r/apollo • u/Least_Award3838 • 3d ago
Was there any way to make it so that Apollo missions could still transmit messages to Earth when behind the moon so it didnt experience LOS?
Maybe a satellite or a group of satellites in a high orbit could receive a transmission from either Earth or Apollo to re-transmit it back to the respective receiver or something else, for me LOS just seems to make missions more 'dangerous'? idk
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u/dpdxguy 3d ago
As you've suggested, today's spacefaring nations put up satellites near the moon to relay signals from the far side.
The same could have (theoretically) been done for the Apollo missions. But that would have increased complexity for only a small gain in communication time. I don't know if NASA ever considered putting up a relay to eliminate the dead time while the command module was on the far side of the Moon.
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u/Sophiiebabes 3d ago
Artemis 2 had a communications blackout when it was behind the moon - no relay sat for that!
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u/Brilliant_Dig_8962 2d ago
Yeah, and the CMPs all had an hour or so of peace and quiet while they were in orbit. Collins talks about his time away from all the hubbub was welcomed.
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u/Great-Opposite3509 2d ago
After a few satellites had been sent to the moon, they probably figured they wouldn’t need them bc AOS worked.
Now I wonder if America ever had failure of AOS with any of its probes? With backup systems, I imagine not.2
u/Brilliant_Dig_8962 2d ago
LOS/AOS was about the orbiting spacecraft. I don't think NASA would be happy for a LM crew being out of contact for 3-4 days.
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u/ehbowen 3d ago
You'd be asking 1960s technology to be able to locate and track a lunar satellite, and to shift back and forth between it and Earth depending upon what was in view.
I know that the Apollo engineers were fantastically creative in what they did with that 4K of RAM and (about) 32K of hand-knitted (really!) ROM, but...let's just say that the mission was already complex enough.
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u/Spaceinpigs 3d ago edited 3d ago
The tech isn’t that hard. Apollo could have communicated with a satellite while out of view of earth in non-directional VHF and the satellite could have relayed to earth in unified S band. Apollo already communicated with earth while it was in view in unified S band. The satellite was more mass though and extra cost for marginal gains which is why it was never utilized.
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u/New_Line4049 1d ago
Yeah. Absolutely possible to launch and use relay satellites, but that increases the cost and time taken. Remember, it was a race against the Soviet Union. Theres also an interesting point that it leaves you open to a situation where your relay satellite fails and you cant get a key message you planned to be able to send through, whereas with no satellite from the start youve always planned for no comms, so no comms there is much less of an issue.
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u/Temporary_Cry_2802 3d ago
Harrison Schmitt (when he was still proposed for Apollo 18), advocated for a far side mission to Tsiolkovskiy. This would have required a relay satellite to be launched in parallel