If a radio telescope ever intercepts a message from an alien life-form, is there a protocol in place? Or will we humans just have to figure it out as we go?
The answer may come as a relief: Scientists have thought this through carefully. Seth Shostak, senior astronomer at the Search for Extraterrestrial Intelligence Institute, said there actually is a loose outline in place.
It's not an officially sanctioned plan. There isn't any kind of "United Nations for alien communication," he explained. It's more of a "gentleman's agreement" about what SETI researchers should do if they pick up a signal from E.T., and it's a pretty simple series of steps.
So what will we do if we pick up an alien signal?
Step 1: Confirm it's really an alien signal. The first step is to confirm that whatever we've picked up really is coming from aliens. We'd have to double-check it's not just interference from Earth satellites or radios.
"That's just good science," Shostak said.
Step 2: Tell everybody. Telling everyone is inevitable, Shostak said. When false alarms happen, SETI researchers get a taste of how the real thing might play out. The first thing that happens is media outlets immediately start calling.
"There's no secrecy in this business," Shostak said.
Plus, getting the word out is actually an important part of the first step. We'll need the giant telescopes in countries around the world to help confirm the signal is authentically alien.
Step 3: Don't reply until consulting with the rest of the world. This part of the agreement was originally added because of the Cold War, Shostak said. The U.S. and Russia wanted peace of mind that neither would try to monopolize alien communications.
But it naturally feeds into the other two steps. If everyone already knows, they'll likely expect to have a say in how we respond.
How will we know if the aliens are friendly or not?
The short answer: We won't.
There's a distance problem. If we picked up a signal from a star system 1,000 light-years away, that signal is 1,000 years old. The same life-forms that sent the signal probably aren't even there anymore, Shostak said.
"Then if you grab the mic, it takes another thousand years before your reply gets there," Shostak said.
There's a technology problem. Just figuring out that aliens exist would be huge, but the first thing people will ask is "What are they saying?" and "What do they look like?"
"The challenge will be turning that discovery into learning something about them," Shostak said.
The kinds of instruments we have for listening for signals are nowhere near powerful enough to actually decode those signals or assign any meaning to them. We'd have to build something much larger and more advanced first, Shostak said.
If we pick up a signal, should we reply?
This is a hotly debated subject. On one hand, we might learn a lot if we get in touch with aliens. On the other, they might decide to come vaporize us.
Shostak has an interesting way to look at it.
If a society has the technology to travel that far across the cosmos, it has almost certainly already intercepted the telecommunications signals coming from Earth.
"We're already telling them we're here," Shostak said.