A Laser Message from Space
 
June 18, 2014:  Anyone who remembers dialup internet can sympathize with the
plight of NASA mission controllers.  Waiting for images to arrive from deep
space, slowly downloading line by line, can be a little like the World Wide
Web of the 1990s.  Patience is required.
 
A laser on the International Space Station (ISS) could change all that.  On
June 5th, 2014, the ISS passed over the Table Mountain Observatory in
Wrightwood, California, and beamed an HD video to researchers waiting below. 
Unlike normal data transmissions, which are encoded in radio waves, this one
came to Earth on a beam of light.
 
"It was incredible to see this magnificent beam of light arriving from our
tiny payload on the space station," says Matt Abrahamson, who manages the
Optical Payload for Lasercomm Science at NASA's Jet Propulsion Laboratory.
 
http://youtu.be/S8uL8ox-SlQ
 
The bright spot in this telescopic image of the ISS is the OPALS laser beam
transmitting HD video to Earth. A new ScienceCast video explains how it
works.  Play it
 
Better known as "OPALS," the experimental laser device was launched to the
space station onboard a Space-X Dragon spacecraft in the spring of 2014. Its
goal is to explore the possibility of high-bandwidth space communications
using light instead of radio waves.  If successful, researchers say OPALS
would be like an upgrade from dial-up to DSL, achieving data rates 10 to 1,000
times higher than current space communications.
 
So far so good.
 
The entire transmission on June 5th lasted 148 seconds and achieved a maximum
data rate of 50 megabits per second. It took OPALS 3.5 seconds to transmit a
single copy of the video message, which would have taken more than 10 minutes
using traditional downlink methods. The message was sent multiple times during
the transmission.
 
Abrahamson says "the video is an homage to the first output of any standard
computer program: 'Hello, World.'"
 
https://www.youtube.com/watch?v=hPOstCZKycI
 
Click on the image to play the complete "Hello World" video.
 
Because the space station whips around Earth at 17,500 mph, "laser-tagging" a
telescope on the fast-moving ground below can be tricky. To accomplish the
precision tag-up, a laser at the ground station illuminated the station. OPALS
responded by sending its own 2.5 watt encoded laser signal right back in the
same direction, carrying the HD video. During the 148-second transmission,
OPALS maintained pointing to the ground station within 0.01 degrees while
tracking at speeds up to 1 degree per second.
 
"NASA missions collect an enormous amount of data out in space," says
Abrahamson. "Laser communications is a faster alternative for getting those
data to the ground."
 
"With this demonstration, we're paving the way for the future of
communications to and from space."
 
Credits:
Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit:
Science@NASA
 
Web Links:  OPALS -- home page at JPL   OPALS --information from NASA HQ
 
 
Regards,
 
Roger

--- D'Bridge 3.99
 * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)