[Laser] NASA achieves multi-Mb/s per sec LASER comms via lunar repeater

[bernieS]

I believe this sets a new DX record for 
multi-Mb/s data communications.  Very impressive.

-bernieS


http://www.wired.com/wiredscience/2013/10/nasa-internet-laser/

NASA Shoots Lasers at the Moon to Create Insanely Fast Internet

By Adam Mann
10.23.13
1:22 PM

NASA’s Lunar Lasercom Optical Communications 
Telescope Laboratory (OCTL) Terminal, sending a 
laser beam to the moon. Image: 
<http://esc.gsfc.nasa.gov/assets/images/LLCD/D2005_1010_T020b.jpg>NASA

NASA has set a new record for communication in 
space, beaming information to and from a probe 
named LADEE that is currently flying around the moon 380,000 kilometers away.

Aboard LADEE is the 
<http://esc.gsfc.nasa.gov/267/271.html>Lunar 
Laser Communication Demonstration (LLCD), which 
achieved super-fast download speeds of 622 
megabits per second (Mbps) and an upload rate of 
20 Mbps. In comparison, the internet at WIRED’s 
office in San Francisco gets download rates of 75 
Mbps and uploads at 50 Mbps. NASA’s typical 
communications with the moon are about five times 
slower than what LLCD provided.

Until now, NASA has used radio waves to 
communicate with its spacecraft out in the solar 
system. As a probe gets farther away, you need 
more power to transmit a signal. Earth-based 
receiving dishes have to be bigger, too, so that 
NASA’s most-distant probe, Voyager 1, 
<http://www.wired.com/wiredscience/2013/09/vintage-voyager-probes/>relies 
on a 70-meter antenna to be heard. LLCD relies on 
three ground-based terminals at telescopes in 
<http://esc.gsfc.nasa.gov/267/271/Ground-Segment.html>New 
Mexico, California, and Spain to communicate.

The agency is currently interested in creating 
better laser-based communication relays. With a 
concentrated beam of light, a spacecraft could 
send data at much faster rates that could carry 
higher resolution images and transmit 3-D videos 
from deep space. Of course, the method is 
challenging because it requires very high 
precision. If the skinny laser beam doesn’t 
exactly hit its target over a ridiculously far 
distance, it will lead to dropped calls and no 
communication. LLCD also has a slower 
transmission rate when the moon is on the horizon 
­ and the signal has to travel through a greater 
amount of interfering atmosphere ­ than when it is directly overhead.

LLCD is actually a precursor to a larger and even 
more capable project, the 
<http://www.nasa.gov/mission_pages/tdm/lcrd/>Laser 
Communications Relay Demonstration (LCRD), which 
will further test the technology and is expected 
to launch in 2017. One day, such communication 
systems could be part of a fast 
<http://www.wired.com/wiredscience/2013/05/vint-cerf-interplanetary-internet/>interplanetary 
internet that will beam data around the solar system.