- Written by Pallab Ghosh
- Science Reporter
Europa, one of Jupiter’s icy moons, is the most likely place in our solar system to be home to alien life
Many astronomers no longer wonder whether there is life elsewhere in the universe.
The question on their minds is: When will we find him?
Many are optimistic that signs of life on a distant world will be discovered within our lifetime – perhaps in the next few years.
One scientist, leading a mission to Jupiter, goes so far as to say that it would be a “surprise” if there was no life on one of the planet’s icy moons.
NASA’s James Webb Space Telescope (JWST) recently detected tantalizing signs of life on a planet outside our solar system, and it has several other worlds in its sights.
Several missions underway or about to begin represent a new space race for the greatest scientific discovery ever.
“We live in an infinite universe, with an infinite number of stars and planets,” says Professor Catherine Heymans, Astronomer Royal of Scotland. “It was clear to many of us that we could not be the only intelligent life out there.”
“We now have the technology and ability to answer the question of whether we are alone in the universe.”
“Goldilocks zone”
Telescopes can now analyze the atmospheres of planets orbiting distant stars for signs of chemicals that, on Earth at least, can only be produced by living organisms.
The first glimmer of such a discovery occurred earlier this month with a possible signal of a gas produced by simple marine organisms on Earth in the atmosphere of a planet called K2-18b, which is 120 light-years away.
Artwork: K2-18 b orbits a cool dwarf star that appears red at a distance sufficient for its temperature to support life.
The planet lies in what astronomers call the “goldilocks zone” — the right distance away from its star so that the surface temperature is neither too hot nor too cold, but just right for the presence of liquid water, which is essential to support life. life.
The team expects to know within a year whether the exciting hints they received have been confirmed or have disappeared.
Professor Nico Madhusudan, of the University of Cambridge’s Institute of Astronomy, who led the study, told me that if these hints are confirmed “it will fundamentally change the way we think about searching for life.”
“If we find signs of life on the first planet we study, this will increase the possibility that life is common in the universe.”
Even if they don’t find signs of life on K2-18b, the team has 10 more planets on their list to study and perhaps many more after that.
Professor Madhusudan expects that within five years there will be what he described as a “major shift” in our understanding of the habitability of planets for life and life in the universe.
“By then, we will have the opportunity to study six planets like K2-18b or ones that are a little hotter.
“It is likely that we are close to the first discovery. On the other hand, not detecting any will also provide important insights into the possibility of life on such planets.”
But as powerful as the James Webb Space Telescope is, it has its limitations. The Earth’s size and proximity to the Sun enable it to support life. But the James Webb Space Telescope will not be able to detect distant planets as small as Earth (K2-18b is eight times larger) or close to their parent stars, due to glare.
So, NASA is planning to establish the Habitable Worlds Observatory (HWO), scheduled for the 2030s. Using a high-tech sunshade, it reduces the light of the star around which the planet orbits. This means that it will be able to detect and sample the atmospheres of planets similar to our own.
Artwork: The Habitable Worlds Observatory places a solar shield in front of the star to see the planets surrounding it more clearly
Also coming later this decade will be the Extremely Large Telescope (ELT), which will be on the ground, looking at the clear skies of the Chilean desert. It has the largest mirror of any instrument ever made, at 39 meters in diameter, and can therefore see much more detail in planetary atmospheres than its predecessors.
These three telescopes used to analyze the atmosphere use a technique that chemists have used for hundreds of years to distinguish chemicals within materials by the light they emit.
But JWST and HWO are so powerful that they can do it through a tiny pinprick of light from the atmosphere of a planet orbiting a star, hundreds of light-years away.
Close to home
While some look to distant planets, others limit their search to our own backyard, to the planets of our solar system.
The most likely home for life is one of Jupiter’s icy moons, Europa. It is a beautiful world with cracks on its surface that resemble tiger stripes. Europa has an ocean beneath its icy surface, from which plumes of water vapor shoot out into space.
Europe’s tiger stripes are caused by cracks on its glacial surface
NASA’s Clipper missions and the European Space Agency’s (ESA) Jupiter Icy Moons Explorer (Juice) mission will arrive there in the early 2030s.
Shortly after the Goss mission was approved in 2012, Professor Michelle Dougherty, the mission’s lead scientist, said if she thought there was a chance of finding life: “It would be surprising if there was no life on one of our planet’s icy moons.” Jupiter.”
NASA is also sending a spacecraft called Dragonfly to land on one of Saturn’s moons, Titan. It is a strange world with lakes and clouds made of carbon-rich chemicals that give the planet a strange orange haze. These chemicals, along with water, are believed to be a necessary element for life.
A view of Titan captured by the European Space Agency’s Huygens lander as it descended to its surface
Mars is currently considered very inhospitable to living organisms, but astrobiologists believe the planet was once fertile, with a thick atmosphere and oceans and capable of supporting life.
NASA’s Perseverance rover is currently collecting samples from a crater that was thought to be an ancient river delta. A separate mission in the 2030s will bring those rocks back to Earth to analyze for possible microfossils of simple life forms that are now long gone.
These are just some of the many missions underway or planned in the coming years to search for signs of planetary life on our planet. Solar System – Others search much further Deep space.
Smart life
Could aliens out there somewhere be trying to reach us?
Some scientists consider this the realm of science fiction and far-fetched, but the search for radio signals from alien worlds has continued for decades, not least through the Search for Extra-Terrestrial Intelligence (Seti) Institute.
The entire space is a big place to search, so the searches have been random so far.
But the ability of telescopes, such as the James Webb Space Telescope, to pinpoint where alien civilizations are most likely to exist, means SETI can focus its search. This has injected new momentum, according to Dr. Nathalie Cabrol, director of the Carl Sagan Center for the Study of Life in the Universe at SETI.
Image source, Dr. Seth Shostak/Science Image Library
The Allen Collection of SETI radio telescopes. Its search for signals of intelligent life has doubled
The institute has upgraded its array of telescopes and now uses instruments to search for communications from powerful laser pulses from distant planets.
As a highly qualified astrobiologist, Dr. Cabrol understands why some scientists are skeptical of SETI’s search for a signal.
But chemical signatures from distant atmospheres, interesting readings from lunar flybys, and even microfossils from Mars are all open to interpretation, Dr. Cabrol says.
Searching for a sign “may seem like the furthest of all the different ways to find signs of life. But it will also be the most obvious and could happen at any time.”
“Imagine we have a signal that we can actually understand,” says Dr. 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 a stunning scientific breakthrough, according to Dr. Subhajit Sarker of Cardiff University, a member of the team studying K2-18b.
He added: “If we find signs of life, it will be a revolution in science, and it will also be a huge change in the way humanity views itself and its place in the universe.”
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