Apollo 50th Anniversary

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fatso
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Apollo 50th Anniversary

Post by fatso » Fri May 24, 2019 11:55 pm

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Some rarely seen film from the Apollo missions during the late 60s and early 70s. Unfortunately, only playing on the HD channel and not the 4K. When these are playing there is an "Apollo 50th" logo in the top right of the screen. Some interviews with Gene Cernan and others who walked on the moon. Those sure were the glory days of NASA...

Anyone know what kind of feed they were using on their antenna?

Apollo_17_Cernan_on_moon.jpg.png
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Re: Apollo 50th Anniversary

Post by belter-one » Sat May 25, 2019 1:34 pm

fatso wrote:
Fri May 24, 2019 11:55 pm
127W
3920 V 28070

Some rarely seen film from the Apollo missions during the late 60s and early 70s. Unfortunately, only playing on the HD channel and not the 4K. When these are playing there is an "Apollo 50th" logo in the top right of the screen. Some interviews with Gene Cernan and others who walked on the moon. Those sure were the glory days of NASA...

Anyone know what kind of feed they were using on their antenna?


Apollo_17_Cernan_on_moon.jpg.png
fatso wrote:
Fri May 24, 2019 11:55 pm
127W
3920 V 28070

Some rarely seen film from the Apollo missions during the late 60s and early 70s. Unfortunately, only playing on the HD channel and not the 4K. When these are playing there is an "Apollo 50th" logo in the top right of the screen. Some interviews with Gene Cernan and others who walked on the moon. Those sure were the glory days of NASA...

Anyone know what kind of feed they were using on their antenna?


Apollo_17_Cernan_on_moon.jpg.png
Good Morning!

Thank you for sharing this. From what this article says, it was some sort of C band antenna for transmission and then received by ground based radar stations https://www.popsci.com/how-nasa-broadca ... -from-moon . We have really enjoyed the NASA programming on this bird. For those interested, "This Week at NASA" a.k.a. TWAN seems to play on the NASA Public channel every saturday morning at 3:00 AM PST. If anyone wants these uploaded to this site every week, I would be happy to.

May the Force be with you :-),

belter-one

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Re: Apollo 50th Anniversary

Post by tek2000 » Mon May 27, 2019 5:36 am

fatso wrote:
Fri May 24, 2019 11:55 pm
Anyone know what kind of feed they were using on their antenna?

I believe it was a helical feed and was a 3.0 m diameter wire mesh antenna, similar to what most of you have purchased to watch satellite tv. :biggrin

The flat earth society claims the Apollo Moon missions were a hoax and point to the fact that radio communication from the Earth to the Moon is impossible. After all, the local tv station may broadcast several kWs of power and only reach 80 kms, but the moon is 380,000 km away. So how is it possible? Such people are clueless about antenna beam patterns and the fact that a 3.0 m parabolic reflector is highly directional.

One simple way to prove it is possible is as follows. Geostationary orbit is roughly 42,000 km from the center of the Earth. So the moon is roughly 9 times further away. These geostationary satellites transmit about 15-20 W of power and lets assume the Apollo astronauts did the same. So what size dish do we need on the ground? Since the moon power received is 1/81th of the satellite power, we would need reflector with 81 times the surface area or 9 times the diameter, to receive the same power. It scales exactly as the diameter, so 9 x 3.0m = 27 m. In actual fact, they used a 64 m ground dish:

https://en.wikipedia.org/wiki/Parkes_Observatory


How big a dish do you need for Earth - Mars communications, assuming again, the astronauts have only 3.0 m antenna and transmit 15-20 W of power? Earth - Mars distance is 54 million km. Hint, hint you will need to use higher frequencies to get more gain and an array of giant dishes here on Earth.

So if Nasa needs an array of giant earth stations to just just barely communicate with deep space probes like Voyager on the outskirts of the solar system, all that SETI business designed to detect extra terrestrial intelligence light years away sure smells like a swindle to me...taxpayers, are you listening?

S-band_antenna_on_lunar_surface_-_taken_during_Apollo_12_mission.png
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Re: Apollo 50th Anniversary

Post by belter-one » Mon May 27, 2019 12:37 pm

tek2000 wrote:
Mon May 27, 2019 5:36 am
fatso wrote:
Fri May 24, 2019 11:55 pm
Anyone know what kind of feed they were using on their antenna?

I believe it was a helical feed and was a 3.0 m diameter wire mesh antenna, similar to what most of you have purchased to watch satellite tv. :biggrin

The flat earth society claims the Apollo Moon missions were a hoax and point to the fact that radio communication from the Earth to the Moon is impossible. After all, the local tv station may broadcast several kWs of power and only reach 80 kms, but the moon is 380,000 km away. So how is it possible? Such people are clueless about antenna beam patterns and the fact that a 3.0 m parabolic reflector is highly directional.

One simple way to prove it is possible is as follows. Geostationary orbit is roughly 42,000 km from the center of the Earth. So the moon is roughly 9 times further away. These geostationary satellites transmit about 15-20 W of power and lets assume the Apollo astronauts did the same. So what size dish do we need on the ground? Since the moon power received is 1/81th of the satellite power, we would need reflector with 81 times the surface area or 9 times the diameter, to receive the same power. It scales exactly as the diameter, so 9 x 3.0m = 27 m. In actual fact, they used a 64 m ground dish:

https://en.wikipedia.org/wiki/Parkes_Observatory


How big a dish do you need for Earth - Mars communications, assuming again, the astronauts have only 3.0 m antenna and transmit 15-20 W of power? Earth - Mars distance is 54 million km. Hint, hint you will need to use higher frequencies to get more gain and an array of giant dishes here on Earth.

So if Nasa needs an array of giant earth stations to just just barely communicate with deep space probes like Voyager on the outskirts of the solar system, all that SETI business designed to detect extra terrestrial intelligence light years away sure smells like a swindle to me...taxpayers, are you listening?

Hi tek2000,

Thank you for an educational post. Perhaps SETI will be able to pick up those tightly focused tachyon bursts that alien civilizations use, according to many a good science fiction tome.

Cheers, :comp

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Re: Apollo 50th Anniversary

Post by tek2000 » Thu May 30, 2019 5:15 am

belter-one wrote:
Mon May 27, 2019 12:37 pm
Perhaps SETI will be able to pick up those tightly focused tachyon bursts that alien civilizations use, according to many a good science fiction tome.

Cheers, :comp

belter-one
I highly doubt it!

I get a lot of emails from people using these parabolas for moon bounce or astronomy experiments. I think a better use of the parabolic reflector would be to launch say 1,000 or more space probes with high-gain antennas (similar to those in your backyard) and arrange them as relay links all the way to a neighboring star system. The lead probe could then transmit data (e.g. pictures and other information) all the way back to Earth along this antenna relay chain link!

You can actually perform back of the envelope calculations for these antenna links to prove it is feasible with reasonable sized antennas and power levels. You just need to remember that it all works according to the inverse square law. For example, the Voyager 2 probe is now at the edge of our solar system and uses a 3.7m antenna (very small) to communicate with a 70m (very big) ground antenna here on Earth. The probe transmits 20W of power, while the ground antenna transmits around 20kW. This radio link allows a few hundred bits/s of data to be transferred back and forth. See for example,

https://en.wikipedia.org/wiki/Voyager_2

and real-time data reception from these probe can be found at

https://eyes.nasa.gov/dsn/dsn.html

Of course, nobody wants to wait 30,000 years for a probe like Voyager 2 to reach the nearest star system, so some work would have to be done to speed up the travel velocities of these probes by say a factor of 1,000 times. If this could be accomplished, then we could in theory see real pictures of neighboring star systems in the decades or centuries ahead rather than wasting time and resources with something as silly as SETI!

You just have to think outside of the box and make due with the resources you already got in your backyard and you'll be surprised at the results! :wink

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Re: Apollo 50th Anniversary

Post by fatso » Thu May 30, 2019 10:46 pm

New symbol rate for NASA mux is now 32720. Was just watching some moon footage in 4K just now and it looks awesome like you are right there on the moon! The 50th anniversary is just a couple months away, so keep watching cause I think they will have all kinds of new goodies for us. :bananna:
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Re: Apollo 50th Anniversary

Post by belter-one » Fri May 31, 2019 1:41 am

Hello,

Which satellite? Galaxy 13's NASA transponder seems not to have changed, and is at ~ 15.0 SNR at the moment. Could you include the frequency, Symbol Rate, ... , and what satellite has a new symbol rate?

Thank you for sharing,

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Re: Apollo 50th Anniversary

Post by dishcrank » Fri May 31, 2019 2:47 am


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