Aliens exist – but they haven't visited Earth, claims a NASA veteran.
Dr. Gentry Lee has worked at the US space agency since 1968, when he was first involved in the Viking mission to Mars.
He has spent more than half a century designing probes to land on distant planets – but argues that Earth has yet to be visited by other plant or mechanical creatures.
"There is nothing today to indicate that any aliens or any alien vehicles have ever landed on planet Earth," he said at the American Association for the Advancement of Science (AAAS) conference in Phoenix.
"If you think otherwise, you are deluding yourself."
According to the expert, in every alleged case of a UFO or alien encounter, there is usually a simpler explanation for those phenomena.
But when it comes to distant planets, life "just has to exist somewhere out there."
"We will find life, in one form or another, somewhere else. The probability is extremely high," he added.
Scientists believe the best candidates for alien life are "Earth-like" worlds orbiting distant stars in other parts of the galaxy.
One of them is the planet TRAPPIST-1e, similar in size to Earth, just 40 light-years away, within the habitable zone of its star.
Another candidate is K2-18b, which some studies suggest could be teeming with life. This planet, 124 light-years from Earth in the constellation Leo, is a large world completely covered in oceans – what scientists call a “Hycean world.”
Even within our solar system, Saturn's moons, Enceladus and Titan, may have the right conditions for the development and survival of life.
Dr. Lee added that space scientists must be prepared for life forms very different from those we know on Earth.
“All life on our planet – you, me, an elephant, mold, bacteria – uses DNA to reproduce itself,” he said.
“Extraterrestrial biologists would come to Earth and report: 'Boring planet. All life is the same. They all reproduce in the same way using the same molecule [DNA].'”
Lee is currently a chief engineer in the Solar System Exploration Directorate at NASA's Jet Propulsion Laboratory. He oversaw the design of the Curiosity rover for Mars, the Dawn and Juno missions, and the Grail mission to the Moon.
Promoting the new documentary Spaceman, Dr. Lee said that space telescopes like Kepler have studied a significant portion of our galaxy and found a large number of planets orbiting other stars.
“If the part of the universe that Kepler has studied is representative [of the entire Milky Way], then there are approximately a trillion planets in our galaxy,” he said.
"So, going over the probabilities of life forming, you finally say: it just has to exist somewhere out there."
Finally, he also commented on the recent political discussions about UFOs: NASA refused to publish mysterious documents about aliens, explaining that many unexplained phenomena are more related to expensive programs than to extraterrestrial life. /GazetaExpress/
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