In a tropical Chinese rainforest, seven savannah-dwelling African rhinos are said to be awaiting release into the wild, raising fears for their welfare in a country with a booming rhino horn trade.

The animals arrived with a blaze of publicity in March at the vast Pu'er National Forest Park in the humid hills of Yunnan province in southwest China, with television images showing cranes lowering the huge beasts into paddocks.

Scientists on Friday called NASA's Opportunity rover gimpy and arthritic, but hailed its new discoveries about early water on Mars made almost 10 years after it was launched toward the Red Planet.

The unmanned solar-powered vehicle has just analyzed what may be its oldest rock ever, known as Esperance 6. It contains evidence that potentially life-supporting water once flowed in abundance, leaving clay minerals behind.

Russia's Valentina Tereshkova, the first woman to go to space, said on Friday she was ready to score another coup and fly to Mars, even if it would be just a one-way trip.

"Mars is my favorite planet," the 76-year old told a news conference in Zvyozdny Gorodok (Star City) outside Moscow, home to a cosmonaut training centre.

A "dust trap" surrounding a young star could help explain how planets are formed, astronomers with Chile's ALMA space observatory said on Thursday.

The findings provide insight into how dust particles in the disk around a young star grow in size so that, over time, they form comets and planets.

Palaeontologists on Wednesday said they had found the fossilised remains of a tiny tree-dwelling creature that lived around 55 million years ago, making it the oldest primate ever found.

The discovery will help chart the evolution of primates, a family that includes humans, and should strengthen a once-contested theory that primates originated in Asia, they said.

U.S. agriculture giant Monsanto, in the spotlight over unauthorized genetically modified wheat, said it has a new GM strain under development after an eight-year freeze.

The company is developing a new form of wheat impervious to its Roundup herbicide in a bid to improve yield, Monsanto chief technology officer Robb Fraley said in a conference call with reporters.

A record 6.6 tonnes of cargo were hurtling towards the International Space Station after being blasted into orbit by a European rocket from French Guiana.

The space freighter with food, water, oxygen, science experiments and special treats for the ISS astronauts was launched on an Ariane 5 rocket from Europe's spaceport in Kourou as planned at 6:52:11 pm (21:52:11 GMT).

Japanese whalers hunting the mammals in the northwestern Pacific caught a record-low 34 minke whales this Spring, the fisheries agency said Thursday, blaming bad weather.

The whaling, conducted in the name of "scientific research", took place from April 18 to June 3 and netted 17 male and 17 female minke. The catch is the lowest since Tokyo started the program in 2003, the agency said.

Less than three months after being battered by snow and ice, central Europe now finds itself fighting floods -- and some scientists are pointing the finger at human interference with the climate system.

Leading the charge is the Potsdam Institute for Climate Impact Research (PIK) near Berlin, which says a low-pressure system that dumped the rain was locked into place by a disturbance with a global wind pattern.

Leading marine scientists warned the Australian government on Wednesday of the growing threat to the Great Barrier Reef from unchecked industrial development.

More than 150 scientists from 33 institutions signed a statement saying that the mining and gas boom along the Queensland state coast was hastening the decline of the World Heritage area.