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Shining a Laser at The Moon!

CheesyWalnut

CheesyWalnut

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These are two lasers shining at the moon not one reflecting off of it. It would be pretty cool if it was reflecting though :D

484520main_observethemoon_946-710.jpg


This photograph shows the Laser Ranging Facility at the Geophysical and Astronomical Observatory at NASA's Goddard Space Flight Center in Greenbelt, Md. The observatory helps NASA keep track of orbiting satellites. In this image, the lower of the two green beams is from the Lunar Reconnaissance Orbiter's dedicated tracker. The other laser originates from another ground system at the facility. Both beams are pointed at the moon -- specifically at LRO in orbit around the moon.
Click to expand...

More info here :)
 
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Tmack

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Ha that does look like a reflection of the beam. Cool stuff happening close to home :D
 
Atomicrox

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Do you guys figure you can actually see the dot with a huge ass telescope?
 
Pi R Squared

Pi R Squared

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Atomicrox said:
Do you guys figure you can actually see the dot with a huge ass telescope?
Click to expand...

That's something I would sure like to see, but if the dot was 30Km wide it would have to be pretty damn bright to be visible. This brings up another question, what is the practical limit on distance for communication by laser? Could we communicate by laser between Earth and Mars? I would think that with the best optics that the beam may be wider than the planet after traveling that distance and then might not be powerful enough even with the best equipment but I don't know.

Alan
 
Atomicrox

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You can always lower divergence by increasing diameter. For huge distances it probably makes sense to use a 1000x beam expander to get very low divergence.
Lets say you have a 1mrad, 1mm beam - with a 1000x beam expander you'd have a 1urad, 1m beam instead. The dot on the moon would "only" have about 385m.
 
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Pi R Squared

Pi R Squared

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Atomicrox said:
You can always lower divergence by increasing diameter. For huge distances it probably makes sense to use a 1000x beam expander to get very low divergence.
Lets say you have a 1mrad, 1mm beam - with a 1000x beam expander you'd have a 1urad, 1m beam instead. The dot on the moon would "only" have about 385m.
Click to expand...

Now that I think about it your right. They would have to do that because the probe (the LRO) communicates both ways by laser, if the beam when it reached the LRO was 30Km wide I doubt you could put sensitive enough equipment on something so small for it to work.

Alan
 
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