El impacto del mayor meteorito que chocó contra la Luna

"Me quedé espantado", contó el profesor José Madiedo, el científico que observó el impacto del meteorito.

Se trata del meteorito más grande detectado hasta el momento que haya chocado contra la Luna y pudo haber generado un cráter de por lo menos 40 metros de diámetro.

"Esa noche estaba observando las imágenes que arrojaba el telescopio, como de costumbre, monitoreando los impactos de meteoritos sobre la Luna y de repente me quedé congelado", le cuenta a BBC Mundo el profesor José Madiedo, de la Universidad de Huelva, en España.

Contenido relacionado

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Madiedo recuerda con lujo de detalles aquella noche del 11 de septiembre de 2011, cuando observó el evento. Ahí se inició una investigación, publicada este lunes, sobre el impacto de un fenómeno que los científicos califican de sin precedentes.

El equipo de investigadores está acostumbrado a observar con regularidad los destellos de rocas que chocan contra la Luna y que son, por lo general, del tamaño de una nuez o de una pelota de tenis.

Lo llamativo aquella noche fue que el haz de luz que generó el impacto fue muchísimo más brillante y que duró unos ocho segundos.

"Cuando observé la magnitud del destello y la duración, me di cuenta de que aquello no era normal, que aquí había ocurrido algo bastante extraordinario", le dijo a BBC Mundo el científico.

Por lo general, los impactos de estas rocas sobre el satélite lunar tienen una corta duración, literalmente fracciones de segundos, señaló el profesor Madiedo.

Por ejemplo, el que hasta ahora se consideraba el impacto más grande, que fue detectado por la Nasa en marzo del año pasado, duró poco más de un segundo, comparado con los ocho segundos que registró este último.

"Nos movilizamos inmediatamente"

"Me conecté con el segundo telescopio", cuenta Madiedo, para comprobar que había grabado las mismas imágenes y efectivamente así había sido".

"Cuando observé la magnitud del destello y la duración me di cuenta de que aquello no era normal, que aquí había ocurrido algo bastante extraordinario" José Madiedo, investigador de la Universidad de Huelva, en España

"Eran las ocho de la noche y avisé al resto de mis colegas. Nos movilizamos inmediatamente y dejamos de lado otras cosas para comenzar a analizar el tamaño de la roca y su posible impacto", destacó.

El choque del meteorito fue observado mediante el Sistema de Análisis y Detección de Impactos sobre la Luna, Midas por sus siglas en inglés.

"ASTEROID IMPACTS THE MOON - ACTUAL FOOTAGE" By MRSTARGAZERNATION

El científico estima que la roca tenía un peso de unos 400 kilos, y llevaba una velocidad de unos 61.000 kilómetros por hora.

El meteorito dectectado por la NASA hace un año, en comparación, pesaba alrededor de 40 kilogramos.

El destello que generó fue tan brillante que podía haber sido observado a simple vista desde la Tierra.

Por qué importa este fenómeno

Es obvio que un fenómeno como este es espectacular, aún más cuando la tecnología hoy en día nos permite ser testigo de toda su fuerza e impacto.

El científico le dijo a BBC Mundo que la roca tenía un peso aproximado de 400 kilogramos.

Pero, ¿qué relevancia tiene para los seres humanos aquí en la Tierra?

"Justamente el proyecto busca conocer mejor con qué frecuencia rocas como éstas pueden impactar la Tierra. Observando la Luna podemos saber con más certeza la frecuencia con la que pueden producirse esos impactos en nuestro planeta", dijo el científico.

Y precisamente una de las conclusiones del estudio es que "la frecuencia con la que estas rocas pueden chocar contra la Tierra es diez veces mayor de lo que se pensaba".

Sin embargo, para que un meteorito tenga un impacto así sobre nuestro planeta tiene que ser mucho más grande.

La mayoría de las rocas de ese tamaño se desintegran cuando entran en contacto con la atmósfera y se convierten en una bola de fuego.

Según Madiedo, a lo sumo se hubieran encontrado algunos fragmentos del meteorito.

ORIGINAL: BBC Mundo

Redacción BBC Mundo
25 de febrero de 2014

NASA Researchers: DNA Building Blocks Can Be Made in Space

ORIGINAL: NASA

08.08.11

NASA-funded researchers have evidence that some building blocks of DNA, the molecule that carries the genetic instructions for life, found in meteorites were likely created in space. The research gives support to the theory that a "kit" of ready-made parts created in space and delivered to Earth by meteorite and comet impacts assisted the origin of life.

"People have been discovering components of DNA in meteorites since the 1960's, but researchers were unsure whether they were really created in space or if instead they came from contamination by terrestrial life," said Dr. Michael Callahan of NASA's Goddard Space Flight Center, Greenbelt, Md. "For the first time, we have three lines of evidence that together give us confidence these DNA building blocks actually were created in space." Callahan is lead author of a paper on the discovery appearing in Proceedings of the National Academy of Sciences of the United States of America.

NASA-funded researchers have evidence that some building blocks of DNA, the molecule that carries the genetic instructions for life, found in meteorites were likely created in space. The research gives support to the theory that a "kit" of ready-made parts created in space and delivered to Earth by meteorite and comet impacts assisted the origin of life. (Credit: NASA's Goddard Space Flight Center) › Download this and related videos from NASA Goddard's Scientific Visualization Studio

The discovery adds to a growing body of evidence that the chemistry inside asteroids and comets is capable of making building blocks of essential biological molecules. For example, previously, these scientists at the Goddard Astrobiology Analytical Laboratory have found amino acids in samples of comet Wild 2 from NASA’s Stardust mission, and in various carbon-rich meteorites. Amino acids are used to make proteins, the workhorse molecules of life, used in everything from structures like hair to enzymes, the catalysts that speed up or regulate chemical reactions.

In the new work, the Goddard team ground up samples of twelve carbon-rich meteorites, nine of which were recovered from Antarctica. They extracted each sample with a solution of formic acid and ran them through a liquid chromatograph, an instrument that separates a mixture of compounds. They further analyzed the samples with a mass spectrometer, which helps determine the chemical structure of compounds.

Meteorites contain a large variety of nucleobases, an essential building block of DNA. (Artist concept credit: NASA's Goddard Space Flight Center/Chris Smith)

The team found adenine and guanine, which are components of DNA called nucleobases, as well as hypoxanthine and xanthine. DNA resembles a spiral ladder; adenine and guanine connect with two other nucleobases to form the rungs of the ladder. They are part of the code that tells the cellular machinery which proteins to make. Hypoxanthine and xanthine are not found in DNA, but are used in other biological processes.

Also, in two of the meteorites, the team discovered for the first time trace amounts of three molecules related to nucleobases: purine, 2,6-diaminopurine, and 6,8-diaminopurine; the latter two almost never used in biology. These compounds have the same core molecule as nucleobases but with a structure added or removed.

It's these nucleobase-related molecules, called nucleobase analogs, which provide the first piece of evidence that the compounds in the meteorites came from space and not terrestrial contamination. "You would not expect to see these nucleobase analogs if contamination from terrestrial life was the source, because they're not used in biology, aside from one report of 2,6-diaminopurine occurring in a virus (cyanophage S-2L)," said Callahan. "However, if asteroids are behaving like chemical 'factories' cranking out prebiotic material, you would expect them to produce many variants of nucleobases, not just the biological ones, due to the wide variety of ingredients and conditions in each asteroid."

The second piece of evidence involved research to further rule out the possibility of terrestrial contamination as a source of these molecules. The team also analyzed an eight-kilogram (17.64-pound) sample of ice from Antarctica, where most of the meteorites in the study were found, with the same methods used on the meteorites. The amounts of the two nucleobases, plus hypoxanthine and xanthine, found in the ice were much lower -- parts per trillion -- than in the meteorites, where they were generally present at several parts per billion. More significantly, none of the nucleobase analogs were detected in the ice sample. One of the meteorites with nucleobase analog molecules fell in Australia, and the team also analyzed a soil sample collected near the fall site. As with the ice sample, the soil sample had none of the nucleobase analog molecules present in the meteorite.

Thirdly, the team found these nucleobases -- both the biological and non-biological ones -- were produced in a completely non-biological reaction. "In the lab, an identical suite of nucleobases and nucleobase analogs were generated in non-biological chemical reactions containing hydrogen cyanide, ammonia, and water. This provides a plausible mechanism for their synthesis in the asteroid parent bodies, and supports the notion that they are extraterrestrial," says Callahan.

"In fact, there seems to be a 'goldilocks' class of meteorite, the so-called CM2 meteorites, where conditions are just right to make more of these molecules," adds Callahan.

The team includes Callahan and Drs. Jennifer C. Stern, Daniel P. Glavin, and Jason P. Dworkin of NASA Goddard's Astrobiology Analytical Laboratory; Ms. Karen E. Smith and Dr. Christopher H. House of Pennsylvania State University, University Park, Pa.; Dr. H. James Cleaves II of the Carnegie Institution of Washington, Washington, DC; and Dr. Josef Ruzicka of Thermo Fisher Scientific, Somerset, N.J. The research was funded by the NASA Astrobiology Institute, the Goddard Center for Astrobiology, the NASA Astrobiology: Exobiology and Evolutionary Biology Program, and the NASA Postdoctoral Program.

Related Link

› Related videos from NASA Goddard's Scientific Visualization Studio

Bill Steigerwald
NASA's Goddard Space Flight Center, Greenbelt, Md.

Discovery: Earth's Oldest Crater Is Largest Too

ORIGINAL: Space

Douglas Main, OurAmazingPlanet Staff Writer

Date: 29 June 2012 Time: 04:42 PM ET

An artistic interpretation of how a large meteorite impact might have looked. The crater formed in modern-day Greenland may be the oldest and largest yet discovered on Earth. CREDIT: Carsten Egestal Thuesen, GEUS 

A study of Greenland's rocks may have turned up something unexpected: the oldest and largest meteorite crater ever found on Earth.

Researchers think the crater was formed 3 billion years ago, making it the oldest ever found, said Danish researcher Adam Garde. The impact crater currently measures about 62 miles (100 kilometers) from one side to another. But before it eroded, it was likely more than 310 miles (500 km) wide, which would make it the biggest on Earth, Garde told OurAmazingPlanet.

The team has calculated it was caused by a meteorite 19 miles (30 km) wide, which, if it hit Earth today, would wipe out all higher life.

Mystery feature

In the 3 billion years since impact, the land has been eroded down to about 16 miles (25 km) below the original surface. But the effects of the intense shock wave and heat penetrated deep into the Earth, and remain visible today, said Garde, a researcher at the Geological Survey of Denmark and Greenland. [ Meteor Mania: How Well Do You Know 'Shooting Stars'? ]

Garde had been conducting research on Greenland's geology and noticed several strange features that didn't make sense. One day in September 2009, he came up with the extreme explanation of an impact from a meteorite. His team collected samples over the years and published the results in the July issue of the journal Earth and Planetary Science Letters. He's now "100 percent positive" it's a crater, for several reasons, he said.

For one, he found widespread crushed rocks in a circular shape that seemed to be caused by the shock waves of a massive impact.
Second, there are deposits of a melted mineral called K-feldspar (or potassium-feldspar) that could have been liquefied only at extremely high heat, like that caused by an meteorite's crash-landing .
There's also widespread evidence of weathering by hot water, which he thinks was caused by the ocean rushing into the crater after it struck the area. The area may have been covered by a shallow ocean at the time, but even if it wasn't, it doesn't matter, Garde said. "The crater from a meteorite that big would have caused the sea to rush in," he said.

Mining for minerals

The black circle on map shows the location of the meteorite impact near the town of Maniitsoq in Greenland. CREDIT: Geological Survey of Denmark and Greenland

John Spray, a meteorite expert at the University of New Brunswick, who wasn't involved in the research, said he thinks it's probably a meteor crater, but points out that it hasn't been proved, and may not be for some time. "It's very interesting and it's good science," he said. "But we don't really know how to recognize very old impact craters, because they are typically so highly modified."

That's because Earth is alive and constantly changing due processes such as erosion, precipitation and plate tectonics. At one time Earth likely had as many craters as the moon, which is essentially geologically dead. But these have mostly been wiped away, destroyed by erosion and the like.

Only around 180 impact craters have ever been discovered on Earth, and nearly one-third of them contain significant minerals deposits such as precious metals. The Canadian mining company, North American Nickel, is exploring the region where the potentially newfound crater is for nickel and other mineral deposits, company geologist John Roozendaal said. They are conducting airborne surveys and will soon do more mapping, small-scale sampling and drilling to see if they can find an area that could be economical to mine.

These impacts are of interest to mining companies not because of the large meteorites themselves — they typically vaporize — but because of the effect upon the Earth's surface. The impact heats rocks so much that metals can melt and then collect toward the bottom of the crater. Craters can also be important sources of oil and gas; the crushed, permeable rocks can act like a sponge, absorbing hydrocarbons.

Before this discovery, the oldest crater was thought to be the Vredefort crater in South Africa, estimated to be 2 billion years old. At 186 miles (300 km) wide, it's also the largest crater that remains visible. Scientists expect that there were many more craters formed around 3-4 billion years ago when Earth lacked a protective atmosphere.

Garde said the most interesting thing about the experience was finding an alternate explanation for something outside of his training. "I had a problem I couldn't solve in a region I knew very well," he said. "A meteor impact was the idea that made everything fall into place — It's not something I was looking for."

This article was provided by OurAmazingPlanet , a sister site of SPACE.com. Reach Douglas Main at dmain@techmedianetwork.com . Follow him on Twitter @Douglas_Main . Follow OurAmazingPlanet on Twitter @OAPlanet . We're also on Facebook and Google+ .

Study finds new evidence supporting theory of extraterrestrial impact

ORIGINAL: EurekAlert 

This is James Kennett. UCSB

(Santa Barbara, Calif.) –– An 18-member international team of researchers that includes James Kennett, professor of earth science at UC Santa Barbara, has discovered melt-glass material in a thin layer of sedimentary rock in Pennsylvania, South Carolina, and Syria. According to the researchers, the material –– which dates back nearly 13,000 years –– was formed at temperatures of 1,700 to 2,200 degrees Celsius (3,100 to 3,600 degrees Fahrenheit), and is the result of a cosmic body impacting Earth.

These new data are the latest to strongly support the controversial Younger Dryas Boundary (YDB) hypothesis, which proposes that a cosmic impact occurred 12,900 years ago at the onset of an unusual cold climatic period called the Younger Dryas. This episode occurred at or close to the time of major extinction of the North American megafauna, including mammoths and giant ground sloths; and the disappearance of the prehistoric and widely distributed Clovis culture. The researchers' findings appear today in the Proceedings of the National Academy of Sciences.

"These scientists have identified three contemporaneous levels more than 12,000 years ago, on two continents yielding siliceous scoria-like objects (SLO's)," said H. Richard Lane, program director of National Science Foundation's Division of Earth Sciences, which funded the research. "SLO's are indicative of high-energy cosmic airbursts/impacts, bolstering the contention that these events induced the beginning of the Younger Dryas. That time was a major departure in biotic, human and climate history."

 

Microscopic Images of Grains of Melted Quartz. These are microscopic images of grains of melted quartz from the YDB cosmic impact layer at Abu Hureyra, Syria, showing evidence of burst bubbles and flow textures that resulted from the melting and boiling of rock at very high temperatures. (Light microscope image at left; SEM image at right.). UCSB

Morphological and geochemical evidence of the melt-glass confirms that the material is not cosmic, volcanic, or of human-made origin. "The very high temperature melt-glass appears identical to that produced in known cosmic impact events such as Meteor Crater in Arizona, and the Australasian tektite field," said Kennett.

"The melt material also matches melt-glass produced by the Trinity nuclear airburst of 1945 in Socorro, New Mexico," he continued. "The extreme temperatures required are equal to those of an atomic bomb blast, high enough to make sand melt and boil."

The material evidence supporting the YDB cosmic impact hypothesis spans three continents, and covers nearly one-third of the planet, from California to Western Europe, and into the Middle East. The discovery extends the range of evidence into Germany and Syria, the easternmost site yet identified in the northern hemisphere. The researchers have yet to identify a limit to the debris field of the impact.

Photos of Melt Glass Known as Trinitite. These are photos of melt glass known as trinitite formed at the ground surface from the melting of sediments and rocks by the very high temperatures of the Trinity nuclear airburst in New Mexico in 1945. This material is very similar to the glassy melt materials now reported from the cosmic impact YDB layer, consistent with the very high temperature origin of the melt materials in the YDB layer. UCSB

"Because these three sites in North America and the Middle East are separated by 1,000 to 10,000 kilometers, there were most likely three or more major impact/airburst epicenters for the YDB impact event, likely caused by a swarm of cosmic objects that were fragments of either a meteorite or comet," said Kennett.

The PNAS paper also presents examples of recent independent research that supports the YDB cosmic impact hypothesis, and supports two independent groups that found melt-glass in the YDB layers in Arizona and Venezuela. "The results strongly refute the assertion of some critics that 'no one can replicate' the YDB evidence, or that the materials simply fell from space non-catastrophically," Kennett noted.

He added that the archaeological site in Syria where the melt-glass material was found –– Abu Hureyra, in the Euphrates Valley –– is one of the few sites of its kind that record the transition from nomadic hunter-gatherers to farmer-hunters who live in permanent villages. "Archeologists and anthropologists consider this area the 'birthplace of agriculture,' which occurred close to 12,900 years ago," Kennett said.

"The presence of a thick charcoal layer in the ancient village in Syria indicates a major fire associated with the melt-glass and impact spherules 12,900 years ago," he continued. "Evidence suggests that the effects on that settlement and its inhabitants would have been severe."

###

Other scientists contributing to the research include Ted Bunch and James H. Wittke of Northern Arizona University; Robert E. Hermes of Los Alamos National Laboratory; Andrew Moore of the Rochester Institute of Technology; James C. Weaver of Harvard University; Douglas J. Kennett of Pennsylvania State University; Paul S. DeCarli of SRI International; James L. Bischoff of the U.S. Geological Survey; Gordon C. Hillman of the University College London; George A. Howard of Restoration Systems; David R. Kimbel of Kimstar Research; Gunther Kletetschka of Charles University in Prague, and of the Czech Academy of Science; Carl Lipo and Sachiko Sakai of California State University, Long Beach; Zsolt Revay of the Technical University of Munich in Germany; Allen West of GeoScience Consulting; and Richard B. Firestone of Lawrence Berkeley National Laboratory.

Out of this world, quite literally: The beautiful and mysterious Fukang meteorite

ORIGINAL: Daily Mail

Lyle Brennan
14 April 2012

When it slammed into the surface of Earth, there was little sign of the beauty that lay inside.

But cutting the Fukang meteorite open yielded a breathtaking sight.

Within the rock, translucent golden crystals of a mineral called olivine gleamed among a silvery honeycomb of nickel-iron.

Cosmic wonder: Marvin Killgore of the Arizona Meteorite Laboratory lets the sun shine through a polished slice of the Fukang rock

The rare meteorite weighed about the same as a hatchback when it was discovered in 2000, in the Gobi Desert in China's Xinjiang Province.

It has since been divided into slices which give the effect of stained glass when the sun shines through them.

An anonymous collector holds the largest portion, which weighs 925lb. in 2008, this piece was expected to fetch $2million (£1.26million) at auction at Bonham's in New York - but it remained unsold.

It is so valuable that even tiny chunks sell in the region of £20-30 per gram.

Arizona's Southwest Meteorite Laboratory, which holds about 70lb of the rock, says the remarkable find will turn out to be 'one of the greatest meteorite discoveries of the 21st century'.

It says the Fukang specimen outshines all other known examples of the pallasite class, which makes up just one per cent of all meteorites. However, it is not the biggest - in 2005 space rock hunter Steve Arnold dug up a 1,400lb sample in Kansas.

Valuable: The main mass of the Fukang meteorite, which failed to sell after being valued at $2million. The intact space rock weighed as much as a small car

The Arizona lab's experts say pallasites, whose make-up of half nickel-iron, half olivine gives them their mosaic-like appearance, are 'thought to be relics of forming planets'.

They are believed to originate from deep inside intact meteors created during the formation of the solar system about 4.5 billion years ago and very few specimens are thought to have survived their descent through Earth's atmosphere.

February 2005 saw the Chinese space rock transported all the way to the Tucson Gem and Mineral Show, in Tucson, Arizona.

The U.S. lab claims their polished slice of the original meteorite is the world's biggest pallasite cross section, measuring 36in by 19in.

4.5 billion years in the making: Golden olivine meets silvery nickel-iron to create a stunningly beautiful mosaic effect