New York Times: In 1949 scientists at the Naval Research Laboratory in Washington, DC, determined that the Soviet Union had succeeded in testing its first atomic bomb. They did so by measuring the gamma radiation emitted by rainwater collected in a barrel on an NRL roof. According to a report by the National Research Council, the US is at risk of losing the specialized knowledge needed to perform such feats of nuclear forensics. The New York Times‘s William Broad reports that the US government has recognized the problem and is taking measures to address it.
Monthly Archives: July 2010
Physics helps father-daughter team prevail in soapbox derby
Rockford Register Star: Thanks to the application of some elementary physics, Mark Overmyer of Oregon, Illinois, enabled his daughter Laura (shown here) to triumph in the speed event of last week’s 73rd All-American Soap Box Derby in Akron, Ohio. For the past three years, Overmyer has been perfecting two soapbox innovations: a polyurethane and rubber compound for the wheels and prism glasses, which eliminate the need for the driver to poke her head up in a drag-inducing way to see where she’s going.
Ocean greenery under warming stress
Nature: Phytoplankton, the tiny photosynthesizing organisms that inhabit Earth’s oceans, provide half the planet’s oxygen and sequester 100 megatons a day of atmospheric carbon dioxide. Phytoplankton also make up the oceanic food chain’s first link. Monitoring the health of this vital population is essential but tricky because it fluctuates strongly on multiple scales of time and space. Now, as Nature‘s Quirin Schiermeier reports, a team led by Boris Worm of Dalhousie University in Halifax, Nova Scotia, has met that challenge by combining satellite imagery with data gathered over the past century from ocean-going ships. The team’s conclusion is alarming: The total biomass is steadily falling at a rate of 1% per year, possibly because seawater is becoming warmer and more acidic. The accompanying image, taken by NASA’s SeaWIFS orbiter, shows vast “rivers” of plankton (green) between two masses of seawater off the coasts of Argentina and the Falkland Islands.
Building better space robots
Science: Robots for future space exploration missions will need to be smarter: Researchers are working to program robots to circumvent danger, spot enticing features on their own, and perform experiments without human input. Besides achieving better results, greater autonomous behavior would make robots more efficient by improving their energy storage, speed, and heating and cooling capabilities, among other things. Toward that end, NASA has been designing software, which has been used on the Mars rover Opportunity, to seek out a single property of an object, such as finding the largest or the darkest rock. Paradoxically, however, the rover has to be told when to be autonomous and when not to.
Energy department funds center dedicated to artificial photosynthesis
Nature: Photovoltaic solar panels convert sunlight into electrical energy with efficiencies up to 20%. No photosynthesizing plant, alga, or bacterium can match that efficiency—sugar cane comes closest with 8. But the photosynthesizers have one big advantage over the photovoltaics: Chemical energy in the form of fuel is much easier to store and transport than electrical energy is. Recognizing that advantage, the US Department of Energy has just announced the foundation of the Joint Center for Artificial Photosynthesis. Led jointly by Caltech and Lawrence Berkeley National Laboratory, JCAP will receive $122 million over five years. Its aim, as Nature‘s Jeff Tollefson reports, will be to develop systems that convert sunlight directly to fuel.
Asteroid could hit Earth in September 2182
Daily Mail: It has been calculated that asteroid 1999 RQ36, which is more than 500 meters in diameter, has a 1-in-1000 chance of colliding with Earth by the year 2200, most likely on 24 September 2182. Although the asteroid’s current orbit is known, no one can predict its future path with absolute certainty because of the Yarkovsky effect, which arises when a rotating asteroid absorbs and re-radiates the Sun’s energy, thus altering the asteroid’s orbit. One solution to prevent the asteroid’s potentially devastating collision with Earth: Deflect the asteroid’s trajectory by detonating a nuclear warhead on its surface.
Undergraduates need better guidance on research projects
Chronicle of Higher Education: Alison Head and Michael Eisenberg of the University of Washington in Seattle have analyzed the written guidance that a wide sample of US undergraduates received from their professors when assigned research projects. In most cases, the handouts gave clear instructions on how the eventual research paper should appear, but lacked big-picture advice on how to conduct research. Another common feature of the research assignments, the Chronicle‘s Kelly Truong reports, was an adherence to the traditional single-author paper. The option for teams to submit multimedia studies was rarely offered.
Small satellites, big science
SPACE.com: Miniaturization is all the rage now in such devices as laptop computers and cell phones—and now satellites can be added to the list. Nanosatellites, some no bigger than a Klondike ice cream bar, can contain the same components as their full-size counterparts but cost less and create less space debris. And because of their small size, they don’t require a dedicated launch vehicle; they can piggyback on someone else’s rocket. Although nanosatellites cannot replace larger satellites for some experiments, they are proving invaluable in certain fields of study, such as astrobiology.
How smart aliens would try to contact us
Time: Science-fiction author and physicist Gregory Benford, his twin brother James, and James’s son Dominic have come up with a new proposal for detecting signals beamed into the galaxy by aliens who want to be discovered. According to the Benfords, aliens are most likely to send bursts of pulses now and again, rather than strong continuous beams, which consume far more energy. To find those pulses, the best strategy is to monitor several stars continuously, rather than slowly sweep the entire galaxy. Time‘s Michael Lemonick describes the proposal, which the Benfords wrote to mark the 50th anniversary of the SETI program.
Cosmologist optimizes the rigging of rowing boats
New Scientist: Cosmologist John Barrow of the University of Cambridge has been studying the physics of rowing, in particular, the best way to arrange the port and starboard rowers in racing boats. 
The conventional rig, in which the port and starboard rowers alternate, causes a slight but energy-wasting side-to-side wiggle as the rowers move up and down the hull on each stroke. In an analysis published in the American Journal of Physics, Barrow found all the rigs for four- and eight-person boats that eliminate the wiggle. Some of the rigs are already in use, but two of them were previously unknown. Earlier this week, the New Scientist tested Barrow’s rigs on London’s river Thames. Justin Mullins describes the results.