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)