On the horizon
Bunchberry dogwoods - flowering shrubs with edible berries - are remarkable to more than the moose that eat them. Researchers have found that when the dogwood flowers eject pollen, they display the fastest movement yet recorded in a plant. When the petals part and the stamen flips upward, it accelerates at a rate that would leave a BMW eating dust.
A team of biologists and physicists from Williams College in Massachusetts and Oberlin College in Ohio used a high-speed camera to film the flowers as they let fly. For the first three milliseconds the flowers opened, the stamens accelerated at a blurring 24,000 meters per second. For all that hustle, they reach a top speed of only about 3 meters a second (six miles an hour). But that's enough to hurl the pollen to a height nearly 10 times that of the flower. The team describes its discovery in Thursday's edition of the journal Nature.
Robot, replicate thyself. Researchers at Cornell University claim to have built the first self-replicating robot. Replication is about all it does. But the array of computerized cubes illustrates the principles of self-replication, says Hod Lipson, a professor of mechanical and aerospace engineering at Cornell who led the team that designed the repli-bots.
Each "robot" is a small tower of computerized cubes linked by magnets. The magnets allow the cubes to link up with or detach themselves from one another. One stack of cubes puts its "head" on the table, then it picks up a new cube and sets it on this "seed." It repeats the process to build its sibling. Moreover, the new robot begins to assist the old in the building process.
With additional development, the team foresees robots on Mars or in hazardous environments that can fix themselves when one of their circuit modules fails.
"Although the machines we have created are still simple compared with biological self-reproduction, they demonstrate that mechanical self-reproduction is possible and not unique to biology," the team reports. It published its work in Thursday's edition of the journal Nature.
X-rays protect infant planets. That's the conclusion some astronomers are drawing after looking at young stars in the constellation Orion's famous nebula. Using the Chandra X-Ray Observatory, the team found 30 stars that appear to be much like the sun was when it was from 1 million to 10 million years old. Like cranky tots, these stars are prone to angry fits. They produce frequent, violent X-ray flares far larger and more energetic than anything the sun emits today. Roughly half the young stars also display evidence of disks of dust and gas that form the building blocks of planets.
Recent calculations by theorists suggest that these outbursts generate turbulence in the protoplanetary disks. These outbursts in effect can prompt rocky planets to form farther from the parent star than they might otherwise. The greater distance reduces the likelihood that the planet will orbit the star in an ever-tightening spiral until it vanishes into its sun. "Big x-ray flares could lead to planetary systems like ours, where Earth is a safe distance from the sun," notes Eric Feigelson, who heads the team making the observations. The work is set for publication in an upcoming edition of the Astrophysical Journal.
Planetary scientist Michael Malin, whose company built a camera orbiting on NASA's Mars Global Surveyor, says he has spotted what looks to be the wreckage site for the Mars Polar Lander. The spacecraft vanished in 1999 after entering the Martian atmosphere. The probe was tasked with studying weather on the planet and looking for signs of past climate change.
In a forthcoming issue of Sky and Telescope magazine, Dr. Malin describes the landing site near Mars' south pole and published photos that show what appears to be a parachute not far from what looks like an impact site. He hopes to get a clearer look when Mars Global Surveyor again orbits over the site.