Comet find boosts hope for alien life

NASA scientists have found compelling new evidence that life may be common in the universe and not just special to Earth. They discovered one of the basic building blocks of life in samples of a comet that a spacecraft brought back to Earth.

For the first time, they have found a vital amino acid called glycine. It was collected from Comet Wild 2 by the agency’s Stardust probe. The find is important because it suggests that fundamental ingredients for life to form are common in the universe – in which case life could be widespread throughout space too.

NASA’s Dr Carl Pilcher hailed the discovery, saying it “strengthens the argument that life in the universe may be common rather than rare.”

Many scientists believe that life began on Earth after we were battered by billions of asteroids and comets in the early days of the solar system. All the water in the sea may have come from icy comets.

Stardust flew through the dense gas and dust surrounding Comet Wild 2’s icy head, or nucleus, in January 2004. It collected microscopic particles with a gel-covered device resembling a tennis-racket sized fly-swat.

The total amount of dust in the haul weighed less than 1,000th of an ounce with many just a hundredth the width of a human hair. But it was hoped they would hold clues to how the planets formed and life began.

Samples of this material were stored in a capsule which was parachuted back to Earth when Stardust flew by two years later in January 2006.

Since then, scientists have been busy analysing the precious particles from the comet – a leftover from the formation of the solar system.

Dr Jamie Elsila of NASA’s Goddard Space Flight Centre in Greenbelt, Maryland, said yesterday: “Glycine is an amino acid used by living organisms to make proteins, and this is the first time an amino acid has been found in a comet.

“Our discovery supports the theory that some of life’s ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts.”

Dr Carl Pilcher, Director of the NASA Astrobiology Institute, said: “The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare.”

Proteins are the workhorse molecules of life, used in everything from structures like hair to enzymes, the catalysts that speed up or regulate chemical reactions.

Having delivered its valuable cargo back to Earth, Stardust is now headed on a new mission to catch up with another Comet, Tempel 1, in February 2011.

Picture: An artist’s impression of Stardust flying through Comet Wild 2. (Credit: NASA).

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Paul Sutherland

Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.
Paul Sutherland

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Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.

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