Alien Megastructures Ruled Out? Not Yet.

The SETI Institute didn’t find evidence for E.T.s, but scientists want to look again with a bigger and better telescope

Could there be aliens around the star KIC 8462852? You may either be relieved or disappointed to find out that the Allen Telescope Array scanned the star for evidence of advanced civilizations, and has come up empty.

The star attracted a lot of attention last month after researchers reported an odd phenomenon happening there. Located 1480 light-years away, the star sometimes dims by up to 20 percent–that’s a much larger shadow than a planet could cast. And the dimming happens at an irregular pattern, too.

Trying to explain these weird effects, scientists have come up with a variety of hypotheses. Could it be a family of comets? Does the star have a distorted shape that’s bending the light? One team went so far as to suggest the dimming could be caused a huge structure built by aliens. These are serious, legitimate scientists we’re talking about. So the SETI (Search for Extraterrestrial Intelligence) Institute turned its Allen Telescope Array toward KIC 8462852 to find out.

“Although it’s quite likely that this star’s strange behavior is due to nature, not aliens, it’s only prudent to check such things out.”

“The history of astronomy tells us that every time we thought we had found a phenomenon due to the activities of extraterrestrials, we were wrong,” astronomer Seth Shostak from the SETI Institute said in a press release. “But although it’s quite likely that this star’s strange behavior is due to nature, not aliens, it’s only prudent to check such things out.”

The array of 42 radio dishes listened for two kinds of signals from the star, which scientists are informally calling “Tabby’s Star.” The first is a narrow-band transmission which alien civilizations, if they’re out there, might use as a beacon to say, “Hey, we’re over here.” The second was a broad-band signal that might be produced if the hypothetical alien civilization propels its spacecraft using microwaves.

The telescopes scanned frequencies between 1 and 10 GHz, but detected no evidence of aliens.

But the investigation is likely not over yet. The proponents of the ET hypothesis–astronomers Tabetha Boyajian, Jason Wright, and Andrew Siemion–had also hoped to listen to the star’s radio emissions. But they would do it in a different way.

Green Bank Telescope

The Green Bank Telescope is the world’s largest fully steerable radio telescope.

Thanks to a big investment from Silicon Valley’s Yuri Milner, the Green Bank telescope in West Virginia is getting some upgrades. Next year it will be testing out some new equipment that could result in the largest ever search for extraterrestrial life. The equipment will be able to scan 1.5 billion frequencies at once.

“The [Allen Telescope Array] results do not change our plans at Green Bank,” Wright told Popular Science in an email. “The Green Bank telescope is thousands of times more powerful than the ATA, so it will be able to make much more sensitive measurements than the ATA can.”

Siemion adds: “It also covers a much wider bandwidth (up to 115 GHz) and can search for a much broader range of signal types.”

Wright, Boyajian, and Siemion aim to use Green Bank’s state-of-the-art equipment to look for radio signals that alien technologies might accidentally give off, just like our electronics here on Earth give off a distinct radio signal. Perhaps the broader approach will turn up some interesting results–or perhaps not.

Although it would be impossible to prove that there are no aliens in that sector (there’s always the possibility that we’re just not looking for the right signals), the best science can do is take a look using the best instruments available.

Update 11/6/2015 at 3:40 pm ET: This post was updated with quotes from the researchers.