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May 7, 2004

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SETI and the Smallest Stars - Space.com   For the astrobiologists at SETI and many other institutions, M dwarfs are taking center stage in a debate on whether or not they can be habstars, that is, stars that can support a web of advanced lifeforms the way our Sun does. M dwarfs are as numerous as the sand on the seashore, making up perhaps ninety percent of all the stars. And these 300 billion or so stars live an exceedingly long time. The very first M stars ever made are still shining.

A Conveyor Belt For The Nano-Age - SpaceDaily  Left: A glimpse into the factory of the future. Four images, each taken 60 seconds apart, portray the rightward march of indium atoms along a carbon nantoube subjected to about two volts (courtesy of Zettl Research Group).  In a development that brings the promise of mass production to nanoscale devices, Lawrence Berkeley National Laboratory scientists have transformed carbon nanotubes into conveyor belts capable of ferrying atom-sized particles to microscopic worksites. "We're not transporting atoms one at a time anymore — it's more like a hose," says Chris Regan of Berkeley Lab's Materials Sciences Division, who co-authored the article along with fellow Materials Sciences researchers Shaul Aloni, Ulrich Dahmen, Robert Ritchie, and Alex Zettl. Aloni, Regan, and Zettl are also scientists in the University of California at Berkeley's Department of Physics, where much of the work was conducted. The ability to shuttle a stream of particles to precise locations fills a void that has stymied the efficient assembly of nanostructures. For years, scientists have been able to simultaneously deliver millions of atoms to millions of sites simply by mixing chemicals. "It's either all at once, or excruciatingly serial," says Regan. "So we combined incredibly precise localization with something that has higher throughput." This middle ground is made possible by carbon nanotubes, which are hollow cylinders of pure carbon about ten thousand times smaller than the diameter of a human hair. Since their discovery in the sooty residue of vaporized carbon rods, these incredibly strong and versatile macromolecules have been engineered into frictionless bearings, telescoping rods, and the world's smallest room-temperature diodes. Now, they're poised to change the way these and other devices are constructed.

What If ...   Asteroids blasting the planet may seem unlikely, but how extreme would the devastation be if it really did happen? Now you can find out in excruciating detail, thanks to a new Web-based project (http://www.lpl.arizona.edu/impacteffects) that allows anyone to calculate the grim reality of a cosmic collision like the ones that wiped out the dinosaurs. Let's say, for example, an asteroid chunk about a half-mile in diameter and made up of porous rock crashes into Earth. The Web project's originators estimate it would create a crater 6.7 miles wide and trigger a fireball that would spread for 4.7 miles, spontaneously igniting grass, trees and clothes, and severely burning anyone in its path.