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A comment on The digital ranging system that measured the distance to the Apollo spacecraft. Parent comment

Re:The digital ranging system that measured the distance to ... by kens on Saturday April 23, 2022 @02:51PM (#31137176)
Testing the systems for Apollo was a huge task, more than I can describe here. Everything from component testing to putting a Lunar Module in a giant vacuum chamber on Earth. Each flight pushed things further so they could test in Earth orbit (Apollo 7), then Lunar orbit (Apollo 8).

For the ranging system specifically, they could do most of the testing on Earth. As long as they could predict the antenna behavior at long distances, everything could be tested pretty accurately. In addition, the Apollo Guidance Computer provided the same ranging data in a completely redundant way. So even if the ranging system completely failed, they still had a backup.

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Re:The digital ranging system that measured the distance to ... by ncmncm on Sunday April 24, 2022 @05:39AM (#31142523)
I guess Apollo 13 had to rely on the LEM's guidance computer for ranging, because the command module was powered down?
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Re:The digital ranging system that measured the distance to ... by TedDoesntTalk on Saturday April 23, 2022 @03:34PM (#31137651)
How did the AGC have the same ranging data? I thought it was a completely different system.
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Re:The digital ranging system that measured the distance to ... by kens on Saturday April 23, 2022 @03:37PM (#31137689)
The AGC computed the position (including range) using inertial guidance and star sightings by the astronauts. So yes, it was a completely independent system, but the results should be the same.
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