For years, scientists have searched far and wide for any evidence of life in the cosmos. Certain planets like Mars and Venus have offered some hope in the form of microscopic organisms, such as methanogens. In 2019, efforts were ramped up after the Curiosity rover discovered traces of methane in the Red Planet’s atmosphere.
But, further investigations proved fruitless.
Then, there was the breakthrough discovery of phosphine on Venus — a toxic gas whose presence usually indicates the presence of life.
Yet, again, nothing was ever found.
Efforts within the methods of searching for extraterrestrial life (SETI) and messaging extraterrestrial intelligence (METI) have ramped up since the beginning of the Tens, however.
So much so that in 2015, then chief NASA scientist Ellen Stofan claimed that by 2025, scientists will likely discover the first signs of alien life in space.
Her prediction places us just three years from a potential breakthrough — a tantalising thought for extraterrestrial buffs.
Speaking during a panel discussion that focused on the space agency’s efforts to search for habitable worlds and alien life, she said: “I think we’re going to have strong indications of life beyond Earth within a decade, and I think we’re going to have definitive evidence within 20 to 30 years.
“We know where to look.
“We know how to look.
“In most cases, we have the technology, and we’re on a path to implementing it.
“And so I think we’re definitely on the road.”
John Grunsfeld, a physicist and astronaut, added: “I think we’re one generation away in our solar system, whether it’s on an icy moon or on Mars, and one generation [away] on a planet around a nearby star.”
Recent discoveries suggest that the solar system and broader Milky Way galaxy are teeming with environments that could support life.
Oceans of liquid have been found sloshing beneath the icy shells of Jupiter’s moons Europa and Ganymede, as well as Saturn’s Enceladus.
Oceans once covered Mars, with seasonal dark streaks found across its surface potentially caused by once flowing salty water.
Further away, observations by NASA’s Kepler space telescope suggest that nearly every star in the sky hosts planets.
Many of these worlds may be habitable, with Kepler having found myriad rocky worlds like Earth and Mars, its observations suggesting that those worlds are far more likely to exist than gassy giants like Jupiter and Satur.
And, just as the solar system appears to be awash with water, Paul Hertz, director of NASA’s Astrophysics Division, said the galaxy at large seems similar.
Speaking at the same event as Ms Stofan, he described the Milky Way as a “soggy place”, and said: “We can see water in the interstellar clouds from which planetary systems and stellar systems form.
“We can see water in the disks of debris that are going to become planetary systems around other stars, and we can even see comets being dissipated in other solar systems as [their] star evaporates them.”
More recently, a team of researchers from the University of Cambridge have identified a new class of habitable planets that could change the game completely.
Dubbed “Hycean” planets — meaning hot, ocean-covered worlds with hydrogen-rich atmospheres — the newly identified exoplanets are far greater in number and easier to spot than Earth-like planets.
More importantly, researchers say specifically hunting for Hycean planets could lead to us discovering biosignatures of life outside our Solar System within the next two or three years.
Dr Nikku Madhusudhan from Cambridge’s Institute of Astronomy told BBC Science Focus magazine that he believes researchers have opened a huge window of opportunity at finding new life.
He said: “Hycean planets open a whole new avenue in our search for life elsewhere.
“Essentially, when we’ve been looking for these various molecular signatures, we have been focusing on planets similar to Earth, which is a reasonable place to start.
“But we think Hycean planets offer a better chance of finding several trace biosignatures.