Mars would have formed in a few million years

Mars as a planet was developed in as little as two to four million years after the birth of the solar system, much faster than Earth, according to a new study published in the journal Nature. The rapid formation of the red planet helps explain why it is so small, scientists said Nicolas Dauphas of the University of Chicago, and Ali Pourmand, University of Miami.



Mars is probably not a planet like Earth, which grew to full size between 50 and 100 million years through collisions with other small bodies in the solar system, said Dauphas, associate professor of geophysical sciences.

"The Earth as embryos was Mars, but Mars is an embryonic planet stranded not collided with other embryos to give rise to a planet like Earth," said Dauphas.

Geological record
Pourmand Dauphas and were able to refine the age of Mars using, by way of a timer, the radioactive decay of hafnium in tungsten in meteorites. Hafnium 182 decays into tungsten 182 in an average life of nine million years. This relatively fast process means that almost all Hafnium 182 will disappear in 50 million years, providing a way to build a refined chronology of the early solar system events.

Previous estimates of the formation of Mars presented a range as high as 15 million years because the chemical composition of the Martian mantle is largely unknown. Scientists are still struggling with large uncertainties in the composition of the mantle because they alter the composition of processes such as fusion.

The secret in chondrites
The resolution of some lingering uncertainties about the composition of chondrites, a common type of meteorites, provided the data they needed. Remains essentially unchanged surplus of birth of the solar system, chondrites Rosetta stone used to deduce the chemical composition of the planet.

The cosmochemical chondrites have been studied intensively, but still have little understanding between the abundances of the two categories of items they contain, including uranium, thorium, hafnium and lutetium.

Pourmand Dauphas and analyzed the abundances of these elements in more than 30 chondrites, and compared with those of 20 other compositions of Martian meteorites.

Hafnium and thorium are both elements are refractory or non-volatile, meaning that their compositions are relatively constant in meteorites. Litofilos elements are also those who have remained in the mantle when the core of Mars was formed. Therefore, if scientists can measure the ratio of hafnium-thorium in the mantle of Mars, would the rate for the entire planet, they need to rebuild their formation history.

A premature birth
Relations between hafnium-thorium and tungsten dictated that the hafnium-thorium ratio in the mantle of Mars should be similar to the same ratio as in chondrites. To calculate the proportion of the Martian mantle hafnium-thorium ratio is divided thorium-tungsten Martian meteorites hafnium-thorium ratio of the chondrites.

Once Pourmand Dauphas and determined this relationship were able to calculate how long it took to become a planet Mars. The simulation shows that Mars must have reached half its current size only two billion years after solar system formation.

Rapid formation of Mars could help explain the puzzling similarities in the content of xenon in its atmosphere and the Earth. "Maybe it's just a coincidence, but maybe the solution is part of the Earth's atmosphere was inherited from an earlier generation of embryos that had their own environments, perhaps an environment like Mars," said Dauphas.