Chapter 4 of 5

Seventeen minutes of pictures

Ranger 7 transmits the first close-up images of the Moon by a U.S. spacecraft

Told in Ranger 7’s imagined voice · the events are real · source

Engineers stand with Ranger 7 on Dec.
Ranger 7My cameras warmed up, and at 13:08:45 UTC the first picture left for Earth.
NASA/JPL-Caltech
01I was about 2,110 kilometers above the Moon. My wide-angle camera sent a view that included the 108-kilometer crater Alphonsus.
As I fell, my cameras kept looking and my radio kept sending.
02Different cameras offered wide views and tighter close-ups. The partial-scan cameras could return rapid sequences, and the images reached Earth through two television channels.
Ranger 7 took this image, the first picture of the Moon by aU.S.
Ranger 7The pictures showed a surface covered with craters, not a sea of deep dust.
NASA/JPL
03Scientists saw rounded, overlapping craters and bright rays of material. The images gave them confidence that the smoother mare regions could support an Apollo landing, though later Surveyor landers would test the surface directly.
In about 17 minutes, I sent 4,308 pictures.
04My last full frame came about 2.3 seconds before impact, from roughly 1,600 feet above the ground. It could show details as small as 15 inches across.

The big idea

A series of images at increasing resolution can turn a distant, fuzzy world into a place with measurable features.

Think about it

Why would scientists want both wide views and close-up views of the same surface?

Fact file

First image
13:08:45 UTC · 2,110 km altitude
The wide-angle F-a camera returned a view that included the 108-km crater Alphonsus.
Source ↗
Picture total
4,308 photographs in about 17 minutes
NASA History and NSSDCA list 4,308. NASA Science's short mission overview sometimes gives 4,316; this book uses the archive and history figure.
Source ↗
Final full frame
About 2.3 seconds before impact · 1,600 ft
NASA History describes detail down to about 15 inches. NSSDCA lists the final image resolution as 0.5 m, a slightly different measure.
Source ↗
Television downlink
Channel F 959.52 MHz · Channel P 960.05 MHz · 60 W each
A separate 3 W transponder used 960.58 MHz. The two TV channels had independent power supplies, timers and transmitters.
Source ↗

In this chapter: Six RCA Vidicon cameras, two television channels and the Goldstone receiving stations

Sources: Main record · NASA · First image of the Moon from a U.S. spacecraft (PIA02975) · NASA · Guericke Crater from Ranger 7 (PIA02974) · LPI · Ranger 7 photographic archive · NSSDCA · Ranger 7 television experiment

Machine illustration: AI-made. Photos: NASA Image and Video Library, credited on each picture.

Chapter 4 of 5

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