Life on another planet: what scientists say – 10/02/2023 – Science

Many astronomers are no longer asking whether life exists elsewhere in the Universe. The question on their minds now is: when will we find her?

Different experts are optimistic about detecting signs of life on a distant world within the lifetime of current generations — possibly in the coming years.

A scientist leading a research mission to Jupiter is so convinced of this that he says it would be “surprising” if there were no life on one of the planet’s icy moons.

NASA’s James Webb Space Telescope (JWST) recently detected exciting clues of life on a planet outside our Solar System — and has many other worlds on its radar.

Numerous missions that are underway or about to begin mark a new space race in search of the greatest scientific discovery of all time.

“We live in an infinite universe, with infinite stars and planets. And for many of us, it has been obvious that we cannot be the only intelligent beings in the universe,” says Professor Catherine Heymans, Astronomer Royal of Scotland (an honorary title).

“Now we finally have the technology and the ability to answer the question of whether we are truly alone in the cosmos.”

The ‘Goldilocks zone’

Telescopes can now analyze the atmospheres of planets orbiting distant stars, looking for substances that — at least on Earth — can only be produced by living organisms.

The first indication of this type of discovery emerged earlier this month. The possible signal of a gas that on Earth is produced by simple marine organisms was detected in the atmosphere of a planet called K2-18b, which is 120 light years away.

The planet is in the zone that astronomers call “Goldilocks” — the right distance from its star so that the surface temperature is neither too hot nor too cold, but perfect for the existence of liquid water, which is essential to sustain the life.

The team hopes to know within a year whether the clues are actually life.

Professor Nikku Madhusudhan of the University of Cambridge’s Institute of Astronomy, who led the study, told me that if the discovery is confirmed, “it would radically change the way we think about the search for life.”

“If we find signs of life on the first planet we study, it would raise the possibility that life is common in the Universe.”

He predicts that within five years there will be “a significant transformation” in our understanding of life in the Universe.

If his team finds no signs of life on K2-18b, they have 10 more planets in the zone on their list to study — and possibly many more after that. Even finding nothing “will provide important clues about the possibility of life on such planets,” he says.

His project is just one of many that are underway or planned for the coming years in search of signs of life in the Universe.

Some look for life on the planets and satellites of our Solar System — others look far beyond, into deep space.

As powerful as NASA’s James Webb is, the telescope has its limits. The size of the Earth and its proximity to the Sun allow it to support life.

However, James Webb would not be able to detect distant planets as small as Earth (K2-18b is eight times larger) or as close to their parent stars due to their intense brightness.

Therefore, NASA is creating the Habitable Worlds Observatory (HWO), scheduled to operate in the 2030s.

Using what acts as a high-tech solar shield, it minimizes light from the star around which a planet orbits. This means it will be able to identify and analyze the atmospheres of planets similar to ours.

The Extremely Large Telescope (ELT) will also come into operation later this decade, which will observe the crystal clear skies of the Chilean desert from the ground.

It has the largest mirror of any instrument built, at 39 meters in diameter, and can therefore observe much more detail in planetary atmospheres than its predecessors.

These three atmosphere-analyzing telescopes use the same technique used by chemists for hundreds of years to discern the chemicals inside materials based on the light they emit.

They are so incredibly powerful that they can do this from the tiny point of light coming from the atmosphere of a planet orbiting a star, hundreds of light years away.

While some look to distant planets, others restrict their search to our own backyard, to the planets in our own Solar System.

The most likely home for life is on one of Jupiter’s icy moons, Europa. It’s a beautiful world with cracks on the surface that look like tiger stripes. The moon Europa has an ocean below its icy surface, from which clouds of water vapor are expelled into space.

NASA’s Clipper and the European Space Agency’s (ESA) Jupiter Icy Moons Explorer (Juice) missions will arrive there in the early 2030s.

Shortly after the Juice mission was approved in 2012, we asked Professor Michelle Dougherty, who is the lead scientist on the European mission, whether she thought there was a chance of finding life.

She replied: “It would be surprising if there were no life on one of Jupiter’s icy moons.”

NASA is also sending a spacecraft called Dragonfly to land on one of Saturn’s moons, Titan.

It’s an exotic world with lakes and clouds made of carbon-rich chemicals, which give the planet an eerie orange atmosphere. Along with water, these chemicals are considered necessary ingredients for life.

Mars is currently very inhospitable to living organisms, but astrobiologists believe the planet was once lush, with a thick atmosphere, oceans and capable of supporting life.

NASA’s Perseverance rover is currently collecting samples from a crater believed to have been an ancient river delta. A separate mission in the 2030s will bring these rocks to Earth to analyze them for potential microfossils of simple life forms that are long gone.

Could aliens be trying to contact us?

Some scientists consider this question to be something in the realm of science fiction and unlikely, but the search for radio signals from alien worlds has been going on for decades, mainly by the Institute for the Search for Extraterrestrial Intelligence (known as Seti).

Space is immense, so your searches so far have been random. However, the ability of telescopes like JWST to identify the most likely places for alien civilizations to exist allows SETI to focus its search.

This injected new energy, according to Nathalie Cabrol, director of Seti’s Carl Sagan Center for the study of life in the Universe. The institute has modernized its telescope array and is now using instruments to look for communications from powerful laser pulses from distant planets.

As a highly qualified astrobiologist, Cabrol understands why some scientists are skeptical about Seti’s search for a signal.

But chemical signatures from distant atmospheres, interesting readings from flybys of moons, and even microfossils from Mars are all open to interpretation, Cabrol argues.

Looking for a signal “may seem like the most unlikely approach of all to finding signs of life. But it would also be the most unambiguous and could happen at any time.”

“Imagine if we had a signal that we could actually understand,” says Cabrol.

Thirty years ago, we had no evidence of planets orbiting other stars. Now, more than 5,000 have been discovered, which astronomers and astrobiologists can study in unprecedented detail.

All the elements are in place for a discovery that will be more than just an incredible scientific revolution, according to Subhajit Sarker of Cardiff University, who is part of the team studying K2-18b.

“If we find signs of life, it will be a revolution in science and will also represent a huge change in the way humanity sees itself and positions itself in the Universe.”

The text was originally published here.