The U.S. space shuttle Endeavour is making its final journey, at the less than rocket-propelled speed of two miles an hour, in a meticulously planned and stately trip through the streets of Los Angeles.

Some 400 trees have had to be cut down -- provoking initial protests from locals -- and power lines turned off to make way for the 78-ton vehicle on the two-day, 12-mile (19-kilometer) journey to the California Science Center.

At its prime, the space shuttle Endeavor cruised around the Earth at 17,500 mph, faster than a speeding bullet.

In retirement, it's crawling along at a sluggish 2 mph, a pace that rush-hour commuters can sympathize with.

Twinkling stars are not the only diamonds in the sky. Scientists reported Thursday the existence of a "diamond planet" twice the size of Earth and eight times its mass, zooming around a nearby star.

In fact, this is not the first diamond planet ever discovered, but it is the first found orbiting a sun-like star and whose chemical makeup has been specified.

A rock analyzed by NASA's Mars rover Curiosity has a surprising and more varied composition that resembles rare rocks from the bowels of our planet, the U.S. space agency said Thursday.

"This rock is a close match in chemical composition to an unusual but well-known type of igneous rock found in many volcanic provinces on Earth," Curiosity co-investigator Edward Stolper of the California Institute of Technology in Pasadena said in a statement.

The University of Nottingham says that Keith Campbell, a prominent biologist who worked on cloning Dolly the sheep, has died at 58.

University spokesman Tim Utton said Thursday that Campbell, who had worked on animal improvement and cloning since 1999, died last Friday. Utton did not specify the cause of death. Campbell had worked at the university until recently.

The ice goes on seemingly forever in a white pancake-flat landscape, stretching farther than ever before. And yet in this confounding region of the world, that spreading ice may be a cockeyed signal of man-made climate change, scientists say.

This is Antarctica, the polar opposite of the Arctic.

A 520-million-year-old, three-inch (7.6-centimeter) fossil has yielded evidence that complex brains evolved much earlier than previously thought, scientists said Wednesday.

The preserved external skeleton of Fuxianhuia protensa, an extinct type of arthropod, is the earliest known fossil to show a complex brain, according to a study published in the journal Nature.

Astronomers using a powerful Chile-based telescope on Wednesday released a rare image of a spiral shell of cosmic dust and gas surrounding a red giant star.

The discovery marks the first time that scientists have found such a structure and obtained full three-dimensional information about the spiral.

Americans Robert Lefkowitz and Brian Kobilka won the 2012 Nobel Prize in chemistry Wednesday for studies of proteins that let body cells respond to signals from the outside.

The Royal Swedish Academy of Sciences said the two researchers had made groundbreaking discoveries on an important family of receptors, known as G-protein-coupled receptors.

NASA says a small bright object detected on Mars is likely a piece of plastic from the Curiosity rover.

The six-wheel spacecraft captured an image of the puzzling object Monday after scooping up Martian sand and dust over the weekend.