Scientists have found evidence of a powerful earthquake 3,000 years ago in central China, apparently the earliest known tremor in the country's history, state media reported.

The earthquake, which hit an area now part of Henan province, was of magnitude 6.8 to 7.1, archaeologists told the state-run Xinhua news agency on Thursday.

NASA counted down Friday to its second try at test-launching the deep space Orion capsule on its first journey into orbit, after wind gusts and rocket problems delayed Thursday's attempt.

The unmanned four-hour flight aims to test crucial systems like the heat shield and parachute splashdown on a spacecraft that could one day transport humans to an asteroid, the Moon or Mars.

A union representing 15,000 Canadian government scientists said Wednesday their right to speak publicly about their work regardless of what they discover should be addressed in contract negotiations.

The scientists feel they are not allowed to speak freely to the media -- especially if findings contradict government positions -- because of rules requiring them to seek permission first, according to the Professional Institute of the Public Service of Canada.

A rare dinosaur skeleton goes on display at London's Natural History museum on Thursday -- the first to be exhibited there in a century.

The near-complete fossilized remains of a Stegosaurus, a plant-eating dinosaur, were bought by the museum in the United States last year.

Anthropologists on Wednesday said they had found the earliest engraving in human history on a fossilised mollusc shell some 500,000 years old, unearthed in colonial-era Indonesia.

The zigzag scratching, together with evidence that these shells were used as a tool, should prompt a rethink about the mysterious early human called Homo erectus, they said.

The Orion spacecraft, designed to carry humans farther in deep space than ever before, is poised to blast off Thursday in what NASA hailed as a first step in mankind's journey to Mars.

No astronauts will be on board the capsule when it launches aboard the United States' largest rocket, the Delta IV Heavy made by United Launch Alliance, but engineers will be keenly watching to see how it performs during the four-and-a-half hour flight.

Japan's panda population grew by two, a zoo announced Wednesday, with the birth of twin cubs Tuesday night.

The pair came into the world weighing less than 200 grams (7 ounces) each, a spokesman for Wakayama Adventure World in western Japan said.

Analysis of a meteorite that fell in the Moroccan desert three years ago revives theories about life on Mars, scientists said on Tuesday.

Scrutiny of cracks in the rock revealed "unique" carbon traces, according to a team led by the Federal Polytechnic School of Lausanne (EPFL) in Switzerland.

Environmental activist group Sea Shepherd on Wednesday left Australia on a campaign targeting illegal fishing in the wild Southern Ocean, having successfully seen off Japanese whalers after a decade of harassment.

The conservationists said with Japan's annual hunt on hold after an International Court of Justice ruling, it would focus its summer campaign on halting the fishing of rare Antarctic and Patagonian toothfish, vowing to "track down the criminal profiteers".

Like ailing giants, the tropical glaciers of the Andes Mountains are melting at worrying speed, raising scientists' fears that many will disappear before anything can be done to save them.

These icy castles, scattered across Ecuador, Bolivia, Colombia and Peru, are under a microscope at the United Nations climate talks this month in the Peruvian capital Lima, where 195 countries are trying to hammer out the framework of a global deal to cut the carbon emissions warming the planet.