Analysis of Mars rocks by the Curiosity rover uncovered the building blocks of life -- hydrogen, carbon and oxygen -- and evidence the planet could once have supported organisms, NASA said Tuesday.

"A fundamental question for this mission is whether Mars could have supported a habitable environment," Michael Meyer, lead scientist for NASA's Mars Exploration Program said. "From what we know now, the answer is yes."

Facing public outrage over smog-choked cities and filthy rivers, China's leaders are promising to clean up the country's neglected environment — a pledge that sets up a clash with political pressures to keep economic growth strong.

An array of possible initiatives discussed by officials and state media ahead of this week's meeting of China's legislature include tightening water standards and taxing carbon emissions. No change is expected at the National People's Congress, which will be dominated by the installation of a new Cabinet under Communist Party leaders who took power in November. But the meeting offers a platform to try to appease the public by discussing possible changes.

Russian officials on Tuesday proposed ideas ranging from planting beacon transmitters on asteroids to megaton-sized nuclear strikes to avert the threat from meteor collisions with the Earth.

Saving the world from asteroid strikes has moved out of the realm of science fiction in Russia into a political reality after a spectacular meteor explosion injured over 1,500 people in the Russian Urals in February.

Australian scientists on Tuesday hailed a breakthrough discovery in the hunt for a vaccine against a savage facial tumor disease threatening the endangered Tasmanian devil with extinction.

A research team headed by University of Tasmania immunologist Greg Woods has established how the disfiguring cancer, spread from devil to devil by biting during fights, manages to take hold and grow so rapidly.

The El Nino and La Nina climate patterns are unlikely to make an appearance during the first half of this year, the U.N.'s weather agency said Monday.

"Model forecasts and expert opinion suggests that the likelihood of El Nino or La Nina conditions developing during the first half of 2013 is low," the World Meteorological Organization (WMO) said in a statement.

The tsunami that ravaged northeast Japan in March 2011 created the biggest single dumping of rubbish, sweeping some five million tonnes of shattered buildings, cars, household goods and other rubble into the sea.

About three-and-a-half million tonnes, according to official Japanese estimates, sank immediately, leaving some 1.5 million tonnes of plastic, timber, fishing nets, shipping containers, industrial scrap and innumerable other objects to float deeper into the ocean.

Conservationists at a global wildlife conference on Monday voted to regulate the trade of shark species that have been threatened because their fins are used to make expensive delicacies in Asia.

Delegates at the triennial meeting in Bangkok of the Convention on International Trade in Endangered Species of Wild Fauna adopted the proposals to put the oceanic whitetip, hammerhead and porbeagle sharks on a list of species whose trade is closely controlled.

The colossal earthquake that sent a devastating tsunami barreling into Japan two years ago on Monday was so big it could be heard from space, a study has said.

A specially fitted satellite circling the Earth was able to detect the ultra-low frequency sound waves generated by the massive shift in the planet's crust, when the 9.0-magnitude quake struck.

Russian scientists on Saturday dismissed initial reports that they had found a wholly new type of bacteria in a mysterious subglacial lake in Antarctica.

Sergei Bulat of the genetics laboratory at the Saint Petersburg Institute of Nuclear Physics had said Thursday that samples obtained from the underground Lake Vostok in May 2012 contained a bacteria bearing no resemblance to existing types.

A rough, whitish block recovered from an Elizabethan shipwreck may be a sunstone, the fabled crystal believed by some to have helped Vikings and other medieval seafarers navigate the high seas, researchers say.

In a paper published earlier this week, a Franco-British group argued that the Alderney Crystal — a chunk of Icelandic calcite found amid a 16th century wreck at the bottom of the English Channel — worked as a kind of solar compass, allowing sailors to determine the position of the sun even when it was hidden by heavy cloud, masked by fog, or below the horizon.