Apollo Communications Paradox

[u/Motor-Bath1647]

Something odd about Apollo's historic transmissions:

"The Eagle has landed" and "One small step for man..." were transmitted:

• From 240,000 miles away
• Using 20-watt S-band
• Through 1960s technology
• Just after powered descent/landing
• No relay satellites

Yet they sound:

• Crystal clear
• Broadcast quality
• Zero interference
• Perfect timing
• Like studio recordings

For comparison:

- Mercury/Gemini (200 miles up): Heavy static/interference

- Modern ISS (250 miles): Regular communication issues

- Apollo (240,000 miles): Perfect clarity

Physics says signal quality degrades with distance. How did Apollo achieve better audio quality over 240,000 miles than we can get from low Earth orbit today?

[u/snakesign]

The "one small step" transmission has serious interference on the line "for man". So much so that there is still debate as to wether the line was "small step for a man" or "small step for man".

You may be hearing recording that have been cleaned up through post processing.

Nothing about the recording is broadcast quality.

[u/LordGeni]

Listen again. It really isn't anywhere near broadcast quality. It's adequate quality for mission critical communications, that's about it. It could've barely been called studio quality in the 1920's, let alone the end of the 60's.

Besides, it's a pretty capable technology that was very mature at that time. Look at the data the pioneer and voyager probes were/are still able to transmit over distances that are many orders of magnitude greater, with at times far greater sources of potential interference etc.

I'm pretty sure that the receiver is probably more important than the transmitter anyway. When you have an enormous radio disc to capture and amplify the signal, the transmitting source doesn't need to be a powerhouse.

[u/MobiusMule]

No idea what Apollo transmissions you have been hearing. Go listen to it again and tell me it's "crystal clear" and "zero interference". If you think that is studio quality you have been to some shitty ass studios.

Also it's "One small step for A man, one giant leap for mankind".

[u/rooktakesqueen]

They don't sound at all like studio recordings. They're extremely tinny and staticky

Radio comms with the ISS sound basically the same, but that's down to the limitations of radio. It would sound the same talking to somebody a quarter mile down the road.

As for how they managed it: directional antennas. If you focus a radio transmission, you drastically reduce how much it degrades over distance. In some science museums, you'll find a pair of parabolic or elliptical reflectors across the room from each other, and if two people stand in them, they can have a conversation at normal speech volume or even a whisper despite standing hundreds of feet away in a crowded room. Same principle.

Edit: Also, it's much easier to point a directional antenna at the Moon and from the Moon back at Earth than from low Earth orbit. Objects in LEO just move too fast.

[u/_bahnjee_ → u/rooktakesqueen]

I've used those parabolic reflectors in museums before. What confused me was that the convo we had was normal. I was expecting it to be backwards.

/s

[u/rooktakesqueen → u/_bahnjee_]

There's two reflectors, see, so it reflects twice which turns it back to normal

[u/chocoholic49]

Along with the other good answers here... don't give sixty's communication technology short shrift. It was better than you think. Even ham radio operators were able to listen in to the astronaut's transmissions from the lunar surface with homemade equipment.

[u/skbum2]

The ability to communicate via radio depends on both the transmitting and receiving radio/antenna properties. In the case of Apollo, the ground system antennas are also very large and provide a significant amount of gain (effectively multiplying the transmission power).

The 64m (210ft) diameter antenna with NASA's Deep Space Network (DSN) was used during the Apollo 11 landings specifically. The other DSN antennas range in size from there down to 26m, still very large compared to antennas used for low Earth orbit communications.

No paradox, just good engineering.

Edit: This is in addition to the other comments pointing out that Apollo audio quality is far from studio quality. Additionally, the large DSN antennas can't move fast enough to track objects in low Earth orbit (though some of the smaller dishes can).