Moon”s biggest crater exposes its hidden lower crust

Washington, March 5 (ANI): Reports indicate that the biggest and deepest crater on the Moon can provide glimpses of the hidden lower crust of Earth”s natural satellite.

Shortly after the Moon formed, an asteroid smacked into its southern hemisphere and gouged out a truly enormous crater, the South Pole-Aitken basin, almost 1,500 miles across and more than five miles deep.

Asteroid bombardment over billions of years has left the lunar surface pockmarked with craters of all sizes, and covered with solidified lava, rubble, and dust.

Glimpses of the original surface, or crust, are rare, and views into the deep crust are rarer still.

Fortunately, a crater on the edge of the South Pole-Aitken basin may provide just such a view.

According to Noah Petro of NASA”s Goddard Space Flight Center in Greenbelt, Maryland, “We believe the central part of the Apollo Basin may expose a portion of the Moon”s lower crust. If correct, this may be one of just a few places on the Moon where we have a view into the deep lunar crust, because it”s not covered by volcanic material as many other such deep areas are.”

“Just as geologists can reconstruct Earth”s history by analyzing a cross-section of rock layers exposed by a canyon or a road cut, we can begin to understand the early lunar history by studying what”s being revealed in Apollo,” he said.

Petro and his team made the discovery with the Moon Mineralogy Mapper (M3), a NASA instrument on board India”s Chandrayaan-1 lunar-orbiting spacecraft.

Analysis of the light (spectra) in images from this instrument revealed that portions of the interior of Apollo have a similar composition to the impact melt in the South Pole-Aitken (SPA) basin.

As you go deeper into the Moon, the crust contains minerals have greater amounts of iron. When the Moon first formed, it was largely molten.

Minerals containing heavier elements, like iron, sank down toward the core, and minerals with lighter elements, like silicon, potassium, and sodium, floated to the top, forming the original lunar crust.

“The asteroid that created the SPA basin probably carved through the crust and perhaps into the upper mantle. The impact melt that solidified to form the central floor of SPA would have been a mixture of all those layers,” said Petro.

“We expect to see that it has slightly more iron than the bottom of Apollo, since it went deeper into the crust. This is what we found with M3,” he said.

“However, we also see that this area in Apollo has more iron than the surrounding lunar highlands, indicating Apollo has uncovered a layer of the lunar crust between what is typically seen on the surface and that in the deepest craters like SPA,” he added. (ANI)

250-mln-yr volcanic shutdown may have led to ‘snowball Earth’

London, May 11 (ANI): In a new study, scientists have determined that a 250-million-year shutdown of volcanic activity which is thought to have occurred early in Earth’s history may be what turned the planet into a glacier-covered snowball, and give rise to our oxygen-rich atmosphere.

Previous studies have noted that very little volcanic material has been dated to between 2.45 and 2.2 billion years ago, but it was widely assumed the gap would vanish as more samples were dated.

Now, according to a report in New Scientist, an analysis of thousands of zircon minerals collected from all seven continents indicates that the gap may be real after all.Zircons provide a record of past volcanic activity, as the date they were formed can be calculated from the radioactive isotopes they contain.

The failure of so many samples from all over the world to fill the gap suggests there was a major slowdown in the planet’s volcanic activity during this period, according to Kent Condie of New Mexico Tech in Socorro, who led the study.

“Volcanism didn’t shut off, but it became much, much less widespread during this time,” he added.

“The lull could be tied to a pause in the motion of tectonic plates, which drives much of Earth’s volcanic activity,” said Condie.

Computer simulations suggest this motion, which now takes place continuously, would have been intermittent early in Earth’s history, when the planet’s interior was hotter and less viscous, so less able to drag the plates.

The lull may in turn be a major factor behind a suspected “snowball Earth” event between 2.4 and 2.3 billion years ago, when much of the planet is thought to have been covered with ice.

With no new carbon dioxide (CO2) being spewed from volcanoes, its concentration in the atmosphere would have declined, leading to global cooling.

The lull could also be behind the rise in atmospheric oxygen that is known to have taken place around 2.4 billion years ago.

Prior to the lull, any oxygen produced by marine microorganisms was consumed in reactions with iron in the ocean.

With no fresh volcanic material to replenish the iron, oxygen would have been free to build up in the atmosphere.

This in turn could have further cooled the Earth by removing methane, another powerful greenhouse gas from the atmosphere. (ANI)

In Germany, an outpost of Pompeii shows its age

Aschaffenburg, Germany – So ancient is Europe that even a “new” building often seems as battered and worn as an “old” one. East of Frankfurt, restorers have struggled to remove the scars of nearly 160 years from a reproduction Roman villa which used to offer a vision of luxury living in the Italian city of Pompeii before a volcanic eruption on August 24 in 79 AD.

Mount Vesuvius exploded, raining ash on the city, sending streams of lava racing down the mountainside and suffocating its people with toxic gases. In three days, the Italian city was covered by a 2.6- metre-thick layer of volcanic material.

In the 19th century, archaeological excavations brought much of the city back to light, inspiring not just a fascination with Roman life but also a desire to look beyond the faded frescoes, grey old stone and blank marble of Ancient Rome and visualize it in full colour.

The Pompejanum was built in the German city of Aschaffenburg as a replica of a villa in Pompeii. The rich reds, intense blues and greens of its wall paintings are a shock to anyone expecting the dullness of the ancient ruins.

“The excavations were expanding during the reign of King Ludwig I of Bavaria,” explained a Pompejanum art historian, Werner Helmberger.

Like many educated Europeans, Ludwig had made the Grand Tour to Italy and had been fascinated by the discoveries.

“He noticed how quickly the colourful Roman frescoes faded when they were brought to light,” said Georg Fahrenschon, today’s Bavarian finance minister, who oversaw funding of the replica’s restoration. That gave him the idea of building a reproduction villa.

“He never intended to live there. Its purpose was to educate Bavarians about classical architecture,” said Helmberger.

In 1843, Ludwig laid the foundation stone at Aschaffenburg, a town in the far north of his kingdom, and the replica with its colourful interior was completed in 1850. But within a century it was as much a ruin as Pompeii was.

During the Second World War, the US Army shelled Aschaffenburg. The walls of the Pompejanum were smashed and the frescoes lost. The building is close to the Main River, and dampness from the soil crept into what was left, worsening the damage, along with vandalism.

Teenagers lit campfires in the rooms or scratched hearts into the plaster. A bullet which remains impacted in the nose of the goddess Hera in a mosaic apparently dates from those violent days.

Restoration of this outpost of Campania began in the 1960s. In the decades since, fashions in historical preservation have regularly changed and each phase followed different principles. The last, intensive phase began in 1989.

In line with current principles that advocate showing a building’s many phases, parts of the Pompejanum are fully restored to their 1848 state and others seem frozen in their state of war destruction in 1945.

The Housewife’s Room, opened to the public this month when the work was completed, has largely grey walls, where the US shells wrecked the frescoes. They have only been restored at a few spots.

Restorer Armin Schmickl-Prochnow said: “We make a point of only using the materials of 2,000 years ago. They are simply earth pigments with some lime added to bond them.”

Raimund Wuensche, head of the Bavarian state antiquities collection, said the 12.7 million euros (17 million dollars) spent since the 1960s on restoring the Pompejanum had been well worth it.

“It’s a unique feeling here: the space, the frescoes, the culture, all in one place.”

Scientists bring 2000-year-old statue of Amazon warrior to virtual life

Washington, Jan 13 (ANI): A team of scientists in the UK is digitally restoring a 2000-year-old painted statue of an Amazon warrior to her original glory.

The scientists are from WMG Solutions at the University of Warwick, the University of Southampton, and the Herculaneum Conservation Project.

The Roman statue was discovered by the Herculaneum Conservation Project in the ancient ruins of Herculaneum, a town preserved in the same eruption that buried nearby Pompeii in AD 79.

It is thought to represent a wounded Amazon warrior, complete with painted hair and eyes preserved by the ash that buried the town.

Researchers from WMG at the University of Warwick, Southampton and Herculaneum are now scanning, modelling and digitally recreating the Amazon statue.
Dr Mark Williams, a leader in laser measurement at WMG, took his team and equipment to the site.

“The statue is an incredible find. Although its age alone makes it valuable, it is unique because it has retained the original painted surface, preserved under the volcanic material that buried Herculaneum,” he said.

Dr Williams used state-of-the-art equipment to accurately measure (within 0.05 of a millimetre) every surface of the bust and translated that information into a computer model.

Dr Greg Gibbons, also of WMG, then used rapid prototyping to create a physical 3D model of the head revealing the smallest detail.

Further recording was carried out on site by experts in archaeological computing from Southampton, led by Dr Graeme Earl.

They used a novel form of photography which provided an extremely detailed record of the texture and colour of the painted surfaces.

The Southampton team is now digitally re-modelling and re-painting the sculpture. They are using techniques derived from the film industry to recreate the original carved and painted surfaces.

In the final step, Professor Alan Chalmers, head of WMG’s visualization team and an expert in ultra-realistic graphics, will apply techniques to the computer model to exactly reproduce the lighting and environmental conditions under which the painted statue would have originally been created and displayed.

This visualization will provide archaeologists with an otherwise impossible view of how the original statue may have looked in context, and allow them to experiment with alternative hypotheses.

According to Professor Chalmers, “Our work will be used both for educational and research purposes to give people new insights into the statue’s design, to provide a record for conservators, and to explore how it may have been appreciated over 2000 years ago.” (ANI)