Science  13 Apr 2012:
Vol. 336, Issue 6078, pp. 137

You are currently viewing the .

View Full Text

Log in to view the full text

Log in through your institution

Log in through your institution

  1. Huge Dust Devil Prowling Mars

    A martian dust devil, 20 kilometers high.


    Earth may have terrifying tornadoes, but when it comes to dust devils, Mars has us beat. A camera onboard the Mars Reconnaissance Orbiter captured a swirling funnel of dust spinning up to an altitude of 20 kilometers.

    On Earth, tornadoes often reach such heights, but dust devils seldom reach more than a few hundred meters. That's because dust devils only draw their energy from the solar heating of the surface; tornadoes also tap the heat energy from the condensation of water vapor in a tornadic storm.

    Mars is too dry for that, but the thinness of its air allows dust devils to soar, lofting dust high into the atmosphere between major dust storms. Some Mars scientists suspect dust devils generate enough static electricity to produce bleachlike chemicals that consume any organic matter—and any living thing—in martian soil. And dust devils can also lend NASA a hand; they occasionally blow the dust off a rover's solar cells.

  2. Majorana Fermions Found

    Seventy-five years after Italian physicist Ettore Majorana proposed their existence, ephemeral particles now known as Majorana fermions have been spotted by researchers.

    Online this week in Science, Leo Kouwenhoven and colleagues at Delft University of Technology and Eindhoven University of Technology in the Netherlands report that they spotted expected signatures of Majorana fermions in specially designed transistors. In standard transistors, applying a voltage to an electrode called a gate turns on the flow of current between two other electrodes. Previous theoretical predictions suggested that if one of the secondary electrodes was a superconductor, and the current was allowed to flow through a special semiconductor nanowire under a magnetic field, the combination would force electrons in the nanowire to behave collectively as if Majorana fermions were present at opposite ends of the wire. That’s exactly what Kouwenhoven’s team found

    The old-yet-new particles are expected to have properties that make them ideal for constructing a quantum computer (Science, 8 April 2011, p. 193). When you move two Majorana fermions with respect to one another, they essentially “remember” their former position, a property that could be used to encode data at the quantum level. Kouwenhoven’s group hasn’t spotted that signature yet, but they’re on the hunt now.