Astronomers are standing on a “great threshold” of space exploration that could see evidence of extra-terrestrial life being discovered in the next 20 years, an expert has claimed.
Life beyond the Earth seems “inevitable” given the immensity of the universe, according to US planetary scientist Sara Seager.
In the coming decades, chemical fingerprints of life written in the atmospheres of planets orbiting nearby stars could be found by the next generation of space telescopes.
Writing in the journal Proceedings of the National Academy of Sciences, Seager, from the Massachusetts Institute of Technology (MIT), said: “We can say with certainty that, for the first time in human history, we are finally on the verge of being able to search for signs of life beyond our solar system around the nearest hundreds of stars.”
Astronomers now know that statistically, every star in our galaxy, the Milky Way, should have at least one planet, and small rocky worlds like the Earth are common.
“Our own galaxy has 100 billion stars and our universe has upwards of 100 billion galaxies – making the chance for life elsewhere seem inevitable based on sheer probability,” said Seager.
In the next decade or two, a handful of ‘potentially habitable’ exoplanets will have been found with atmospheres that can be studied in detail by sophisticated space telescopes.
The first of these ‘next generation’ telescopes will be the American space agency Nasa’s James Webb Space Telescope (JWST) due to be launched in 2018.
Studying a planet’s atmosphere for signs of life involves capturing starlight filtering through its gases.
Different elements absorb different wavelengths of light, providing information about the atmosphere’s make-up.
Living things, from bacteria to large animals, are expected to produce ‘biosignature’ gases that could be detected in a planet’s atmosphere. They include oxygen, ozone, nitrous oxide, and methane.
Maximising the chances of finding evidence of extraterrestrial life will require a technological leap to methods of directly imaging large numbers of exoplanets.Such an undertaking is daunting, given that directly imaging an Earth-like exoplanet is equivalent to picking out a firefly in the glare of a searchlight from a distance of 2,500 miles.
Yet, two techniques now under development could make direct imaging of Earth twins possible.