It's time to think about a return to the moon. Thanks to being able to stand on the shoulders of giants, we know where to watch for problems - even in the dust. Dust could be more than a housekeeping issue for astronauts who visit the moon because the health of astronauts may depend on the amount of exposure they have to the tiny particles.

During the Apollo lunar missions in the late 1960s and 1970s, the clingy particles were easily transported via spacesuits into the lunar lander following moonwalks. The amount of dust inside the vehicle was so great some astronauts reported they could smell it.

Even though there were no known illnesses due to exposure, lunar dust is a concern because it has properties comparable to that of fresh-fractured quartz, a highly toxic substance. However, the Apollo flights lasted only a few days. During the proposed return to the moon, astronauts will be exposed to lunar dust for longer periods of time, including missions that could last months.

A new study of possible links between climate and geophysics on Earth and similar planets finds that prolonged heating of the atmosphere can shut down plate tectonics and cause a planet's crust to become locked in place.

"The heat required goes far beyond anything we expect from human-induced climate change, but things like volcanic activity and changes in the sun's luminosity could lead to this level of heating," said lead author Adrian Lenardic, associate professor of Earth science at Rice University. "Our goal was to establish an upper limit of naturally generated climate variation beyond which the entire solid planet would respond."

Lenardic said the research team wanted to better understand the differences between the Earth and Venus and establish the potential range of conditions that could exist on Earth-like planets beyond the solar system.

Chile’s Chaiten Volcano is shown spewing ash and smoke (centre left of image) into the air for hundreds of km over Argentina’s Patagonia Plateau in this Envisat image acquired on 5 May 2008.

The 1000 m-high volcano had been dormant for thousands of years before erupting on 2 May, causing the evacuation of thousands. Chaiten Volcano is located in southern Chile 10 km northeast of the town of Chaiten on the Gulf of Corcovado.

Envisat’s Medium Resolution Imaging Spectrometer (MERIS) instrument processed this image at a resolution of 1200 m.

A comparison of recorded Antarctic temperatures and snowfall accumulation to predictions by major computer models of global climate change offer both good and bad news.

The good news is that the numerical models’ predictions covering the last 50 years broadly follow the actual observed temperatures and snowfall for the southernmost continent, although the observations are very variable.

The bad news is that a similar comparison that includes the last 100 years is a poor match. Projections of temperatures and snowfall ranged from 2.5 to five times what they actually were during that period.

Beads known to geologists as carbon cenospheres were formed from liquefied carbon deep in the earth when an asteroid struck some 65 million years ago, according to a new theory.

The carbon cenospheres were deposited next to a thin layer of the element iridium -- an element more likely to be found in Solar System asteroids than in the Earth's crust. The iridium-laden dust is believed to be the shattered remains of the 200-km-wide asteroid's impact. Like the iridium layer, the carbon cenospheres are apparently common. They've been found in Canada, Spain, Denmark and New Zealand.

But the cenospheres' origin presented a double mystery. Cenospheres had been known to geologists only as a sign of modern times -- they form during the intense combustion of coal and crude oil. Equally baffling, there were no power plants burning coal or crude oil 65 million years ago, and natural burial processes affecting organic matter from even older ages -- such as coals from the 300-million-year-old Carboniferous Period -- had simply not been cooked long or hot enough.

A new model of inner Earth constructed by Arizona State University researchers pulls past information and hypotheses into a coherent story to clarify mantle motion.

“The past maybe two or three years there have been a lot of papers in Science and Nature about the deep mantle from seismologists and mineral physicists and it’s getting really confusing because there are contradictions amongst the different papers,” says Ed Garnero, seismologist and an associate professor in Arizona State University’s School of Earth and Space Exploration.

“But we’ve discovered that there is a single framework that is compatible with all these different findings,” he adds.

Garnero partnered with geodynamicist and assistant professor Allen McNamara, also in the School of Earth and Space Exploration in ASU’s College of Liberal Arts and Sciences, to synthesize the information for their paper to be published in the May 2 issue of Science.

Scientists probing volcanic rocks from deep under the frozen surface of the Arctic Ocean have discovered a special geochemical signature until now found only in the southern hemisphere. The rocks were dredged from the remote Gakkel Ridge, which lies under 3,000 to 5,000 meters of water; it is Earth’s most northerly undersea spreading ridge.

The Gakkel extends some 1,800 kilometers beneath the Arctic ice between Greenland and Siberia. Heavy ice cover prevented scientists from getting at it until the 2001 Arctic Mid-Ocean Ridge Expedition, in which U.S and German ice breakers cooperated.

This produced data showing that the ridge is divided into robust eastern and western volcanic zones, separated by an anomalously deep segment. That abrupt boundary contains exposed unmelted rock from earth’s mantle, the layer that underlies the planet’s hardened outer shell, or lithosphere.

The earthquake on April 18, 2008, about 120 miles east of St. Louis, registered 5.2 on the Richter scale and hit at 4:40 a.m. with a strong aftershock occurring at approximately 10:15 a.m. that morning, followed by lesser ones in subsequent days. The initial earthquake was felt in parts of 16 states.

To the surprise of many, originated in the Wabash Valley Fault, not the better-known and more-dreaded New Madrid Fault in Missouri’s boot heel.

The concern of Douglas Wiens, Ph.D., and Michael Wysession, Ph.D., seismologists at Washington University in St. Louis, is that the New Madrid Fault may have seen its day and the Wabash Fault is the new kid on the block.

Gondwana was a ‘supercontinent' comprised of Antarctica, South America, Africa, Madagascar, Australia-New Guinea, and New Zealand, as well as Arabia and the Indian subcontinent of the Northern Hemisphere.

It existed between 500 and 180 million years ago but geologists have debated for decades over how it eventually broke up. The two primary camps support a theory claiming the continent separated into many small plates and a second theory believes it broke into a few large pieces.

In a new paper published in ‘Geophysical Journal International’, Dr. Graeme Eagles at the University of London says he has the answer.

New geological evidence radiometric dating indicates the Grand Canyon may be so old that dinosaurs once lumbered along its rim, pushing back its assumed origins by 40 million to 50 million years.

The researchers from the University of Colorado at Boulder and the California Institute of Technology gathered evidence from rocks in the canyon and on surrounding plateaus that were deposited near sea level several hundred million years ago before the region uplifted and eroded to form the canyon.

"As rocks moved to the surface in the Grand Canyon region, they cooled off," said CU-Boulder geological sciences Assistant Professor Rebecca Flowers. "The cooling history of the rocks allowed us to reconstruct the ancient topography, telling us the Grand Canyon has an older prehistory than many had thought."