the tracking network), a life support system, three cameras, and instrumentation to monitor levels of noise, vibration and radiation.

Because it was suspected that a transient voltage caused the malfunction of Mercury-Atlas 3's programmer (and that a similar problem had been responsible for Big Joe's failure to stage),[3] Convair equipped the autopilot to give the engines a counteracting capability.

The Spin Motor Rotation Detection System, invented to prevent an Atlas from launching with an improperly operating gyroscope, was just being phased in and would not appear in a Mercury vehicle until Mercury-Atlas 5.

[4] One hour and 22 minutes after splashdown the destroyer USS Decatur[5] (which was 34 miles from the landing point)[4] picked up the capsule, which was found to be in good condition with little damage from either liftoff, orbit, or reentry.

The biggest problem encountered on Mercury-Atlas 4 was an uncomfortably high level of liftoff vibration from T+5 to T+20 seconds, so a few more small modifications were made to the Atlas's autopilot.