Three icebreaking ships were Thursday hurrying to reach a Russian vessel carrying 74 people on a scientific expedition which is trapped by ice off Antarctica, with Australian authorities coordinating the rescue mission.

The Australian Maritime Safety Authority (AMSA) said the MV Akademik Shokalskiy sent a distress message on Wednesday to say it was stuck about 100 nautical miles east of the French base Dumont D'Urville.

Space station astronauts repaired a crippled cooling system during a rare Christmas Eve spacewalk Tuesday, braving a "mini blizzard" of noxious ammonia as they popped in a new pump.

It was the second spacewalk in four days for U.S. astronauts Rick Mastracchio and Michael Hopkins, and only the second Christmas Eve spacewalk ever.

His code breaking prowess helped the Allies outfox the Nazis, his theories laid the foundation for the computer age, and his work on artificial intelligence still informs the debate over whether machines can think.

But Alan Turing was gay, and 1950s Britain punished the mathematician's sexuality with a criminal conviction, intrusive surveillance and hormone treatment meant to extinguish his sex drive.

A NASA spacecraft has sent holiday greetings from the outer solar system.

The space agency on Monday released dazzling new images of the ringed planet Saturn and its moons. The Cassini spacecraft took the pictures earlier this year.

A cave discovered near the source of Indonesia's massive earthquake-spawned tsunami contains the footprints of past gigantic waves dating up to 7,500 years ago, a rare natural record that suggests the next disaster could be centuries away — or perhaps only decades.

The findings provide the longest and most detailed timeline for tsunamis that have occurred off the far western tip of Sumatra island in Aceh province. That's where 100-foot (30-meter) waves triggered by a magnitude-9.1 earthquake on Dec. 26, 2004, killed 230,000 people in several countries, more than half of them in Indonesia.

Two American astronauts prepared to step out Tuesday on a rare Christmas Eve spacewalk to wrap up repairs to the cooling system at the International Space Station, NASA said.

The spacewalk is set to begin at 7:10 am (1210 GMT), marking the second outing to replace an ammonia pump module whose internal control valve failed December 11.

Another Chinese city has capped the total number of car licence plates it will issue annually, state media said Sunday, following moves by Beijing and other metropolises to curb pollution and congestion.

The world's most populous nation is also the world's largest car-buyer. But it is trying to curb poor air quality and other environmental damages caused by rapid development.

A vast store of water equivalent in area to Ireland lies beneath Greenland's icesheet, and it may provide answers to one of the big riddles of climate change, scientists reported on Sunday.

In 2011, U.S. scientists crossed the southern Greenland icesheet on an expedition to drill ice cores, a benchmark of annual snowfall.

A Chinese rocket launched Bolivia's first telecommunications satellite early Saturday with the president of the South American country declaring it a success.

The Long March-3B carrier rocket blasted off from the Xichang satellite launch center in China's southwestern Sichuan province at 00:42 am (1640 GMT Friday), television images showed.

Two U.S. astronauts on Saturday stepped outside the International Space Station for the first of three spacewalks to fix a broken equipment cooling system, NASA said.

"Today's spacewalk has officially begun," said a NASA commentator as the space agency broadcast live images of Japanese astronaut Koichi Wakata leading the operation from inside the space station.