Science briefs: How a bombardier beetle explodes

The bombardier beetle is famous for producing a hot, lethal toxin expelled forcefully through a channel near its abdomen. Now, using a technique known as synchrotron X-ray imaging, researchers have witnessed exactly what happens inside the beetle's body when the explosion occurs.

"The beetle has a really complicated explosion system that's all connected together," said Christine Ortiz, a materials scientist at MIT and an author of the new report in the journal Science.

The beetle has two chambered glands in which the explosive chemicals are produced. When a predator approaches or the beetle becomes alarmed, a valve opens, and a single drop of the chemical falls from one chamber into the second, where it combines with a catalyst and sets off an explosion.

A flexible membrane closes off the valve while the spray is being released. After the explosion, the valve reopens, so another drop of the toxin can enter the explosion chamber.

The mechanism creates a pulsed spray of toxin, rather than a steady stream, which allows the explosion chamber to cool down between pulses, Ortiz said.

"It can be much hotter than a stream, and it can go much faster because it's a smaller amount of material," she said.

Ortiz and her colleagues are studying the beetle and other species to develop military armor inspired by biology. They have already developed a flexible, protective material based on an armored fish.

Mystery of sun's corona revealed?

One of the greatest mysteries of how stars behave has been right in our own back yard: the sun's corona.

Scientists have long wondered what heats this thin, ethereal shell of particles to roughly 300 times the temperature of the surface of the sun itself.

Now, after combining evidence from a sounding rocket and a black-hole-hunting telescope and computer modeling, researchers say they've found the cause: nanoflares.

"We have for the first time direct proof that nanoflares exist and heat the corona," said Jim Klimchuk, a solar scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "This proof takes the form of superhot plasma. It's a real breakthrough."

The findings may help solve the decades-old mystery of what powers the corona and help scientists better predict the effects of space weather on Earth. The scientists think these nanoflares are caused by the twisting and breaking of magnetic field lines around the sun, Klimchuk said, though it will be a while before they can probe exactly how the nanoflares work.

Tracking how nanoflares might contribute to the space weather that reaches Earth is very important, he added, because such solar radiation can disrupt terrestrial technology, including weapons guidance systems, navigation systems and anything that involves radio transmissions.

"We need to understand how these hot plasmas are created and produce these X-rays and UV radiation so we can better understand and prepare for their effects here on Earth," Klimchuk said.

News services