A Flashing Success

A group of San Antonio astronomers shine a light visible from orbit

(Don Pettit)

Flashing space station with beams of light as it passes overhead had never been successfully done—until yesterday.

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 the space station with a one-watt blue laser and a white spotlight 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:

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.

About Don Pettit
Don Pettit

NASA astronaut Don Pettit is an engineer by schooling, a scientist by profession, and an explorer by heart. He trains to fly in space and on occasion, finds himself in orbit. Don blogged for Air & Space during his stay on the International Space Station in 2011-2012.

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