If there’s an advanced extraterrestrial civilization inhabiting a nearby star system, we might be able to detect it using its own atmospheric pollution, according to a new Nasa research.
The study looked at the presence of nitrogen dioxide gas (NO2), which on Earth is produced by burning fossil fuels but can also come from non-industrial sources such as biology, lightning, and volcanoes, The Independent reported.
While the evolution of a civilization that has developed to oil- or coal-based industries seems slim, the gas is also sourced from other materials including lightning and biological processes.
“On Earth, most of the nitrogen dioxide is emitted from human activity - combustion processes such as vehicle emissions and fossil-fueled power plants,” said Ravi Kopparapu of Nasa’s Goddard Space Flight Center.
“In the lower atmosphere - about 10 to 15 kilometers - NO2 from human activities dominate compared to non-human sources. Therefore, observing NO2 on a habitable planet could potentially indicate the presence of an industrialized civilization.”
Kopparapu is lead author of the paper on this research accepted by the Astrophysical Journal and published online on February 9 in arXiv.
Nitrogen dioxide gas could be what scientists call a “technosignature”, which is when there is presence of a gas that is released as a byproduct of an industrial process. This is similar to a biosignature, which are gases such as oxygen and methane produced by organic activity.
This study is the first time NO2 has been examined as a possible technosignature.
Due to the huge number of planets in the universe, as well as their distance, scientists need to use these indications - which can be measured at great distances - to determine which worlds are worth investigating.
Astronomers have found over 4,000 planets orbiting other stars to date.
Some might have conditions suitable for life as we know it, and on some of these habitable worlds, life may have evolved to the point where it produces a technological civilization.
Scientists used computer modeling to predict whether nitrogen dioxide could produce a signal that is able to detect with current and future telescopes.
The gas absorbs some colours of visible light, meaning that it can be measured by observing light reflected from the planet.
A planet similar to the Earth could be detected up to 30 light-years away over 400 hours using a large Nasa telescope; while this is a huge amount of time to study a single planet, it is not unprecedented.
Nasa’s Hubble Telescope took a similar amount of time for the Hubble Deep Field Observations which has helped scientists’ study dark matter.
