SCIENCE
Notebook

Monday, April 2, 2007

Cloud Puzzles Saturn Watchers

The handiwork of giant alien bees? A cosmic bathroom floor tile? These are among the explanations not being considered by befuddled NASA scientists wondering why Saturn has an enormous six-sided cloud formation hovering above its gaseous north pole.

The weird, hexagonal feature, 15,000 miles across and unlike anything ever spotted in space, was first photographed by the twin Voyager spacecraft more than two decades ago. But scientists really started scratching their heads when the Cassini space probe recently aimed its infrared imager at Saturn and found that the slowly rotating cloud is still there.

"This is a very strange feature, lying in a precise geometrical fashion with six nearly equally straight sides," said Kevin Baines of NASA's Jet Propulsion Laboratory in Pasadena, Calif., noting the contrast with the familiar circular swirls seen on other planets and near Saturn's south pole.

NASA scientists seeking ideas need look no further than the countless Web sites devoted to conspiracy theories and paranormal phenomena, more than a few of which presume that NASA knows the answer -- and is covering it up.

"I can't wait to hear NASA explain this thing," one blogger wrote. "Isn't there some statement out there that straight lines in nature are impossible? Well, here are six."

Another hypothesized that the cloud "involves masonic black sun worship from all around the world. So whatever is happening here is possibly the energy fluctuations alien beings are toying with to influence our daily lives."

The military, at least, seems to have escaped blame this time: "Good thing it wasn't a pentagon," one contributor wrote on a conspiracy-theory-friendly Web site, "or there would be lot of freaked-out people."

-- Rick Weiss

Dust May Deter Hurricanes

The Sahara may have helped make last year's hurricane season a relatively tame one, according to a NASA study.

Several major dust storms over the African desert in June and July kicked up vast amounts of dust that then drifted westward over the Atlantic Ocean and blocked sunlight from reaching the surface, researchers found. That cooled ocean waters, which may have made it harder for hurricanes to develop.

By soaking up the sun's energy, the dust also warmed the atmosphere, contributing to an increase in surface winds. Researchers say that promoted evaporation and fostered greater ocean churning, pulling up colder waters. The waters cooled quickly in the two weeks after the largest of the dust storms.

The 2006 season saw five hurricanes and four tropical storms, compared with 15 hurricanes and 12 tropical storms in 2005.

"This research is the first to show that dust does have a major effect on seasonal hurricane activity," said William Lau, lead author and chief of the Laboratory for Atmospheres at NASA's Goddard Space Flight Center.

The study appeared in Eos, a publication of the American Geophysical Union.

-- Christopher Lee

'Buckyballs,' Bacteria Coexist

Bacteria appear not to be harmed when the soil they live in becomes contaminated with "buckyballs" -- microscopic spheres of carbon that are being manufactured in increasing quantities for a variety of applications.

Buckyballs are a kind of nanoparticle: atomic-scale constructs with novel properties that make them useful in electronic devices, fabrics, cosmetics and other products. Earlier studies had shown they can kill soil bacteria in laboratory dishes, raising concerns that their release could upset soil ecosystems.

Now researchers at Purdue University have performed the first tests of buckyball toxicity on bacteria in actual soil. Using a variety of measures of microbial health -- including bacterial respiration, enzyme activity and various chemical analyses -- they showed that buckyball concentrations of up to 1,000 micrograms per gram of soil had no discernible impact.

It may be that natural chemicals in soil buffer the toxic effects seen in the laboratory, researchers conclude in the April 15 issue of the journal Environmental Science & Technology.

Still, noting that different kinds of nanoparticles have very different toxicities, a number of organizations have recently called for beefed-up environmental risk studies. Last week, a government commission in Britain criticized that country's lagging effort to assess nanotechnology's potential hazards. And an international coalition of 336 trade unions in 120 countries in March called for a moratorium on nanotech products in food and agriculture.

A U.S. report in December also called for more research. And last month, members of Congress asked the Government Accountability Office to study whether enough U.S. nano research funding is going into safety studies.

-- Rick Weiss