Deep Impact Ready for Encore

For rent: used spacecraft, impeccable condition.

NASA is accepting proposals for a follow-on mission for the Deep Impact flyby spacecraft that took close-up pictures as comet Tempel 1 collided with an 820-pound "impactor" and obliterated it on July 4.

The spacecraft, which sent the impactor to its spectacular end, emerged unscathed from the encounter, and last week controllers ordered a rocket "burn" to put it into a slightly elliptical orbit about 140 million miles from the sun.

It is now 70 million to 90 million miles from Earth and looking for a new job, either in the asteroid belt or closer in, which is easier for tracking and communications, said Andrew Dantzler, director of NASA's solar system division in the Science Mission Directorate.

"All the instruments are working just fine, and there's a significant amount of fuel," Dantzler said in a phone interview. "We can do any burn we want to head it toward any target we want." It is on a trajectory to fly past Earth in December 2007.

The flyby spacecraft has both a "high-resolution imager" and a "medium-resolution imager," whose bona fides were spectacularly established during the Tempel 1 encounter. The high-resolution imager is the largest telescope ever sent into deep space, and Dantzler said the two telescopes together are capable of good work either close in or far away.

Because NASA is asking for proposals, Dantzler declined to discuss the merits of possible follow-on missions, but he suggested the spacecraft would be elegantly equipped to visit an asteroid or another comet: "We'll look at anything," he said.

-- Guy Gugliotta

Rare Turtle Saved by Microchip

In a first for wildlife conservation efforts, an implanted microchip has been used to identify a smuggled turtle and return it to the wild.

The animal, a rare "royal" turtle, was confiscated last week by Vietnamese officials in a 330-pound crate of turtles being smuggled from Cambodia to China. After border officials noticed the unusual appearance of the 35-year-old turtle, a researcher who happened to be on the scene with a special scanner determined that the turtle was "chipped." The information on the chip, which had been implanted as part of a study, traced it to the Sre Ambel region of Cambodia.

The 33-pound mangrove turtle was returned to Cambodian officials in a small ceremony last week in one of the first examples of "two governments working together to repatriate a rare turtle," said Douglas Hendrie of the New York-based Wildlife Conservation Society.

Mangrove turtles, once considered exclusive property of the Cambodian royal family, have become extremely rare in the last decade because of hunting and habitat loss. There are only two hatching females left in Cambodia, so "every turtle for this population counts," Hendrie said from his home in Hanoi.

There is a large illegal trade in Asian turtles for food and medicine, and some are prized by collectors. Rarer species can cost more than $1,500 apiece. Officials said they hope that the incident would be a step toward saving the turtles.

Microchips may not be the ultimate solution, however. Researchers use the chips as a more sophisticated alternative to plastic or metal tags because the chips cannot be removed "unless you do invasive surgery," Hendrie said. But they are not tracking devices, and the scanners carry a hefty price, which limits their availability.

-- Naseem Sowti

Arsenic Detected in King's Hair

Scientists have found high levels of arsenic in a lock of hair from King George III, which they say could explain the 18th-century British monarch's famous bouts of madness.

One of the longest-reigning British sovereigns, George ruled the empire from 1760 to 1820. During his time, Great Britain expanded its empire and defeated Napoleonic France. But George is perhaps best remembered for losing the American colonies and his well-documented episodes of insanity.

Many explanations have been put forth for the episodes, including the possibility that George suffered from a hereditary blood disorder called porphyria.

In the new research, Martin J. Warren of the University of Kent in Canterbury and his colleagues analyzed a sample of hair collected upon the king's death that has been on display at London's Science Museum.

The researchers found surprisingly high levels of arsenic -- 17 parts per million, suggesting he had ingested it, the researchers reported in the July 23 issue of the Lancet medical journal.

They speculated that the king could have repeatedly imbibed arsenic through tonics popular at the time that contained the substance. Arsenic could have triggered his attacks, especially if he had inherited the defect for porphyria, the researchers said.

"The presence of arsenic in a sample of the King's hair provides a plausible explanation for the length and severity of his attacks of illness," the researchers wrote. "We propose that exposure to arsenic would exacerbate attacks of porphyria in a genetically predisposed individual."

-- Rob Stein

Researchers celebrate the rescue of a royal turtle.