Somewhere in the galaxy, an advanced alien civilization may be harnessing the energy of its star.
NASA wanted to know if it could detect this activity.
The space agency has some powerful telescopes and is building more. As scientists increasingly look at other rocky Earth-like worlds, they assess whether it is possible to find signs of widespread solar farms on such distant planets. After all, alien societies need energy, and stars like our sun can provide nearly inexhaustible energy for billions of years. For example, human civilization has evolved from primarily burning wood to using coal, and now increasingly uses modern energy sources such as solar energy.
“We think this is a natural technological evolution that advanced civilizations can achieve,” said NASA planetary scientist Ravi Kopparapu, who led the study published in the journal Science. The Astrophysical Journaltells Mashable.
NASA scientists view the first Voyager images. What he saw made him shudder.
Solar panels are made from silicon, which is abundant in the universe, and are highly reflective. That makes giant solar arrays potentially attractive targets for NASA, which is working to determine whether life, whether microbial or complex, might exist on planets outside our solar system, known as exoplanets.
The researchers asked whether large space telescopes, such as the Habitable Worlds Observatory under development, could detect such solar power plants on worlds as far away as about 30 light-years (trillions of miles, but still relatively close) to the Milky Way. (approximately 100,000 light-years in diameter). Dubbed “Super Hubble,” the habitable world observatory will feature a mirror about 6 meters (nearly 20 feet) in diameter; the legendary Hubble telescope has a 2.4-meter (7.8-foot) wide mirror.
On Earth, researchers estimate that humans could meet all of their energy needs (plus energy storage, of course) by covering about two and a half percent of the surface with solar panels. If we assume that the population surges to 30 billion, this represents 9% of land cover. But how much of the surface of a distant exoplanet might need to be covered by these reflector arrays in order to be detected? The team simulated how Super Hubble would observe the technical features of these distant solar panels and found that 23% of the surface of an Earth-like world would need to be covered.
Mix and match speed of light
“That was huge,” Kopalap said.
This may be an unlikely scenario from the perspective of our species—although as discussed below, this may not be the case for other species. What’s more, another civilization might not need to generate large amounts of energy at all, so there would be no need to build huge energy-generating solar plants or buildings. Another civilization might have efficient technology, or have a smaller population. This would make widespread coverage of solar panels impossible.
“A civilization may not need as much energy as we think,” Kopalap said.
Concept illustration of what the Habitable World Observatory would look like as it gazes into the universe.
Image source: NASA Science Visualization Studio
Artist’s conception of an exoplanet with an advanced technological civilization.
Image credit: NASA/Jay Freidlander
It’s conceivable, however, that an intelligent species on a rocky desert world like Mars might choose to cover large swaths of its landmass with solar panels. It could see it as the best renewable energy option, especially in a world that may lack significant amounts of hydropower. Or it might have a reason we can’t imagine.
“We can’t tell what a civilization’s motivations are,” Kopalap points out.
“We can’t tell what a civilization’s motivations are.”
In addition to solar panels, some scientists have been thinking about the possibility of building giant structures around stars for decades, harnessing massive amounts of their energy. Of course, these behemoth energy harvesters known as Dyson spheres may not be the most practical approach to technological advancement.
Vincent Kofman, a NASA research scientist who also worked on the technology signature, said in an agency statement: “A society that can place huge structures in space will certainly be able to adopt nuclear technology.” Fusion or other space-saving ways to generate electricity (Humanity is looking at nuclear fusion energy – although realizing this technology is still a long way away.)
TRAPPIST-1 Conceptual image of the solar system, which contains seven rocky worlds about 40 light-years from Earth. Some may be habitable.
Image credit: NASA/JPL-Caltech
Future telescopes, such as the Habitable World Observatory, will search for many possible signs of life—and such studies can give scientists an idea of what they might be looking for. They will look for signs of pollution, atmospheric components that produced life, and perhaps other forms of technology. Although testing solar panels currently seems unlikely, the possibility cannot be ruled out. In the search for potential civilizations—which may be rare or even nonexistent in any galaxy—almost anything is possible.
Who knows what large, powerful instruments might detect many light-years away.
“They might even find city lights,” Kopalap said.
