Two astronomers say that data coming from a recently “reawakened” space probe that landed on a comet last November indicate the presence of microbes below the water ice.
The Philae lander dropped from the Rosetta spacecraft orbiting a comet called 67P/Churyumov-Gerasimenko last November tried to land, but instead of attaching itself to the surface, bounced several times and landed in the shade. This caused the lander to shut down due to lack of sunlight to power itself.
But 7 months later, as the comet raced toward the sun, more of the surface was exposed to sunlight and Philae woke up. Since then, it has been sending back pictures and reams of data to scientists on earth.
The experts say the most likely explanation for certain features of the 67P/Churyumov-Gerasimenko comet, such as its organic-rich black crust, is the presence of living organisms beneath an icy surface.
Rosetta, the European spacecraft orbiting the comet, is also said to have picked up strange “clusters” of organic material that resemble viral particles.
But neither Rosetta nor its lander probe, Philae, are equipped to search for direct evidence of life after a proposal to include this in the mission was allegedly dismissed.
Astronomer and astrobiologist Professor Chandra Wickramasinghe, who was involved in planning for the mission 15 years ago, said: “I wanted to include a very inexpensive life-detection experiment. At the time it was thought this was a bizarre proposition.”
He and colleague Dr Max Wallis, from the University of Cardiff, believe 67P and other comets like it could provide homes for living microbes similar to the “extremophiles” that inhabit the most inhospitable regions of the Earth.
They say comets may have helped to sow the seeds of life on Earth and possibly other planets such as Mars early in the solar system’s existence.
Philae failed to attach itself to the surface of Comet 67P after being dropped by mothership Rosetta in November, and bounced several times before landing in the shade.
After being forced into hibernation by the lack of sunlight reaching its solar panels, scientists were euphoric when it began “waking up” as the comet raced towards the sun. It is currently about 176.7 million miles from Earth and travelling at more than 73,000 mph.
Computer simulations have suggested microbes could inhabit the comet’s watery regions.
It has a black hydrocarbon crust overlaying ice, smooth icy “seas”, and flat-bottomed craters containing “lakes” of re-frozen water overlain with organic debris.
Prof Wickramasinghe said: “What we’re saying is that data coming from the comet seems to unequivocally, in my opinion, point to micro-organisms being involved in the formation of the icy structures, the preponderance of aromatic hydrocarbons, and the very dark surface.
This is an extremely tantalizing clue, but probably won’t be accepted by most scientists as “evidence” of alien life. “Extraordinary claims require extraordinary proof” said the late astronomer Carl Sagan. Wickramsinghe and Wallis have fallen far short of that standard.
There’s nothing new in the theory that comets and even asteroids deposited life, or the building blocks of life on earth more than 4 billion years ago. We’ve known that comets carry organic compounds and amino acids on their journey through space by examining their remnants that fall to earth.
But the fascinating thing about this potential discovery is that several moons in our solar system also have abundant water ice. Jupiter’s moon Europa may even be covered by a vast ocean of liquid water that exists below an ice crust that may be several miles thick. The idea that microbes exist below the water ice on a comet will probably spur NASA to fully fund a mission to Europa , tentatively scheduled sometime in the next decade. The agency is still working out a way for a lander to penetrate the ice in order to reach the liquid water below to test for life.
We may have to wait until then for confirmation that alien life exists in our solar system.