NASA Laser Communication System Sets Record with Transmissions to and from Moon

How huge is a 1mm beam when it hits the moon (and visa-versa) ?<p>I wonder if wolframalpha can tell me...<p>Actually, I don&#x27;t even know how to ask it the proper question.<p>Can anyone make this formula work in wolfram?<p><a href="http://laserpointerforums.com/attachments/f51/17952-calculate-expansion-laser-beam-schematic_laser_beam.jpg" rel="nofollow">http:&#x2F;&#x2F;laserpointerforums.com&#x2F;attachments&#x2F;f51&#x2F;17952-calculat...</a><p>update:<p>I think I figured this out as<p><pre><code> ((λ * L) &#x2F; d)* 2 (((630nm in meters)*(380000km in meters)) &#x2F; (1mm in meters)) * 2 </code></pre> Which would be a nearly 500km wide for a 1mm beam on earth from a red laser at 630nm<p>The shortest wavelength laser I can find online is experimental violet at 400nm which would make a 300km beam on the moon.

The article cites 622 Mbps down, 20 Mbps error-free up. Is the implication that the 622 Mbps down is before error correction?<p>Either way, it&#x27;s pretty incredible. Even if the 622 Mbps down isn&#x27;t completely error free, but maybe 99%, you just need to use a video compression algorithm that is error tolerant.

There is an xkcd that seems awfully appropriate here - <a href="http://what-if.xkcd.com/13/" rel="nofollow">http:&#x2F;&#x2F;what-if.xkcd.com&#x2F;13&#x2F;</a> - shooting lasers at the moon.

The latency must be huge though.

Background information: <a href="http://www.spaceflight101.com/ladee-lunar-laser-communication-demonstration.html" rel="nofollow">http:&#x2F;&#x2F;www.spaceflight101.com&#x2F;ladee-lunar-laser-communicatio...</a>

Should be &quot;laser&quot; with the quotes. Also, LLCD isn&#x27;t catchy - the project should be renamed to &quot;The Allan Parsons Project&quot;.

So fine for torrenting crappy for gaming?

That is better than the connect at my house. I am moving there!

Would it help at all to signal over RF to a low-orbit relay, and then go optical just between two points in space? Much less atmosphere to contend with...

622mbps is interesting. Same as OC-12c... Something COTS?

I remember reading on reddit or maybe it was here on HN that a laser is not a thing it&#x27;s a method i.e. LASER, we use LASER not a laser.

Couldn&#x27;t we set-up a laser system to detect asteroids from farther away? Or would that be pretty inefficient?

That&#x27;s some lag!