Opto EME

[VK2XSO]

What ? You thought they were using Morse or JT65 ?
http://esc.gsfc.nasa.gov/assets/images/ ... al.web.pdf

[VK2AVR]

So the 4" telescope on LADEE uses a 0.5W infra-red laser for the downlink, and the telescopes on earth are 4 x 6" for transmitting and 4 x 17" for receiving. Didn't see a mention of ground-based power levels but obviously a lot more than half a watt.

I guess optical EME is a bit out of reach for us hams.. pity, laser bounces off the moon would be cool

[VK2OMD]

There was a lunar laser ranger on the ridge above Ororral Valley SW of Canberra.

I used see it regulary on bushwalks in that region, and sometime walk right past it (but it is a steep walk up from the valley).

I probably have some pics, but it is not a very exciting building... rather small and traditional telescope tower with rotatable / retractable cover.

I suspect they use a reflector, that the laser is not simply bounced of the Moon's surface. I have a vague recollection that one of the early Apollo misions left a reflector on the Moon.

Anyway, it was there a long time ago, and if still operational, been going more than 40 years IIRC.

Owen

[VK2GOM]

Yes, there are a number of retroreflectors left on the moon from the Apollo 11 and 15 missions. They are used to this day to determine accurately distance between Earth and moon.

I remember back in 2005, flying in a Piper Dakota near Mt. Panomar and the 200" Hale telescope in California, and we had to be quite careful to avoid a danger area marked on the charts around the telescope facility location since they were firing lasers at the moon. There are a few other laser ranging places around, scattered across the globe.

73 - Rob VK2GOM / GW0MOH

[VK3AIF]

From a failing memory I seem to recall that the Soviet Lunarcods had reflectors too and that was how the missing one was relocated just a few years ago.

[VK2JDH]

Yes, there are a number of retroreflectors left on the moon from the Apollo 11 and 15 missions. They are used to this day to determine accurately distance between Earth and moon.


73 - Rob VK2GOM / GW0MOH

In the TV show 'Big Bang Theory' one of the episodes they bounced a laser of the Apollo reflector, as part of a science experiment.

Show outline:
■The gang's lunar laser ranging experiment utilizes a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, as is referenced on the whiteboard near Sheldon and Leonard's apartment door. Nd:YAG crystal lasers typically emit light with a wavelength of 1064 nm, in the infrared. However, the high-intensity pulses may be efficiently frequency doubled to generate green laser light at 532 nm. Both of these wavelengths are written on the lower half of the whiteboard, along with the chemical formula Y3Al5O12 for the yttrium aluminum garnet crystal structure and the atomic transition 4F3/2 → 4I11/2 in the neodymium ion, after being "pumped" into excitation. The upper half of the whiteboard calculates the round-trip travel time of a light pulse bouncing off lunar retro-reflectors as 2.56 seconds, based on the ratio of the semi-major axis of the lunar orbit to the speed of light.

[VK1UU]

Although not EME, this mob do interesting things with opto

http://www.eos-aus.com/?

[VK3DXE]

Yes, there are a number of retroreflectors left on the moon from the Apollo 11 and 15 missions. They are used to this day to determine accurately distance between Earth and moon.

I remember back in 2005, flying in a Piper Dakota near Mt. Panomar and the 200" Hale telescope in California, and we had to be quite careful to avoid a danger area marked on the charts around the telescope facility location since they were firing lasers at the moon. There are a few other laser ranging places around, scattered across the globe.

73 - Rob VK2GOM / GW0MOH

You sure they weren't using them for adaptive optics?

[VK2XSO]

I guess optical EME is a bit out of reach for us hams.. pity, laser bounces off the moon would be cool

Actually, I'm thinking it's easier than it looks.
But there's only one way to find out, so I'm working on it in some spare time.
I think it can be done.

[VK2AVR]

Actually, I'm thinking it's easier than it looks.
But there's only one way to find out, so I'm working on it in some spare time.
I think it can be done.

One of the discussions I read said that the retroreflectors illuminated a diameter of 15km centred on the transmitter. So if you aim for them your coverage is quite limited. If you aim for the general surface then it scatters but with an additional loss around 24dB.. it commented that considering the difficulty with hitting the reflector accurately you'd be better off using atmospheric scattering instead.

I think it would be very interesting to do though!

[VK2GOM]

Don't forget your prohibited weapons permit for the laser (in NSW)!

73 - Rob VK2GOM / GW0MOH

[VK2AVR]

Don't forget your prohibited weapons permit for the laser (in NSW)!

Yep. Obtaining the required permission looks relatively straightforward as long as you are doing something sane.

[VK2XSO]

Also, don't forget to actually read the law closely because there is more it doesn't say than what people think it does say

5mW green laser pointer is illegal.
A 5MW YAG laser is legal.

[VK2GFR]

Ah yes Ash... but you were always one for the bigger power option.
But ONLY 5MW?
My lights dimmed a bit just after I typed the comment, was that u firing up?

[VK2AVR]

LOL, talk about QRO!

[VK2XSO]

Heheh, my highest power laser is a 500W Q switched ruby laser, but it's not much good for coms unless it's PPM modulation.