How to Communicate with Astronauts Aboard the ISS

Have you ever wanted to ask an astronaut a question, or just talk to one in general? Wouldn’t it be cool if you could speak to an astronaut even as they were floating on the ISS in space, looking down on Earth? It’s not actually difficult to do just that. All you need is ham radio.

Amateur Radio on the International Space Station Program

Believe it or not, a space station as advanced as the ISS is still equipped with amateur radio equipment. It has a dedicated program for making contact with the station, called the Amateur Radio on the International Space Station (ARISS) Program. It’s a cooperative international program that includes amateur radio organizations world wide, as well as official space agencies like NASA. Basically, it just means that the ISS is ready and willing to receive radio transmissions from you!

Of course, you will need several things in order to contact the astronauts aboard the ISS.

To contact the ISS using ham radio, you’ll need an antenna, transceiver, and a radio license. Specifically, you’ll need a VHF/UHF dual-band transceiver capable of sending or receiving transmissions on both 2 meter and 70 centimeter bands. You technically don’t need a specific antenna, but you’ll want with with a wide area of coverage, like an omni-directional base antenna.

You’ll also need a license allowing you to operate a ham radio, which is managed by the Federal Communications Commission in the United States. There are three license classes, but even the most basic one will allow you legally communicate with the ISS. An examination is required to get a radio operator license.

You’ll may also need to register for scheduled contact opportunity in advance of trying to make contact with the ISS via the official ARISS website.

If you don’t want to acquire all of this equipment and the license yourself, you can always look to join an amateur radio club, which will usually have everything you need. You can also start your own club, though you’ll still have to procure equipment and a license in that case.

Once you have access to the required license and equipment, it’s time to try and make contact with the ISS. To start, understand that you’re not guaranteed to get through to the astronauts up there, though it’s not because they don’t want to talk to you! The ISS orbits the Earth at around 17,500 miles per hour, so your contact window when it passes over your area is only a few minutes long.

There may be other ham radio operators trying to contact the ISS at the same time as you as well, so you may be competing for a shot to talk. On top of that, you just might get unlucky and not get a solid transmission during your window of opportunity. But don’t worry too much—the ISS orbits the Earth about every 90 minutes, and even if you don’t get the chance to speak to them directly, you can tune in to conversations that another operator may be having with the ISS.

Still, you probably want the chance to talk directly to the astronauts up there on the station. To do that, there are several steps to follow, though bear in mind that there’s never a guarantee of making successful contact. You may have to try multiple times in order to hold a short conversation with someone aboard the ISS.

Determine When the ISS Will Pass Over Your Area

The radio range of the ISS is changing constantly during its 90-minute orbit of the Earth. To make contact, you need to know when it’s going to pass over your area for the best chance of getting a transmission through. There are websites that track the ISS as it orbits and predict the areas it will pass over, such as ARISS.org or Heavens-Above.com. Check these and use them to estimate your window of opportunity to make contact.

Ensure You’re Using the Right Frequency

If the ISS is going to pass over your area, you’ll want to turn on your radio equipment about 15 minutes ahead of time. That way, you can get everything situated and not eat into your window of opportunity setting things up. The ISS uses UHF and VHF amateur radio bands, so you’ll need to tune to the right frequency to contact them. The most common frequencies are 145.800 MHz for voice contact and 437.800 MHz for packet radio contacts.

If you’re on the right frequency, the next thing to do is just wait and listen for radio signals. Because the ISS travels so quickly, its radio signal will fade both in and out quite quickly. Because of this, the best time to make contact is when the station is as close to directly overhead as possible. If an astronaut is transmitting from the ISS, they’ll be using the call sign NA1SS. If you hear that call sign, you have a shot at speaking directly to someone on the station.

Send a Transmission

If you have a license at this point or are part of a radio club, you will almost definitely know the proper radio etiquette when contacting the ISS. Regardless, if you hear a transmission from an astronaut aboard the ISS, make sure you wait for them to stop transmitting before sending your own call sign and make sure you use the phonetic alphabet (Bravo for B, Whiskey for W, etc.)

Now, even if your transmission is received, this doesn’t necessarily mean that the astronaut manning the radio will respond directly to you, though sometimes, they do call for any available station to contact them. If you are invited to contact them or they respond directly to you, be sure to include your name and location in your transmission alongside whatever else you want to say. Your transmissions will need to be brief, generally under 10 seconds.

What Are You Allowed to Say to the Astronauts?

There’s not really a strict set of rules on what you are and aren’t allowed to say to the astronauts onboard the ISS when you make contact. But generally speaking, the goal is to be polite and avoid controversial or antagonistic topics. You probably won’t be talking to the astronaut for very long if you go out of your way to offend them, or if you try to rope them into some hotly contested topic they don’t want to talk about.

After all, the astronauts aboard the ISS are government employees, and notable ones at that. They’re not going to talk about anything that will get them in trouble. Instead, focus on lighthearted conversation or asking questions about their job, their daily routine, or even what they are up to at the exact time you’ve managed to contact them. They’ll probably be more than happy to talk about those things.

For an amateur radio operator, making contact with the ISS may be one of the most exciting things you can do. With the right equipment and procedures, it’s not even that hard to do either, requiring just a bit of patience and luck. Get the right gear, figure out when your next window of opportunity is coming, and start thinking of the things you’ve always wanted to ask an astronaut!