NASA research could shed light on early stages of planet formation

Written by: Anita Nair
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Washington, Dec 10 (ANI): A new research from NASA has claimed that planets gained the final portions of their mass from a limited number of large comet or asteroid impacts more than 4.5 billion years ago. These impacts added less than one percent of the planets' mass.

Scientists hope the research not only will provide a better historical picture of the birth and evolution of Earth, the Moon and Mars, but also allow researchers to better explore what happened in our solar system's beginning and middle stages of planet formation.

The team used numerical models, lunar samples returned by Apollo astronauts and meteorites believed to be from Mars to develop its findings.

The scientists examined the abundances of elements such as gold and platinum in the mantles, or layers beneath the crust, of Earth, the Moon and Mars.

They concluded the elements were added by a process called late accretion during a planet's final growth spurt.

"These impactors probably represent the largest objects to hit Earth since the giant impact that formed our Moon. They also may be responsible for the accessible abundance of gold, platinum, palladium, and other important metals used by our society today in items ranging from jewelry to our cars' catalytic convertors," said William Bottke, principal investigator from the Southwest Research Institute (SWRI) in Boulder, Colo.

The results indicate the largest Earth impactor was between 1,500 and 2,000 miles in diameter, roughly the size of Pluto. Because it is smaller than Earth, the Moon avoided such enormous projectiles and was only hit by impactors 150 to 200 miles wide.

"Keep in mind that while the idea the Earth-Moon system owes its existence to a single, random event was initially viewed as radical, it is now believed that large impacts were commonplace during the final stages of planet formation," Bottke said.

"Our new results provide additional evidence that the effects of large impacts did not end with the Moon-forming event."

The paper was published in the Dec. 9 issue of Science. (ANI)

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