Light (top center) flashed from the Lozano Observatory, about 40 miles north of San Antonio, was easily visible from orbit. Click on the image to see it full-sized.
Radio amateur and ISS astronaut Don Pettit KD5MDT describes how he succeeded in receiving signals on a frequency of 650 THz.
Flashing the International Space Station with beams of light as it passes overhead had never been successfully done—until now.
It sounds deceptively easy. In an earlier post I wrote about the technical requirements. But like so many other tasks, it becomes much more involved in the execution than in the planning.
Early Sunday morning, at 01:27 our time, the San Antonio Astronomical Association, an amateur astronomy group, succeeded in flashing space station with a one-watt blue laser and a white spot light as we passed overhead. This took a number of engineering calculations. Projected beam diameters (assuming the propagation of a Gaussian wave for the laser) and intensity at the target had to be calculated. Tracking space station’s path as it streaked across the sky was another challenge. I used email to communicate with Robert Reeves, one of the association’s members. Considering that it takes a day, maybe more, for a simple exchange of messages (on space station we receive email drops two to three times a day), the whole event took weeks to plan.
I was ready with cameras for the early morning San Antonio pass and can report that it was a flashing success. Here’s one of the pictures to prove it.
AMSAT-UK 
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