in New paper Published in Astrophysical JournalDr. Ravi Kopparapu of NASA’s Goddard Space Flight Center and colleagues assessed the detectability of silicon solar panels on Earth-like exoplanets as potential technological signatures.
Conceptual illustration of an exoplanet with an advanced extraterrestrial civilization. The structure on the right is an orbiting solar panel array that collects light from the parent star, converts it into electricity and transmits it via microwaves to the surface. The exoplanet on the left shows other potential technological features: on the night side there are city lights (the glowing circular structures), and on the day side there are multi-colored clouds representing various forms of pollution, such as nitrogen dioxide gas from the burning of fossil fuels and chlorofluorocarbons used in refrigeration. Image credit: NASA/Jay Freidlander.
“The search for extraterrestrial life has primarily focused on detecting biosignatures – remote observations of atmospheric or ground-based spectral properties that indicate signs of life on exoplanets,” said Dr Kopparapu and his co-authors.
“Recently, there has been a rise in interest in technosignatures, which refer to observational signs of extraterrestrial technology that can be detected or inferred through astronomical surveys.”
“While the search for extraterrestrial intelligence through radio observations has been popular for decades, recent studies have proposed an alternative: searching for technological signatures in the ultraviolet to mid-infrared spectral range.”
Astronomers speculate that extraterrestrials might build solar panels out of silicon because it is relatively abundant compared to other elements used in solar power generation, such as germanium, gallium, and arsenic.
Silicon is also excellent at converting light emitted by stars like the Sun into electricity, and it is cost-effective to mine and manufacture into solar cells.
The researchers also assume that a hypothetical extraterrestrial civilization would rely solely on solar energy.
However, if other energy sources, such as nuclear fusion, were used, the technological signature of silicon would be diminished, making the civilization even more difficult to detect.
Furthermore, they assume that the population of the civilization will stabilize at some point, and if for some reason this does not happen, they may end up expanding the Eternal Father into deep space.
For the study, scientists used computer models and NASA satellite data to simulate Earth-like planets with different degrees of silicon solar panel coverage.
They then modeled an advanced telescope, like NASA’s proposed Habitable Worlds Observatory, to see if it could detect the solar panels of a planet about 30 light-years away, a relatively close galaxy that is more than 100,000 light-years across.
The researchers found that hundreds of hours of observation time would be required with this type of telescope to detect signals from solar panels covering about 23% of the land area of an Earth-like exoplanet.
However, the solar panel coverage needed to support 30 billion people with a high standard of living was only around 8.9%.
“We find that even if the current population of around 8 billion were to stabilise to a high standard of living of 30 billion and run solely on solar energy for power, it would still use far less energy than the total amount of sunlight illuminating the Earth,” Dr Kopparap said.
The research has implications on the Fermi Paradox, proposed by physicist Enrico Fermi, which asks why extraterrestrial civilizations have not spread across the galaxy by now, given that our own Milky Way galaxy is ancient and vast, making interstellar travel difficult but possible.
“This suggests that if a civilisation chooses a very high standard of living, it may not feel the need to expand across the galaxy because it can achieve sustainable population and energy use levels,” Dr Kopparap said.
“They may expand within their own star system, or neighboring star systems, but there may not be a galaxy-wide civilization.”
“Furthermore, our own technological expertise may not yet be able to predict what more advanced civilizations will be able to achieve.”
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Ravi Kopparap others2024. Detectability of Solar Panels as a Technology Signature. ApJ 967, 119; doi: 10.3847/1538-4357/ad43d7
This article is based on a press release provided by NASA.
Source: www.sci.news
