It has been 60 years since a spacecraft snapped the USA's first close-up images of the lunar surface, a mere five years before astronauts set foot on the Moon. Ranger 7 finally achieved the feat in July 1964.

The Ranger program began in 1960 and was managed by NASA's Jet Propulsion Laboratory (JPL) in California. The Soviet Luna 3 spacecraft had already captured the first images of the Moon's far side in 1959, but the US sought to show off its technical prowess with something more high-resolution before a landing expected by the end of the decade.

It was a stepwise program. The first Block I mission would check out the Atlas-Agena launch vehicle by placing the Ranger spacecraft in a highly elliptical Earth orbit to check out the hardware. The second set of missions, Block II, would impact the Moon and capture images and science data on the way down. They also carried a payload intended to survive the landing and operate for 30 days, transmitting the seismic data to Earth.

The final Block III phase would have the spacecraft carry a high-resolution imaging system comprising six television cameras with wide and narrow-angle capabilities.

It is fair to say that, until Ranger 7, things did not go well. The first two missions failed - the Ranger spacecraft were left in a Low Earth Orbit due to a booster failure. The first Block II mission, Ranger 3, missed the Moon by 22,000 miles and sailed into a solar orbit. Ranger 4 did hit the Moon, but a power failure in its central computer meant it didn't send back any images or data.

Ranger 5 missed the Moon, but this time only by 450 miles. However, a power failure also prevented it from sending back any images or data.

The first Block III spacecraft, Ranger 6, did manage to hit the Moon, but a short circuit meant that, again, no images were returned.

It is difficult to imagine the pressure that must have been on the team as Ranger 7 was readied for launch. After all, only a few short years remained before human crews were due to land on the Moon. The Surveyor program, designed to demonstrate the feasibility of a soft landing on the lunar surface, was also preparing for its first launch. However, questions about the lunar surface still remained, which the Ranger program was designed to answer.

The launch, from Cape Canaveral's long-since dismantled LC12, went ahead on July 28, 1964. The Atlas-Agena placed the spacecraft into Earth orbit before sending it on to its destination. The spacecraft carried out a mid-course correction and, on July 31, reached the Moon.

This time, it worked and the cameras turned on as planned. The scientists got their images as Ranger 7 hurtled towards the Moon. According to NASA, in the spacecraft's last 17 minutes of flight before it hit the lunar surface at 1.62 miles per second, it sent back 4,308 images of the lunar surface. The last, 2.3 seconds before impact, had a resolution of 15 inches.

The final two Ranger missions also worked as planned, and images from the final mission - Ranger 9 - were broadcast "live" as the spacecraft approached what would become its crash site.

The images confirmed what is taken for granted today - the lunar surface would be able to support a soft landing. The Surveyors could be launched with a little more confidence. Just under five years later, Apollo 11 delivered the first humans to the Moon. ®

https://www.theregister.com//2024/07/31/ranger_7_60_years/