The crust that encases rocky planets and makes possible the emergence of life took shape on Mars earlier than thought and at least 100 million years sooner than on Earth, researchers said Wednesday.
Analysing grains of the mineral zircon extracted from a Martian meteorite known as Black Beauty, they determined that the Red Planet’s outer layer hardened 4.547 billion years ago, only 20 million years after the birth of the Sun.
“Mars’s primary crust formation — which is the end product of planet formation — happened much faster than previously thought,” said Martin Bizzarro, a scientist at Denmark’s Centre for Star and Planet Formation and senior author of a study published in Nature.
“Our results indicate that Mars could have had an environment with oceans, and potentially life, much earlier than Earth,” he told AFP.
Water is considered to be an essential precursor for life, at least as we know it.
Mars was once much more Earth-like, with a thick atmosphere, abundant water and global oceans.
Up to now, mathematical models have suggested that the solidification of the Red Planet took up to 100 million years.
The new study tackles the question by examining a chunk of Mars that streaked into the Saharan Desert and was discovered in 2011.
The Black Beauty meteorite weighed 320 grammes (11 ounces) when found. The researchers secured 44 grammes of the precious space rock, and crushed five — enough to extract seven bits of zircon that could be used in experiments.
– ‘Like a time capsule’ –
By measuring the lead decaying from uranium that had been trapped in zircon as the young Mars’s molten magma hardened, the scientists were able to precisely date the crust from which the zircon formed.
“I’m glad we chose that strategy,” said Bizzarro. “Zircon is like a time capsule.”