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I'm guessing that this is way harder than the article makes it sound. The satellite is moving very fast and has to hit an extremely precise target, but adding o

I'm guessing that this is way harder than the article makes it sound. The satellite is moving very fast and has to hit an extremely precise target, but adding on another layer of complexity, the atmosphere and temperature differences effect the transmission.

mnw21cam 12y ago
Affect. The laser effects the transmission, but the atmosphere affects it. But not much. The laser was aimed with an accuracy of 0.01 degrees. Astronomical seeing (the distortion due to atmospheric disturbance) is on the order of an arcsecond, or 36 times smaller than this.
- kordless 12y ago
  > the atmosphere and temperature differences "caused or brought about" the transmission. Sometimes I wonder if the subtleties of English are worth the effort and frustrations of dealing with it day to day.
  - mnw21cam 12y ago
    Nonsense! It's wonderful fun.
- easytiger 12y ago
  Indeed, but the mount the projector and receiver on must be constantly calibrating movements and adjusting smoothly. In achievement terms this is almost all software (once you take putting stuff in space for granted). Think of proving it to work in theory, ground based prototypes etc. Error detection is also interesting (though mostly solved but with many options available). High bandwidth laser comms have been around for a while. Originally developed for the financial industry for intra city comms.
  - mnw21cam 12y ago
    To be honest, it's probably less difficult than the tracking that a compact disc player has to achieve to play an off-centre bent wobbly CD. The error correction would be fairly similar too. How long have CDs been around now?
bsilvereagle 12y ago
Kind of related fun fact, when astronauts take images of Earth they have to rotate the camera while taking the photo to compensate for the ISS moving so quickly. I think there are now computer controlled gimbals that account for that automatically.
- sitkack 12y ago
  Same as a sports photographer tracking a race car.

mnw21cam 12y ago

Affect. The laser effects the transmission, but the atmosphere affects it. But not much. The laser was aimed with an accuracy of 0.01 degrees. Astronomical seeing (the distortion due to atmospheric disturbance) is on the order of an arcsecond, or 36 times smaller than this.

kordless 12y ago
> the atmosphere and temperature differences "caused or brought about" the transmission. Sometimes I wonder if the subtleties of English are worth the effort and frustrations of dealing with it day to day.
- mnw21cam 12y ago
  Nonsense! It's wonderful fun.
easytiger 12y ago
Indeed, but the mount the projector and receiver on must be constantly calibrating movements and adjusting smoothly. In achievement terms this is almost all software (once you take putting stuff in space for granted). Think of proving it to work in theory, ground based prototypes etc. Error detection is also interesting (though mostly solved but with many options available). High bandwidth laser comms have been around for a while. Originally developed for the financial industry for intra city comms.
- mnw21cam 12y ago
  To be honest, it's probably less difficult than the tracking that a compact disc player has to achieve to play an off-centre bent wobbly CD. The error correction would be fairly similar too. How long have CDs been around now?

bsilvereagle 12y ago

Kind of related fun fact, when astronauts take images of Earth they have to rotate the camera while taking the photo to compensate for the ISS moving so quickly. I think there are now computer controlled gimbals that account for that automatically.

sitkack 12y ago
Same as a sports photographer tracking a race car.