On March 3rd, last Sat. night at about 7:30 pm Central time, the local astronomy clubs of San Antonio (SAAA) and Austin (AAS) flashed lights that were observed by astronauts Don Petit and Dan Burbank aboard the ISS. 

This is a first, as far as we know, though others have tried before to signal astronauts (and probably cosmonauts) with light, but failed.

We used two relatively small searchlights and a blue 1000mw laser (445nm).  Both the lights and the laser beam were easily seen by the astronauts.  During the 6 minute (approx.) event, Don Petit had planned to contact us from the ISS using..... a cell phone.  [I guess they have nice reception up there. :)]  But Don was too busy taking pictures to call us.

We learned the next morning that the light was easily seen by them, and they sent pictures to prove it.  [The "flash point" (pun unintended) is up and left of center.]

Did you guys have a schedule coordinated with them to look for this?  Were you able to communicate by radio or the Internet?

That's great to hear about this! I work in aerospace (jet engines), but my father has worked on the Space Shuttle program and/or the Space Suit since 1974.  I've always been fascinated with the space program, and hope that we will see more experimentation in space in the future.

Did you guys have a schedule coordinated with them to look for this?  Were you able to communicate by radio or the Internet?

The key to this entire event is the relationship that one of our local astronomy club members, Robert Reeves (astrophotography author) has with astronaut Don Pettit.  Don has relied on Robert to assist him in his photography taken from space.

From this relationship came Robert's idea to do this flash experiment, which had been tried, apparently, by others, but never successful, according to a blog from Don.

Keith Little, our marketing director and excellent leader, helped stir interest in this idea with our club, SAAA (San Antonio Astronomical Assoc.).  We also involved the AAS (Austin Astronomical Society), who joined us in this event.

I enjoy doing magnitude calculations and found that conventional lighting would require about 50 kw of light in order for our light to be seen as a 0 magnitude star.  [Most lights are designed with wide dispersion angles to illuminate the near, not the far.]  This prompted me to find a search light company to assist us, and we were extremely fortunate to find Sky-View, who not only donated two lights, but also has very low dispersion beams (~ 1.7 deg.).  These lights alone put us close to -5 in apparent magnitude, based on my rough calculations. 

Glare, however, seems to be the biggest culprit in seeing flashing events from the ISS, according to Don.  The ISS appears bright to us from the ground because it is still in sunlight, which causes a great deal of glare.  This problem was not realized by me until a week before the event.  I thought, perhaps, that a colorful spot of light from a laser might help us cut through the glare.  On Monday, before the event on Saturday, I eventually found a laser supplier, Wicked Lasers, that had a 1000mW laser in stock -- all others I talked to had to order from China.  Their blue laser is < 1/3rd the cost of their green one, so I went blue.  [I emailed Don and claimed that I did not choose green because I did not want to make him look sick. *wink*]

Unfortunately, there was no offer to assist my pleas to get the laser shipped overnight or 2nd day air.  The laser did finally arrive just hours before the event and I mounted it upon a special gun two employees of mine constructed earlier in the week. It wasn't aligned to the gun scope until about 10 minutes before the event.

Ron, with Sky-View, joined our club in membership and brought two lights to the event.  [I trusted Ron to attend without having secured a light days before the event.  This caused some trepidation by some.]

Much of what took place during the event itself can be seen by this simple video:

http://www.youtube.com/watch?v=2UoY15WDuHQ&feature=youtube_gdata

It was not until Sunday morning that we heard from Don and Dan -- Dan Burbank (commander) also joined Don in watching for the flashing -- as to whether or not we were seen.  They both had to stay-up late to see us.  [The ISS is on GMT, so they both stayed up late (1:30 am) to see our 7:30 pm flash.]  The plan was for Don to call us on his cell phone during the event, but Don was anxiously taking pictures to confirm the success.  He attempted a call when he was a bit too far out of range. 

Once we got the news that we were successful, we were all thrilled and the news spread quickly.  The dramatic shot taken by Don helped the news on the web go somewhat viral, so there are many links of the event if one Google's.

Of course, it would not be hard to construct a device that could be used by those on the ISS that would the reception of a ton of information if we took advantage of the laser beam as a carrier, and vice versa.

Thanks!  The project was not an advancement for hard science, but such things can help to stir interest in science.  Our local astronomy club has had, at times, over 1,000 people, mostly youngsters, at individual, pro-science events, and the recent "first" with our ISS contact will add spice to our presentations.