Life on Earth triggered by meteorites 4.6 billion years ago: study

Via SWNS

Life on Earth was triggered by blazing fireballs from the outer solar system 4.6 billion years ago, according to new research.

The meteorites carried carbonaceous chondrite - a stony material rich in minerals, say scientists.

They made up ten percent of the space rocks that smashed into the planet during its birth, say scientists.

It provided a fifth of its potassium and half of its zinc.

The latter played a vital role in the creation of DNA, while the former helps produce a cell's fluids.

Two separate studies show the volatile elements were not evenly distributed in the original hot solar nebula.

Lead author Dr. Nicole Nie of Massachusetts Institute of Technology said: "Our studies complement and confirm each other's results in multiple ways.

"Among moderately volatile elements, potassium is the least volatile while zinc is one of the most volatile elements."

The other 90 percent of mass came from non-carbonaceous (NC) material from the inner solar system.

It confirms Earth formed partly from carbonaceous meteorites from asteroids in the outer main-belt.

They housed water ices and clays. They formed very far out and were transported from their distant orbits by smashing into each other.

In analyses of 50 meteorites, the US teams identified a phenomenon known as 'nucleosynthetic isotope anomalies'.

They are small differences in chemical ratios produced when elements form.

During the formation of the solar system, gas condensed into solid dust, which was then incorporated into meteorites and the terrestrial planets - including Earth.

Different nucleosynthetic anomalies were inherited by material in different parts of the early Solar System.

The origin of the material that formed Earth can be constrained by measuring the nucleosynthetic anomalies of meteorites.

But those of volatile elements that condense at low temperature have been difficult to measure.

Nie and colleagues got to the bottom of the puzzle by discovering some anomalies were larger and more variable in carbonaceous chondrite.

The ratio of Earth rocks closely matches that of non-carbonaceous varieties - suggesting they delivered most potassium.

But when compared to the isotopic signature of Earth’s zinc, the researchers found 50 percent of it was derived from carbonaceous chondrite.

The findings in the journal Science indicate material from the outer Solar System could have substantially contributed to Earth's other volatile elements.

Nie said: "Our studies thus predict that a wide range of volatile elements should have preserved nucleosynthetic anomalies."