A young American scientist searching for intelligent aliens across the seven Earth doppelgängers that circle the red dwarf star TRAPPIST-1 says that if this wondrous solar system holds an advanced space civilization, its own stargazers could be scanning the Earth in a mirror search mission.
Nick Tusay, who headed a study titled "A Radio Technosignature Search of TRAPPIST-1 with the Allen Telescope Array," tells me in an interview that although his team hasn't yet discovered any composed radio messages sent out from the TRAPPIST-1 planets, that doesn't rule out the existence of a spacefaring society there.
Tusay is a graduate researcher at Penn State University and its Extraterrestrial Intelligence Center, and teamed up with astronomers across the U.S. to look for narrowband radio transmissions beamed between the TRAPPIST-1 planets that might have "leaked" across interstellar distances, including to Earth.
"There could be a million mundane reasons we didn't detect anything that don't preclude the existence of an advanced civilization on one of the TRAPPIST-1 planets," Tusay says.
If there were a technologically advanced civilization on one of the TRAPPIST-1 planets - roughly equivalent to Earth's current space-tech level - could its radio astronomers detect NASA's Deep Space Network transmissions, and interpret that as evidence of an Earth-based extraterrestrial intelligence?
"It depends on how powerful their receivers are, and whether TRAPPIST-1 lines up with any signals we are sending out," Tusay says.
"Certainly we are leaking signals all the time, but you would need an extremely sensitive telescope to detect our leaked emission."
When the powerful Square Kilometer Array Observatory - a massive network of interconnected radio astronomy telescopes that stretches from South Africa to Australia - becomes operational, he adds, astronomers here will be able to detect even fainter signals from TRAPPIST-1 or other Earth analogs that might in turn hold scientists conducting their own SETI searches for intelligent off-worlders.
And TRAPPIST-1 astrophysicists equipped with a SKA-level web of telescopes would be able to detect radio transmissions by NASA if beamed in the direction of that star, he says.
Sofia Sheikh, a vanguard astronomer and astrobiologist at the California-based SETI Institute who co-authored the "Radio Technosignature Search of TRAPPIST-1" paper, told me in an interview: "TRAPPIST-1 is close enough that a 2020 Earth-level technological species could detect a Deep Space Network-scale transmitter at the distance of the Earth as long as they had a telescope equivalent to the near-future Square Kilometer Array."
If these Earth-transmitted radio messages were picked up by TRAPPIST-1 scientists conducting their own SETI searches, Dr. Sheikh says, they would quickly be characterized as the tech-powered communications of an alien civilization.
The Square Kilometer Array is composed of hundreds of dishes and thousands of antennas, which combined will become the most advanced radio telescope on the planet, its organizers say.
Jill Tarter, an astronomer who has been at the global forefront in conducting scans for signs of intelligent outposts across the galaxy, tells me in an interview that the SKA Observatory will help scientists zoom in on potentially habitable Earth-size planets.
These searches are aimed at discovering cosmologists and coders, along with designers of super-advanced telescopes and space capsules, orbiting alien stars.
In one of her fascinating studies, "NASA and the Search for Technosignatures," Tarter mused that when the new SKA observatory comes online, that will mark the first time the human race will have technology that is advanced enough to find a doppelgänger of itself on another star system.
Dr. Tarter, the superstar space scientist whose groundbreaking searches for aliens across the cosmos inspired Carl Sagan to write his book-turned-film Contact, told Wired magazine in an earlier interview that if two or more of the seven planets revolving around TRAPPIST-1 turn out to have remarkably identical atmospheres and surface temperatures, that would be a powerful sign that a spacefaring contingent on one of these Earth doubles had successfully terraformed, or re-engineered, an entire nearby TRAPPIST globe to colonize it.
Back on Earth, leading-edge space-tech leaders, including Elon Musk, have proposed terraforming Mars, or recreating it in the Earth's image, and Robert Zubrin, founder of the Mars Society, has written a series of futuristic handbooks outlining the geo-engineering, geodesic domes and extraterrestrial architecture that would push forward Mars being terraformed - with its ocean and atmosphere revived and surface temperatures raised - and settled as a new branch of a hyper-tech human civilization.
When Mars is completely terraformed - into a close clone of the Earth - that would present unmistakable evidence to astronomers across this section of the galaxy that our solar system hosts a sophisticated spacefaring and planet-changing species.
If the TRAPPIST-1 solar system, with multiple planets in the habitable zone of its M dwarf star, turns out to be currently uninhabited, could it become a magnet for ingenious spacefarers from another solar system who might regard TRAPPIST-1 as a perfect New World that could be terraformed and settled as a multi-planet colony?
"It's a fascinating idea," says Nick Tusay.
"The TRAPPIST-1 system is particularly unique and interesting for a number of reasons. It has multiple planets, all about the same size, in resonant orbits (evenly spaced), around a very small star that will last a long long time by stellar standards."
"Such small stars tend to be quite active and volatile," Tusay points out, "but maybe that wouldn't be such a problem for an advanced civilization looking for a new place to set up shop, just a problem for life getting started."
While humanity might find a new sanctuary on Mars as it is terraformed, ultimately the globe's denizens will need to find another haven in the heavens - within about one billion years, say NASA scientists.
"Earth will become uninhabitable for higher forms of life in a little over 1 billion years, as the Sun grows warmer and dries our planet," NASA researchers report via the agency's official website.
"Stars slightly cooler than our Sun - called orange dwarfs - are considered better for advanced life. They can burn steadily for tens of billions of years," the NASA scientists add.
"The even more abundant star type called red dwarfs (also known as M dwarf stars) have even longer lifetimes" that can stretch out for more than 100 billion years.
Red dwarfs account for nearly three-quarters of the Milky Way's 100 billion stars, so if humanity begins discovering Earth-like twins around these tiny suns, in the habitable zone and with an oxygen-rich atmosphere and oceans, they might present an archipelago of potential oases scattered across the galaxy.
Yet red dwarfs typically have violent early lives, sending out extreme levels of X-ray and ultraviolet radiation that can strip away the primary atmospheres and oceans of close-by planets, NASA scientists say.
Yet Michael Gillon, the Belgian-based astrophysicist who initially discovered the TRAPPIST-1 star system, says there is a spectrum of scenarios in which at least some of its planets could have retained part of their oceans, and generated a secondary atmosphere that would safeguard its habitability.
In a recent study, "TRAPPIST-1 and its compact system of temperate rocky planets," Professor Gillon says: "TRAPPIST-1 is exceptional on many levels. It is indeed the system with the largest number of Earth-sized planets."
Although the TRAPPIST-1 star has emitted high-energy super-flares, he notes, it planets might have formed far beyond the ruddy red sun, and only later migrated inward, escaping the most intense period of radiation.
Telescopic observations suggest its outer planets might feature "an Earth-like composition enhanced in light elements, such as a surface water layer."
"Rocky planets around low-mass M-dwarfs," he adds, could start out with oceans that are "orders of magnitude larger than the Earth whose outgassing could ... maintain a significant secondary atmosphere in a steady state."
More extensive studies of TRAPPIST-1 with the Webb Space Telescope are essential, Gillon says, because it could be a model for the billions of other red dwarf solar systems in the Milky Way alone.
"In this context," he posits, "the TRAPPIST-1 system represents a unique laboratory to assess the capacity of Earth-sized terrestrial planets in short orbits around a late-type M-dwarf to maintain a significant atmosphere, and to develop habitable surface conditions for those orbiting in the circumstellar habitable zone."
"Detecting an atmosphere around any of these 7 planets," he says, is of fundamental importance "to determine if low-mass M-dwarfs, the larger reservoir of terrestrial planets in the Universe, could truly host habitable worlds."
So could it turn out that TRAPPIST-1, with three of its globes in the perfect-temperature habitable zone of the star, and potentially studded with oceans, might provide a New Eden-like refuge for Homo sapiens lifting off from an overheated Earth one time in the far future?
"While TRAPPIST-1 is a remarkable system," says Sofia Sheikh, "I think we'll need to further characterize its planets' atmospheres before we have any sense of whether it hosts any habitable worlds."