ma7

This shot, dated one week before MA-7 launch day, shows the artwork of Cece Bibby, an artist employed by Chrysler, who also did the insignia on MA-6 and MA-8. The MA-9 insignia was painted by B. R. Schuster, a McDonnell employee. What I find puzzling is the yellow rig that appears to be load-bearing. The cables are attached at the red clamp ring that marks the spacecraft/adapter separation point. The spacecraft was already mated to the Atlas and I do not understand what purpose such a rig would serve, at this point. UNSUPPORTED WILD GUESS: A safety back up that might prevent launch vehicle damage in the event of a loss of pressure in the Atlas tanks. The booster was often referred to as a "stainless steel balloon" and the Mercury spacecraft weighed around a ton. If the nitrogen pressure in the propellant tank (or tanks) had been lost, the weight would probably have caused the booster to collapse.

Nice shot!

If you zoom in on the Atlas you will see this is Atlas 88D which indeed was the Atlas missile used for MA-4. This also corresponds with the date mentioned. However Atlas 107D was used for MA-7 (Scott Carpenter) in May of 1962.