Physicists said Tuesday that a so-called optical lattice clock, touted by some as the time-measuring device of the future, had passed a key accuracy test.

The performance boosts chances that the world's timekeepers will one day adopt it for defining the second, they said.

The next rover to Mars should hunt for signs of ancient life and gather rocks that a future mission could bring back to Earth for the first time, a team of scientists appointed by the U.S. space agency said Tuesday.

The scientists' new report outlines ambitious goals for a mission to Mars that NASA wants to launch in 2020.

Australia admitted Wednesday conditions at the Great Barrier Reef are "poor" as it battles UNESCO threats to downgrade its heritage status over concerns about pollution and development.

Environment Minister Mark Butler released a report card showing that the reef's health had slumped since 2009 due to cyclones and floods, despite progress on reducing agricultural runoff.

The world typically sees about 90 tropical cyclones a year, but that number could increase dramatically in the next century due to global warming, a U.S. scientist said Monday.

Rising greenhouse gas emissions could lead to a 10 to 40 percent increase in the frequency of tropical cyclones by the year 2100, said prominent climate scientist Kerry Emanuel of the Massachusetts Institute of Technology (MIT).

It took longer than expected, but NASA's Curiosity rover is finally heading toward a Martian mountain.

The nuclear-powered, six-wheel rover drove a total of 190 feet (58 meters) since July Fourth, leaving the spot where it spent the past seven months examining rocks and dirt.

A new study links heavy air pollution from coal burning to shorter lives in northern China. Researchers estimate that the half-billion people alive there in the 1990s will live an average of 5½ years less than their southern counterparts because they breathed dirtier air.

China itself made the comparison possible: for decades, a now-discontinued government policy provided free coal for heating, but only in the colder north. Researchers found significant differences in both particle pollution of the air and life expectancy in the two regions, and said the results could be used to extrapolate the effects of such pollution on lifespans elsewhere in the world.

The experimental Solar Impulse plane, powered by the sun, completed a transcontinental trip across the United States late Saturday, touching down in New York despite a rip in the fabric of one wing.

The giant, single-person plane landed at New York's John F Kennedy airport at 0311 GMT, ahead of its originally scheduled time due to a 2.5 meters (8 foot) long tear that appeared on the fabric of the lower side of the left wing.

Toxic radioactive substances have once again been detected in groundwater at the crippled Fukushima nuclear plant, its Japanese operator said on Sunday, the latest in a series of incidents at the tsunami-battered complex.

Tokyo Electric Power Co (TEPCO) said tests showed that tritium, a radioactive isotope of hydrogen used in glow-in-the-dark watches, was present at levels 10 times the permitted rate.

Home to meditating monks and Himalayan nomads, the sleepy kingdom of Bhutan has set its sights on becoming an unlikely energy powerhouse thanks to its abundant winding rivers.

Hydropower plants have already harnessed the country's water flows to light up nearly every Bhutanese home, generating electricity that is sent to remote villages by cables strung through rugged mountain terrain.

A female giant panda donated by China to Taiwan four years ago gave birth to a cub on Saturday after being artificially inseminated, the Taipei city government said.

Yuan Yuan and her partner Tuan Tuan have become star attractions in Taipei Zoo in the island's capital since their arrival from China in late 2008 amid improving ties between the two sides.