S band weapon against Apollo HB's

[notawoowoo]

found this informative you tube vid, about how a few hams used S band dish antennas to listen to the diect
voice communications from the Apollo missions on the moon. As explained in the vid, the highly directional
nature of the 2.3ghz S band microwave signals proves,they had to be from the moon, instead of relayed
from earth orbit...there is a mistake in the video however..the narrator says the apollo communications were rebroadcast over shortwave via sattelites..this is not true..in fact they were done so live over the Voice of America short wave network...using the VOA's regular megawatt earthbound transmitters.

To conclude IMHO this fine video should give most HB's fits...

http://www.youtube.com/watch?v=qO9Fx...e_gdata_player

[notawoowoo]

i forgot to mention in theory nasa still could have tried to fake the S band transmissions by relaying them from earth via a geosyncronous satelite directly inline with the moon, however as probably none were close enough to be maneauvered into
place, they would have had to secretly launch one at great expense just for that purpose.. Of course we all know all the Apollo missions were real..,

[notawoowoo]

yet again nasa could have soft landed a unmanned S band repeater probe on the moon, or,flown the entire Apollo 11 lunar hardware stack unmanned via radio control to the moon and landing its LM equipeed to be an S,band repeater..given the extreme trickiness of doing,that as well as secretly launching a secret geostatioanry repeater sattelite, ocams razor says by
far the simplest easiest route was to sctually do the real manned moon missions, which of course is the fact they did.

[chrlzs]

A minor point - a geosynch/geostat satellite would only align with the Moon for a very short time and only at one location, so that couldn't have worked anyway...

[djellison]

As explained in the vid, the highly directional
nature of the 2.3ghz S band microwave signals proves,they had to be from the moon, instead of relayed
from earth orbit...

And how does this change Apollo HB's ideas? Obviously, they will say, the Surveyor landers were sent to act as radio beacons to make it LOOK like we went to the moon.

You're not thinking like a conspiracist..Remember, they do not get to their position via logic. They can not be argued out of it with logic either.

[JayUtah]

A minor point - a geosynch/geostat satellite would only align with the Moon for a very short time and only at one location, so that couldn't have worked anyway...

Not even. A geostationary satellite has an inclination of zero, meaning that even when the Moon is in the correct longitude, it will still be above or below the zero-inclination plane. The only way an orbiting object can pace the Moon is if it's at the same altitude as the Moon. If you've ever watched an eclipse, you know that the Moon is a moving object as seen from Earth. And the only way it can mimic the same location in space over time is to be in the same orbit.

A geosynchronous satellite could be one whose orbital elements (chiefly its period) are merely harmonic with the movements of Earth and Moon. But the problem remains that the only way you can get full-time placement of the signal so that it appeared to be coming from the Moon is to make it essentially coincident with the Moon. Orbital mechanics is fairly unforgiving in that respect.

[Glom]

Was the Moon in the equator for any the Lunar surface stays?

Hang on, geostationary is a complete red herring. A geostationary satellite doesn't move across the sky, but the Moon does and quite quickly.

[Clanger]

Was the Moon in the equator for any the Lunar surface stays?

Hang on, geostationary is a complete red herring. A geostationary satellite doesn't move across the sky, but the Moon does and quite quickly.

Geostationary to the Moon. Not only what Jay said above is relevant to why this wouldn't work, but because of the way the Moon moves through 3 types of libration, you would never get a straight line to a landing site through a Lunar geostationary satellite from Earth and maintain it. Cannot be done.

[HenrikOlsen]

"Geostationary" to the moon would mean on the moon. Simple as that.

Lower orbits just won't work.

[Clanger]

"Geostationary" to the moon would mean on the moon. Simple as that.

Lower orbits just won't work.

Since the Moon rotates once per 28 days, I think a geostationary satellite could only work from the L4 lagrange point all around in a half circle on the opposite side of it.

http://en.wikipedia.org/wiki/File:L4_diagram.svg

For it to be in a direct line with Earth, it would be highly unstable(very close to the Earth) and would be affected by Earth gravity more than lunar. It really is not a viable theory.

[Glom]

Geostationary to the Moon. Not only what Jay said above is relevant to why this wouldn't work, but because of the way the Moon moves through 3 types of libration, you would never get a straight line to a landing site through a Lunar geostationary satellite from Earth and maintain it. Cannot be done.

So selenostationary?

You mean the satellite was at L1.

[Clanger]

So selenostationary?

You mean the satellite was at L1.

Thanks for the new word

I just did some rough calculations on the speed and distance. The Moon moves at about 16kph at its equator. 4.44 metres per second.

So to get a satellite moving at that speed it needs to be nearly 250 million kilometres away from it! - that is a bit on the unfeasible side.

I wonder if anybody can check my figures, as that is the first time I've worked out an orbital speed. I used V = Sqrt(GM/r)

[BigDon]

I asked over in the big questions area and was shone that you can't have a geosync orbit on the moon because the mass of the Earth would keep pulling you off of alignment without constant station keeping.

[HenrikOlsen]

The closest you can have is to stick the satellite in one of the Earth-Moon Lagrange points where it will be stationary relative to the moon, but there's not many of those and it still won't make it possible to simulate the direction to a Moon lander's communications, which is where this started.

[violentquaker]

Would it be possible to fake the local voice communications by bouncing a directional radio signal transmitted from the earth off of the moon's surface?

[Clanger]

Would it be possible to fake the local voice communications by bouncing a directional radio signal transmitted from the earth off of the moon's surface?

That's 2.6 extra seconds delay and the return from a Moon bounce is pretty poor compared to what we actually got from the S-band antennae.

[Swift]

Would it be possible to fake the local voice communications by bouncing a directional radio signal transmitted from the earth off of the moon's surface?

How would you bounce it? Would you have a reflector on the moon, in which case I have to ask, how did the reflector get there. If you just use the moon's surface as the reflector, I would guess that the percentage of signal reflected back, particularly along a specific direction, would be very, very tiny.

[Van Rijn]

If you just use the moon's surface as the reflector, I would guess that the percentage of signal reflected back, particularly along a specific direction, would be very, very tiny.

Yes. EME works, but you don't get much signal back even with an extremely powerful transmitter. Here's the Wikipedia page on EME:

http://en.wikipedia.org/wiki/EME_%28communications%29

[Clanger]

Thanks for the new word

I just did some rough calculations on the speed and distance. The Moon moves at about 16kph at its equator. 4.44 metres per second.

So to get a satellite moving at that speed it needs to be nearly 250 million kilometres away from it! - that is a bit on the unfeasible side.

I wonder if anybody can check my figures, as that is the first time I've worked out an orbital speed. I used V = Sqrt(GM/r)

OK, so nobody corrected this - I used the wrong equation. That one gives orbital velocity, but the speed at geostationary is much quicker than the surface!

Using the correct formula - R^3 = (GMT^2)/4p^2
R=Radius from planet centre in metres.
G=Gravitational constant.
M=mass of planet in kg.
T=sidereal period in seconds.
P=pi.

I validated the formula and I got the correct Earth geostationary orbit of 35,894km.

The Moon geostationary orbit distance is 86,787km - that is well within the greater influence of the Earth's gravity, so completely unstable.

[Webbo]

Why would a relay satellite need to be geostationary with respect to the moon? The CSM orbited at 100 km and took 2 hours I believe but higher and longer orbits could be achieved without any discernable loss of signal from the direction of the moon. What's the longest continuous reception recorded by the home made receivers?

[JayUtah]

Why would a relay satellite need to be geostationary with respect to the moon?

Because the Doppler shift would give it away as an orbiting spacecraft and not something on the lunar surface.

The CSM orbited at 100 km and took 2 hours I believe but higher and longer orbits could be achieved without any discernable loss of signal from the direction of the moon.

A higher orbit means a larger lateral deflection from the spot on the Moon where the spacecraft was supposed to be, as well as motion across the line of sight. The beam widths of these antennas are a fraction of a degree and already had to be adjusted continually for Earth's rotation. Orbital motion will be detectable to the users of directional antennas.

What's the longest continuous reception recorded by the home made receivers?

The Soviets recorded basically the entire 200-hour mission. The amateurs recorded the entire Apollo 11 EVA as well as conversation before and after.

[Webbo]

The 9 meter dish used by the amateurs in the video only had 1 degree accuracy and a 2 degree bandwidth and needed to be aligned by hand. They didn't have anywhere near the resolution required to point to a specific point on the moon. Possibly the doppler shift could provide proof but the only doppler record I can see is of the CSM. In fact they never received voice from the surface of the Moon, only from the CSM. Do you have another link for the amateur recording of the Apollo 11 EVA?

[HenrikOlsen]

The 9 meter dish used by the amateurs in the video only had 1 degree accuracy and a 2 degree bandwidth and needed to be aligned by hand. They didn't have anywhere near the resolution required to point to a specific point on the moon. Possibly the doppler shift could provide proof but the only doppler record I can see is of the CSM. In fact they never received voice from the surface of the Moon, only from the CSM. Do you have another link for the amateur recording of the Apollo 11 EVA?

Did you miss that for a reflector to work it would have to follow the purported trajectory the entire flight path of the Apollo crafts from start to landing. Not just on the moon, but for the trip to the moon and back again.
And for the trip out and back the doppler of a reflector would be double that of the moving craft.

[Webbo]

Did you miss that for a reflector to work it would have to follow the purported trajectory the entire flight path of the Apollo crafts from start to landing. Not just on the moon, but for the trip to the moon and back again.
And for the trip out and back the doppler of a reflector would be double that of the moving craft.

That the craft were sent to the moon isn't in question. Obviously the receivers tracked the CSM but they were not sensitive enough to know if any landing was made.

[Clanger]

That the craft were sent to the moon isn't in question. Obviously the receivers tracked the CSM but they were not sensitive enough to know if any landing was made.

Sure they were. Jodrell Bank:

http://www.jb.man.ac.uk/multimedia/i...o11-eagle.html

[chrlzs]

That the craft were sent to the moon isn't in question. Obviously the receivers tracked the CSM but they were not sensitive enough to know if any landing was made.

Also.. what sort of orbit (or other positioning method) would they have had to use to ensure there were no breaks in transmission from going behind the moon?

Seems to me they would either have to land or go into a 'face-on' orbit - any other possibilities? I'm no orbital mechanics expert, but I seem to recall that the latter might be rather difficult...

[Webbo]

Sure they were. Jodrell Bank:

http://www.jb.man.ac.uk/multimedia/i...o11-eagle.html

Obviously we were discussing the independent amateur receivers. I'm not saying this isn't proof but it's not what the OP was about. Also, that is the same shape that an orbiting craft would give moving accross the face of the moon so further evidence would be needed to prove it's the LM.

[Webbo]

Also.. what sort of orbit (or other positioning method) would they have had to use to ensure there were no breaks in transmission from going behind the moon?

Seems to me they would either have to land or go into a 'face-on' orbit - any other possibilities? I'm no orbital mechanics expert, but I seem to recall that the latter might be rather difficult...

Well from the video the amateurs never seemed to receive more than a few snippets and lost all communication when the CSM went behind the moon. The voices received were only from the CSM.

[Clanger]

Obviously we were discussing the independent amateur receivers. I'm not saying this isn't proof but it's not what the OP was about. Also, that is the same shape that an orbiting craft would give moving accross the face of the moon so further evidence would be needed to prove it's the LM.

That is incorrect and I really cannot fathom how you could make that claim

The shape on the graph shows doppler effects as the LM descends. In terms of Earth distance, effectively increasing as it moves to the surface from orbit. If the craft tracked across the Moon, there would be mild doppler as it came around and mild opposite doppler as it disappeared back in its orbit. There would be no signs of the maneuvre Armstrong performed.

[JayUtah]

The video mentions only amateur attempt. There were several successful ones, not all of which were limited in this way.