65: 5. Lunar Orbit Insertion and the Disappointment of the Moon's Surface. Bob Zimmerman discusses how on Christmas Eve, Apollo 8 approached the moon. The critical moment was Lunar Orbit Injection (LOI), requiring the firing of the Service Propulsion System (

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John Batchelor

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🗓️ 8 November 2025

⏱️ 10 minutes

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Summary

5. Lunar Orbit Insertion and the Disappointment of the Moon's Surface. Bob Zimmerman discusses how on Christmas Eve, Apollo 8 approached the moon. The critical moment was Lunar Orbit Injection (LOI), requiring the firing of the Service Propulsion System (SPS) engine. This burn had to occur while the craft was behind the moon, resulting in a dramatic Loss of Signal (LOS) for Earth. Susan Borman particularly dreaded this moment because the SPS engine, which had no redundancy, was their only way into and out of lunar orbit. NASA believed firing the engine would clear any potentially problematic bubbles in the fuel lines, adding another risk. Once in orbit, the astronauts were visually disappointed, with Frank Borman describing the moon's surface as looking like a "skull" or a lifeless sandbox. Their direct observation settled the debate among scientists, confirming that the moon's craters were the result of impacts, not volcanic activity.
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Transcript

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0:00.0	This is CBSI on the world. I'm John Batchel, continuing with Bob Zimmerman, author of Genesis,
0:05.8	the story of Apollo 8, the first man flight to another world at Christmas time. The Saturn 5,
0:13.1	with Apollo 8, autopit, launches on December 21st. It is now Christmas Eve, December 24th. They are approaching the moon.
0:23.9	They've been inside the moon's gravity for some time now. Frank Borman, Jim Lovell, and Bill
0:32.1	Anders. Bob, thank you for continuing this exciting story, even though I know it's going to come out all right.
0:38.5	This is a moment where everybody worried on Earth paying attention.
0:42.8	Two acronyms that NASA used again and again.
0:47.9	LOS of LOI, lunar orbital injection, and then loss of signal, LOS.
0:53.8	Let's deal with both of them because these are dramatic moments.
0:57.1	They're going very fast.
0:59.5	They're in the moon's gravity pull.
1:02.7	The moon is pulling them towards it.
1:05.2	They're outside of the Earth's gravity.
1:07.4	However, they've got to, in some way, put themselves into lunar orbit.
1:12.2	How do they do that, Bob?
1:14.4	It's interesting.
1:15.4	On the entire three-day journey to the moon, the way the capsule is oriented, they never saw the moon.
1:21.0	They actually were pointing back to the Earth with the engine behind them, pointing at the Moon.
1:26.0	So their windows always showed the earth.
1:28.1	It wasn't until just before landing, just before reaching the moon, that they finally turned
1:34.3	the capsule around. But they did first, they had to fire the SPS engine. Now, the SPS engine
1:39.9	was on the service module of the lunar capsule.
	...

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