Ancient Impacts Stained Vesta with Carbon-Rich Material

Composite-color 3D image of Cornelia crater on Vesta (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

Ever since arriving at Vesta in July 2011, NASA’s Dawn spacecraft has been capturing high-resolution images of the protoplanet’s surface, revealing a surprisingly varied and complex terrain covered in ridges, hills, grooves and, of course, craters of many different sizes and ages. Many of Vesta’s largest craters exhibit strange dark stains and splotches within and around them, some literally darker than coal. These stains were a puzzle to scientists when they were first seen, but the latest research now confirms that they may actually be the remains of the ancient impacts that caused them: dark deposits left by the myriad of carbon-rich objects that struck Vesta over the past four-and-a-half billion years.

Even though Vesta had a completely molten surface 4.5 billion years ago it’s believed that its crust likely solidified within a few million years, making the 530-km (329-mile) -wide world a literal time capsule for events taking place in the inner Solar System since then… one reason why Vesta was chosen as a target for the Dawn mission.

714973main_pia16632-43_946-710Using data acquired by Dawn during its year in orbit around Vesta, a team led by researchers from Germany’s Max Planck Institute for Solar System Research and the University of North Dakota investigated the dark material seen lining the edges of large impact basins located on the protoplanet’s southern hemisphere. What they determined was that much of the material was delivered during an initial large, low-velocity impact event 2–3 billion years ago that created the largest basin — Veneneia — and was then partially covered by a later impact that created the smaller basin that’s nearly centered on Vesta’s southern pole — Rheasilva.

“The evidence suggests that the dark material on Vesta is rich in carbonaceous material and was brought there by collisions with smaller asteroids.”

– Vishnu Reddy, lead author, Max Planck Institute for Solar System Research and the University of North Dakota

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Dawn framing camera images of dark material on Vesta. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

Subsequent smaller asteroid impacts over the millennia likely brought more carbonaceous material to Vesta’s surface, both delivering it as well as revealing any that may have existed beneath brighter surfaces.

Read more: Asteroid’s Unusual Light and Dark Crater

 

The dark, carbon-rich material observed on Vesta by Dawn also seems to match up with similarly dark clasts found in meteorites that have landed on Earth which are thought to have originated from Vesta.

“Our analysis of the dark material on Vesta and comparisons with laboratory studies of HED meteorites for the first time proves directly that these meteorites are fragments from Vesta,” said Lucille Le Corre from the Max Planck Institute for Solar System Research, another lead author of the study.

If evidence of such collisions between worlds can be found on Vesta, it’s likely that similar events were occurring all across the inner solar system during its early days, providing a clue as to how carbon-rich organic material was delivered to Earth — and possibly Mars as well. Such material — the dark stains we see today lining Vesta’s craters — would have helped form the very building blocks of life on our planet.

The team’s findings were published in the November/December issue of the journal Icarus.

Read more on the Max Planck Institute’s news page here, and on the NASA release here. Learn more about the Dawn mission in the video below, narrated by Leonard Nimoy.

Is This Icy “Mega” Meteorite Really From Outer Space?

Earlier today, Euronews reported an icy “mega meteorite” fall in a farmer’s field in the Hrira region of Morocco. The farmer found the chunk of supposed space ice and put it in his freezer for later investigation by scientists, who apparently confirmed that it is in fact from space.

But… really?

Continue reading “Is This Icy “Mega” Meteorite Really From Outer Space?”

Meteorite Crashes Into London Cab


Londoners awoke this morning to news of a meteorite which struck a taxi in the heart of the city’s busy shopping district Covent Garden. Witnesses were left stunned by what looked like a scene straight out of a science fiction film. An incident team arrived almost immediately to cordon off the meteorite and keep the public at a safe distance.

No one was injured as a result of the incident, but it’s a cosmic harbinger of things to come…

Of course, the “things to come” turn out to be 4 weeks of science programs on Eden TV’s Science Month, which starts up in July.

The incident was in fact a well-orchestrated publicity stunt by the UK’s Eden TV (Sky 532 Virgin 208). Science Month will run all day every day during the month of July. Highlights in the first week include Wonders of the Universe (Monday 2 July at 9pm), Finding Life Beyond Earth (Monday 2 July at 10pm), The Code (Wednesday 4 July at 10pm) and Deadliest Volcano (Thursday 5 July at 7pm).

Sure, after all’s said and done it was a PR stunt. But it was a cool PR stunt (even if not quite scientifically accurate!)

Come on, we all know that meteorites aren’t steaming hot when they land. 😉

New Mineral Found in Meteorite is From Solar System’s Beginnings

Scientists have discovered a new mineral embedded in a meteorite that fell to Earth over 40 years ago, and it could be among the oldest minerals, formed in the early days of our solar system. The mineral is a type of titanium oxide and has been named panguite, after Pan Gu, the giant from ancient Chinese mythology who established the world by separating yin from yang to create the Earth and the sky.

“Panguite is an especially exciting discovery since it is not only a new mineral, but also a material previously unknown to science,” says Chi Ma, from Caltech and author of a new paper detailing the discovery.

The Allende meteorite arrived at Earth in 1969 as an exploding fireball in the skies over Mexico, scattering thousands of pieces of meteorites across the state of Chihuahua. The Allende meteorite is the largest carbonaceous chondrite—a diverse class of primitive meteorites—ever found on our planet and is considered by many the best-studied meteorite in history.

Ma has been leading nanomineralogy investigations of primitive meteorites, which looks at tiny particles of minerals, and has now found nine new minerals, including allendeite, hexamolybdenum, tistarite, kangite and now panguite.

“The intensive studies of objects in this meteorite have had a tremendous influence on current thinking about processes, timing, and chemistry in the primitive solar nebula and small planetary bodies,” said coauthor George Rossman, also from Caltech.

The team said the new mineral is likely among the first solid objects formed in our solar system and could date back to over 4 billion years ago, before the formation of Earth and the other planets.

According to Ma, studies of panguite and other newly discovered refractory minerals are continuing in an effort to learn more about the conditions under which they formed and subsequently evolved. “Such investigations are essential to understand the origins of our solar system,” he said.

The new mineral’s chemical name is Ti4+,Sc,Al,Mg,Zr,Ca, so it contains some unusual elements like zirconium and scandium.

The mineral and the mineral name have been approved by the International Mineralogical Association’s Commission on New Minerals, Nomenclature and Classification.

Image credit: Chi Ma/Caltech

Source: Caltech

Rare Pallasite Meteorite Found in Missouri

Dr. Randy Korotev at Washington University with the Conception Junction meteorite.
Dr. Randy Korotev at Washington University with the Conception Junction meteorite.

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Meteorite hunter Karl Aston finds meteorites not by digging in the ground, but by placing ads in local newspapers. He asked people who found unusual rocks to contact him. Most responses were bum leads, but in 2009 Aston heard from a farmer in the northwestern Missouri of Conception Junction, who found something interesting: An unusually heavy stone buried in a hillside. The overall size was similar to that of a basketball and had a mass of 17 kilograms (37 pounds). Its rusty exterior hid its true nature. When the farmer had sawed off one end, olive-green crystals embedded in a shining metal shone forth. It was one of the rarest types of meteorites, a pallasite, of which only 61 samples are currently known. Recently, scientists at Washington University in St. Louis have gotten involved in an attempt to discover the meteorite’s history.

Pallasites and other meteorites are relics of the formation of the solar system. The most commonly accepted story for their formation is that they represent a boundary region inside larger asteroids where the heat from formation melted the iron and nickel metal which sunk to the core. The lighter crystals would float, and near this transition, there would be some mixing which, when broken apart due to later impacts, would form the pallasites. These asteroids formed in the asteroid belt between Mars and Jupiter and similar layers would likely be found in larger asteroids still present as well as in planets like the Earth. An alternative theory is that the materials formed independently and were mixed more recently due to large impacts.

The rusting fusion crust on the outside of the Conception Junction meteorite disguises it as just another rock, but one glimpse of the interior gives the game away. The olive-green crystals set in lustrous metal are unique to pallasites. Image credit: Dave Gheesling
The rusting fusion crust on the outside of the Conception Junction meteorite disguises it as just another rock, but one glimpse of the interior gives the game away. The olive-green crystals set in lustrous metal are unique to pallasites. Image credit: Dave Gheesling

Within the United States, 20 pallasite meteorites have been discovered. The majority of them belong to a single family of “main group” pallasites due to a similar chemical composition of their olivine crystals. When compared to other samples, the Conception Junction meteorite was unique. Because of this, the sample was given a unique designation this past August, named after the location of discovery. Before the Meteoritical Society recognizes a designation, it is required that a museum or other institutional collection houses a “type specimen” which will make the material available for scholarly research. As such a portion of the sample will be housed at UCLA where the chemical analysis on the metal was performed (the olivine was examined at Washington University).

The rarity of pallasite meteorites makes them uncommonly valuable. Some slices of the Conception Junction meteorite are still available for sale or trade, but don’t expect it to be an impulse buy. While more common stony meteorites sell for a few dollars per gram, pallasite meteorites sell for a few hundred dollars per gram. The overall price is also determined by the condition (some are unstable in Earth’s atmosphere) and whether or not it has a unique history. Meteorites for which the fall was observed are especially prized.

Wondering if the discovered meteorite was part of a larger body, Aston and other meteorite collectors including Robert Ward and Dave Gheesling conducted an extensive search of the region. They looked for 16 months in concentric circles centered on the original discovery location, but did not find any other specimens.

A Meteorite Visits the Comettes

This 88-gram (3.5 oz.) meteorite broke through the roof of the Comette family

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When your last name is Comette, I’m sure the occasional astronomy-themed joke is never far away. But it’s no joke that the Comette family living in Draveil, a suburb south of Paris, was paid a visit by a real extraterrestrial a couple of weeks ago – in the form of an 88-gram (3.5 oz.) meteorite that broke through their roof!

The Comettes were on vacation at the time, so didn’t realize their house had been struck by a space rock until they noticed a leak in the roof. When they called in a roofer it was discovered that a thick tile had been completely broken through.

The meteorite was found wedged in insulation.

Mineral scientist Alain Carion investigated the meteorite and determined that it’s an iron-rich chondrite, a 4.57-billion-year-old remnant of the early Solar System that most likely came from the main asteroid belt between the orbits of Mars and Jupiter. About 3/4 of all meteorites that have been observed landing on Earth are chondrites.

While obviously not impossible, the odds of your home being hit my a meteorite are incredibly slim. Only 145 meteorites have been documented landing in the US in the past 200 years. On March 26, 2003, just before midnight, hundreds of fragments of a large meteorite fell in the Park Forest area of Chicago. Several fell through roofs of houses and one punched a hole in the roof of the fire station. One large piece weighing about 2.5 kg (5.5 lb) crashed into a bedroom, narrowly missing a boy who was asleep in his bed! On September 23, 2003, a 20 kg (44 lb) stone meteorite tore straight through a two-storey house in New Orleans and came to rest in the basement. (Source: University of New Mexico Institute of Meteoritics.)

Only about 50 meteorites have been found in France over the past four centuries, and none has ever before been discovered less than 80 km (50 miles) from Paris.

While they could attempt to sell the meteorite that struck their home, possibly fetching several hundred euros for it, the Comettes have decided to keep their otherworldly visitor.

“A piece of the history of space of which we know nothing, but which is fascinating, has fallen on us,” Mrs. Comette told the Le Parisien newspaper. “It’s like a fairytale, and less likely than winning the lottery, we’re told.”

Read more on The Guardian or on The Local.

Image found on Stargazers Lounge.