Tuesday, December 16, 2014

Scientists Find New Evidence for Life on Mars

SEM images of the organic carbon in Tissint. (a-b) Dark organic carbon fills all of the fractures and cleavages in olivine (Ol); (c-e) organic matter inclusions in a shock-melt vein. Credit: igg.cas.cn

Scientists have found new evidence for possible life on the Red Planet in a piece of Martian meteorite that landed on Earth after about 700,000 years of space travel. According to research carried out by teams of Chinese, German, Swiss, and Japanese scientists, more than 10 pieces of coal-like carbon particles, thinner than one-tenth of the width of a strand of hair, were found in a thumb-sized piece of the meteorite. "We used advanced equipment to determine the carbon particles are organic matter, and to rule out the possibility of graphite, which is inorganic," said Lin Yangting, a lead scientist of the research team from the Institute of Geology and Geophysics, Chinese Academy of Sciences (CAS). The study was published as a cover article in December 2014 in the international journal of Meteoritics & Planetary Science. "Lin's team's new finding in Tissint is so far the most inspiring evidence for life on Mars," said Ouyang Ziyuan, chief scientist of China's lunar exploration project.

Professor Yangting Lin and his team, Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS), cooperating with scientists from the Institute of Geochemistry, CAS, Guangzhou Institute of Geochemistry, CAS, National Astronomical Observatories, CAS, and Universität Bayreuth, EPFL, Tohoku University, found carbon grains in the Tissint Martian meteorite. Using microscopic analysis techniques, which included NanoSIMS and Laser Raman spectrometer at IGGCAS, they obtained Laser-Raman spectra, high-resolution elemental distribution images and H, C, N isotopic compositions of these carbon grains. The laser-Raman spectra and NanoSIMS analyses indicate these carbonaceous components are kerogen-like organic carbon, similar to coal. The authors assert that the organic matter that they found in Tissint is pristine and is not terrestrial contamination.

"Furthermore, we found an enrichment of the light carbon isotope in the organic matter," said Lin. "It's so exciting! This could be a promising indicator of life on Mars."

The meteorite, officially named Tissint, is new to Earth, with witnesses who saw it fall.

At about 2 a.m. local time on July 18, 2011, a bright fireball was observed by several people in the region of the Oued Draa Valley, east of Tata, Morocco, according to the Meteoritical Society, an organization that records all known meteorites.

It was first yellow in color, and then turned green, illuminating the entire area before it appeared to split into two parts, said eyewitness Aznid Lhou.

Three months later, nomads began to find fresh, fusion-crusted stones near Tissint village.

The Tissint Martian meteorite.
The Tissint Martian meteorite. Credit: igg.cas.cn

In addition to our home Planet, Earth, life was probably present on Mars. Evidence from the exploration of Mars, which includes topographic features and the presence of aqueous alteration minerals and sulfates, suggests the existence of liquid water, even oceans, on the surface of Mars, which is essential for life. The detection of methane (30 ppb) in the Martian atmosphere by the Mars Express orbiter in 2004 has further inspired Martian exploration.

The Mars rover Curiosity, more than two billion dollars in value, has successfully land on Mars with the goal of investigating the paleoenvironment and paleoclimate of Mars, and eventually detecting the sign of biotic activity on Mars. Another approach is to analyze Martian meteorites in laboratories. 

To-date, the number of record Martian meteorites is more than 120. The Tissint meteorite is the fifth witnessed fall of a Martian meteorite and fell in July 2011 in the Moroccan desert. This meteorite supplies us with uniquely fresh samples to search for traces of biotic activities on Mars and to study Martian paleoenvironment suitability for life.

The lighter the carbon isotope, the greater the possibility of biological activity, while a heavy carbon isotope indicates the opposite, Lin said. Paleontologists analyze ancient rocks' carbon isotope ratio to determine the date of Earth's earliest life forms.

He explained that organic matter like coal and petroleum on Earth are formed as a result of biological activity. But not all organic matter is related to biological activity. Organic compounds have been synthesized in labs. Carbon isotopes are a key indicator in judging whether organic matter resulted from life.

They used the NanoSIMS, an ion microprobe that can analyze particles smaller than one-millionth of a meter, to analyze their elemental and isotopic composition. "No one has ever seen the organic carbon components in the stone with such clarity," Lin said.

Carbon isotopic composition of the organic matter in Tissint. These organic matter are significantly lighter than the Martian Atmospheric CO2 and carbonate in Martian meteorite, but similar to the terrestrial organic materials. Credit: igg.cas.cn
Carbon isotopic composition of the organic matter in Tissint. These organic matter are significantly lighter than the Martian Atmospheric CO2 and carbonate in Martian meteorite, but similar to the terrestrial organic materials. Credit: igg.cas.cn

But could the signs of life have come from Earth, rather than Mars? What if the stone was contaminated immediately when it landed on Earth?

Lin's team ruled out this possibility by analyzing the hydrogen isotope in the organic compounds.

"It has a Martian fingerprint, different from the one on Earth. So we say the organic compounds come from Mars," Lin said.

Previously, scientists had claimed to find organic compounds or signs of life in Mars meteorites, but were met with doubts. Lin says his team's findings need further testing.

More than 120 pieces of Martian meteorite have fallen to Earth, according to the meteorite database of the Meteoritical Society. They were blasted off the planet when asteroids hit Mars.

"Most of them were recovered after staying for a long time in Atlantic ice or hot deserts," Lin said. "People have no idea when they came to earth and, year by year, they may have been contaminated by substances on earth."

Though there have been four other meteorites with witnesses before Tissint, the most recent was more than 51 years ago, Lin said. "Tissint is a new Martian meteorite that can supply us with fresh samples."

"At first we were looking for traces of water in it, and accidentally found carbon particles. That's a rare case," Lin said. Though scientists have confirmed that Tissint formed six hundred million years ago on Mars, it's still unclear when the organic carbon components came into being.

Scientists say the surface of Mars has not been suitable for life for the past three billion years. "If life existed after that, it might have been living underground," Lin said.

Despite the inspiring findings, Lin admits that they cannot draw a final conclusion about life on Mars until they analyze samples collected directly from Mars.

But the 52-year-old scientist seems confident. "If I were to make a bet," he said, "I would wager that there was once life on that planet."

1 comment:

  1. Не стоит рассматривать бездну, пока мы, как слаборазвитые, живем в обществе, раздираемом религиозными и классовыми противоречиями, совершенно не понимая, как устроен Мир. Думаю после событий, на которые указывают пирамиды Гизы, на Земле будет единое Мировое правительство. Хочется добавить,"Остановись Америка!"

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