Asteroids brought both water and compounds to the early Earth - helping lay the foundation for life on the planet..!!!

Life began after asteroids slammed into earth, scientists say

Life on Earth began after asteroids crashed into the planet, scientists have claimed.

Astronomers have confirmed for the first time that a giant space rock contains frozen water on its surface.

Analysis of asteroid 24 Themis also shows evidence of widespread organic chemicals.

The scientists say this supports the theory that asteroids brought both water and compounds to the early Earth - helping lay the foundation for life on the planet.

Using an Hawaii based NASA telescope they studied infrared sunlight reflected by 200-kilometer wide 24 Themis that sits halfway between Mars and Jupiter in an area called the Main Belt.

They found the spectrum was consistent with frozen water and determined the object is coated with a thin film of ice. They also detected organic matter.

Asteroids were once believed to be dry and lifeless but it is now believed they played a vital role in the evolution of life.

Planetary scientist Dr Josh Emery, of the University of Tennessee, said: "The organics we detected appear to be complex, long-chained molecules.

"Raining down on a barren Earth in meteorites, these could have given a big kick-start to the development of life."

Dr Emery, whose findings are published in Nature, said discovering ice on 24 Themis was a surprise because the surface is too warm for it to stick around for a long time.

He said: "This implies ice is quite abundant in the interior of 24 Themis and perhaps many other asteroids. This ice on asteroids may be the answer to the puzzle of where Earth's water came from."

Still, how the water got there is unclear as the asteroid's proximity to the sun causes ice to vaporize. But the researchers' findings suggest its lifetime of ice ranges from thousands to millions of years depending on the latitude.

So the ice is regularly being replenished possibly by a process of "outgassing" in which ice buried within the asteroid escapes slowly as vapor migrates through cracks to the surface or as vapor escapes quickly and sporadically when 24 Themis is hit by space debris.

Since Themis is part of an asteroid "family" that was formed from a large impact and the subsequent fragmentation of a larger body long ago, this scenario means the parent body also had ice and has deep implications for how our solar system formed.

Dr Emery said: "Asteroids have generally been viewed as being very dry. It now appears when the asteroids and planets were first forming in the very early Solar System ice extended far into the Main Belt region.

"Extending this refined view to planetary systems around other stars, the building blocks of life - water and organics - may be more common near each star's habitable zone.

"The coming years will be truly exciting as astronomers search to discover whether these building blocks of life have worked their magic there as well."

The scientists' discovery also further blurs the line between comets and asteroids. Asteroids have long been considered to be rocky and comets icy.


(C) The Telegraph Group London 2010


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