Over the last 25 years, thousands of exoplanets have been discovered. The abundance of worlds outside our Solar System strengthens the case that life beyond Earth is certainly a possibility. To this end, astronomers have been working on catalogs of possible biosignatures, hallmarks that a planet might have life and is habitable.
NASA has now awarded a grant to study technosignatures, possible telltale signs of advanced technology on a planet that would indicate that an alien civilization is present. This will be the first grant focusing on technosignatures, not biosignatures, a work that could complement SETI’s decades of observations searching for alien signals.
“SETI has always faced the challenge of figuring out where to look,” project leader Professor Adam Frank, from the University of Rochester, said in a statement. “Which stars do you point your telescope at and look for signals? Now we know where to look. We have thousands of exoplanets including planets in the habitable zone where life can form. The game has changed.”
The team has selected two types of signatures to start with: solar panels and pollutants. The question they are asking is what solar panels or air pollution might look like from hundreds of light-years away. Light reflected off solar panels and pollution would leave “fingerprints” on the light bouncing off the planets. The team needs to understand what these signals will look like.
Astronomers can already study the atmosphere of giant planets orbiting close to their stars and have found many interesting worlds this way. In the near future, the atmosphere of Earth-sized worlds will be detectable and researchers will look for signs of oxygen and other signatures that may be key for life to develop and thrive.
The work is currently just theoretical but technosignatures could potentially be detectable by the next generation of observatories both on the ground and in space, such as the James Webb Space Telescope or the Extremely Large Telescope (ELT).
“In principle, it's possible that any instrument capable of detecting a biosignature could also detect a technosignature depending on the nature of the technosignature,” Professor Frank told IFLScience. “Detecting spectral lines of an atmospheric “pollutant” from a technological is the same idea as detecting one from a biospheric source. In practice the larger the telescope the better the chance of seeing fainter signals. The ELT class telescopes will give us sensitivity to do some very interesting kinds of studies.”
A recent estimation suggests that there may only be at most a few hundred technologically capable civilizations out there. This new research is just one of several ways to estimate how likely it is to find alien life. You can play with this cool alien civilization calculator, to see how such estimates work.