A burst of radiation on the sun's surface may trigger a geomagnetic storm on Earth today that could disrupt satellite communications and the Global Positioning

System by mid-morning, scientists at the Space Weather Prediction Center said Monday.

The Mariana Trench in the western Pacific runs for about 2,500km and extends down to 10,994m.

This measurement for the deepest point - known as Challenger Deep - is arguably the most precise yet.

Russian engineers are fighting to save the country's latest mission to Mars.

The Phobos-Grunt probe launched successfully but then failed to fire the engine to put it on the correct path to the Red Planet. Russian space agency officials say the craft is currently stuck in an Earth orbit and that engineers have three days to correct the fault before the probe's batteries run out.

Pale-faced but smiling, the crew of a long-duration isolation study emerged bleary-eyed to daylight and applause Friday after 520 days locked away in windowless, cramped cells to simulate the length of a journey to Mars.

The $15 million Mars500 experiment aims to answer one of the big unknowns of deep-space travel: can people stay healthy and sane during six months rocketing to the Red Planet?

Docking may be a decades-old space technology in the eyes of veteran aerospace watchers and fans, but seeing how China is going to do it will be a new experience.

China has announced it will launch Shenzhou VIII Tuesday morning. The unmanned spacecraft is expected to practice China's first space docking with the orbiting space lab module Tiangong-1. The technology is crucial to build the nation's first space station.

The US has launched NPP, its $1.5bn (£0.9bn) next-generation weather and climate satellite.

NNP rode into its polar orbit on a Delta II rocket, lifting away from the Vandenberg, California, spaceport at 02:48 local time (09:48 GMT). The two-tonne satellite has some onerous tasks ahead of it.