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 on Wednesday.
Analyzing grains of the mineral zircon extracted from a Martian meteorite known as “Black Beauty,” they determined that Mars’ outer layer hardened 4.547 billion years ago, only 20 million years after the birth of the sun.
“Mars’ 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.”
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 Mars 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 meteorite weighed 320g when found. The researchers secured 44g of the precious space rock and crushed 5g — enough to extract seven bits of zircon that could be used in experiments.
By measuring the lead decaying from uranium that had been trapped in zircon as the young Mars’ molten magma hardened, the scientists were able to precisely date the crust from which the zircon formed.
“I’m glad we chose that strategy,” Bizzarro said. “Zircon is like a time capsule.”
There are two main models for the formation of planets.
In one, it occurs in stages, with small dust particles coalescing into “planetesimals” — rock fragments 10km to 100km in diameter — that collide to form planetary embryos, and then planets, over a time scale of 50 to 100 million years.
According to a more recent model, planetary growth unfolds more quickly and is fueled by so-called “pebble accretion,” the layered accumulation of particles measured in centimeters and meters that are loosely bound with gases.
“Our data supports newer models indicating the very rapid formation of terrestrial planets,” the authors said.
The new time line suggests that something similar might have happened on our planet, but only after Earth was “reset” by the giant impact that formed the moon about 4.4 billion years ago, Bizzarro said.
Mars is thought to have a dense metallic core with a radius of about 1,800km, consisting primarily of iron, nickel and sulfur.
The core is surrounded by a largely dormant mantle — about 1,500km thick — made mainly of silicon, oxygen, iron and magnesium.
Finally, the crust averages about 50km in depth, with a maximum of about 125km.
Earth’s crust averages 40km, but is one-third the thickness of the Martian crust once planet size is taken into account.
An Australian university student who has never visited China and has only a modest social media following would seem an unlikely target for the Chinese government. However, when a Chinese Ministry of Foreign Affairs spokesman personally denounced Drew Pavlou at a news conference, it was just the next phase in an extraordinary campaign against the 21-year-old that has fueled concerns over China’s targeting of critics overseas. Pavlou first placed himself in the superpower’s sights when in July last year he organized a small sit-in at the University of Queensland, where he studies, to protest against various Chinese government policies. Since then, the Global
‘ASKED TO MOVE OUT’: Indonesian coast guard personnel argued with a Chinese vessel over territorial claims after it entered the country’s exclusive economic zone An Indonesian patrol ship confronted a Chinese coast guard vessel that spent almost three days in waters where Indonesia claims economic rights and that are near the southernmost part of China’s disputed claims to the South China Sea. The Indonesian Maritime Security Agency on Friday night detected Chinese ship 5204 entering Indonesia’s exclusive economic zone (EEZ) in what Indonesia calls the North Natuna Sea. The agency sent a patrol ship that closed within 1km of the Chinese coast guard vessel and they communicated to affirm their position and their nation’s claims to the area, Indonesian Maritime Security Agency head Aan Kurnia said. “We
BEFORE WINTER COMES: Snow cuts off roads into Ladakh for four months or more each year, so the crunch is on to get food, tents and high-altitude equipment to Leh From deploying mules to large transport aircraft, the Indian military has activated its entire logistics network to transport supplies to thousands of troops for a harsh winter along a bitterly disputed Himalayan border with China. In the past few months, one of India’s biggest military logistics exercises in years has brought vast quantities of ammunition, equipment, fuel, winter supplies and food into Ladakh, a region bordering Tibet that India administers as a union territory, officials said. The move was triggered by a border standoff with China in the snow deserts of Ladakh that began in May and escalated in June into hand-to-hand
Since her personal telephone number was posted online, Hong Kong democracy advocate and Hong Kong Confederation of Trade Unions chairperson Carol Ng has received menacing calls from strangers and been bombarded with messages calling her a “cockroach.” She is not alone. A sophisticated and shady Web site called HK Leaks has ramped up its “doxxing” — where people’s personal details are published online — of Hong Kong democracy advocates, targeting those it says have broken Hong Kong’s National Security Law. Promoted by groups linked to the Chinese Chinese Communist Party and hosted on Russia-based servers, HK Leaks has become the most prominent “doxxing”