Now—if you catch a lucky window—you can video chat with the International Space Station.

Amateur radio enthusiasts have set up a “ham TV” system—the video counterpart to amateur or “ham” radio—from which folks on Earth can get video and sound from the space station. Astronauts aboard the space station, meanwhile, are able to hear (but not see) their Earth callers and respond.

Actually making the call takes a bit of planning. The connection only works if the space station has a clear line of sight. The longest window of time a caller has is 20 minutes, and that’s only if five portable ground stations are positioned in just the right way. So, sadly, unlike with ham radio, it would be difficult for anybody to call into the ISS at any time. Instead, interested parties should contact the Amateur Radio on the International Space Station group, which helps set up calls for classrooms, museums and space camps.

Of course, ham radio operators have always been able to hail the space station using readily available equipment. The ISS’ orbit is well within range of radio waves. Whether an astronaut will pick up at the time you call is another question.

The ham TV hardware was designed by an Italian engineering company called Kayser Italia and assembled by the Amateur Radio on the International Space Station group. There’s equipment that’s housed in the space station, plus ground equipment and antennas. The Amateur Radio on the International Space Station group manages the antennas.

On April 12, ISS staff confirmed ham TV is ready to take general calls. So far, it has tested its abilities in a call between NASA astronaut Mike Hopkins and ground stations in Italy.

European Space Agency