quinta-feira, 29 de agosto de 2013

Life came from Mars on a meteorite, scientist says

An element believed to be crucial to the origin of life would only have been available on the surface of the Red Planet, it is claimed.

Geochemist Professor Steven Benner argues that the "seeds" of life probably arrived on Earth in meteorites blasted off Mars by impacts or volcanic eruptions.

As evidence, he points to the oxidised mineral form of the element molybdenum, thought to be a catalyst that helped organic molecules develop into the first living structures.

"It's only when molybdenum becomes highly oxidised that it is able to influence how early life formed," said Prof Benner, from The Westheimer Institute for Science and Technology in the US.

"This form of molybdenum couldn't have been available on Earth at the time life first began, because three billion years ago the surface of the Earth had very little oxygen, but Mars did (had oxygen).

"It's yet another piece of evidence which makes it more likely life came to Earth on a Martian meteorite, rather than starting on this planet."

All living things are made from organic matter, but simply adding energy to organic molecules will not create life. Instead, left to themselves, organic molecules become something more like tar or asphalt, said Prof Benner.

He added: "Certain elements seem able to control the propensity of organic materials to turn to tar, particularly boron and molybdenum, so we believe that minerals containing both were fundamental to life first starting.

"Analysis of a Martian meteorite recently showed that there was boron on Mars; we now believe that the oxidised form of molybdenum was there too."

Another reason why life would have struggled to start on early Earth was that the planet was likely to have been covered by water, said Prof Benner.

Water would have prevented sufficient concentrations of boron forming and is corrosive to RNA, a DNA cousin believed to be the first genetic molecule to appear.

Although there was water on early Mars, it covered much less of the planet.

"The evidence seems to be building that we are actually all Martians; that life started on Mars and came to Earth on a rock," said Prof Benner, speaking at the Goldschmidt 2013 conference in Florence, Italy.

"It's lucky that we ended up here nevertheless, as certainly Earth has been the better of the two planets for sustaining life.

"If our hypothetical Martian ancestors had remained on Mars, there might not have been a story to tell."

The Goldschmidt conference is jointly sponsored by the European Association of Geochemistry and the Geochemical Society.

Source: Irish Independent

quinta-feira, 22 de agosto de 2013

Rare meteorite preserved for present and future scientists

The main mass of a rare meteorite that exploded over California's Sierra foothills in April 2012 will be preserved for current and future scientific discoveries, thanks to the collaborative efforts of five U.S. academic institutions.

found a permanent home divided among UC Davis, the Smithsonian Institution's National Museum of Natural History in Washington, D.C.; American Museum of Natural History in New York City, The Field Museum of Natural History in Chicago, and Arizona State University in Tempe.

Together, the institutions have successfully acquired the biggest known portion of the Sutter's Mill meteorite.

The meteorite is considered to be one of the rarest types to hit the Earth - a carbonaceous chondrite containing cosmic dust and presolar materials that helped form the planets of the solar system.

Its acquisition signifies enhanced research opportunities for each institution and ensures that future scientists can study the meteorite for years to come.

"With these museums and institutions storing the meteorite's main mass, it leaves it in a pristine condition to preserve for future generations to study," said UCD geology professor Qing-zhu Yin. "Fifty or 100 years from now, we may have new technology that will enable later generations to revisit the meteorite and do research we haven't thought of. This gives us a better chance to realize the full scientific value of the meteorite, rather than have it be just a collector's item."

The meteorite formed about 4.5 billion years ago. While it fell to Earth roughly the size of a minivan before exploding as a fireball, less than 950 grams have been found. Its main mass weighs just 205 grams (less than half a pound) and is about the size of a human palm. The main mass was X-rayed by CT scan at the UC Davis Center for Molecular and Genomic Imaging. This was the first time a meteorite acquisition was CT scanned before its division among a consortium of institutes, allowing prior knowledge of each piece's contents. Then it was cut into five portions, reflective of each institution's investment, before being delivered to the institutions.

When the meteorite landed near Sutter's Mill, the gold discovery site that sparked the California Gold Rush, it spurred a scientific gold rush of sorts, with researchers, collectors and interested citizens scouring the landscape for fragments of meteorite. The institutions that have acquired the main mass were among those that acted on this rare scientific opportunity to gain insights about the origins of life and the formation of the planets.

At UC Davis, for instance, the meteorite fell just 60 miles east of the main campus. Yin immediately traveled to the site with students and colleagues, looking for specimens and reaching out to the public to provide meteorite donations for science. He confirmed for the original discoverer of the main mass that it was carbonaceous chondrite. Yin and his UC Davis colleagues have also X-rayed the meteorite and determined its age and chemical composition.

"It just happened in our backyard," said Yin. "I felt obligated to do something, and I still do."

Source: dailydemocrat.com

quarta-feira, 14 de agosto de 2013


Meteorites, ores and rare metals are the subjects of an unusual exhibition in Tokyo and may be visited until September 29.

The University of Tokyo’s museum is sponsoring the exhibition, with the aim of prompting visitors to consider how to obtain natural resources that are running out. The display includes a 2 centimeter fragment of a meteor that fell in Chelyabinsk province in central Russia in February.

The fragment contains more platinum and iridium than ores found on Earth. This suggests that similar asteroids could be a potential source of natural resources in the future.

The visitors may also admire a meteorite believed to have fallen in present-day Africa about 450 million years ago. The meteorite is over 90 percent iron and contains about 3 times the amount of iron than ores produced on Earth.

Mud containing rare earths is also being exhibited. A university team collected the sample from the seabed near Japan’s eastern tip in the Pacific.

Associate professor Hideaki Miyamoto, involved in the organizing of the event said to the media that he hopes that the exhibition will prompt visitors to consider whether to look to space for resources or to invent new ways of making good use of the Earth’s limited supply.

Source: tokyotimes.com

terça-feira, 13 de agosto de 2013

Meteorites' age is at center of Mars history debate

Planetary scientists dream of sending a geologist to Mars to study its rocks by hand. Until then, they have to settle for examining meteorites - chunks of the Red Planet that land on Earth after hurtling through space and surviving the searing fall through our atmosphere.

Though a little banged up, these meteorites provide a vital up-close view of our rust-hued neighbor. But it can be hard for geologists to interpret what they see when they can't agree how old a rock is. Conflicting age estimates for certain rocks differ by up to 4 billion years - the vast majority of Mars' planetary existence.

Do these rocks tell the beginning, or the end, of Mars' story?

In a paper last month in the journal Nature, an international team of scientists sought to sort out this issue for a particular group of meteorites known as shergottites. Martian space rocks tend to be very old, but shergottites are generally thought to be remarkably young - forming as a result of volcanic activity about 150 million to 250 million years ago, around the same time that dinosaurs roamed during Earth's Jurassic period.

If so, shergottites are a sign that Mars might have been geologically active fairly recently, and thus perhaps still amenable to some form of life, said Munir Humayun, a planetary geochemist at Florida State University who was not involved in the study.

But a few researchers recently estimated that shergottites are about 4 billion years old - a finding that had far-reaching implications for scientists' understanding of Mars' history.

"Most of us understand that if there is to be life on Mars it's not going to be roaming on the surface, but it could be thriving underground with the heat energy provided by volcanism," Humayun said. But "if there hasn't been (volcanic activity in) 4 billion years ... it would be very difficult to believe there was life left on Mars."

To settle the question, researchers led by Desmond Moser of Western University in Ontario, Canada, examined a meteorite known as Northwest Africa 5298. They looked at very tiny deposits within it known as baddeleyites - tough, zirconium-rich minerals that are "10 times smaller than the diameter of a human hair," said study co-author Axel Schmitt, a geochemist at the University of California, Los Angeles.

Researchers generally measure relative amounts of pairs of radioactive elements in rocks to gauge how long a rock has been around since it fully crystallized. But that isotopic ratio can be reset by a big impact that melts the rock down, erasing the geochemical trail.

That's why scientists picked the tiny baddeleyites: Once they form, they are resilient little minerals. It's not easy to melt them down and reset their isotopic clock. By looking at the isotopic ratios of radioactive uranium and lead in this tough rock, the scientists found that it formed about 187 million years ago (give or take 33 million). This confirmed that the baddeleyites were young.

The scientists could also see evidence of the damage done to the meteorite by the event that may have released it from the Martian surface about 22 million years ago (give or take 2 million). The shock from that impact muddled up the mineral structure inside, while keeping the chemicals themselves mostly intact - like shaking up a sealed gift box of chocolates.

"It looks good on the outside, but all the pieces are dislodged on the inside," Schmitt said.

The study further shows that the shergottites weren't old rocks, Humayun said - although he also called the argument that they were ancient a "straw man that's been set up that everybody's trying to take down."

"If they had found that it was 4 billion years old, I would eat my hat," he said.

The researchers say they can use their method of dating these rocks to study the other Martian meteorites in Earthly possession, and see if it reveals new information about the Red Planet's geophysical inner life.

Source: http://phys.org

quinta-feira, 1 de agosto de 2013

The Insides of Meteorites Are Nature's Stained Glass

On the outside meteorites look like volcanic rocks. But astronomy photographer Jeff Barton cracks them open to reveal the glittering geodes inside.

Barton-who is the director of Sciences at Cowell, Texas's Three Rivers Foundation-calls the innards of space debris ""natural stained glass."" He's been collecting these gems since 2004. The photos from this set are from the Allende Meteorites, which rained on the Mexican state of Chihuahua in 1969.

To capture the stunning shots of meteorite guts, Barton cuts the rocks open with a rock saw with a diamond-coated blade. He'll then grind down a stamp-sized piece so thin light can pass through it, like sun through the windows of a cathedral. Photos are subsequently taken with polarizing filters and a DSLR attached to a petrographic microscope. Aren't they just beautiful? I wish I could wear one on a necklace.

Source: gizmodo.in