Nature: New evidence of water on Mercury has surfaced, according to three reports published in Science. One team of researchers, using IR laser pulses, has identified bright regions that they believe indicate water ice, inside nine craters near the planet’s north pole; a second team, using thermal modeling based on data collected by the Messenger spacecraft, has located ultracold spots that line up perfectly with those bright regions; and a third team, also using Messenger data, has spotted hydrogen, another indicator of water ice, in the same areas. The researchers suggest that any water on Mercury probably came from comets or asteroids that struck its surface. The reason the water ice ended up in frigid craters at the pole could be that, over time, it migrated there from the blistering hot surface through a process of vaporization and precipitation.
Daily Archives: November 30, 2012
Making elastic conductive material with nanoparticles
Ars Technica: Adding conductive nanoparticles to elastic materials usually makes them much more brittle. A group of Korean researchers led by Unyong Jeong from Yonsei University and Jongjin Park from the Samsung Advanced Institute of Technology has developed a technique that maintains the original material’s elasticity. The group spun a combination of butadiene and polystyrene into stretchy fibrous mats. They then soaked the mats in a solution of silver ions, which were absorbed into the material. Using a chemical process, they converted the ions into nanoparticles, resulting in a stretchy mat loaded with conductive fibers. A mat 150 µm thick has a conductivity similar to that of thin gold strips used in large-scale devices. When the material is fully stretched, the conductivity drops only 40%. Jeong and Park used the material as an RF antenna, tunable by how much it is stretched, and as electrodes in an LED.
Debate is stirred over Grand Canyon’s age
Washington Post: The Grand Canyon is generally believed to be only 6 million years old. A new study using a technique called thermochronology claims the accepted age is off by an order of magnitude. Thermochronology determines the history of rocks based on their phosphate crystals. The crystals, known as apatite, can trap the helium created by the decay of uranium and thorium. If there is helium in the crystal, then the crystals were formed near the surface. By collecting samples from multiple sites and levels, scientists can determine how long ago the crystals in the rocks formed. Rebecca Flowers of the University of Colorado believes that the thermochronology data her team has collected puts the age of the canyon at 70 million years, and that the canyon was cut in multiple stages. The 70-million-year-old western section was carved by a river flowing opposite the direction of the current Colorado River, And the eastern section would have been carved by a second river 55 million years ago. The Colorado joined the two sections 6 million years ago. Flowers’s theory is facing stiff resistance from other geologists who believe that she is misinterpreting the data she has collected and that the evidence for the 6-million-year-old age is overwhelming.
Scientists improve estimate of polar ice loss
BBC: The melting of Earth’s polar ice sheets has contributed 11 mm, or about one-fifth, of the overall global sea-level rise over the past two decades, according to the most definitive study to date, published online today in Science. The latest finding is the result of the combined efforts of 20 polar research teams, who used improved modeling and data from NASA and European Space Agency satellites. Because of the remoteness and sheer size of the ice sheets, accurate measurements have been a challenge. The satellites have to distinguish snow from ice, and scientists have to account for the “post-glacial rebound,” or the amount the land rises when the ice melts. By pooling all the researchers’ data, the most recent estimate is “two to three times more reliable than the last one,” according to Andrew Shepherd, a professor at the University of Leeds in the UK and lead author of the study. The next big challenge, say the researchers, is to predict what will happen over the next century.