Scientists in Alaska said Tuesday they have figured out how to make squirrels hibernate, a process that could be used to preserve brain function in humans who suffer strokes or heart attacks.

But the technique only worked in squirrels who were awakened by researchers during their hibernation season, not outside normal hibernation times, said the study in The Journal of Neuroscience.

"Dirty Dozen" chemicals, including the notoriously toxic DDT, are being freed from Arctic sea ice and snow through global warming, a study published on Sunday suggested.

The "Dirty Dozen" -- formally known as persistent organic pollutants (POPs) -- were widely used as insecticides and pesticides before being outlawed in 2001.

Hong Kong physicists say they have proved that a single photon obeys Einstein's theory that nothing can travel faster than the speed of light -- demonstrating that outside science fiction, time travel is impossible.

The Hong Kong University of Science and Technology research team led by Du Shengwang said they had proved that a single photon, or unit of light, "obeys the traffic law of the universe".

A giant new Russian space telescope on Saturday unfurled its dish-like antenna which will observe radio waves from galaxies and black holes billions of light years away.

The operation to deploy the 10-meter-diameter antenna of the Spketr-R telescope, which was launched into orbit on Monday, was successfully carried out, space agency Roskosmos said in a statement.

The U.S. space agency's unmanned Curiosity rover will explore a mountain on Mars that should read like "a great novel," revealing if signs of life ever existed on the red planet, NASA said Friday.

The landing site for the 2.5 billion dollar Mars Science Laboratory (MSL) was unveiled the day after the 30-year shuttle era ended with the return to Earth of Atlantis after its final mission to the International Space Station.

China said Friday it had hooked its first so-called "fourth generation" nuclear reactor to the grid, a breakthrough that could eventually reduce its reliance on uranium imports

The experimental fast-neutron reactor is the result of more than 20 years of research and could also help minimize radioactive waste from nuclear energy, the state-run China Institute of Atomic Energy (CIAE) said.

The space shuttle passed into history Thursday, the words "wheels stop" crackling over the cockpit radio for the very last time.

In an almost anticlimactic end to the 30-year-old program, Atlantis and its four astronauts glided to a ghostly landing in near-darkness after one last visit to the International Space Station, completing the 135th and final shuttle flight.

Japanese bio engineers have succeeded in growing a tooth from cells implanted into a mouse kidney, using a technique that could create replacement organs faster than previously tested methods.

Biologists have previously cultivated teeth in a laboratory and successfully transplanted them into the jaws of mice, but Japanese researchers have hailed the latest development as offering much faster growth rates.

Nepal's government has ordered a new measurement of Mount Everest to determine exactly how high the world's highest mountain is, an official said Wednesday.

Nepal has continued to recognize the decades-old measurement of 29,028 feet (8,448 meters). However, there have been other claims recently by China and western climbers.

An expectant silence hangs over the Pukaha bird sanctuary as hundreds of spectators await a glimpse of a rare white kiwi, a bird held sacred by New Zealand's indigenous Maori people.

A collective sigh follows his unveiling to the crowd, although this appears to be prompted more by the chick's cute appearance than any mystical qualities.