The Search for Extraterrestrial Intelligence is bigger than ever, thanks to a big cash infusion from Russian billionaire Yuri Milner. That $100 million, decade-long Breakthrough Listen initiative could put us on the cusp of finding out if we're alone in the universe.
For Margaret Turnbull of the SETI Institute, it's a welcome breath of fresh air for SETI.
"I'm anxious to see the SETI search become more methodical in conducting and publishing well-designed search programs,” she says. "Breakthrough Listen will help enormously with that."
In some ways, though, it's a fairly traditional search. They're looking in specific areas of the radio spectrum for hints of stray alien signals, kind of like what's seen in Contact. But there are other ways to hunt for aliens, some of which have yet to be explored.
Andrew Siemion, director of the Berkeley SETI Research Center, says that a wider radio search beyond the so-called "hydrogen line" (which is where the most abundant element in the universe "broadcasts," and is a smart bet for finding stray radio signals) will require more computing power. Once that's in place, a radio telescope might be able to tune into radio signals across the entire broadcast spectrum.
He also says that at the end of the Breakthrough Listen initiative in 2025, the Square Kilometer Array will open up shop in South Africa. This will be the widest radio telescope array when it opens and one of the most precise when it begins operation in 2020, combining 250 dishes while leaning on other facilities for a little extra oomph. It will also have the computing power to match. It will make spying on other planets easier than ever.
"This next-generation facility will be the first telescope capable of detecting Earth-level leakage from nearby stars," Siemion says.
He also mentions another type of SETI research still in its infancy: optical SETI. This involves looking for light beacons from other civilizations. A paper published last year in Publications of the Astronomical Society of the Pacific identified more than 200 possible candidates, but the claims weren't taken very seriously.
Optical SETI actually stretches back decades. Even before the possible (but not suuuuper likely) "alien megastructure" candidate known as Boyajian's Star or Tabby's Star, there were several searches for similar megastructures. One particular example was in 1980, when astronomer Frederick Witteborn then of the University of Arizona looked for Dyson Spheres around 20 nearby stars.
"I was hoping that we would eventually be able to compare such spectra with ‘Dyson sphere' candidates if any were ever found in infrared surveys," Witteborn says. "Dyson spheres would presumably need to radiate efficiently in the thermal infrared and so would be relatively featureless, but would exhibit a smooth peak in this region."
But in the end, none were found.
Still, that area of research could yield results in the coming decades by "searching very wide fields-of-view with many beams on the sky," Siemion says. "At optical and infrared wavelengths, we will extend our current searches spatially, temporally and spectrally."
One researcher has an intriguing idea for looking for aliens by peering into our own backyard. While admitting it's a far-out possibility, Abraham 'Avi' Loeb of Harvard University suggests that we could look for lights or exhaust from a probe passing through. (We just, of course, had a close encounter with an alien asteroid, so we're getting visited by interstellar objects already.)
Loeb suggests looking in or beyond the Kuiper Belt, the same region of space where Pluto resides.
"The outer parts of the solar system have two advantages: they occupy the biggest region around the sun, so the probability of passing through them is higher than the inner solar system," Loeb says. "There's also no reason to go in closer something something gravity well."
Right now, no telescopes are capable of hunting for those directly, though he suggests an indirect search (like a sky survey that takes several pictures of the night sky over succeeding nights) could find something interesting worth a follow-up. And next generation telescopes might be up to the task.
"If you monitor the flux from the objects as it changes distance from the sun, then you would be able to tell," Loeb says. "Surprisingly, a city like Kyoto produces enough light to be seen all the way from the Kuiper Belt."
Of course, next generation telescopes may be able to find habitable worlds through simpler means: by looking at planets. Some of it will be merely looking to see if they have atmospheres to match our own. But Loeb thinks we may be able to tell if they're harvesting vast amounts of sunlight.
Most planets on the two dozen or so list of "habitable" worlds (in the right place for water to be liquid) are around red dwarf stars. These are small, highly active stars, and any habitable planet is so close in that the same side always faces a star. While the red dwarf's flares may strip away an atmosphere, if it doesn't, this "hot" side may be the perfect place to build an array of solar panels and move heat and energy to the other side.
"That would be at a different wavelength than vegetation," Loeb says. "Such electronic devices have a special band or a particular wavelength over which the spectra changes."
If we detect something, Turnbull says it will answer questions about how aliens communicate with each other. She says we should look at animals on Earth — "especially in collective 'hive' minds" and that we should look out for senses that some animals have that humans lack, as well as the nature of memory.
"To me, all of this hints at how limited we are in the way we look at the universe, and pondering this deeply could help us think about ways to broaden our search for intelligence elsewhere," she says.
However we find aliens — beacon, radio wave, probe, or megastructure — there's a bright future for the hunt. We just need to equip ourselves with the next generation tools to do so. And as SKA and upcoming massive telescopes demonstrate, many of those are on the way.