Life on early Earth could have been propelled into space after asteroid impacts on Earth, Harvard astronomer Professor Abraham Loeb has revealed. He wrote in Scientific American: “The launch of the space dog Laika onboard Sputnik 2 on November 3, 1957, was a historic milestone, the first demonstration that humans are capable of shipping life into the cosmos. But Mother Nature has accomplished the same task many times over, when terrestrial rocks were launched into space as a result of asteroid impacts on Earth.”
Almost 20 years ago, scientists discovered Martian meteorite named ALH84001 in Antarctica, was never heated above 40C (104F) after being ejected from the surface of Mars.
Mini astronauts are far better suited for taking a space ride than our very best human pilots
Professor Abraham Loeb
A controversial paper published in Science argued there was evidence for past alien life activity inside the space rock.
Although this claim remains contentious, the astronomer believes the principle remains “valid”.
This raises the possibility if organisms were transferred from Mars to Earth billions of years ago, they could have been the original seeds of life on our own planet.
He added: “If so, we could all literally be Martians.
“Given the existence of this delivery system for biological organisms, it is natural to wonder whether a terrestrial package might have been sent not just to Mars but out of the Solar System entirely long before Voyager 1 and 2 were launched.”
Most asteroid impacts are too weak to eject rocks on terra firma with enough energy to leave the Solar System.
But many entries in the solar system spend most of their time in the Oort cloud, an area loosely bound to the Sun, up to 100,000 times further away than Earth.
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Some of these celestial bodies occasionally appear as comets with unexpected orbits bringing them close to our star, where they can get gravitationally influenced by planets all the way out of the Solar System.
Those asteroid approaching Earth, passing just 30 to 60 miles (50 to 100km) above the surface would theoretically be capable of collecting life from the atmosphere.
While the abundance of microbes in the uppermost atmosphere is poorly constrained, it is well known that microorganism colonies exist at such altitudes.
Professor Loeb wrote: “In a new paper written with my undergraduate student Amir Siraj, we calculate that there could have been tens of such life-exportation events over the lifetime of Earth.
“A similar number of events are expected to be associated with asteroids that came from outside the Solar System before they grazed our planet’s atmosphere.
“This number would increase by orders of magnitude if life existed above an altitude of 100km (60 miles) during points in Earth’s history as a result of enhanced atmospheric turbulence or volcanic activity.”
Such Earth-grazing objects would scoop microbes at accelerations of millions of gs – the gravitational acceleration binding objects to Earth.
He added: “Could they survive the jolt? Possibly!
“As it turns out, these mini astronauts are far better suited for taking a space ride than our very best human pilots.”
Microbes such as Bacillus subtilis and Caenorhabditis elegans have been shown to live through accelerations only one order of magnitude smaller.
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