Launched on July 28, 1964, Ranger 7 was designed to achieve a lunar-impact trajectory and to transmit high-resolution photographs of the lunar surface during the final minutes of flight up to impact.

[4] Although NASA had attempted to put a positive spin on Ranger 6 on the grounds that everything except the camera system had worked well, William J. Coughlin, editor of the publication Missiles and Rockets, called it a "one hundred percent failure" and JPL's record thus far was "a disgrace".

On February 14, 1964, JPL released a report noting that an internal command switch could have activated prematurely or that arcing had occurred in the umbilical connector on the payload fairing.

The NASA review board found that Ranger 6's systems were not as redundant as Jet Propulsion Laboratory had claimed, that prelaunch testing was inadequate, and there had been instances of the cameras turning themselves on at the RCA plant in New Jersey.

RCA also promised to look into workmanship standards at their main plant in Hightstown, New Jersey, when examination of a sealed Ranger module discovered a plastic bag with screws and washers inside.

This umbilical connector would normally be attached on the ground to permit testing of the Ranger's subsystems and only a thin hinged door covered it during launch.

Alexander Bratenahl, a physicist at JPL's Space Sciences Division, suggested that the electrical short was caused by venting propellant during Atlas booster section jettison.

Convair technicians confirmed that 51 kilograms (112 lb) of LOX was vented from the Atlas after staging, but although the shock wave theory seemed tempting, James Kendall, another Jet Propulsion Laboratory physicist, dismissed it out of hand.

Bratenahl persisted and studied more film of Atlas launches with the frames enlarged, which revealed light flashes in the post-staging plume.

Another phone call to Convair revealed that 30 kilograms (67 lb) of RP-1 were also dumped during staging and that the Atlas's sustainer engine exhaust ignited the propellant cloud, producing these flashes.

Since the umbilical door on the payload shroud was only held in place with a thin latching mechanism, hot gases from igniting propellant could have contacted the electrical connector and caused a short.

Among the changes made for Ranger 7 included new procedures to apply full power testing to the spacecraft off of the launch pad, where there was no risk of the midcourse correction engine activating on top of a fully fueled Atlas-Agena.

The spacecraft consisted of a hexagonal aluminum frame base 1.5 meters (4 ft 11 in) across on which was mounted the propulsion and power units, topped by a truncated conical tower which held the TV cameras.

[4] Propulsion for the mid-course trajectory correction was provided by a 224-newton (50 lbf) thrust monopropellant hydrazine engine with four jet-vane vector control.

The flight trajectory for Ranger 7 was quite accurate, but a short midcourse correction was carried out early on the morning of July 29 to ensure impact in the Sea of Storms instead of the far side of the Moon.

Images of the cratered lunar surface continued to filter back to JPL headquarters in Pasadena, California, and finally, at 6:25, impact occurred and all signals from the probe ceased.

Ranger 7 had delivered the first close-distance imagery of the lunar surface and "more than anything, even the manned Mercury missions, had at last undone the sting Americans felt at Sputnik 1's launch".

The spacecraft performance was excellent and the success of the mission finally brought a turnaround in NASA's fortunes after the endless string of lunar probe failures since 1958.